ORTHODONTICS

1. The time required to upright a molar can vary from: 2. The time required to stabilize the molar can vary from: 2-3 weeks l-2 months 2-6 months 6-12 months 2-3 years

6-12 months 2-6 months *** A severely tipped molar or one that requires mesial movemmt to shorten the pontic space requires a longer treatment time. A fixed edgewise orthodontic appliance is usually used for molar uprighting. The bracket slot size of0.022 inch allows a wide mnge of wire sizes to be used. The altemate slot size is 0.018 inch, which can also upright the molar, but limits the wire sizes available. The tipped second molar should be banded because ofthe con- siderable posterior masticatory forces produced can easily shear offbonded brackets. Facts about molar uprighting: . . A severely lingually tipped mandibular molar is more difficult to control and upright proP€rly. Molar uprighting treatment in high angl€s cases will tend to result in excessive bite opening (increases vertic a I d imens i on of occ lusion). . stebilization should lasi until the lamin{ durr and PDL reorganize. This ranges ftom approximately 2 months . (simple uprightind to 6 monrhs (uprighting plus osseous s rgery, grafts, etc.). Retention (slabilization) can be provided by an appliance or by a well-fitting provisional restoration, which will stabilize the tooth positions. This will allow for reorganization ofthe PDL. \ote: Slow progess in molar uprighting in an adult patient is most likely due to occlusal int€rf€rences. When an orthodontic forc€ is applied lo a tooth, t\do scena os can develop depending on whether the force is heavy or light: . . Heavy force: - lniti^l peiiod (from secoruls to weeks)t causes n?crosis.) and "undermining " hyalinization" (blood supplv is lost and results in resorptionn(osleoclasts atlackthe lanina dura lamina dura). When this occun an inevitable delay in tooth movement occurs. -Secondary period oftooth movement fdfer ftom the underside ofthe lhe above happens)t lhe PDL heals and there is second- ary tooth movement. Note: It is best to Nvoid excessive orthodontic force. Light force: the use ofliglt forces causes smooth continuous tooth movement without formation ofa sig_ nificamly hyalinized zone in the PDL. Osteoclasts attack the adjacent lamina dura, removing bone in the process of"fiontal resorption" which begins tooth movement. As a result teeth start to move earlier and in a more physiologic way than do teeth subjected to hea\y forces. Important: For a tooth to move, osteoclastic cells must be formed, which will remove bone from the area ad- jacent to compression ofthe PDL. Osteoblasts also must form newbone on the tension side, but the timing of osteoclestiq not osteoblaslic, activify is critical.

The existence of a forward shift of the mandible during closure to avoid incisor interference is found in "True" Class III malocclusions "Pseudo" Class III malocclusions "Sunday bite" All ofthe above

"Pseudo" Class III malocclusions Mesio-occlusion 1Class Clinically. there are two types of mesio-occlusion. The first t,?e is considered to be a positional form, as a result of a mesial displacement ofthe mandible into an anterior position and has been named in a different ways (pseudo, functional or apparent).The other form of mesio-occlusion is a truc skeletal Class lIL Thc characteristics ofthis malocclusion result from a combination ofskclelal and dentoalveolar features. \ote: In order to ayoid the interference of teeth, a patient Inay adopt a jaw position on closure, \r hich is forward to normal. This may look like a Class III position in the absence ofa true skele- tal Class lll relationship. Hence termed 'pseudo Class lll malocclusion." In most cases they have an edge-to-edge bitc. Mandibular incisors are forward of maxillary incisors in centric occlusion bul the patient can bring the mandible back without strain so that the mandibular inciso$ touch the maxillary incisors. T}le benefits attributed to the treatment ofpseudo-Class lll malocclusion in the mixed dentition are: . Preventing unfavorable growth ofskeletal components (infact, early treatment ofanterior crossbite can help lo ninimize adaptations that ate often seen in seyere late adolescent maloc- ch6iotl) . Preventing functional posterior crossbite and habits, such as bruxism that can develop from an- tenor or posterior interferences . Gaining space for eruption ofcanines (lack of space could be catsed by retro-inclination of upper incisors . frequentlyfound in pseudo or Class III malocclusion) Avoiding the risk ofperiodontal problems to mandibular incisors caused by the traumatic occlusion due to the crossbite. \ote: The "Sunday bite" is a term given to the forward postural position ofthe mandible which is adopted by people with Class II profiles in an effort to improve their esthetics.

All ofthe following statements regarding the effect ofenvironmental influences during growth and development ofthe face, jaws and teeth are true EXCEPT one Patients who have excessive overbite or anterior open bite usually have posterior teeth that are infra- or supra-erupted respectively . A non-nutritive sucking habit leads to malocclusion only if it continues during the mixed dentition stage Negative pressure created within the mouth during sucking is not considered a cause of constriction of the maxillary arch "Tongue thrust swallowing" leads to an open bite "Adenoids" which lead to mouth breathing, cannot be indicted with certainty as an etiologic agent ofa long-face pattem ofmalocclusion because studies show that the maj- ority ofthe long-face population have no nasal obstruction

"Tongue thrust swallowing" leads to an open bite Recent studies indicate that "tongue tbrust swallowing" can not be blamed for an open bite as it was shown that there is no tongue-force on the teeth during swallowing even though the tip ofthe tongue is placed forward. The tendency to place the tongue forward between the teeth (in cases ofanterior open bite) appears to originate from the need to attain an oral seal during swallowing. So, the for- ward position ofthe tongue during swallowing is due to the arterior open bite, the re- tongue thrust swallow therefore should be considered the result ofdisplaced incisors, not the cause." verse is not true r** -"A 1. A sucking habit that is stopped prior to mixed dentition has not been shown to lead to malocclusion. 2. The negative pressure created within the mouth during sucking is not what causes the maxillary constriction. It is the force from the buccinator muscles that does.

Prior to direct bonding, ? is used as an etching agent. Prior to placing bands, ? is used as an etching agent. Nothing; 35-50% unbuffered phosphoric acid 35-50% unbuffered phosphoric acid; nothing Nothing l0-l5% unbuffered phosphoric acid 10-15% unbuffered phosphoric acid; nothing

35-50% unbuffered phosphoric acid; nothing When placing bands, eitherglass ionomerorzinc phosphate cements are used and do not require etching. The tooth surface must not be contaminated with saliva, which promotes immediate remineralization, until bonding is completed; otherwise re-etching is required. Topicalfluoride should not be used before etching because fluoride decreases the solubility ofenamel. Remember: After etching, the tooth surface should have a frosted appearance. Note: 37% phosphoric acid is the most commonly used etching agcnt. lndications for using bands instead ofbonded brackets: . . To provide better anchorage for greaier tooth movement For teeth that will need both lingual and labial attachment . Teeth with short clinical crowns . Tooth surfaces that are incompatible with successful bonding Cementation ofbands: Glass ionomer cements (resin or non-resin based) because oftheir fluoride releasing prcperties and retentive strenglbs are fast replacing Zinc phosphate cement. The cold slab is used for mixing regardless olwhich ofthe two cements is used ("liozen slab technique amount ofpowder into th€ cement liquid and thus produces a stronger cement. '). This allows the addition ofa greater Important: Anchorage is the word used in ofihodontics to mean resistance to displacement. The age vafue" ofany tooth is roughly equivalent to its root surface area ame t area). Dilferent anchorage situations include: . fu'hich " anchor- is the same os its periodontal lig- Reciprocal tooth movem€nt: is produced when two teeth or resistance units of equal size are moved against each other and move the same amount toward or away iiom each other. . Reinforced anchorage: is accompl ished by adding additional teeth to the unit to di stribute the force over a larger rcot surface ar€a in the anchorage unit. Not€: Another method for reinforcing anchonge would be to add an exffaoml force such as headgear or interarch elastics, . Stationary anchorage: displacement ofanchor teeth can b€ minimized by ananging the force system so rhat anchorteeth must movebodily (translation) ifat all, wbile movement teeth are allowed to tip. This ap- anchorage." . proach is called "stationary Corticrl anchoruge: anchor teeth roots are moved into cortical bone whichresorbs more slowly than does medullary bone. This situation may be encountered at an old extraction site, it can be almost impossible to close such an extraction site, because tooth movement is slowed to a minimum as the roots encounter cortical bone along the resorbed alveolar ridge. . Implants for rochorrg€: implanls can serve as anchorage for holding or moving teerh. The implant r/drle/ \r'ill not move because it has no PDL.

Angle class I represents what % of the population? Angle class II represents what % of the population? Angle class III represents the remainder 40;55 50;45 60;35 70;25

70;25 Classification of Human Occlusion (Angleb): . Cfass I: most common (about 70 o% of the populatior). The triangular ridge ofthe mesiobuccal cusp ofthe maxillary first molar articulates with the buccal groove ofthe mandibular first molar. The maxillary central incisors overlap the mandibulars. Maxil- lary canine lies between the mandibular canine and first premolar. Class I is associated rvith an orthognathic (straigh) facial profrle where the nose, lips, and chin are harmo- niously related. It is most commonly caused by a discrepancy between tooth structure and the amount ofsupporting bone length. . Class II: less common (about 25 %r'). The mesiol:uccal cusp of the maxillary first molar falls approximately b€tween the mandibular first molar and the second premo- lar (the buccal groove of the mandibular mesiobucctl cusp of the maillary first molar articulates posteriorly to the Jirst molar). The lowerjaw and chin may also ap- pear small and withdrawn. The mandibular incisors occlude even more posterior to the maxillary incisors so they may not touch at all. Maxillary canine is mesial lo mandibular canine. Class ll is associated with a retrognathic (convex) facial profile. . Class III: the least common than 5 Zo). The mesiobuccal cusp ofthe maxillary first molar falls approximately between the mandibular first molar and second molar. (the (less buccal groove ofthe mandibularfrst molar articulotes qnteiorly to the mesiobuccal cusp ofthe marillaryfrst molar) The chin may also protrude like a bulldog's does. The mandibular incisors overlap anterior to the ma"\illary incisors. The maxillary canine is distal to mandibular canine. Class III is associated with a prognathtc (concave) facial profile. Note: The nasolabial angle is the angle between the base of the nose and the upper lip, it should be perpendicular or slightly obtuse.

What % of 6 year old children have a median (maxillary) diastema? 78% 98% 49% Less than 25%

98% *** It is prevalent in 49% of l1-year-old children. The cause ofa median diastema could be anv ofthe followins: . . A tooth-size discrepancy A mesiodens . An abnormal frenum attachment . A normal stage ofdevelopment The spaces tend to close as the permanent canines erupt. The greater the amount ofspacing, the less the like- Iihood that a maxillary central diastema will totally close on its own. As a general guideline, a maxillary cen- tral diastema of 2 mm or less will probably close spontaneously, while total closure of a diastema initially g€arer than 2 mm is unlikely. Note: lfthe space is 2 mm or less and the maxillary laterals are in a tion, it is most likely the result ofa normal developmental proccss. Ifit is caused by an rbnormal frenum, it is best to align the teeth orthodontically and then do a frenectomy. Usually this is not done until the permanenl caoines erupt. Accepted methods ofclosing a diastema: . Using a lingual arch with finger springs . I . srnr a Halrley appliance with finger springs Using cemcntcd orthodontic bands with inter-tooth traction \ote: Space closure is least likely to occur following early loss ofa primary maxillary central incisor. \oL3, _ ' 1. In rhe United States, clefting ofthe lip and/or palate occurs in I of 700 - I,000 bifihs, making i! the most common craniofacial birth defect. 2. The lip and primarJ- palat€ begin to develop at four to five w€eks gestational age. The two me- '-' dial nasal swellings and the maxillary s$'ellings fuse io form the upper lip. Failure ofthis fusion rcsults in clcft lip. Clefts ofthe lip are more frequent in malcs. Cleft lip involvement is more frequent on the left side than the right. 3.The secondary palate develops at approximately nine weeks dev€lopmental age. Tle paired palatal shelves arise from the iDtraoral maxillary processes. good posi- These shelves, originally in a vertical position, reorientto a horizontal position as the tongue assumes a more inferior position. Thc palatal shelvcs fuse with one another andwith the primarypalate anteriorlt which, in tum arises from the fusion ofmaxillary and mandibular processes. Failure of fusion results in a cleft palatc. Clcft palate is more frequent in females.

Treatment of the ectopic eruption of a permanent maxillary 1st molar consists of Disking the distal of the primary first molar . An appliance incorporating a finger spring to move the primary second molar mesially . A brass wire placed between the primary second molar and permanent first molar . Extraction ofthe Drimarv second molar

A brass wire placed between the primary second molar and permanent first molar . This separating device (brass wire) will cause the permanent first molar to be tipped distally. Ectopic eruption occurs when a tooth erupts in the wrong place. It is most likely to occur in the eruption of maxillary first molars and mandibular incisors. Its occurrence is much more common in the ma"rilla and is often associated with a developing skeletal Class II pattern. It is seen in about 2-6Yo of the population and spontaneously corrects itself in about 60olo ofcases. Ifthe eruption path ofthe maxillary lirst molar carries far too mesially at an early stage, the permanent molar is unable to erupl and the root of the primary molar may be damaged. The mesial position of the permanent molar means that the arch will be crorvded unless the child receives treatment. Remember: This mesially inclined position ofthe permanent molar makes it susceptible to decay. If it shows signs ofcaries, extract the adjacent primary second molar immediately. The resultant space can then be maintained as part of orthodontic treatment. Ectopic eruption of mandibular lateral incisors, which occurs more frequently than mandibular first molars, may lead to transposition ofthe lateral incisor and canine. A poor eruption direction of the canine, sometimes leading to impaction, is observed often but usually is due to the eruption path being altered by a lack ofspace.

What is needed so that soft tissues are clearly visible on a lateral cephalometric radiograph? Adjustment in kilovoltage Adjustment in milliamperage A soft tissue shield A hard tissue shield Nothing must be done to make soft tissues visible

A soft tissue shield The lateral head radiograph (cephalometric x-ray) must be compared with the "nor- mal" lateral radiographs form an accepted norm. Linear and angular measurements are obtained utilizing known anatomical landmarks in the lateral head radiography ofthe pa- tient. These measurements are then compared with those considered within normal lim- its and in that way enable the orthodontist to assess aberration in the dentition and structures, which result in malocclusion. Aaalysis ofcephalometric radiographs is not limited to the hard structures such as bone and teeth, but also includes measurements of soft tissue structures such as the nose, lips and soft tissue chin. Superimposition in longitudinal cephalometric studies is generally on a reference plane and a registration point. This will best demonstrate the groMh ofstructures furthest from the plane and the point. The most stable area from which to evaluate craniofacial growth is the anterior cranial base because ofits early cessation ofgrowth. Cephalometrics is useful in assessing tooth-to-tooth, bone-to-bone and tooth-to-bone relationships. Serial cephalometric films can show the amount and direction of gro{th. ),Iote: A lateral cephalograph usually shows magnification with up to 7-8olo magnification considered acceptable. The resuldng double shadows are traced and the average is used for measurements. Cephalometric studies show that, on the average: . . *** The maxilla, during growth, is translated in a downward and forward direction llandibular growth stops after maxillary gowth

In predicting the time of the pubertal growth spurt while treating jaw mal-relationships in a growing child, the orthodontist can get the most valuable information from: A wrist-hand radiogaph Height-weight tables Presence ofsecondary sex characteristics Stage of dental development

A wrist-hand radiogaph The physiologic age or developmental age can be judged by finding out the skeletal devel- opment. The wrist-hand radiograph offers the best aid for this purpose. By looking at the os- sification and development ofthe carpal bones ofthe wrist, the metacarpals ofthe hands and the phalanges ofthe finge$ the orthodontist can have an idea about the cbronology ofskele- tal development. Comparing the overall pattem observed in the hand-wrist radiograph, with age standards in a reference atlas, does this. Important: Dental age refers to the state of dental maturation. Rememb€r: The ulnar sesamoid or hamate bones are considered as landmarks to obtain an estimate ofthe timing ofthe adolescent growth spurl Wrist-hand radiographs in the dental office can be obtained by using a standard cephalometric cassette and dental x-ray. The state ofphysical maturity or skeletal development co-relates well with the fthodontists use this information to predict how much jaw growth can be expected. Note: After sexual maturity much less growth is expected and therefore growth modification is not attempted. Remember: Hand-wrist radiographs are less useful in evaluating whether growth has stopped or is continuing (patient's position on growth curve). Seial Cephalometric radiographs are used for this pupose.

What cephalometric analysis measurement is characteristic of class 1 malocclusion SNA angle of> 84degrees SNB angle of< 78degrees ANB angle of < 4degrees None ofthe above

ANB angle of < 4degrees Remernber: An SNA Algle of> 84' indicates maxillary prognathism, An SNB angle 78' indicates mandibular retrognathism and an ANB angle of < 4' indicates a har- monious skeletal profile. Note: The ANB angle describes the relation of the maxillary and mandibular denture bases. Severe mdocclusion may compromise all aspects oforal function. There may be difficulty in masticating ifonly a few teeth meet, andjaw discrepancies may force adaptive alter- ations in swallowing. It can be difEcult or impossible to produce certain sounds in the presence of severe malocclusion, and speech therapy may require some preliminary or- thodontic treatment. Referral to a speech therapist is helpful because both patient and parents are likely to benefit from the counseling. Even less severe malocclusions tend to affect mastication, swallowing and speech; not so much by making the function impossible as by requiring physiologic compensation for the anatomic deformity.

The rationale for retention in orthodontics (accomplished with fixed or removable retainers) is to: Allow for reorganization ofthe gingival and periodontal tissues Minimize changes due to growth Maintain teeth in unstable conditions All of the above

All of the above Maintainins the treatment result followins orthodontic treatment is one of the most difficult aspects ofthe entire treatment process. Retention is necessary in orthodontics for the following reasons: l. The gingival and periodontal tissues are affected by orthodontic tooth movement and require time for reorganization when the appliances are removed. 2. Changes produced by growth may alter the orthodontic treatment result. 3. The teeth may be in an inherently unstable position after the treatment, so that the soft tissue pressures constantly produce a tendency for relapse. In the last situation, gradual withdrawal ofan orthodontic appliance is ofno value. The only possibilities are accepting relapse or using permanent retention. Fortunately, only the first two reasons apply to most orthodontic patients, and maintaining the position of the teeth until remodeling ofthe supporting tissues is completed and growth has essentially ceased allows a stable orthodontic result without further retention. Note: Retention is accomplished with either fixed or removable retainers. Remember: . The corection ofan anterior crossbite is easily retained after orthodontic correction by the overbite achieved during treatment. . Supracrestal fibers are commonly associated with relapse following orthodontic rotation ofteeth. l. Significant reorganization ofthe PDL occurs in 3 to 4 months, and full-time retention is critical during this time. 2. Part-time retention is recommended up to a year and often longer

Which of the following is false concerning mixed dentition analysis It is used to predict the amount of crowding after the permanent teeth erupt It determines space available vs. space required The analysis is based on a correlation of tooth size It is performed during the mixed dentition It is performed with a boley gauge, study models and a prediction table Analysis is done for each quadrant

Analysis is done for each quadrant *** This is false; analysis is done for each arch. Procedure for rnixed dentition analysis: L \4easure the mesial-distal diameter ofthe mandibular incisors and add them together 2. Veasure the space available for the rrandibular incisors 3. Subract # I from #2 *** -1. A negative number indicates crowding in the incisor region \leasure the space available lor the canine and premolars on each side ofthe arch 5. Calculate ftom the prediction table the size olthe canine and premolars 6. Subtract #5 from #4 on each side """ *** *** Once again, a negative number indicates crowding At this point, there will be 3 numbers: . . . The number for incisor crowding or excess space The number for the right canine and premolar crowding or excess space The number for the left canine and premolar crowding or excess space Add the three numbers: . . A negative number = crowding A positive number = space Note: For the maxillary arch, use the mandibular incisors to predict the size ofthe max- illary canines and premolars. Follow the same steps as described for mandibular teeth.

Once bone is formed it grows by Interstitial growth only Appositional growth only Both appositional and interstitial growth Degenerative changes into bony structures

Appositional growth only Which is grorvth by the addition ofnew layers on those previously formed. Bone formation begins in the embryo whete mesenchymal cells differentiatc into either fibrous membrane or cartilage. This leads to two paths ofbone development: 1. Intramembranous ossification is so called becausc it takcs place in mcmbranes of connec- tive tissue. Osteoprogenitor cells in the membrane differentiate into osteoblasts: a collagen ma- trix is lbrmed which undergoes ossification. \ote: The maxilla and mandible as well as the cranial vault are lbrmed lhis way :. Endochondral ossification is how the remainder ofthe skeleton fornrs and takes place within a hvaline cartilage modef. Cartilage cells are replaccd by bone cells (osleocytes rcplace choh- drocr 1es;. organic matrix is laid down and calcium and phosphate are deposited. This type ofos- sification is principally rcsponsible for the formation ofshort and long bones. Note: The cthmoid, sphenoid and occipitalbones lbones of the cranial base) form this way. L The growth ofthe cranial vault occurs almost entirely in response to growth ofthe \otcs brain. Remember: The bones ofthc cranial base are not affccted to a great degree by .-.,,.._, growth ofthebruilr' lsince thqt are endochondral bones). 2. Growth ofthe cnnial base is primarily the result ofendochondral rcplac€ment at the synchondroses, which have independent growth potential. 3. The greatest period ofcranial growth occurs between birth and 5 years ofagc. 4. ln fetal life growth and bony , at about the third month, the head takes up almost 50% ofthe total body length. At birth, the head is 30% ofthe body. In the adult, the head repres€nts about part ofthe normal growth pattem, retlect the l2% ofthe total body lenglh -all ofthese changes, which are "cephalocaudal gradient of gro\ryth." 5. In determining a patient's skeletal growth pattem, the most important factor is hered- itv. 6. Remodcling ofbone occu.s on both endosteal and periosteal surlbces. 7. Remodeling ofbone rcsults in the histologic structurcs called osteo[s. 8. Deposition and resorption may not occur in cqual amounts.

Headgear applicance is used for Anchorage Traction Both anchorage and traction Neither anchorage or traction

Both anchorage and traction Anchorage is used to maintain space. Tmction is used to create space. Headgear is used to modiry growah ofthe maxtlla, to dislalize (retracl, or protract maxillary teeth, or to reinforce anchorage. Headgear is an orthopedic appliance that allows orthodontists to: . . . Control growth of facial structures Use various designs (cervical pull, straighl pull, high pull, awl reverse pull) Use with gowing patients Headgear components: . . . Force applied to first molars that are banded via a facebow with a headcap or a neckstrap for anchorage Facebow: Outer bow dillerent lenglhs lnner bow sized, connects to the maxillary molars Headstraps: Cervical and high pull Optim!l usage of headgear: . wom rcgularly lor 10-12 hours per day, minimum is 8 hours per day . Normally, orthodontists suggest l4 hours/day . . Crow,th hormone released in lhe early evening Ideal to place headgear aftcr dinner not before bedtime llagnitude oI Force: . . . Ideal amount offorce for onlropedic changes is 250450 gm per side Ideal amount offorce for teeth movement is 100-200 gm per side \losl mo\emenr lhrough intermrnent forces . Ilyalinized bone around molars . \lobilit-Y ofmolars is normal \ote: One ofthe greatest advantages ofusing extraoral anchomge mo\ement ofteetb in one arch without adversely disturbing the opposile arch. *** fl.e., headgear) is that it permits posterior

A post orthodontic circumferential supracrestal fibrotomy is performed to sever collagen fibers thus reducing the tendency of a rotated tooth to collapse. The first statement is true; the second statement is false The first statement is false; the second statement is true Both statements are true Both statements are false

Both statements are true One of the most importart aspects of orthodontic therapy is retention. After malposed teeth have been moved into the desired position, they must be mechanically supported until the hard and soft tissues have been thoroughly modified function -to -both in structure and in meet the demands of the new position. Once the desired occlusal results are achieved and the hard tissues are in normal function, the next step is to maintain or to modify the soft tissues in the retention phase. Important: Most clinicians believe that the collagen fibers in the supra-alveolar tissue are signifrcantly responsible for the re- lapse oforthodontically rotated teeth as well as the redevelopment ofspaces between orthodontically moved teeth. Remember: Collagen fibers are the primary components ofthe attached gingiva. When teeth are orthodontically moved, the fibers stretch like rubber bands to adjust to the new position. However, like rubber bands, they have a strong tendency to retum to their former position, pulling teeth with them as they go. The circumferential supracrestal fibrotomy is a minor surgical procedure. A simple incision in the sulcus is made to the crest of the bone. This incises all of the collagen fibers that are inserted into the root ofthe tooth. By cutting the collagen fibers, two things are accomplished: 1. Eliminate the polential for relapse due to collagen fiber retraction. 2. Allow new fibers to form that will help retain the tooth in its new position. \ote: Post-orthodontic circumferential supracrestal fibrotomy is most often performed on a rotated maxillarv lateral incisor.

Orthodontic forces can be treated maathematically as vectors Forces either produce translation (bodily movements) rotation or a combination of the two depending on the relationship of the line of action of the force to the center of resistance of the tooth The first statement is true; the second statement is false The first statement is false; the second statement is true Both statements are true Both statements are false

Both statements are true Orthodontic forces can be treated mathematically as vectors. When mor€ than one force is applied to a tooth, the forces can be combined !o determine a single overall resultant. Forces can also be divided into components in order to determine effects parallel and perpendicular to the occlusal plane, Franlfort horizontal, or the long axis ofthe tooth. Forces produce eith€r translation (bodib movement), rotation, or a combination oftransla- tion and rotation, depending upon the relationship ofthe line ofaction of the force to the center of resistance oftbe tooth. The tendency to rotat€ is due to the moment ofthe force, which is equal to force magnitude multipliedby the perpendicular distance offhe lin€ ofaction to the center ofresistance. The only force system lhat mome t *-ith no netforce) is a cottple, which is two equal and opposite, noncoflinear but can produce pure rctation (a paralfel forces. The movement of a tooth (or a set of teet ) can be described through the use ofa center ofrotation. The mtio between the net moment and net force on a toolh (M/F ratio) \nith reference to the center ofresistance determines the center ofrotation. Since most forces are applied at the bracket, it is necessary to compute equivalent forc€ systems at the center ofresistance in o.der to predict tooth mov€ment. A graph ofthe M/F ratio plotted againsi lhe c€nter of rotation illusirates the precision rcquired for controlled tooth movement. Principles of Biomechanics in Fixed Orthodontic Appliancesl . Forc€: is a load applicd to an object that will tend to move it to a different position in spac€- A force has magnitude, point ofapplication, and direction. Therefore, forces are r€presented and treated mathemati- cally as vectors. . C€nter ofresistance: a point at which aesistance to movement can be concentmted for mathematic analy- sis. In single-rooted teeth, the center ofresistance is on the long axis ofthe tooth one-third to one-halfthe ay ftom the alveolai crest to the apex. [n multirooted teeth it isjust apically to the furcation. Note: A force rhrough the center ofr€sistance causes all points ofthe tooth to move the same amount in the same direcdon. Tlris '!\ RDe ofmovement is called translation or bodily movement. . Rotation: occurs when a force is applied away from the center ofresistatce. Thc potential for rotalion is rermed a moment. Note: A force, applied by a bmcket that does not act through the center ofresistance, causes rotation ofa tooth. This tendency to rotate is measured in moments and is calledthe momentofthe force. . C ou ple: is rwo equal and oppos ite, noncol inear but paral lel forces. Thc result of applying two forces in lhis \r'ay produces pure rotation without translation, Note: Couples are usually applied by engaging awire in an edgewise bracket slot.

The sole function of the alveolar process is to Both the statement and the reason are correct and related Both the statement and the reason are correct but NOT related The statement is correct, but the reason is NOT The statement is NOT correct, but the reason is correct NEITHER the statement NOR the reason is correct

Both the statement and the reason are correct and related The bone ofthe alveolar prccess exists only to support the teeth. Ifa tooth fails to erupt, alveolar bone never forms irl that area; and ifa tooth is extracted, the alveolus resorbs after the extmction until finally the alveolar ridge completely atrophies. The space betwe€n the jaws into wbich the teeth erupt is gene.ally considered to be provided by growth at th€ mandibular condyles (especially the moldlt. The condyle is a major site of vertical growth in the mandible. Many arguments have been made about the condyles function in mandibular gron'ih. Most author- iiies agree that sofFtissue development carries the mandible forward and downward, while condylar growth fills in thc resultant space to maintain contact with the base ofthe skull. In infancy, the ramus is located at about the spot wh€re the primary fir$ molar will erupt. Progressive posterior remodeling creates space for the second primary molar and then for the sequential eruption ofthe perma- nent molar teeth. More often than not, however, this growth ceases before enough space has been created for eruprion oflhe third permanent molat which becomes impacted in the ramus. Note: After age 6, the great- elt increese in size ofthe mandibl€ occurs distal to the first molars. Irnportlnt: In contrast to the maxilla both endochondral and periosteal aclivity are important in growth of tbe mandible. Cartilage covcrs the surface ofthe mandibular condyl€ at the TMJ. Akhough this cartilage is not like rhe cartilage at an epiphyseal plate or a synchondrosis, hlperplasia, hypenropht and endochondral replacem€nt do occur there. All other ar€as ofthe mandible are formed and grow by direct surface appos! tion and remod€ling. Remember: Gro\\,th ofthe mandible occurs at the mandibular condyle and along lhe postedor sudace ofthe ramus. Tte body ofthe mandible grows longerby periosteal apposition ofbone on its posterior surface, while rhe ramus grows higher by €ndochondral replacement at the condyle accompanicd by surfac€ remodeling lon the onterior surface oflhe ramus). . .. rda, ';e; To summarize the growth ol the maxilla and mandible: 1. Growth ofrhe maxilla and its associated structurcs occurs from a combination of growth at su- tures and direci remodeling ofthe surfaces ofthe bone. 2. The maxilla is translated downward and forward as the face grows, and new bone fills in at the sutures. Growth ofthe surrounding soft tissues s€ens to be important. 3. Grow'th ofthe mandible occurs by both endochondml proliferation at the condyle and apposition and resomlion ofbone at surfaces. 4. The mandible is translated in space by the g.owth ofmuscles andother adjacent soft tissues and fiat addition of new bone at the condyle is in response to the soft tissue changes.

The Hawley retainer is the most common retainer in orthodontics because it can use the palate for anchorage. Both the statement and the reason are correct and related Both the statement and the reason are correct but NOT related The statement is corlect, but the reason is NOT The statement is NOT correct, but the reason is correct . NEITHER the statement NOR the reason is corect

Both the statement and the reason are correct but NOT related Multiple appliances can use the palate for anchorage. The true reason that the Hawley retainer is the most common is because ofthe varietv ofbenefits it has and can have when used properly. The palatal coverage ofa removable plate like a Hawley retainer makes it possible to incor- porate a bite plane lingual to the upper incisors to control the bite depth. This design consid- ention is important for ary patient who once had an excessive overbite. This palatal coverage (agylic) is the major source of anchorage in th€ Hawley appliance, A Hawley retainer can be made for the upper or lower arch. The lower retainer is somewhat fragile and may be difficult to insert because ofundercuts in the premolar region. Note: Apa- tient may have difficulty pronouncing linguoalveolar consonants for a few days after re- ceiving a maxillary Hawley appliance until the tongue adapts to the palatal covemge. llajor components of a remoyable appliance: l. Retentiv€ component: retains the appliance in function: consist olvarious clasps. The best example is Adam's crib. 2. A framework or baseplate: usually acrylic. This provides anchorage. 3. Tooth-moving elements: typically either springs or screws. '1. Anchorag€ component: resists force ofactive components (e.g., Acrylic base-plate). 5. -{ctive components or tooth moving components: springs, screws or elastics. lndications for removable appliances: . . . Retention after comprehensive treatment Limited tipping movements Gronth modification during the mixed dentition \ote: Components ofanchorage can also bing about (desired or undesired) toothmovements.

Which of the following may cause extrusion of the maxillary first molars which can cause an open bite? Straight-pull headgear Reverse-pull headgear Cervical-pull headgear High-pull headgear

Cervical-pull headgear Cervical-pull headgear consists of a cervical oeck strap (as ahchorage.) and a standard facebow in- serting into the headgear tubes of the maxillary first molar aftachments The objeotives of treatment with these types ofheadgear are to rcstrict anterior growth ofthe maxilla and to distalize and erupt max- illary molars. A major disadvantage of treatment using cervical headgear is possible extrusion of the maxillary molars. Likely results include: opening the bite, first molars will move distally and forward growth ofthe maxilla will decrease. Indications: Class II malocclusions with deep bite High-pull headgear consists ofa high-pull headstrap and a standard facebow inserting into the headgear tubes ofthc maxillary fi.st molar attachments. The objectives oftreatment with these typcs ofheadgear ar€ restriction ofanterior and downward maxillary gowth and/or molar distalization and control ofmaxillary molar eruption.These types ofheadgear have a more direct effect on the anterior segmcnt ofthe a{ch. Indications: CIass II malocclusions. with increased vertical dimension and minimal overbite. Straight-pull headgear is similar to the cervical-pull headgear. Howevet this appliance places a force in a straight distal direction from the maxillary molar Like cervical-pull headgear, the indications are Class II, Division I malocclusions (wlen bite ope i g is undesirable). Reverse-pull headgearunlike all ofthe otherheadgears above, has an extraoral component that is sup- ported by the chin, cheeks, forehead or a combination ofthese structures. [t consists of two pads that rest on the soft tissue ofthese structurcs. These pads are connected to a midline framework and are adjustable. Side effects include downward and backward rotation of the mandible. Indications: Class lll maloc- cllJsions (\rhere protraction ofthe maxilla is desirable). Chin ctp (chin capl ar€ devices to utilize cxtra-oral traction to restrain or alter mandibular growth. In- dications: Class II maloccltJsions

Which angle classification does the arrangement of the anterior teeth in this frontal view of study casts most likely represent Class I Class II, Division I Class II, Division 2 Class III

Class II, Division 2 Class II, Division 2 is a malocclusion in which the body of the mandible and its superimposed dental arch are also in distat relationship to the maxilla, and the molar and canine occlusion are the same as Class II, Division I type. The distobuccal cusp ofthe maxillary first molar occludes in the buccal developmental groove ofthe mandibular first molar. and the maxillary canines occlude mesial to the mandibular canines. The big dif- ference between Division I and Division II is in Division II the maxillary laterals have tipped labially and mesially. Remember: Class II, Division I = maxillary incisors (centrqls qnd jaws and tooth laterals) are in ex- treme labioversion. Anterior teeth are most likely to be fractured in children with this n ne of mixed dentition malocclusion. I . There is no set rule as to when a malocclusion should be treated. The age at which it is treated depends on the problem involved. 2. Malocclusions are more identifiable in children 7 to 9 years old because the eruption of permanent incisors reveals tooth-arch length discrepancies.

Which angle classification is shown (SEE page 51) Class I Class II,Division 1 Class II, Division 2 Class III

Class II, Division 2 In most cases Class II, Division 1 malocclusions, the body ofthe mandible and its superimposed dental arch are in a distal relationship to the maxilla and the ma,rillary inci- sors are usually in a labial axial inclination. In addition, the relationship ofthe maxillary first molars and canines to their mandibular counterparts is such that the distobuccal cusp ofthe maxillary first molar occludes in the buccal developmental groove ofthe mandibu- lar first molar and the maxillary canines occlude mesial to the mandibular canines. Be- sides the labial axial inclination ofthe maxillary incisors (overjet), various abenations in the individual alignment ofthe teeth (for example, crowding) canbe superimposed upon this class. Remember: Class II, Division I Subdivision includes malocclusions, which have one side ofthe maxillary arch in a Class II relationship with its occluding mandibular quad- rant, while the other side is in a Class I relationship. The maxillary overjet or other ante- rior aberrations are usually confined to one side ofthe maxillary arch. ),{ote: Relative to a heterogeneous population, the incidence of malocclusion in a ho- mogeneous population generally is lower.

Which of the following is the leasat common Class I malocclusion Class II malocclusion Class III malocclusion Normal occlusion

Class III malocclusion Class III malocclusions arc those in which the body ofthe mandible and its superimposed dental arch are in a mesial relationship to the skull base and maxilla. The maxillary first molar therefore occludes distal to the mandibular first molar, while the maxillary canine is an exaggerated distal relationship to the mandibular canine. The mandibular incisors are usually tipped lingually and forward to the maxillary incisors. Also characteristic ofthe "true" @rchuded). Class lll malocclusion is the prognathic mandible. Class III subdivision is a Class III relationship of the teeth on one side $ ith a Class I relationship on the other side. --\ pseudo-class III malocclusion is one in which the mandibular incisors are forward ofthe max- illao incisors when in centric occlusion, however, the patient has the ability to bring the mandible back $ithout strain so that the mandibular incisors can touch the maxillary incisors (this ability is ofren considered diagt?o.ttlc). This type is therefore a milder form ofthe "true" occlusion and more amenable to conservative orthodontic novement than the "true" Class lll malocclusion u,hich often requires sugrcal corection. Different etiological factors have been suggested in pseudo-Class lll malocclusion: Dental factors: . . Ectopic eruption of maxillary central incisors Prenrature loss of deciduous molars Functional factors: . . . Anomalies in tongue position Neuromuscular features Naso-respintory or airway problems Skeletal factors: . Minor transverse maxillary discrepancy prognathic mandible (ptimary cause) and the mandibular shift can be considered a functional (envi Notei It has also been suggested that these sequelae occur more frequently in subjects with a ,o mehtal) factor, therefore the postnatal causative factors may not be the pnmary cause.

An example of a maxillary permanent central incisor in crossbite is shown. In order to treat this condition properly, the dentist should do what? Do nothing until all permanent teeth have erupted Surgically reposition the central incisor Correct the condition immediately with a simple appliance Place a maxillary expander

Correct the condition immediately with a simple appliance Ideally, this anterior crossbite should be corrected before it reached the occlusal plane (vhile il !'as erupting). The rnost probable etiologic factor for this happening is prolonged retention ofthe primary maxillary incisors. Cross-elastics from the maxillary lingual to the mandibular labial can be used to conect a single-tooth crossbite. A maxillary removable appliance can also be used. When elastics are used to move teeth they should be attached directly to the appliance components. -{nterior crossbite, particularly crossbite of the incisors' is mrely found in children rvho do not have a skeletal Class IIIjaw relationship. A crossbite relationship ofone or two anterior teeth, however, may derelop in a child who has good facial proportions. The maxillary lateral incisors tend to erupt to the lin- glal and may become trapped in that location, especially in the presence ofscvere crowding. In this sit- uarion. extmcting the adjacent primary canines usually leads to spontaneous corection ofthe crossbite. Ir is important to evaluate the space situation before attempting to correct any antedor crossbite. If enough space is available to accomplish the movement, a maxillary removable appliance is usually the best mechanism to concct a simple anterior crossbite that requires a tipping movement. Remember: Anterior crossbite in a primary dentition usually indicates a skelet.l growth problem. Note: The permanent antcrior tooth that is most often atypical in size is the maxillary lateral incisor Elastics are available as rubber bands, elastic thread, and formed shapes for specific purposes. They are used to move teeth, to ligate archwires to brackets, for intermaxillary traction, and for separation. Elas- tics are aiways attached to bmckets and archwires, never around a naked tooth. . (intramdxillary)r nsed for traction between tceth and groups of teeth within the same arch. . Cl.ss I elastics Class II elastics (in termaxillary\: :js]'J,ally are wom from a tooth in the anterior part of the ma,{illa (i.e., the petlnd ent canine) to a looth located in the posterior part ofthe mandible nent molar).Usedto correct Class II malocclusion. . Class III elastics fi.e.,jirst (irtemaxillary)r usually are wom from a tooth in the posterior part ofthe max- illa (i.e., the pennanentjirst molar) to a tooth located in the anterior part ofthe mandlble (i.e., per- manent canine).Vsed to improve the overjet in an edge-to-edge or ante.ior crossbite situation. . Crossbite elastics: are wom from the lingual ofonc or more maxillary teeth to the buccal ofone or more teeth in the mandible to helD correct crossbites.

The most common cause of class I malocclusion An abnormal frenum Uneven growth of the arches Mandibular incisor crowding Discrepancy between tooth size and supporting bone

Discrepancy between tooth size and supporting bone The cephalometric analysis ofthe Class I occlusion would indicate an ANB angle ofless than 4 degrees signif ing a harmonious skeletal prohle and sagittal harmony between the maxillary and mandibular dental arches. The most common cause ofClass I malocclusion is a discrepancy between tooth structue and the amount of supporting bone (length). Perhaps the most prevalent characteristic ofClass I malocclusion is crowding (i.e., insulficient alveolar qrch length to qccommodate l{oted; .:.,- l all teeth in ideol alignment qnd good sqgittql position). When a diagnosis is made that crowding does exist and this crowding exceeds 4 mm in the in q mandibular arch, extractions are often required to attain an excellent, stable result. However, the decision whether to exftact teeth depends greatly on a space analysis performed on the mandible. Th€ patient should be ref€rred to the orthodontist for this analysis. In general: . when the space lacking is less than 4mm, in most cases it can be obtained by carefully stripping some interproximal enamel from each ofthe antedor teeth . A space deficiency exc€eding 4mm usually indicates extraction for correction of the malocclusion *** l. Physiologic occlusion: although not necessarily an ideal or Class I occlusion, it is an occlusion that adapts to the stress of function and can be maintained indefi- nitely. 2. Pathologic occlusion: cannot function without contributing to it's own destruc- tion. It may manifest itselfby any combination of: excessive wear ofthe teeth with- out sufficient compensatory mechanisms,TMJ problems, pulpal changes ranging from pulpitis to necrosis and periodontal changes. 3. Tooth movement caused by pathologic conditions is termed pathologic tooth movement.

A "poor mans cephalometric analsis" is performed via a Dental cast analysis Facial profile analysis Photographic analysis Full face analysis

Facial profile analysis The facial profile analysis delineates the same information as that obtained through lateral cephalometric radiographs. The difference lies in the detail obtained through the latter method, however, the former is considered a vital diagnostic technique for primary evaluation. It is a quick and simple (also cheap) technique which readily gives the following information: 1. Anteroposterior position/proportion ofthejaws relative to each other 2. Lip posture (competent/incompetant) and incisor prominence 3. Vertical facial proportions 4. Inclination ofthe mandibular plane angle Note: Within the lower third of anterior face height the mouth should be about one-third ofthe way between the nose and the chin. Important: The most stable area from which to evaluate craniofacial growth is the an- terior cranial base. ; ,- '-.'. No&gf i&;*& l. There is a significant difference in esthetics and cephalometric values among racial and ethnic groups. Z.Individual cephalometric measures, by themselves, should not be used to make a diagnosis. They should be used to explain or support a diagnosis based on all the data required to make a diagnosis. 3. Cephalometric measures in themselves are usually not considered problems, but what they indicate m ybe (i.e., prognathic mandible, small maxilla,Jlared incisors, elc.). 4. In treatm€nt planning: impacted teeth are usually a high priority; within occlusal problems, interarch relationships usually take priority over intra-arch relationships; habits (i.e., thumbsucking, brttxism, elc./ should also be consid- ered.

All of the following are fixed orthodontic appliances EXCEPT Lingual archwires Whip-spring appliances Palate-separating devices Frankel's appliances Edgewise mechanisms Light-wire appliances

Frankel's appliances Frankel's appliancc is a removable functional appliance and is employed in cascs of abnoll]'j,al (h.r-peracti|e) soft tissue pattems. Fixed orthodontic appliances offer controlled tooth movement in all 3 planes ofspace. Exam- ples i[clude: lingual archwire, fixed space maintainen, palate-separuting devices, the edgewise mechanism, light-wire appliances as well as other fixed appliances writersaI appliance). (i.e., tv'int'ire appliance, Important: Removable orthodontic appliances are generally rcstrictcd to tipping teeth. Ex- amples include; / . . i Attached removable appliances l. Active appliances . Extra-oral traction devices: head gears, face masks, chin cups . Lip bumpers . . Active plates: Schwartz appliance, antedor spring aligners Vacuum formed appliances 2. Passive appliances . Bite planes, occlusal splints, retainers Loose removable appliances: functional appliances, functional ' -. . .- jaw orthopedic appliances l. For an orthodontic appliance to be effective in tmnslating the roots of teeth, it Not€d. must be capable of exerting a torque. '&g 2. Remember: The 4 basic components of fixed appliance include: bands, brackets, archwires, and auxiliaies (elastics or ligatures to hold the archwire in brackets). 3. Whip-spring appliances are used to de-rotate one or two teeth. 4. One ofthe easiest mov€ments to accomplish is tipping incisors mesially.

The generalized causes of the failure of tooth eruption or delayed tooth eruption include all of the following EXCEPT Hereditary gingival fibromatosis Down's syndrome Rickets Hlperparathyroidism

Hlperparathyroidism This condition can result in the premature exfoliation of primary teeth The generalized eruption failure or "primary failure of eruption" is caused by the failure ofthe eruption mechanism itself. Bone resorption proceeds normally, but involved teeth simply do not follow the path that has been cleared. The involved teeth do not erupt spontaneously and are not amenable to any orthodonlic recourse. This condition is rare. The localized causes of failure of eruption or the delayed eruption of the teeth include: . Congenital absence . Abnormal position ofthe crypt . . . Lack of space in the arch (crowding) Supemumerary teeth Dilacerated roots Remember: Anodontia, diagnosed in a 5 year old child, primarily affects the growth of the alveolar bone fas opposed to the midface, maxilla, or mandible, etc.). ofthe alveolar process exists only to support the teeth. Ifa tooth fails to erupt, alveolar bone never forms in that area; and ifa tooth is extracted, the alveolus resorbs after the extraction until finally the alveolar ridge completely atrophies.

"Primate spaces" in the primary dentition are found in which TWO locations? In the maxillary arch, the primate space is located between the central incisors and lareral incisors In the maxillary arch, the primate space is located between the lateral incisors and canines . In the mandibular arch, the primate space is located between the canines and first molars In the mandibular arch, the primate space is located between the lateral incisors and canine

In the maxillary arch, the primate space is located between the lateral incisors and canines . In the mandibular arch, the primate space is located between the canines and first molars Spacing is normal throughout the anterior part ofthe primary dentition, but is most noticeable in these t$o locations. primale spaces are normally present from the time the teeth erupt. Developmental spaces between the incisors arc often present from the beginniDg, but become somewhat larger as the child gtows and the alveo_ These lar processes expand. Generalized spacing ofthe primary teeth is a requireme[t for proper alignment ofthe permanent incisors. This slacing is most frequently caused by the growth ofthe dental arches. If spacing is present, there is a possibility that dritting ofthe adjacent teeth will occur if there is a loss of a primary incisor. However, if there is no spacing present and the primary anterior teeth were in contact before the loss, a collapse in the arch after the loss ofone ofthe primary incisors is almost certain. lmportrnt: This is not true in the case ofa lost permanent incisor. Space closure occun mpidly whether spac- ing is present or not prior to the loss. Space maintenance would be indicated. Remember: One ofthe most common cruses of malocclusion is inadequate space management following the early loss of primary teeth. Primary dentition strge: . . Starts with the eruption of the primary teeth and lasts until the first permanent tooth erupts Boys prccede girls in total number of teeth erupted until I 5 months, then girls surpass boys and r€main ahead throughout completion of the primary dentition . Tle mesiolingual cups ofthe maxillary molars occludes in the central fossae ofthe mandibular molars, primary molar usually is somewhat wider mesiodistally than the maxillary giving dse, typically, to a flush terminal and the incisors are vertical, with minimal overbite and overjet. The mandibular second pleDe at the end ofthe primary dentition stage. . mefl the termiral plane is straight until the arival ofth€ first permanent mola$, the latter are usually guided into aD ideal end-to-€nd relationship considered "nomal" for whites in North America. . mther than a flush termiDalplane . IDterproximal cavities, sucking habits, or the skeleial pattem may Foduce Dist l step: the mandibular terminal plane is distal to the maxillary termidal plane . Mesial step: the mandibular terminal plane is mesial to the maxillary terminal plane

Cartilage differs from bone in that cartilage can increase in size by Apposition Sutural expansion Interstitial growth Endosteal remodeling

Interstitial growth Grofih ofcartilage occurs in two ways: l. Appositional by the recruitment of ftesh cells, chondrcblasts, from perichon&al stem cells and the ad- dition ofnew matrix to the surface. Note: The perichondrium consists ofa fibrous outer layer and chondroblastic inner layer 2. Interstitial by the mitotic division of, and deposition ofmore matrix around, chondrocytes already es- tablished in lhe cartilage. Examples ofsites that gow by interslitial growth include the mandibular condyle, nasal septum and spheno-occipital synchondrosis. Notei The "V" principle ofgrowth is illustrated by the maDdibular condyle. Importanti Cartilagc tissue is pressure tolerant and able to providc flexible suppon b€cause it is avascular and contains an intacellular matrix ofproteoglycans. Growth of bone: .Appositionat below the covering periosieal layerofbone- Periosteum consists ofa fibrcus out€r layerand a cellular inner layer ofosteoblasts, which Iay down bone. Bccause ofits rigid structure, interstitial growth is not possible. *** Do not confus€ bone growth with bone formrtion. Bone foms by cither endochondral ossification or in- tmmembranous ossifi cation, It is a truism that grollth is strongly influenced by gcnetic factors, but it can also be significantly allectcd by the environment, in the form ofnutritional status, degee ofphysical activity. health or illness, and a number of similar factors. Thre€ major theories havc atlcmpted to explain the determinants ofcraniofacial growth: l. Bone, likc othcr tissues, is the primary determinant ofits own growth- 2. Cartilagc is the primary determinanr ofskeletal growrh, while bone responds secondarily and passively J. The soft lissue matrix in which the skeletal elem€nts are embedded is the primary determinant of grow1h, and both bone and cartilage are secondary followers. Note: This theory is kno\Mr as the functional matrix theory. T}e major difference in the theories is the location at which genetic control is expressed. The first theory im- plics rhar gcnetic control is expressed directly at the level ofthe bone, and therefore its locus should be the periosteum. The second theoryor cartilage theory suggests that genetic control is expressed in the cartilagc, whilc bone responds passively to being displaced. This indirect control is called epig€netic' The third theory as- sumes gcnetic control is mediated to a large extent outside the skeletal system and occurs only in response to e srsnal from other tissues.

The cranial vault is made up of a number of flat bones that re formed by ?, ? cartileganous precursors. Endochondral bone formation; with Intramembranous bone formation; without Both endochondral and intramembranous bone formation; with Both endochondral and intramembranous bone formation; without

Intramembranous bone formation; without In the cranial vault, the growth process is entirely the resuit ofp€riosteal activity at the surfaces ofthe bones. Remodeling and growth occur primarily at the pcriosteumlincd contact areas between skull bones, the skeletal sutures, but periosteal activity also changes both the inner and outer Jurfaces ofthese plateJike bones. Although the majority ofgrowth in the cranial vault occu^ at the sutures, thcre is a tendency for bone to be removed from the inner surface ofthe cranial vault, while at the same time new bone is added on the exterior surface. In contrast to the cranial vault, the bones (i.e., elhmoid, sphenoid, ond occipitdl rores/ ofthe cranial b.se are formed initially in cartilage and are later transformed by endochondral ossi{ication to bone. As ossification procc€ds, bands ofcartilage called synchondroses remain between the centcrs ofossi- fication. These important growth sites are the synchondrosis between the sphenoid and occipital bones, or spheno-occipital slnchondrosis, the intersphenoid synchondrosis, between the two parts ofthe sphe- noid bone, and the sphenoethmoidal synchondrosis, between the sphenoid and ethmoid bones- Eventually, these synchondroses bccome inactive. Note: The bones ofthe cranial base are not affected to a great degree by growth ofthe brain (siace lhey are endochondral bones). ,'-...., 1. After age 6, the greatest increase in size ofthe mandiblc occurs distal to the lirst molars, ,t!{ote{t 2.The condyle ofthe mandible grows by proliferation of cartilage. 3. The chief factor in thc formation ofthe alveolar process is the eruption of teeth' Arch lengrh space for the eruption of pemanent mandibular second and third molars is created by resorption at the anterior border ofthe ramus. ,1. 5. At birth the greatest dimension ofthe face is width. 6. After a tooth has bcen moved from one position to another, thc resulting bone is transi- tional bone. 7. The dependencc oftooth development and tooth eruption upon growth ofbone and bones is considerable. 8. Grow1h ofthe cranial base generally precedes growth ofthejaws. Important: Mandibular growth is in the downward and forward directions. Growth in the condyle in- creeses lhe anterior-posteior *** (downward and fo' **(td patlern ofg|orlr, dimension ofthc mandible.a

All of the following are signs of incipient malloclusion Lack of spacing in primary dentition Crowding ofpermanent incisors in mixed dentition Premature loss ofmandibular primary canines Larger than normal primary teeth

Larger than normal primary teeth There may be a dispropo.tion between the size ofthe maxilla and mandible or between the size resulting in overcrowding ofteeth or i1r abnormal bite pattems. Supemumerary teeth, malformed teeth, impacted or lost teeth and teeth that eiupt in an abnormal direction may contribute to malocclu- sion. Less fiequent causes ofmalocclusion include habits such as thr-rmb sucking or tongue thrustingSigns of incipient malocclusion: . . . The lack ofinterdental spacing in the primary dentition The crowding ofthe permanent incisors in the mixed dentition The premature loss ofthe primary canines, particularly in the mandibular arch ; '., .. - l.The significance of the lack of sp.cing relates to the increased mesiodistal width of the /Noae*lil Permanentteeth. - - I 2. Arch perimeter does increase after eruption ofthe incisors. Howeveq it is a small increase rn the maxilla, and essentially non-existent in the mandible. Therefore, the minimal arch grofih does not usually contribute to further dental alignment. 3.The premature loss ofthe mandibul.r primary canine reflects insuflicient arch size in the anterior region. As such, the crowns ofthe lateral incisors, during eruption. impingc on the roots ofthe primary canines causing them to resorb. When the canine is shed, the mid- Iine will shift in thc direction ofthe lost tooth. You will have lateral and lingual migration of the mandibular incisors. 4. The maxillary anterior primary teeth are about 7570 ofthe sizc oftheir permanent suc- cessors. 5. The mandibular anterior primary teeth are, on average, about 6 mm narrower mesio- di\rally rhan lheir successors. Rememberi An anterior crossbite in a primary dentition usually indicates a skelet.l growth problem. At birth, the alveolarprocesses are covered by gum pads, which soon are segmented to indicate the sites of lhe developing teeth (called gum pad stage). The maxillary arch is horseshoe-shaped and the gums rend !o extend buccally and labially beyond those in the mandible; furthermore, the mandibular arch is posterior to the maxillary arch when the pads contact.

An 18 year old ptient presents back to you complaining of crowding of his lower anterior incisors. You explain thata this is because of Late mandibular growth Pressure from third molars Maxillary tooth-size excess Trauma An oral habit he must have

Late mandibular growth Thc cunent concept is that late incisor crowding develops as thc mandibular incisors, and perhaps the entirc mandibular dentition, move distally relative to thc body ofthe mandible late in mandibular growth. Late incisor crowding does occur in individuals with no third molars at all, and so the presence ofthesc teeth is not a c tical variable -the extent oflate mandibular growth is a critical variable. Cephalocaudal gradient of growthi simply means that there is an axis of increased growth extending from the head toward the feet. When the facial growth pattem is vierved against the perspective ofthc cephalocaudal gradient, jt is not surprising that the mandible, being further away from the brain, tends to gro$ more than the maxilla, which is closer. Remember: The mandibl€ can and does undergo more gro$th in rhe late teens than does the maxilla. Scammon's gronth curves point out four major tissue systems ofthe body and a percentage ofadult arainmenr at :0 years ofage. The curve for lymphoid tissue which reaches 200olo ofadult attainment ar or around age twelve. The lymphoid tissues then undergo a decrease in size until they reach 100% in adulrhood. The neural tissues reach about 90% oftheir adult attainment at roughly 9 yeaN ofage and tinall) at age 20 are at adult attainment. General body tissue growth follows a direct line to age twenty and t-inally the getrital tissues begin their growth at puberty which is around agc fourteen. Important: L The maxilla, follows a pattem closer to that or neural tissues than does the mandiblc. 2. The mandible grows later and follows a pattem closer to that ofgenital tissues. G.o$th velocity cunes show that groMh in height is very rapid after birth but decelerates quickly to a louer, more consistent level in childhood. Growth accelerates again around puberty before slowing and vifually stopping at maturiry Key point: The timing of : - , $owth spurts is important in orthodontics. .,. l The average peak growth for girls is around age 12, for boys it is around age 14. ,,Noteql' *' -- 2. Generally speaking, the earlier the growth spurt, the shorter the duration ofthe growth .lun and the less overall the grourh will be. 3. Girls will generally start growth sooner, grow for a shorter amorult of time, and will grow less than boys. 4. Because of time and variability, chronologic age often is not a good indicator ofthe in- dividual's crowth status.

All of the following are advantages of the indirect method of bonding brackets to a tooth over the direct method EXCEPT one. Reduced chair-side time More precise location of brackets possible in the laboratory Controlled thickness of the resin between the tooth and the bracket interface Less technique sensitive Easier clean-up during bonding and de-bonding Better visualization in lab (especially for lingual brackets)

Less technique sensitive *** The indirect bonding technique is more complex and technique sensitiv€ and requir€s extra precautions The procedure involves the following steps: 1. An accumte impression with alginate is tak€n and poured up with orthodontic model stone to be used as a working model. 2. Vertical lines arc draM on the teeth to aid in bracket placement and a separating media is aPplied. 3. The brackets are then loaded with a filled resin paste and cured. 4. After its initial set, individual positioning of a ffay with siiicone is prepared by applying it over the brack- eted teeth on plaster model. 5. This whole set-up th€n is placed in warm water to dissolve the separating media 6. Th€ silicone tray is then removed from the plaster model with brackets embedded in it. 7. Brackets are cleaned under running watff making sure that pads have cured resin. 8. Enamel is etched, conditioned and unfilled resin is applied. Unfilled resin is also applied to cued resin on the base of the bracket pads. 9. The silicone tray with embedded brackets is then positioned on the teeth being bonded and held in posi- tion till the initial set ofthe unfilled rcsin is reached. lmportent: f. The conhol of"tfrsh" (e&ess of resin) not only makes clean up easy but also the controlled thickness ofit accurately expresses the built-in prescription ofthe appliance. problen (e.g., linqpal appliance), this technique is almost always employed. 2. Also, in situations where visibility is a l. All orthodontic appliances obey Newton's Third Law: There ir in equel and opposite rcaction to every rction. 2. For each appliance, the sum ofthe forces and the sum ofthe moments acting on it sum to zero. 3. T,?es ofappliances . Equal and opposite forc€s: an elastic band stretched between two brackets produces equal and oppo_ site forces (the . sum ofthe forces equals zero). One.couple applirnces: inserted into a bmcket at one end and tied as a point contact at the other end. A couple is produced only at the engag€d end. The sum of the forces is zero. . Two-couple appliances: inserted into a bracket at each end. Both a couple and a force are produced at each end. The magnihrde ofthe couple is largest at the end closer to the bend in the wire The sum ofthe forces is zero.

Which of the following teeth are required for a dentist to perform a Moyers mixed dentition analysis Mandibular first molars Maxillary first molars Mandibular incisors Maxillary incisors

Mandibular incisors A mixed dentition an^lysis (transitional dentition analysis) detemines space available versus space required. The analysis is based on a cofielation oftooth size; one may measure a tooth or a group ofteeth and predict accurately the size ofthe other teeth in the same mouth. In thc Moyers' mixed dentition analysis, the size ofthe unerupted canines and premoJars is predicted from knowledge ofthe siz,e (nesiodistal \|idth) ofthe mandibular incisors that have already erupted into the mouth early in the mixed dentition. The maxillary incisors are not used in any ofthe predictive pro- cedures, since they show too much variability in size. Notei The mandibular incisors are measured to predict the size ofmaxillary as well as mandibular pos- terior teeth. lf mandibular antcrior crowding is notcd during thc mixcd dcntition phase, thc most appropriate approach to management is to take study models and perform an arch length analysis. This mandibular in- cisor crowding usually results from a tooth size-arch length discrepancy, Mired dentition stage: . That period during which primary and permanent teeth are in the mouth together, the earliest indi- cation ofa mixed dentition consists ofthe prirnary dentition and the permanent mandibular first molars. . . . Supervision ofa child's development ofocclusion is most critical during this mixed dentition stage. From a clinical point ofview, there are two very important aspects to the mixed dentition period: L The utilization ofthe arch perimeter :. The adaptive changes in occlusion that occur during the transition from one dentition to another. The elveolar process is one ofthe most actively adaptable areas ofbone growth during the period of Eansition between the dentitions. Therefore, it is an ideal time for most majo. orthodontic inter\'ention. . \ormal characteristics ofthe mixed dentition stage: molar and canine relationships are Class l; lec$ay space is present; well-aligned incisors or up to moderate crowding ofthe incisors; proximal contacts are tight. . The total leeway space is the important clinical consideration and the method ofutilization ofthe leeway space is the key factor in th€ transitional dentition.

The anomaly depicted in the picture is called a (SEE decks pg 23)

Mesiodens A midline supemumerury tooth (mesioderu) in the mandibular arch is shown. Mesiodens usually occur in the maxillary arch. However, you will see them occasionally in the lower arah. Note the crowding of the mandibular permanent incisors. Extraction of the m€siodens is the heatment of choice. Important For the best therapeutic result, orthodontic treatment to close the space may be necessary. Coorieh 20{o 2004 Uniydny ofwahin8loD. All nshb 6d.d Aas lo lh€ Ad,s of Pedi.tic D€nriry is eov crn d by.lien$. Ulluiioiz.d @s or rprodxrion is fdbiddm enhour thc pno. widd p.mision vdiry of Wshinghn. Fo. inf{lruio'! co.i.cli li jaw groMh. A midline supernumerary toolh (mesiodens) is present. Note that the maxillary right permanent cenhal incisor is (slightry rctated, and that the direction ofthe roots ofthe central incisors is more flared. The cerhal incisors most likely were deflected from their normal paths of eruption by the mesioderc. The mesiodens should be extracted. To localize a supemumerary tooth or impacted tooth and its re- lationship to other teeth, you should take two or rnore periapical x-rays at different angles and an occlusal view film. Conditions associated with multiple supemumerary teeth: . . Gardener's syndrome Cleidocranial dysplasia . . Down's syndrome Sturge-Weber syndrome Note: Oligodontiay'absence ofone or more teeth, is more common in females than males. It is often associated with smaller than averaee tooth-size ratio.

1. The photograph shows a maxillary fixed bilateral space maintainer. This type of space maintainer also is known as a: 2. If both primary canines were present, which of the following space maintainer(s) could be used in place of this appliance that cannot be used in this case? Distal shoe Nance appliance Lingual holding arch Hawley retainer Band and loop (bilateral)

Nance appliance Band and loop (bilateral) Note the small acrylic button thatwill restagainst the palatal tissue with thc Nanceappliance. Some clinicians object to the button since it can create tissue irritation. Thc Nance applianc€ is used in situations where premature bilateral loss of maxillry primary teeth hasa occured.

A 9 year old needs tooth #30 extracted due to caries. Whts the proper space maintenance treatment? Distal shoe on "T" Band and loop on "T" Removable partial denture No space maintenance is needed

No space maintenance is needed (#31 has not erupted yet and it will tend to erupt close to the area of where #30 had been) l. Ifa permanent first molar is extracted on a child tlefore the eruption ofthe permanent second molar, the best approach is to allow the eruption of the second molar and the mesial drifting to occur naturally. This will fill in the space most of the time. 2. A space maintainer can be removed as soon as the permanent tooth begins to erupt through the gingiva. (See picture below). 3. The most reliable indicator ofreadiness of eruption of a succedaneous tooth a space maintainer) is the extent of root development determined by radiographic evaluation. No space maintainer is required if eruption (and the need for ofthe succedaneous tooth is imminent. Very important: l. The most rapid losses in the A-P distance ofthe ach is usually due to a mesial tip- ping and rotation of the permanent first molar after rernoval of the primary second molar. 2.When the primary second molar is lost, always maintain space until the arival of the second nremolar. This photograph demonstrates a tooth partially erupting between the wires ofa space maintainer The space maintainer now can be removed.

Which of the follwing can be used to describe a class II Retrognathism only Overbite only Underbite only Overbite or retrognathism Underbite or prognathism

Overbite or retrognathism Those malocclusions in which there is a illa make up Class II. "distal" Divisions of Class II malocclusions are as follows: . relationshio ofthe mandible to the max- Class II, Division l: a distal relationship ofthe buccal groove ofthe mandibular first permanent molar to lhe mesiobuccal cusp ofthe maxillary first permanent molar along with the maxillary incisors . (centrals and laterals) tn extreme labiovenion Class II, Division 2: a distal relationship ofthe buccal groove ofthe mandibular first permanent molar to the mesiobuccal cusp ofthe maxillary first permanent molar along with the maxillary laterals being tipped labially and mesially (sometimes actually overlapping the centrals). The maxillary centrals are usually retruded somewhat. *** Subdivisions: when the distoclusion occurs on one side ofthe dental arch only, the unilateral distoclusion is referred to as a subdivision of its division. For example: Class II, Division I Subdivision: one side of the maxillary arch is in a Class II relationship with its occluding mandibular quadmnt while the other side is in a Class I re- . lationship. The protruded maxillary incisors (centrals and laterals), maxillary overjet, and other anterior aberrations, are usually confined to one side ofthe maxillary arch.

Displaced teeth related to functional shifts are usually seen in which 2 of the following Posterior crossbite after prolonged thumb sucking Class lI, Division I malocclusion Anterior crossbite in mildly prognathic children An anterior open bite after prolonged thumb sucking

Posterior crossbite after prolonged thumb sucking Anterior crossbite in mildly prognathic children Prolonged sucking habits often produce a mildly narrow maxillary arch and a tendency toward bitateral crossbite. Children with this condition usually shift the mandible to one side on closure to gain better function, which can guide permanent molars, or later, premolars into a crossbite relationship. A young child who has a tendency toward a Class III malocclusion will have end-to-end contact ofthe primary incisors. A true anterior crossbite in the primary dentition is quite rare because mandibular growth lags behind maxillary growth. The primary incisors wear down rapidly, and an anterior shift ofthe mandible to escape occlusal interferences rarely occurs until the permanent incisors begin to erupt. A pattem of anterior displacement of the mandible may develop when the permanent incisors come into contact, however' producing an anterior crossbite ftom the shift. . .. l. An anatomic crossbite (skeletal), as contrasted with a functional crossbite \ote*. (y6y thumb sucking), usually demonstrates a smooth closure to centric occlu- '-A::. sion. 2. A functional crossbite is usually caused by thumbsucking and does not demonstrate smooth closure into CO. 3. A corrected anterior crossbite is best retained by the normal incisor relationship that is achieved through treatment (the overbite), not appliances. 4. Class III relationships are more prevalent in Asian populations, whereas Class II relationships are more commonly found in whites of northern Euro- pean descent. 5. Reverse overjet, suggesting a Class III malocclusion, is much less frequent than Class II in the U. S. population.

Which condition is approprietly treated at n early age? Deviated midline in the absence ofa functional shift Mild crowding of lower permanent incisors Two deciduous molars nearly in crossbite Posterior crossbite with a functional shift

Posterior crossbite with a functional shift Posterior crossbite: . . Should be corrected as soon as possible Should be thoroughly diagnosed as to whether it is ofa dental, functional or skeletal origin . . Ma) be corrected with nalatal expansion May be associated with a mandibular shift It is important to correct poste or crossbites (which are related to lhe t|ansverse plane ofrpdcel and mild anterior crossbites in the first stage oftreatment, even ifthe permanent first molars have not yet cruptod. Se- vere anterior crossbites, in contrast, are usually not corrected until the second stage ofconventional treat- ment, Important: The most common rype rior crossbite frrarrverse problem). ofactive toolh movement in the primary dentition is to correct a poste. Maxiilary or palatal expansion appliances are used to correct trrnsverse discrepancies by skeletal expansion ofthe midpalatal suture. Appliances to correct crossbites: . Hyrax appliance: is the most commonly used tlpe ofappliance for rapid expansion sists ofa hymx screw held in place with a wire framework that is attached to several upper ieeth with cemented bands. The screw is activated by at least 0.25 mm daily . forre qudrler turn). Haas appliatrce: is both tissue and tooth-bome and has an extensive amount ofpalatal acrylic wltich acts on the palatal mucosa. [t consists ofbands that are cemented on maxillary first premolars and first molars. T*o acrylic pads with a midline jackscrew . Harrley-type removable appliance with a dren. . are connected to the rest ofthe appiiance. jack /r.5 ,tnt/dql.lt cor- screw: can bc uscd for mild poste.ior crossbites in chil- Quad-hefix, W-arch: these consist ofhealy stainless steel wire with fonr (quad-helix) or three (ty arch) hcljces rhat are incorporated to increase the range and flexibility. Tlley can be us€d to corect unilateral or bilareral crossbites and for corecting rotated molars. . Transpalatal arch AP,4): is a thin wire that goes across the roofofthe mouth from first molar to first molar. TPA is used to maintain expansion in the molars. An omega loop is tlpically included making the ap- pliance useful in rotating and widening the molars. Remember: A skeletal crossbite, as contnsted with afunctional crossbite, usually demonstmtes a smoolh clo- !ure !o centric occlusion.

During a serial extraction which teeth are typically not removed Primary canines Primary first molars Permanent first premolars Primary second molars

Primary second molars Serial extraction is the orderly removal of selected primary and permanent teeth in a predetermined sequence. It is indicated primarily in severe Class I malocclusion in the mixed dentition that has insullici€nt arch length. This procedure primarily benefits chil- dren who demonstrate an arch-length discrepancy. Stages in serial extraction: The primary canines are the first to be removed, followed by the primary first molars, and then the permanent flrst premolars (usually). Six to fifteen months is the interval between extractions. To aid in support and retention during this time, a lingual arch should be used in the mandible and a Hawley appliance in the maxilla. This is usually followed by full orthodontic treatment. Note: The key to success is extraction ofthe first premolars before the permanent canines erupt. In serial extraction procedures, concems about eruption sequence are usually related to the eruption pattern of the permanent rnandibular canines and first premolars. Note: After extraction ofthe maxillary first premolar in a serial extraction procedure, the maxillary canines path of eruption will usually be downward and backward. Remember: Severe arch space deficiency in the p€rmanent dentitton (over l0 mm) will almost always require extractions to properly align teeth.

Aall of the following are type of tooth movement except one . Tipping Translation Pulling Extrusion Intrusion Torque Rotation

Pulling The optimal force levels for orthodontic tooth movement should bejust high enough to partially but not com- pletely occlude blood vessels in the periodontal ligament. Both the amount of force delivered to a tooth and also the area ofthe periodontal ligament overwhich that force is distributed are important. The PDL response is determined not by force alone, but by force petunit area, or pressure. Thc periodontal lig|ment is a well-organized connective fibrous tissue andremodels significantly during orthodontic movement. Under normal physiologic conditions, the PDL is rich in collagen fibers organized to re- sist the forces ofmastication. Important: On th€ side toward which the tooth is being moved, youwill find activity" that result in bone rasorption. This is called the pressure ot compression side. on the side ofthe root from which the tooth moves, sion side. you will find "osteoblastic "osteoclastic activity" that rcsults id bone apposition. This is called the ten- Types oftooth movement that can be accomplished with orthodontics: L Tipping: the crown moves in one direction while the root tip is displaced in the opposite direction due to rotation or pivoting ofthe tooth around the axis ofresistance or axis of rotalion (localed somewhere in the apical o e-thitd of the root). This $eates two areas of compression and tension. Most readily accomplished with a removable appliance. Accomplish€d most easily with Nnterior incisor teeth. 2.'Ir^nslsJtioln (bodily movement): a force lhrough the center ofresistance causes all points ofthe tooth to move the same amount in the same directioD. This Bpe ofmovemcnt is called translrtion orttodily move- ment. This creates one area ofcompression aad one arca of tension. Very difficult to accomplish. 3. Ertrusiotr: displacement ofthe tooth from the socket in the direction oferuption. 4. Intrusion; movement into the socket along the long axis ofthe tooth. Very dillicult to accomplish. 5. Torque: controlled root movement labiolingually or mesiodistally while the crown is held relatively stable (mesial-distal root movenlent is also termed "uprightingr. 6. RotAtion: the only force system that can prcduce pure rot.tion fd moment with no netJbrce) is ple, which is two equal and opposite, noncolinear but parallel forces. Recuning tooth rotations after ortho- dontic cofiection occur because ofthe persistence of the elastic supracrestal gingival and transseptal.fbels). Importsnt: Need adequrte retention to prevent rclapse. gingival fibers (mainly Crown movement occurs when a force is applied at the bracket and a small couple is also applied to panially negate the tipping ofthe crou'n caused by the force. The center ofthe rctation is at the root apex. Root movement occurs when a forc€ is applied at the bracket and an even larger couple is applied to more than negate the tipping of the crown caused by the force. The center of rotation is at the crown of the tooth.

All of the following are functional appliances EXCEPT one. Frankel Bionator Clark's Twin Block Herbst Activator Quad-Helix

Quad-Helix This frxed appliance, consists of4 helices (2 onterior and 2 posterior). Essettially, this appli- ance is used for posterior cross-bite cases with a digital-sucking habit. Functional appliances are by definition ones that change the posture ofthe mandible, holding it open or open and forward. Stretch ofthe muscles and soft tissues creates pressures transmitted to the dental and skeletal struchrres, moving teeth and modifying growth. They are used to treat Class II malocclusions, Functional Appfian ces . (in biet - Cl^ssified asi Tissu€ borne: The Frankel functional appliance is the only tissue bome functional appliance, which serves to expand the arch by "padding" against the pressure ofthe lips and cheeks on the teeth and postures the mandible forward and downward. . Tooth borne: . Activator: advances the mandible to an edge-lo-edge position to induce mandibular growth for the correction ofClass ll malocclusion. The maxillary teeth arc prevented from erupting by the acrylic shelfwhile mandibular posterior teeth are free to erupt. This improves the deep bite seen in Class II cases. . Bionator: similar to the activator in function but its design is a himmed-down version ofthe activator to make it more comfortable to wear . Herbst appliance: it can be fixed or partially removable. A metal rod and a tube-telescopic apparatus is attached bilaterally to the maxillary first molars and mandibular first premolars. This helps to posture the mandible forward and induce growth. Jasper modified the appliance by replacing the tel€scopic apparahrs with a flexible plastic open coil spring. . Twin block appliance: the two-piece acrylic appliance postures the mandible forward with help ofocclusally inclined guiding planes and bite blocks. The vertical separation ofthejaws is also configured by the height ofthe bite blocks. It postures the mandible forward to induce growth for correction ofClass lI malocclusions.

Arrange the following procedures into their proper sequence for molar uprighting of a tooth requiring both a crown and crown lengthening Band Complete crown preparation and fabrication Complete crown lengthening procedure Separate Upright

Separate Band Upright Complete crown lengthening procedure Complete crown preparation and fabrication A common dental condition that can benefit from orlhodontic treatment prior to prosthetic treatment is the long-term loss ofa rnandibular permanent lirst molar. The loss ofthe first molar results in tipping, migration and rotation of the adjacent teeth into the edentulous space. Note: The best way to upright a second molar that had drifted mesially is by tip- ping its crown distally and opening up space for a pontic to replace the missing first molar, rather than attempting to move the second molar mesially to close the space. Important: A high mandibular plane angle is one ofthe most significant complications of molar uprighting, because if the molar is uprighted unsuccessfully, it can lead to an in- creased open bite and loss ofanterior guidance. A normal angulation ofa molar is desirable since it: . . . Improves the direction and distribution of occlusal forces Decreases the amount oftooth reduction required for parallelism ofthe abutrnents Decreases the possibility of endodontic, periodontic or more complex prosthodontic procedures .Increases the durability ofthe restorations, due to better force distribution . . . Irnproves the periodontal environment by elirninating plaque-retentive areas Improves the alveolar contour Imoroves crown-to-root ratio

A 6 year old and her mother come to your office. He rmom says "my kids overbite make her look like bugs bunny, her front teeth hide her lower lip". Whats wrong with her statement She is mixing up overbite and ovejet She is mixing up overbite and open bite She is mixing up overbite and negative ovejet She is mixing up her cartoon characters

She is mixing up overbite and ovejet This is a common la)?erson mistake. Overjet is in the anterior-posterior dimension, rvhereas overbite is in the vertical direction. Overbite is the vertical overlapping ofthe maxillary anterior teeth over the Overjet is the horizontal projection ofthe maxillary anterior teeth beyond the mandibular anterior teeth 3 mm

A patient presents claiing they have "long face syndrome". The man has obvious mouth breathing. What malocclusion do you immedietly think he has Dental open bite Skeletal open bite Dental cross bite Skeletal cross bite

Skeletal open bite (sometimes called long face syndrome) The following factors are associated with chronic rrouth breathing: . . . . Narrow face Narrow oropharyngeal space Chronic rhinitis: inflammation ofthe mucous membranes ofthe nose Chronic tonsillitis . Allergies . Deviated nasal septum Note: The earliest possible diagnosis ofthis open bite is essential because the condition is not self-correcting and usually worsens with time. Anterior open bites can be classi- fied as a form of apertognathism (which neans open bite deJbrmity)

Primary molar relationships are known as Class relationships Step relationships Primitive relationships Occlusion relationships

Step relationships Class relationships Step relationships Primitive relationships Occlusion relationships The primary molar relationship shown in the figure above is a mesial-step relationship, as the distal surface of the lower second primary molar is mesial to the distal surface ofthe upper second pri- mary molar. The mesial-step molar relationship allows for the first permanent molars to erupt into a normal occlusion immediately on eruption. Note that the permanent nolars are in a normal Class I occlusion. This figure demonstrates the fl ush-terminal-plane relationship for primary molars. The distal surfaces of the maxillary and mandibular second primary molan are in an end-to-end relationshio. (ie/ashlerminal-plane),the fiIst permanent molars do not erupt immediately into a normal relationship. As you can see, the first permanent molars are in a Class Il relationship. The Class II relationship usually is temporary until the second pdmary molars are lost and the permanent nolars move into a Class I relationship. This occurs at approximately age ten or eleven and is called the late mesial shift, Both the mesial-step and flush-terminal-plane relationships usually result in the development of a Class I permanent molar occlusion, although the flush-terminal- plane relationship can result in a Class ll relationship ifthe late mesial shift does not occur An- other stcp relationship involves a situation where the distal suface of the mandibular primary second molar is located to the distal ofthe distal surface ofthe maxillary primary second molar. This is termed a distal-step relationship. In these cases, the permanent molars erupt into a Class ll relationship. lmportant: The terminal plane relationship ofprimary second molars detennines the future anteroposterior positions ofpermaneot firct molars.

A steep mandibular plane correlates with all of the following EXCEPT one? Long anterior facial vertical dimensron . Anterior open bite Tendency to Class III malocclusion Greater maxillary-mandibular plane angle

Tendency to Class III malocclusion The mandibular plane angle can be visualized clinically by placing a mirror handle or other instrument along the border ofthe mandible. Important: A flat mandibular plane angle correlates with short anterior facial verti- cal dimensions (height) and anterior deep bite malocclusion. The angle between the mandibular plane (Go-Me line) and the maxillary plane flN,t-PNS line) rs called the maxillary-mandibular plane angle (MMPA).lts normal value is: 27'(+/- 4"). The greater value indicates a longer anterior face height. There is also an interaction between face height and the anteroposterior position of the mandible; all other things being equal, a long face predisposes the patient to Class II malocclusion. a short face to Class III malocclusion.

Identify the Frankfurt-Ilorizontal planeand the numbered points it uses for its origin. (SEE PIC pg 21 of decks)

The Frankfort-Horizontal plane is constructed by drawing a line connecting porion (4) and orbitale the skull. (8), This has been adopted as the best representation ofthe natural odentation of l. Bolton (Bo): highest point in the upward curvature of the retrocondylar fossa ofthe oc- cipital bone. 2.Basion (Ba):,lowest point on the anterior margin olthe foramen magnum, at the base of the clivus. 3. Articulare (,4r): the intersection of three radiographic shadows, the inferior surface of the cranial base and the posterior surfaces ofthe necks ofthe condyles of the mandible. 4. Porion (Po): midpoint ofthe upper contour ofths metal ear rod ofthe cephalometer. 5. Spheno-occipital synchondrosis (SO): junction between the occipital and basisphenoid bones. 6. Sella /S): midpoint of the cavity ofsella turcica. 7. Pterygomaxillary fissure (Przr): point at base of fissure where anterior and posterior walls meet. 8. Orbitale for: lowest point on the inferior margin ofthe orbit. 9. Anterior nasal spine (lNS): tip ofthe anterior nasal spine. innermost point on contour ofpremaxilla between anterior nasal spine and incisor tooth. 10. Point A fsabsprrale/: Il.PointB (Suplamentqle)| ifi.€rmost point on contour ofmandible between incisor tooth and bony chin. 12. Pogonion fPog): most anterior point ofthe contour ofthe chin. 13. Menton (Me): most inferior point on the mandibular symphysis, the bottom ofthe chin. 14. Gonion (Go): lowest most posterior point on the mandible with the teeth in occlusion. 15. Nasion fNa): anterior point of the inte$ection between the nasal and frontal bones. Important: The most stabl€ point in a growing skull from a cephalometric standpoint is s€lla turcica, the center ofthe pituitary fossa in the cranial base.

Which appliance is probably the most widely used by orthodontists today? The Begg appliance The edgewise appliance The universal appliance None of the above

The edgewise appliance To overcome the dcficiencies ofthe bbon arch (trhich was an eotlier Angle appliance) Angle reoriented the slot from vertical to hoizontal and inserted a rectangularwire rotated 90 degr€es to the orientation it had with the ribbon arch, thus the name "edgewise." The dimensions ofthe slot were altered to 0.022 x 0.028' and a 0.022 x 0.028 precious metalwire was used. These dimensions allowed excellent control of cro"{'n and root position in all three plan€s ofspace. The contemporary edgewise appliance has evolved far from the original design while retaining th€ basic prin- ciple of a rcctangular wire in a rectangular slot. Major steps in the evolution of cdgewise appliances in- clude: . Automatic rotNtional controli this is accomplished either by using twin brackets on the labial surface, or single brackets with extension wings that contact the arch wire to conffol and correct rotations. . Horizontal control: this is accomplished by varying the relative thickness ofth€ bracketbase for teeth of differenr thickness. Note: In the original edgewise appliance this was accomplishedby applying first-order bends ,liliolitgual bcnd! in the arch wire. . ltlesiodistal tip control: is accomplished by angulating th€ bracket or bracket slot to provide the proper tipping movement lor each tooth. Note: In the original edgewise appliance this was accomplished by ap- pll ing second-order bends langled bends) rn the arch wire. . Torque: is accomplished by having the bracket slots inclined to compensate fbr the inclination ofthe fa- cial surface..\-ote: [n the original edgewise appliance this was accomplished by applying third-order bends (r'aning btist in segments ofeach rcctangular arch rire) in the ^rah \Nie. Brackets are the attachments through which forces are appliedto the teeth and they allow the placement of arch* ire and other accessodes to b ng about the desircd tooth movement. The brackets most commonly used are the Edgewise brackets - single and double edgewise- and the Begg brackets. Edgewise b.ackets have an archwire channel which is rectangular in cross-section, with the largest dimension horizontally. These brackets can also be us€d with round cross-section archwires. The slot sizes commonly used are 0.022 inch 10.JJ md) and 0.018 inch (0.45 hm).Thebftcket has tie-wings on opposite sides of the archwire slot for engaging a ligature that is used to bind the archwire to the bracket. Thc Begg bracket has a narrow slot wh€re an archwire is looscly fitted and held in place with a locking pin. Unlike the Edgewise brackets, these Begg brackets can only be used with round cross_seclion archwires.

The length of the mandibular arch is longer than the maxillary arch The difference is only about 2mm The first statement is true; the second statement is false The first statement is false; the second statement is true Both statements are true Both statements are false

The first statement is false; the second statement is true Rememb€r: The maxillary arch is slightly longer in length compared to the mandibular arch. The reason is the sum ofthe M-D diameter ofthe maxillary permanent teeth is ap- proximately 128 mm, whereas the sum of the M-D diameter of the mandibular permanent teeth is approximately 126 mm. l.Permanent teeth move occlusally and buccally while erupting. \ot€ 2. Also, during active tooth eruption there is apposition ofbone on all surfaces 3.The grand design of the human face is the result of remodeling and dis- placement which interact to produce the final result. 4. Displacement and remodeling can occur in opposite directions. 5. The functional matrix theory (the 3rcl theory o the back oJ card #34) holds that: r Qnft ticc,re ic nrim . . . .. , --..-4ry Bone is responsive to soft tissue Deglrtrtion (mandibular function) influences mandibular growth The soft tissues ofthe brain expand thus pacing growth ofthe flat bones of the skull 6. The growth in width ofthejaws is generally completed before the adolescent growth spurt begins. 7. The growth in length ofthe jaws continues through the growth spurt.

The most commonly impacted tooth is the mandibular canine The longer a tooth has been impacted the more likely that it will be ankylosed The first statement is true; the second statement is false The first statement is false; the second statement is true Both statements are true Both statements are false

The first statement is false; the second statement is true The maxillary canine is the most commonly impacted tooth. Failure ofa permanent tooth to erupt may cause damage to roots of other teeth and also create a severe orthodontic problem. Orthodontic consultation is indicated when first ob- served on an x-ray. An impacted canine or other tooth in a teenage patient can usually be brought into the arch by orthodontic traction after being surgically exposed. In older pa- tients, there is an increasing risk that the impacted tooth has become ankylosed. Even adolescents have a risk that surgical exposure ofa tooth will lead to ankylosis. In treatrnent planning for an impacted tooth, three principles should be followed: l. The prognosis should be based on the extent of displac€ment and the surgical trauma required for exposure. 2. During surgical exposure, flaps should be reflected so that the tooth is ultimately pulled into the arch through keratinized tissue, not through alveolar mucosa. 3. Ad€quate space should be provided in the arch before attempting to pull the impacted tooth into position. It{ote: Research suggests the association of impacted canines with missing lateral inci sors or shortened roots oflateral incisors. The distal aspect ol the root of lateral incisors suides the eruotion ofcanines.

A concave profile is associated with a class III occlusion It is also termed a retrognathic profile The first statement is true; the second statement is false The first statement is false; the second statement is true Both statements are true Both statements are false

The first statement is true; the second statement is false *** A concave profile is also termed prognathic. Although the maxilla can be termed prognathic and/or retrognathic. when no clarification is given these tenns refer to the mandible. . 1. An orthognathic profile is one in which the nose, lips and chin are harmo- \otes niously related. This relationship is usually accompanied by a Class I dental 2. A prognathic profile is one in which rhe mandible is markedly forward of the maxilla giving a concave midfacial appearance. This is often indicative of a Class III malocclusion. The maxillary incisors will most likely be tipped lingually. 3. A r€trognathic profile is one in which there is a protruding upper lip or the appearance of a recessive mandible and chin, or convex profile. The convex- ity is due to the relative prominence of the maxilla compared to the mandible. The mandibular incisors will most likely be tipped forward. This relationship is usually accompanied by a Class II malocclusion. 4. As children mature their profiles become less convex. 5. Speech is affected in severe malocclusions along with other oral fturctions (i.e., swallowing and mastication). For example, patienls with a skeletal Class III malocclusion sometimes have difficulty pronouncing "f' and "v" soutds. Important: A bimaxillary dentoalveolar protrusion means that in both protrude. This condition is seen in facial appearances in 3 ways: excessive separation of the lips at rest (rnco mpelence), severe lip strain to bring the lips into closure), and prominence of lips in the profile view.

Leeway space is a calculated difference between primary and permanent tooth size Theres typically more leeway space in the maxillary arch The first statement is true; the second statement is false The first statement is false; the second statement is true Both statements are true Both statements are false

The first statement is true; the second statement is false There is typically more leeway space in the mandibular arch. ImportsDt: l. The primary anterior teeth (ihcisots ahd canines) are narrower than their permanent successors mesiodistally. 2. The primary molars are wider than their permanent successors mesiodistally. *** This size di{ference has clinical significance. The diff€rence is called the leeway space. The mandibular l€eway space avemges about 2.5 mm on esch side while the maxillary leeway space averages about 1.5 mm on e.ch sid€. The important factor is that some space will be avaihble in the posterior palt ofthe mouth. This leeway space serves to at least accommodate the permanent canines, which are generally larger than the primary canines. During the canine-premolar transition period, the permanent first molars generally move mesially into the leeway space after the primary second molars are shed, thus causing a loss in arch length. Note: This is referred to as *** "the late mesial shift ofa permanent first molar." l On occasion, the permanent incisors "spread out" due to spacing. This is referred to as the "ugly duckling stage"of development. With the eruption of the permanent canines, the spaces often will close. As a g€neral guideline, a maxillary central diastema of2 mm or less will probably close spontaneously, while total closure ofa diastema initially geater than 2 mm is unlikely. 2. The permanent dentition stage begins when the last primary tooth is lost. 3. For the maxilla and mandible: Crowth in the width is completed first, then growth in length, and finally glowth in height. 4. Maxillary and mandibular arch widths increase and this is completed before the ado- lescent growth spurt 5. The dental arch perimeter (length) decreases a surprising amount during the late adolescent and young adult periods due to the late mesial shift ofthe permanent molan into the leeway space, the mesial drift tendency ofthe posterior teeth in general, and the lingual po- sitioning of the incisors. 6. Increases in the vertical height ofthe jaws and face continue until 17 or l8 in girls and in the earlv twenties in bovs.

An actiye finger spring of a removable appliance usually touches the tooth with a point contact. What is the most likely type of tooth movement produced in this situation? Tipping Extrusion Intrusion Translation

Tipping The best method for tipping maxillary and mandibular anterior teeth is with linger springs. These fin- gcr springs are attached to a removable appliance. Tte most common problems associated with these simple removable appliances are lack ofpatient cooperation, poor design leading to lack ofretention, and improper activation. An undesimble common side effect ofa finger spring is the tendency for the root apex to move in the direction opposite from the crcwn. Z-springs can also be used but they deliver excessively heary forces and lack rang€ ofmotion. Important: Ma,\illary incisor rotation is not commonly treated during the stage of mixed dentition. It is best teated after all permanent teeth have efl)pted (earll permanent dentition). This is usually ac- complished with a simple removable appliance. Howevet ifthe incisor is in crossbite, it should be cor- rected as soon as possible (while r' - , il is erupling). -, Lwhen using buccal coil springs to try and regain space by pushing a tooth mosially or dis- ,.:Note{ii tally, be careful because what commonly occurs is rotation of that tooth instead of actual i;,r::,,,,,':: movement. *tt 2. Th" fo."" generated in the spring is directly proportional to the distance (d) that an orthodontic spring is deflected and the radius (r) ofthe wire. It is inversely propo(ional to the length ofthe spring. Precisely: Fct Exc€ssile orthodontic force used to move a tooth may: (l) Cause hyalinizatio'l (necrcsis) of the PDL mem- brane; d14 l3 (2) Cause undermining resorption; (3) Crush the periodontal ligament Importanti Pe.iodontal disease dudng orthodontic therapy is preventable and is controllable and in conrinuous studies affer orthodontic therapy has been completed, it has bcen shown that under the properly controlled regimen oftreatment the destruction to the periodontal tissues ofthe teeth is not accen- tuated to a statistically significant degree as great€r than that which occurs during the same intedm \r'ithout orthodontic therapy. Note: When a patrent (young or old) )s in active orthodontic heatment and the gingiva is inflamed. the dentist should encourage better oral hygiene. It may be useful to recommend the use ofwater irrigation devices to help flush food debris away from the brackets.

A periapical radiograph of primary tooth M shows #22 overlapping half the root. The patient is not in the chair so you cant palpate to determine on which side tooth #22 is erupting. What would you presume? Tooth #22 is erupting distally Tooth #22 is erupting mesially Tooth #22 is erupting lingually Tooth #22 is erupting facially

Tooth #22 is erupting facially Sometimes the permanent mandibular canines erupt facially relative to th€ primary canines. However, often they are right in line with the primary canines. Ifthere are problems in eruption. these teeth can be displaced either lingually or labially, but usually they are displaced labi- ally ifthere is not enough room to accommodate them within the arch. .. , l. The mesial inclined plane ofthe primary maxillary canine articulates with the ,\oto* distal inclined plane of the primary mandibular canine. This is the normal rela- '*aii' tionship. 2. In both the maxillary and mandibular arches, the permanent incisor tooth buds lie lingual as well as apical (inferior) to the primary incisors. The result is a tendency for the mandibular permanent incisors to erupt somewhat lingually and in a slightly inegular position. This occurs even in children who have normal dental arches and normal spacing within the arches. 3. Permanent teeth normally move occlusally and buccally while erupting. 4. Remember: The maxillary arch is sli glttly longer (approximately 128 mm) than the mandibular arch (approximqteu 126 mm )-

Bone deposition in the ? region is responsible for the lengthening of the maxillary arch Palate Tuberosity Incisor Zygomatic

Tuberosity The bony maxillary arch lengthens horizontally in a posterior direction. Bone has been de- posited on the posterior-facing cortical surface ofthe maxillary tuberosity. Resorption occurs on the opposite side ofthe same cortical plate, which is the inside surface ofthe maxilla within the maxillary sinus. lmportant: The maxilla develops postnatally entirely by intramembranous ossification. Since there is no cartilage replacement, growth occurs in two ways: (l) by apposition ofbone (2) by surface remodeling. at the sutues that connect the maxilla to the cranium and cranial base and ,-'-- ,.. l. The maxilla migrates downward and forward away from the cranial base and l$ote$j undergoes significant surfac€ remodeling. This surface remodeling includes re- 'k; sorption of bone anteriorly and apposition of bone inferioriy. 2. Much ofthe anterior movement ofthe maxilla is negatedby anterior resorption, and downward migration is augmented by inferior apposition ofbone. 3. As growth of sunounding soft tissues translates the maxilla downward and for- ward, opening up space at its supedor and postedor sutural attachments, new bone is added on both sides ofthe sutur€s. 4. As the maxillary tuberosity grows and lengthens posteriorly, the whole maxilla is simultaneously carried anteriorly. 5. The amount of forward displacement exactly equals the amount of posterior lenglhening. The counterparts to the bony maxillary arch development include: . . . . The nasomaxillary complex The anterior cranial fossa The palate The body ofthe mandible

All of the following are materials used in archwires EXCEPT Stainless steel Beta titanium Nickel-titanium Vitalium

Vitalium (commonly used in partial dentures) The prop€rties ofan ideal wire material for orthodontic purposes can be described largely in terms ofthe fol- (4) High formability lowing criteria. It should possess: (1) High strenglh (2) Low stifliess (3) High working range and In addition, the material should be weldable or solderatrle, so that hooks or stops can be attached to the wire. Loops and helices are incorporated into archwires to increas€ the activation range. St.inless steel wires are very popular because oftheir good mechanical ance, and low cost. Tle properties, excellent corrosion resist- ry?ical formulation for orthodontic use has l8% chromium and 8% nickel. Note: Stainless steel exhibits the highest modulus ofelasticiry frltlresr/ and lowest springback. Nickel-titanium alloys offer a highly desirable combination of a very low modulus ofelasticity and an extremely wide working range. Beta titanium wires are also known as TMA able combination ofstrength and springiness (i-e., (tilanium-molybdenum d//o', wires. They offer a highly desir- formabiliry Note: Each of the major elastic properties (i.e., strength, stillness/springiness, and range) is excellent resilience) and reasonably Sood by a change in the lenglh and cross section ofa wire. Doubling the length of a wire decrease its strength by half, makes it I times less stiff, and gives it 4 times the range. Similarly, when lhe diameter of a wire is doubled, its strength is increased by 8 times, its stifiness by 16 timcs, and its working range is decreased by half. R€member: Strength: Stiffness x Range \€r] important: Deleteious €ff€cts oforthodontic forcel . Effects on the pulp: light forces should have little ifany effect on the ^ffected pulp; loss ofvitality is very rare but has been seen in teeth that are moved with unusually hearry force. Note: Endodontically treated teeth are more prone to root resorption when orthodontically moved. . Effects on root structure: root resorption is a potential side effect ofonhodontic movement; healy con- tinuour forces have more potential to crcate rcot tesorption than do light forces. Areas ofresorption ofboth cemenrum and dentin ofthe root tend to fill in with new cementum so that the original form ofthe root is retained. \ote: Only ifthe attack on the root suface produces large def€cls at the apex that ev€ntually bc_ come separated fiom the root surface is repair ofthe damaged root impossible. . . . \tobilit! ofteeth: moderate mobility occurs and resolves with the completion of the.apy. Pein: usually occurs within a few hours ofinitiation of force application and lasts for 2 to 4 days. Tissue inflammation; usually results liom poor oral hygiene.

A patients SNA angle is 78degrees and the SNB is 76degrees. This tells us that the maxilla is ?, the mandible is ?, and the skeletal profile is ? Prognathic; retrognathic; Class II Retrognathic; prognathic; Class III Prognathic; prognathic; Class I Retrognathic; retrognathic; Class I Prognathic; prognathic; Class II Retrognathic; retrognathic; Class II

answer not in decks

An anterior crossbite should be corrected as soon as it is detected Both the statement and the reason are correct and related Both the statement and the reason are correct but NOT related The statement is correct, but the reason is NOT The statement is NOT correct, but the reason is correct NEITHER the statement NOR the reason is correct

answer not in decks

Maxillary expansion is often done to correct crossbites Tongue thrusting often causes crossbite The first statement is true; the second statement is false The first statement is false; the second statement is true Both statements are true Both statements are false

answer not in decks

The classic symptoms of a sucking habit may include all of the following EXCEPT Anterior open bite Crossbite Expanded maxillary arch Proclination of the maxillary incisors Retroclination of the mandibular incisors A Class II malocclusion

answer not in decks

Match the dental arch relationships on the left with the correct depiction ofthe relationship on the right. (SEE PIC page 41)

see pic