Chapter 6 OA

Openbites

A type of malocclusion when the anterior teeth do not overlap when the patient's posterior teeth are in centric occlusion. This is often the result of a habit when the arches were developing; finger or thumb sucking as well as overuse of a pacifier. At age 5, behavior modification techniques should be recommended to parent. It is also possible to have an occlusal relationship where the anterior teeth are in an edge to edge bite and the posterior teeth are not in occlusion.

Class II Malocclusion

Also referred to as Disto-occlusion MB cusp of maxillary 1st molar occludes mesial to the buccal groove of the mandibular first molar There are two (2) divisions of Class II Malocclusion

Hereditary Factors Influencing Occlusion & Alignment

Congenitally missing teeth (partial anodontia) or development of supernumerary teeth Impacted teeth Development of large teeth (macrodonts); or unusually small teeth (microdonts).

Vertical Alignment

In centric occlusion, the maxillary incisors also overlap the mandibular incisors in a vertical direction. This is called an overbite. This normal amount of vertical overlap in the anterior region allows for contact between the posterior teeth during mastication

Class I Occlusion

Two categories of Class I Occlusion: Class I Ideal Occlusion (only 2-4%) Class I Malocclusion or Neutrocclusion MB cusp of maxillary 1st molar occludes with the buccal groove of the mandibular 1st molar Associated with a mesial step mand canine more anterior than max

How to compare teeth for occlusion

Use first molars to classify occlusion, if extracted then go by canine relationship. another time to use canine is if 1st premolars on one arch and not other,

Centric Relation

is the relationship of the maxillary and mandibular jaws to one another

Centric Occlusion

is the way that the teeth in the mandibular arch come in contact with those of the maxillary arch. way teeth come together like in our typodont

occurs on only one side of the dentition

occurs on both sides of the dentition

Unilateral Posterior Crossbite

occurs on only one side of the dentition

edge to edge

only on aterior and has atritian

Labioversion

: an anterior tooth that has erupted in a position closer to the lip

Functional Occlusion

: the way the teeth come together during mastication

Acromegaly

Excessive secretion of growth hormones by the pituitary gland. Occurs in adults, more often men. See an increase in facial structure; as a result the mandible grows larger than maxilla Complete crossbite of the arch occurs

Musculoskeletal Factors

Facial structure, including the size and shape of the bone as well as the surrounding muscles, like the cheeks and lips, which help to keep the teeth in proper alignment. An over or under developed lip and/or jaw bone can have a detrimental impact on the alignment of the teeth.

Controllable Factors

Failure to restore decayed teeth -thumb suckers. Can change shape of teeth in arch. -finger nail biting or biting on pensils. Premature loss of deciduous teeth and no placement of a space maintainer Oral habits creating an abnormal alignment of the teeth including: thumb and/or finger sucking, chewing on objects, tongue thrusting & mouth breathing

Children will have one of three relationships

Flush Plane: the primary maxillary and mandibular molars are flush with one another. flush means they meet up nicely Mesial Step: the primary mandibular molar is more anterior to the maxillary molar. when taking a step off where the teeth occlude and the other dentition is leaving over so you can take a step off of it like a stair. Distal Step: the primary mandibular molar is distal to the maxillary molar

Underjet

--horizontal ?? mand overlaps max aka cross bite When the lower jaw protrudes forward and the mandibular teeth overlap the maxillary teeth an underjet occurs. We utilize the probe to measure the amount of underjet but this time we measure from the labial surface of the maxillary incisors to the lingual surface of the mandibular incisors.

Overbites

--vertical Slight Overbite: the maxillary incisors overlap the mandibular incisors within the incisal third (NORM) Moderate Overbite: the maxillary incisors overlap the mandibular incisors within the middle third Excessive or Deep Overbite: the maxillary incisors overlap the mandibular incisors within the cervical third

Curve of Wilson

-goes in a medial lateral direction. transverse curve that is found when observing the posterior teeth in a right to left direction . This curve is also lost over time due to attrition (excessive wear on the occlusal surfaces) Bruxism and clenching are two parafunctional habits that cause excessive wear on the biting surfaces of the teeth when the teeth are not being utilized for mastication. These are usually subconscious habits that occur when a person is sleeping or deep in thought.

Often a result of crowding. Commonly caused by:

1) premature loss of deciduous teeth and no space maintainer so adjacent teeth drift into the space 2) a narrow arch 3) secondary teeth are simply too large for the space

Eruption of Permanent Molars

Although the deciduous teeth erupt in an upright position, the permanent first molars erupt in a mesial direction. As a result, they will drive the primary molars forward closing some of these extra spaces. The rest of the spaces are consumed by the larger permanent teeth.

Diastemas on Primary Dentition

Although the maxilla and mandible grow as the child grows the teeth do not. As a result, spaces develop between the primary teeth. ***** The largest diastemas occur mesial to the maxillary canines and distal to the mandibular canines. These spaces are referred to as primate spaces. (Easy to remember primate in primary dentition). As the child grows, s/he may also develop diastemas between the central and lateral incisors. Parents often express concern about these spaces. But the spaces are often necessary to accommodate the larger teeth in the permanent dentition.

Ankylosed Teeth

Ankylosis: occurs when no PDL is present and the cementum on the root of a tooth fuses to the alveolar bone. This can be caused by trauma. A common occurrence with the deciduous mandibular molars but can also occur on the maxilla. -tooth doesnt have PDL then the tooth gets anchored into bone. --results in arch length or supereruption of the opposing tooth.

Individual Habits

Cheeks and lips counter balance and keep teeth in alignment. Those who play a musical instrument, such as woodwind and brass players, purse their lips which can impact the teeth over time.

Making Appropriate Referrals

Children should be referred to a dentist who corrects malocclusions. This specialist is called an orthodontist. Referrals should be made at an early age when bones are still developing. Wearing appliances when the maxilla and mandible are still growing may prevent the need for orthodontic appliances later on and/or can reduce the amount of treatment time.

Supporting Cusps

Cusps that function during centric occlusion are called supporting cusps. These include the lingual cusps of the maxillary posterior teeth & the buccal cusps of the mandibular posterior teeth. Since the maxillary arch is larger than the mandibular arch, the buccal cusps of the maxillary molars sit out over the buccal cusps of the mandibular molars. As a result, they are not considered the functional cusps during mastication.

Anterior Crossbite

Described in one of two ways: 1) Maxillary anterior teeth sit lingual to the mandibular anterior teeth instead of overlapping them 2) Mandibular anterior teeth sit labial to the maxillary incisors. Often occurs when the patient has a protrusive mandible due to the growth of the condyle. This is the and most difficult to treat orthodontically and generally requires some surgery

Class II Divisions

Division I - Class II molar relationship with protrusion of centrals and laterals all four incisors are over jet ? Division II - Class II molar relationship with retrusion of maxillary central incisors and protrusion of max lat incisors

Classification of Occlusion

Dr. Angle developed a system for classifying the occlusion of the permanent dentition. The system utilizes the relationship between the maxillary and mandibular first molars. In the absence of the molars, the canine relationship is evaluated. go by first permanent molar, if not there then canines. if premolars are missing and the molars can move forward, then do canines.

Individual Mal-relationships

Malocclusion of individual teeth in relation to adjacent teeth within the same arch. Often a result of crowding or retained deciduous teeth. Named by their location.

Posterior Teeth curvature

Maxillary Arch: the crowns have a slight buccal inclination Mandibular Arch: the crowns have a slight lingual inclination

Clinical Observations

Mesial step is the most common relationship Second most common relationship is a flush plane The least common and less ideal, is a distal step. It is also the most difficult to correct orthodontically.

Skeletal Classifications

Mesognathic Profile: Retrognathic Profile: Prognathic Profile:

Mesognathic Profile

Mesognathic Profile: facial profile in centric occlusion where the maxilla and mandible give the face a relatively flat appearance or straight profile -relatively flat

Posterior Crossbite

Occurs when the buccal cusps of the teeth in the maxillary arch lie in the fossae of the mandibular teeth instead of overlapping the mandibular teeth as they should. -mand teeth sitting more buccaly. can be one side, unilateral or bilateral. When mand jaw isnt centered basically --when they have that thing in roof of mouth that tightens with a key

Myofunctional Considerations

Orofacial myologists- works with children. believe early identification of tongue thrusters and mouth breathers is critical when treating malocclusion. Properly closed lips help to maintain the normal inclination of the anterior teeth. When the lips are separated at rest the teeth often drift forward.

Dental Curvatures

People often think the teeth are square and flat and in straight lines. However, when looking at the photo on the next slide you will see that both the crowns and the roots of the teeth are slightly inclined. It is essential that you understand this concept for proper adaptation when exposing radiographs and completing instrumentation in the clinical setting.

Steps or Planes

Since the deciduous teeth erupt before the permanent molars, their relationship determines the mesial-distal or anterior- posterior relationship of the permanent molars.

Why Determine Occlusion ?

Some believe occlusion is merely an esthetic correction. However, when one's teeth do not occlude properly, the teeth and the periodontium are unable to effectively perform the functions for which they were designed. Occlusal disharmony may lead to occlusal trauma; and although occlusal trauma does not directly cause periodontal disease it can be a contributing factor that advances the disease.

Terms Used to Describe Malpositioning of Individual Teeth

Supraversion: a tooth that is super erupted or elongated beyond the line of occlusion because there is no opposing tooth in the opposite arch or the tooth has drifted. -tooth missing on opposite arch Infraversion: a tooth that is below the line of occlusion (an example may be a primary tooth that is "ankylosed")

Suggested Treatment curve of wilson

Taking impressions and constructing a removable acrylic occlusal niteguard or a flat plane nonrepositioning splint that the patient wears when sleeping minimizes further attrition and serves to spread the occlusal stresses throughout the entire dentition. (BQ: different than a sports mouthguard)

Note Relationship of 1st Molars

The MB cusp of maxillary 1st molar sits in the buccal groove of the mand 1st molar

Anterior Teeth curvature

The crowns of the anterior teeth on both the maxillary and mandibular arch tip in a labial direction and the roots are tipped in a lingual direction.

Leeway Space

The deciduous molars are actually longer in a mesio-distal direction than their permanent successors (premolars). As a result, additional space is created which is often utilized by the larger permanent canines. When the 2nd permanent molars erupt before the premolars they will move the 1st molar forward shortening the leeway space and creating occlusal disharmony. -space gained because premolars are smaller than decidious molars.?

Supporting Anterior Teeth

The incisal edge of the mandibular anterior teeth are also considered supporting cusps since these edges occlude with the lingual surface of the maxillary incisors.

Primate spaces

The largest diastemas occur mesial to the maxillary canines and distal to the mandibular canines. These spaces are referred to as primate spaces. (Easy to remember primate in primary dentition).

Class II, Division I

The maxillary anterior teeth protrude labially (creating an overjet); and the mandibular anterior teeth super erupt causing a deep overbite.

Class II, Division II

The molars are in the same relationship as Class II, Division I but all of the maxillary incisors are not protrusive. The maxillary central incisors are retruded and have a lingual inclination while the maxillary laterals are protruded labially (overlapping the central incisors).

Centric or Resting Occlusion

The most retruded relationship of the mandible to the maxilla when the condyles of the TMJ are in their most upward, backward and unstrained position in the glenoid fossa. The teeth will not touch when the jaws are in this relationship. The condiles of the TMJ are in most retruded position, so there is space between the teeth meaning they wont touch. 2-3mm space

Benefits of Two Antagonists

The opposing two teeth serve to equalize the forces of impact during occlusion and mastication If a tooth is lost in one jaw, the alignment of the opposing jaw is not immediately disturbed which allows time to get the necessary restorative work completed.

Centric Stops

The three areas of centric stops or centric contacts are: Height of cusp contour Marginal Ridges (Ridges elevated) Central Fossae

Three Spatial Planes

Utilized when determining and classifying occlusion. a) horizontal b) vertical c) transverse Like the top on a shoe box, the maxillary arch is slightly larger than the mandibular arch and the maxillary teeth overlap the mandibular teeth slightly in both a vertical and a horizontal direction when the teeth are in occlusion.

Premature Loss of Permanent Teeth

When a tooth is lost prematurely, the neighboring teeth will drift towards that open space. The tooth posterior to the extraction site will drift in a mesial direction and the tooth anterior to the extraction site will drift distally. In addition, the tooth in the opposing arch will "super" erupt

End-to-End Bite

When the molars are in a cusp to cusp occlusion instead of the mesial buccal cusp of the maxillary 1st molar lining up with the buccal groove of the mandibular 1st molar. An end to end bite can occur unilaterally and bilaterally.

Class I Malocclusion

With a Class I malocclusion the molars are in ideal position but there are other factors contributing to the malocclusion. These might include an open bite, overbite, rotated anterior teeth and/or crowded or overlapped anterior teeth.

Buccoversion

a posterior tooth that has erupted in a position closer to the cheek

Linguoversion:

a tooth that has assumed a position closer to the tongue

Torsiversion

a tooth that is turned or rotated. We generally place an arrow on the chart next to the tooth to designate the direction of the rotation.

Intercuspation

aprat of Centric occlusion: is the mesial-distal and buccal-lingual relationship that determines how the cusps of the maxillary teeth will touch, hit and interlock with the cusps of the mandibular teeth. Teeth are aligned in such a way that each tooth occludes with two teeth in the opposing arch, called antagonists. The only exception to this rule is the mandibular central incisors because they only occlude with one tooth. Max buscal cusps sits over the mand teeth and dont occlude lingual of mx sit in fossae of mand (Max arch is bigger). Mand buccal cusp sit in fossa lingual of mand sit lingual and do nit occlude

Class III Malocclusion

assocaited with prognathic proflile, edge to edge, or a full cross bite. Also referred to as Mesio-occlusion MB cusp of maxillary first molar occludes distal to the buccal groove of the mandibular first molar The anterior teeth are either in crossbite or are in an edge-to-edge relationship if not the width of premolar we say " a tendency"

Prognathic Profile

facial profile with a concave appearance due to a protrusive mandible and a normal or underdeveloped maxilla -underjet or crossbite sometimes or even edge to edge

Retrognathic Profile:

facial profile with a convex appearance as a result of a protruding maxilla and a recessive mandible and chin

overjet.

probe against labial aspect of mand teeth and measure to lingual aspect of max teeth. DO NOT INCLUDE WIDTH this is where 8,9 grow too outward A probe is utilized to measure overjet. The tip of the probe is placed against the labial surface of the mandibular incisors; and the distance between the labial surface of the mandibular incisors and the lingual surface of the maxillary incisors is measured in mm. -The force of the tongue is pushing the maxillary anterior teeth forward. An underdeveloped upper lip is often a factor.

Static Occlusion

when teeth are occluded on study models (we use an articulator to occlude the study models in the lab setting) ex typodont