21-treatment of class I malocclusion

what is the wedge theory?

-take out the teeth further towards the back of the wedge and you get a little bit more of a closing effect on the teeth

how do you treat scissors bite (bu crossbite)

1. dental expansion of the mn arch and constriction of the mx arch 2. jaw surgery

extraction mechanics usually ___________ the bite

deepens (wedge effect, uprighting of incisors)

what do you develop the treatment plan from?

prioritized problems list

critique first premolar extractions

-maximum posterior anchorage -maximum retraction of anterior teeth

how do you treat an antero-posterior discrepancy (with CR-CO shift)

1. anterior crossbite: advancement of the upper incisors 2. typically requires early treatment (two phases)

what are the treatment options for crowding?

1. arch expansion (non-extraction) 2. extractions 3. IPR

what are some factors to consider when treatment planning?

1. chief complaint 2. motivation: cooperation/compliance 3. expectations 4. facial proportions and soft tissue 5. growth potential

how do you correct skeletal posterior crossbites?

1. mx expansion involving opening of the midpalatal suture -RPE/RME

when treating a class 1 malocclusion, what problems should be treated earlier

1. transverse problems -orthopedic palatal expansion 2. vertical growth problems -open bite vs deep bite

what is the most common malocclusion

class I malocclusion

critique second premolar extractions

-less anchorage as compared to option 1 -less retraction of anterior teeth -more difficult to correct anterior crowding -"wedge theory" for open bite treatments

what are the potential problems for a class I malocclusion

1. arch-space discrepancy 2. transverse discrepancy 3. vertical discrepancy 4. soft-tissue problems -lip strain, gingival show, bi-mx dental protrusion 5. anomalies in form, number, and position of teeth 6. antero-posterior discrepancy -anterior crossbites, pseudo class III

rank the malocclusion trends in the US from highest to lowest

1. class I malocclusion (50-55%) 2. normal occlusion (30%) 3. class II malocclusion (15-20%) 4. class III malocclusion (1%)

what are the treatment options for spacing?

1. close spaces -class 1 mechanics/power chain 2. retention concerns 3. evaluate for Bolton discrepancy, potential restorations

how do you treat lip strain due to proclined incisors (bi-maxillary protrusion)

1. consider racial norms (may not want to change) 2. first premolar extractions (retract incisors/lips)

how do you tx dental posterior crossbites?

1. dental tipping -TPA/Quad helix -removable appliances -expanded archwires -cross elastics

how do you treat an open bite caused by a vertical skeletal discrepancy causing lip strain

1. depends on how steep the mn plane is -posterior mx impaction

how do you treat open bites?

1. incisor extrusion (vertical elastics) 2. maintain curve of spee and intrusion of posteriors to deepen the bite (TAD)

how do you treat deep bites

1. incisor intrusion 2. leveling of the curve of spee and extrusion of posteriors to open the bite (intrusion arches)

should you consider extraction when there is 5-9 mm crowding?

1. non-extraction or extraction treatment possible 2. extraction depends on: -hard and soft tissue characteristics -incisor position or angulation 3. non-extraction -tx with transverse expansion across the molars and premolars

what are the class I treatment options for anomalies (form, number, position)

1. open/consolidate space of missing teeth 2. create space for impacted teeth then expose and bond and bring it to the arch 3. restorations will be needed to correct tooth size discrepancy, misshaped, or missing teeth 4. adjunctive orthodontics

should you consider extraction when there is less than 4 mm crowding?

1. rarely indicated 2. only if there is severe incisor protrusion or severe vertical discrepancy 3. consider IPR or dental expansion/incisor advancement and proclination

T/F: there IS a need for growth modification when treatment timing for a class I malocclusion

FALSE

how can you perform a mx skeletal expansion

RPE/RME

T/F: class I malocclusion are good potential invisalign cases

TRUE

T/F: when treatment planning for a class I malocclusion, it is most efficient if started in the LATE MIXED or PERMANENT DENTITION

TRUE

T/F: you should address any pathology/perio prior to treatment

TRUE

what is a dental class I

class I molars

which extraction option will give you the best anchorage control?

extractions of 4

where is IPR most commonly performed?

lower anteriors

what is the goal when extracting to tx a class I malocclusion

maintain class I molar and canine

lip strain due to vertical skeletal discrepancy may require what?

maxillary impaction surgery -best to wait until after growth

when is it indicated for removable appliances (invisalign)

mild crowding/mild spacing

what can a mx skeletal expansion correct?

moderately crowded cases

how do you treat gummy smile (excess gingival show, longer lower facial height)

mx impaction

what is a skeletal class I

normal ANB and facial convexity

how do you perform IPR

polishing strips or rotary discs

should you consider extraction when there is >10 mm of crowding?

premolar extraction almost always required

what can IPR tx?

treat minimal crowding cases <4mm