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Orthodontics > Class 3 Malocclusion > Flashcards

Class 3 Malocclusion Flashcards

1
Q

Class 3 Malocclusion definition

A
  • Lower incisors occlude anterior to the cingulum plateau of upper central incisors
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2
Q

What percentage of population?

A

3% Caucasians
5% population

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3
Q

Feature of class 3 Malocclusion

A
  • Skeletal
  • Soft tissue
  • Dentoalveolar and occlusal
  • Facial growth
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4
Q

Skeletal AP

A
  • class 3
  • maxilla retrusion is most common factor effect 60% of cases.
  • low cranial base angle, forward position of mandible
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5
Q

Skeletal vertical

A
  • Average , increased and reduced
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6
Q

Skeletal - Transverse

A
  • large mandible or small maxilla (hypo plastic) or combination of both.
  • short and narrow max cause cross bites.
  • Asymmetries due to,
    1- Crossbite and occlusal displacement.
    2- Growth
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7
Q

Soft tissue

A
  • Upper to lower lip anterior oral seal
    Not involve in Aetiology but encourage Dento alveolar compensation.
  • Tip teeth to compensate SK relationships
  • Upper to lower lip anterior oral seal
  • Increase vertical skeletal proportion, tongue ti lip seal
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8
Q

Dentoalveolar compensation.

A

A mechanism through which soft tissues (lips, tongue, cheeks) produce more class 1 incisor relatiohship when AP skeletal pattern is SK 2 or SK3.

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9
Q

Dentoalveolar Feature

A

Dentoalveolar compensation
- Upper incisor proclined
-lower incisor retroclined
- class 3 molar
- positive or negative OJ
- Decreased OB

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10
Q

Occlusal Features

A

Overjet
-Can be + OJ and -OJ
- displacement from E-E

Overbite
- depends on vertical discrepency

Buccal cross bite
- uni / bilateral
- broad mand to narrow max.

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11
Q

Occlusal and Dentoalveolar Feature

A
  • Maxilla Retrognathia - crowding
  • Mandible Prognathism- Spaced/ aligned/ crossbite
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12
Q

Facial Growth
Why facial growth matters?

A
  • tends to Unfavourable
  • wait until growth ends for treatment
  • Mandible becomes more Prognathic
  • Vertical growth reduce overbite
  • Dentoalveolar compensation - Maintain positive Overjet
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13
Q

Timing of treatment

A

Mixed Dentition -
- Crowded upper lateral incisors
- Anterior crossbite with displacement
- Buccal crossbite with displacement

Permanent
- orthodontic alone
- orthodontics and surgery

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14
Q

Tteatment Planning on basis of?

A
  • Patient concern
  • Skeletal relationship severity
  • Degree of overbite
  • Growth Age, sex, facial pattern
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15
Q

Treatment planing Aim
Occlusal feature

A
  • Normal or increased overbite
  • able to achieve edge to edge
  • level and align arches
  • correct buccal segment relationships
  • Upper incisor - retroclined / average
  • lower incisor - Proclined/ average
  • Refuced AOB
  • No anterior displacement
  • Significant Dentoalveolar compensation
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16
Q

Poor Prognosis what happens?

A

less favourable facial balance

17
Q

Treatment planing - Mixed Dentition (crowding)

A
  • Extract C’s to aling Incisors
18
Q

Treatment planing - Permanent dentition ( crowding )

A
  • If upper arch Xtn , tend to extract Upper5s’
  • Expansion of upper arch by URA with expansion screw - provide space but reduce overbite
19
Q

What movement should avoided in adult?

A

Distal movement and use of headgear

20
Q

Treatment aim or Options?

A

-Accept (+/- interceptive Xtn)
- Procline Upper labial segmen
- Procline upper labial segment +retroclined lower labial segment.
- Surgery

21
Q

Treatment Modalities or options?

A

-Removable appliances
- Functional appliances
- Fixed appliances
- Reverse headgear

22
Q

Mixed dentition treatment
- incisors X cross bite tx?

A
  • Extract C’s to create space for upper laterals
  • Fit URA to Proclined upper incisors
  • when incisors over the bite Remove posterior bite plane.
  • Once overbite corrected it should not need retention because overlap of overbite protect retention
23
Q

How do we maintain result ?? In mixed dentition

A
  • Anterior crossbite- Protect by correction of overbite
  • Posterior crossbite- Maintain with URA until Permanent dentition
24
Q

Permanent Dentition Tx

A

-Orthodontic Camouflage
- Growth slowing down
- Proclination of upper incisors
- Proclination of upper incisors + Proclination of upper incisors with retrolcination of lower incisors
- Potentially good overbite

25
Q

When do we do Proclination of Upper labial segment - PERMANENT teeth?

A
  • Class 1 / Mild class 3 SK
  • Upper incisors not proclined
  • Good overbite
  • Able to Edge to edge incisors before displacing forward
  • Removable / fixed appliances
26
Q

When do we do Proclination of ULS and Retroclination of LLS?

A
  • Mild / moderate SK class 3 patter
  • Reduced overbite
  • Xtns in lower arch
  • Fixed appliances/ Class 3 elastics / revers pull headgear
27
Q

Severe Skeletal Problems? And tx

A
  • Growth complete or slow down
  • Orthodontic correction not possible
  • ANB <4 degree
  • LI- Mnp < 83 degree
  • Patient unhappy with profile.
  • Treat using orthodontic and surgery
28
Q

Orthognathic Surgery Aim?

A
  • Decompensate incisors prior surgery
  • Co- ordinate arches
  • Patient will look worse before surgery
29
Q

Types of Orthognathic surgery

A

Depend on Sk pattern
-Small maxilla needs advancement
- Large mandible needs set back
-Combination of both - Bi- maxillary surgery

Orthodontics (45 decks)

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