Class II Malocclusions

Question 1

What is the BSI definition of a class II div 1 malocclusion?

Answer 1

The lower incisal edges lie posterior to the cingulum plateau of the upper incisors.There is an increase in overjet.The upper central incisors are proclined OR of average inclination.

Question 2

What are is the incidence of class II div 1 malocclusions?

Answer 2

15-20% of the population.

Question 3

What are is the incidence of class II div 2 malocclusions?

Answer 3

10% of the population.

Question 4

What is the reasoning for treating a class 2 div 1 malocclusion?

Answer 4

Aesthetic concernsSocial concernsConcerns with dental health, if overjet >9mm then trauma is twice as likely, particularly if patient has incompetent lips.

Question 5

What is the IOTN score of an overjet >9mm?

Answer 5

5a, indicating a high need for treatment.

Question 6

What skeletal pattern are class II div 1 malocclusions commonly found in, and why?

Answer 6

Usually associated with a class II skeletal pattern, usually due to a retrognathic mandible - but can also be due to maxillary protrusion and rarely class 3.No associations with transverse problems, but found in a wide variety of vertical patterns.

Question 7

What can an overjet be caused by?

Answer 7

Skeletal pattern, tooth inclination, or a combination of both.

Question 8

What are the typical ranges for angles identified on a cephalogram of a class II occlusion?

Answer 8

SNA = usually the sameSNB = usually decreasedANB = >5

Question 9

How can a class II skeletal pattern be defined?

Answer 9

The maxilla is greater than 3mm in front of the mandible.

Question 10

What complications can a lip trap pose to orthodontic treatment?

Answer 10

May procline the upper incisors, and could cause relapse of over-jet if it persists at the end of treatment.

Question 11

What is a class II division 2?

Answer 11

The lower incisal edges lie posterior to the cingulum plateau of the upper incisors.There is an little to no increase in overjet.The upper central incisors are retroclined or of average inclination.

Question 12

In a class II, where would the mesio-buccal cusp of 16 likely occlude to?

Answer 12

The marginal ridges of 45 and 46

Question 13

In a class II, where would the incisal edge of 13 likely occlude?

Answer 13

Mesially to the incisal edge of 43.

Question 14

What are the occlusional features of a sucking habit?

Answer 14

Proclination of upper anteriorsRetroclination of lower anteriorsLocalized AOB or incomplete OBNarrow upper arch (may see unilateral posterior crossbite)

Question 15

What are the dental features in class II div 1 patients?

Answer 15

Proclined upper incisors Increased OJ Class 2 molars and canines

Question 16

What soft tissue problems are associated with class II div 1 malocclusion?

Answer 16

Often incompetent lips due to prominence of incisors and/or underlying skeletal pattern. Inability to achieve an anterior oral seal May have lip trap and tongue thrusts

Question 17

What makes a class II div 1 malocclusion amendable to correction via removable appliance therapy?

Answer 17

Generally URA have a limited role in the treatment of increased overjet’s unless there is a very mild class II, when overjet’s is due to incisor proclination, there is favorable overbite and only after specialist assessment.

Question 18

What are the treatment options for a class II div 1 malocclusion?

Answer 18

Accept and monitor – when there is reduced risk of trauma Attempt Growth modification – twin block; Frankel 3 or headgear URA – limited use but Robert’s retractor can be used Fixed appliance Orthognathic surgery – only used when growth is complete and where there Is severe skeletal A/P discrepancy or vertical direction

Question 19

What is ANB for class II patients?

Answer 19

> 4 degrees

Question 20

Which skeletal patterns do class IId2 patients present with?

Answer 20

Typically class II but can be I or III

Question 21

Typically what FMPA angle would a class II d2 patient have?

Answer 21

Reduced

Question 22

When is the time when growth modification can be considered for orthodontic patients?

Answer 22

Ideally around time of growth spurt Boys 14 +/- 2 years Girls 12 +/- 2 years

Question 23

List the skeletal features commonly associated with class II div 2 patients.

Answer 23

AP = Usually mild/moderate class 2 skeletal base, but can be class 1 or class 3.Vertical = Reduced FMPA angle and prominent chin (progenia).

Question 24

List the soft tissue features commonly associated with class II div 2 patients.

Answer 24

High resting lower lip line, result of decreased lower facial height.Marked labio-mental fold.High masseteric forces (causes problems for space closure.Issues with lip trap from escape effect of lower lip.

Question 25

List the dental features commonly associated with class II div 2 patients.

Answer 25

Retrocliniation of the upper centralsOften crowded upper 2’s (and rotated)Reducded arch length, which exacerbates crowdingPoor cingulum for lateral incisorsTypically deep overbite and reduced overjetIncreased inter-incisal angle

Question 26

What is the average inter-incisal angle?

Answer 26

135 degrees

Question 27

For what reasons would you treat a class II div 2 patient?

Answer 27

Aesthetic concernsDental health concerns:- Traumatic overbite- IOTN 4f

Question 28

What are the main treatment options for class II div 2 patients?

Answer 28

AcceptGrowth modificationCamouflageOrthognathic treatment

Question 29

For what reasons might you accept a class II div 2 malocclusion?

Answer 29

Acceptable aesthetics Patient not concerned/suitableOverbite not a significant problem

Question 30

What functional appliance would you use for growth modification in a class II div 2 case?

Answer 30

Modified twin block with springs/screws Followed by upper sectional fixed appliance

Question 31

What is orthodontic camouflage?

Answer 31

Accept underlying skeletal base relationshipTreatment aim is to get class I incisor relationshipOrthodontic extraction may be required to make space

Question 32

When should orthognathic surgery be considered?

Answer 32

When too severe a malocclusion for orthodontics alone.Non-growing patientsProfile concerns