Class 2 Div 2 Malocclusions

Question 1

What is the definition of a C2D2 malocclusion?

Answer 1

The lower incisor occludes posterior to the cingulum plateau of the upper incisor
 The upper incisors are retroclined
 The overjet is reduced but can also be increased

Question 2

What is the incidence of the different incisor relationships ?

Answer 2

C1- 60%

C2D1- 15-20%

C2D2- 5-18%

C3- 3-8%

Question 3

What are the AP skeletal features of a C2D2?

Answer 3

Usually mild to moderate Class 2 (can be 1/3)

Question 4

How is vertical discrepancy ascertained?

Answer 4

Look at point FP and mandibular plane meet:
Average FMPA- lines should meet at occiput

Reduced- lines are more parallel, unlikely to meet

Increased- steeper lines

Question 5

What are the vertical skeletal features of C2D2?

Answer 5

Vertical height is reduced- reduced FPMA

Forward rotational pattern of growth

Prominent chin- progenia

Question 6

What are the features of ST in patients with C2D2?

Answer 6

 Lower lip has higher resting position (secondary to shorter LFH)- sits higher up on crowns of upper incisors causing them to become retroclined

 Marked labio-mental fold- overactive mentalis muscle

 Higher masseteric force- unfavourable for space closure, results in poor progress (careful decisions when planning extractions)

 Upper laterals can be shorter escape effect of upper lip and become flared distally, rotated and proclined (as lip gets caught behind it)

Question 7

What are the dental features of C2D2?

Answer 7

Retroclination of upper centrals

Increased OB (increased IAA)
-> may be traumatic

Shorter arch perimeter- more crowding

Crowded upper 2s
-> mesio-labially rotated
-> can be proclined depending on position of lip line

Reduced OJ- usually

Question 8

What is the issue with U2 cingulum being poorly formed in patients with C2D2?

Answer 8

Lack of occlusal stop means OB is more likely to be increased
-> must be normalised by treatment to prevent relapse

Question 9

What ways can soft tissue become traumatised from deep OB in C2D2 patients?

Answer 9

Damage to palate from lowers- may be interdigitation

Damage to labial mucosa from retroclined upper

If traumatic OB- patient will score 4f on IOTN

Question 10

Which dental anomalies are often seen in patients with C2D2?

Answer 10

Impacted canines

Microdontia
-> this can influence canine eruption pattern as lateral not as prominent to be used in eruption of canine

Question 11

What do treatment options for patients with C2D2 depend on?

Answer 11

Severity

Dental health- OH must be satisfactory

Age and motivation of patient

Patient concerns

Question 12

What are the treatment options for treating a patient with C2D2 malocclusion?

Answer 12

Accept

Growth modification- if mild/moderate and still growing

Camouflage

Orthognathic surgery

Question 13

When may the option to accept C2D2 malocclusion be selected?

Answer 13

Acceptable aestehtics

Patient not concerned or suitable

OB is not traumatic

Question 14

When is the time of the growth spurt in males and females?

Answer 14

Males- 14 (+/- 2 years)

Females 12 (+/- 2 years)

Question 15

How is a twin block modified in order to correct a C2D2 into C2D1 which can be then treated with fixed appliances?

Answer 15

 Requires active component with springs and screws to proclined anteriors
-> ELSA spring- expansion and labial segment alignment (very active component)

 Lower block remains the same (may or may not have anterior retentive component)

Question 16

What may be used in conjunction with modified twin block in patients with C2D2?

Answer 16

Sectional fixed appliance may be used to fix upper labial segment
-> some patients may want to stop treatment at this stage as they are happy with result (for most full fixed appliances will be required)

Question 17

What is camouflage treatment?

Answer 17

Accepting the underlying skeletal base relationship and aiming to treat to class 1 incisor relationship

-> suitable for mild/moderate C2D2

Question 18

Why must extraction be planned carefully when carrying out fixed appliance treatment in C2D2 patients with crowding?

Answer 18

Space closure is difficult to achieve due to low angle

Question 19

What are the requirement for stable correction of C2D2 malocclusion?

Answer 19

 Overbite reduction

 Correction of inter- incisal angle (reduction)

-> prevent relapse

Question 20

How is Inter-incisal angle reduced?

Answer 20

 Palatal root torque upper incisors

 Proclination of lower incisors

Question 21

What are the requirements/risk of upper incisor torquing?

Answer 21

Requires adequate cancellous bone levels

Risk- greater level of root resorption

Question 22

When is orthognathic surgery considered for patients with C2D2 malocclusion?

Answer 22

If too severe- discrepancy in AP, V, T planes

If patient is no longer growing

If patient has concerns over profile

Question 23

What are the stages in orthognathic surgery for patients with C2D2 malocclusions?

Answer 23

Pre-treatment ortho in orthognathic surgery allows advancement of mandible (they need to be corrected to division 1 using fixed appliances before this)
-> Consent them- as it is made worse before it gets better (some patients may be happy with this as a result)

SURGERY

 Post-surgical fine tuning and occlusal detailing can be done to give class 1 final result

Question 24

How long can decompensation in pre-orthognathic surgery ortho take?

Answer 24

18 months

Question 25

What post surgical issues can occur following orthognathic surgery?

Answer 25

Lateral open bites- 3 point landing- only incisors and terminal molars contact
-> can take 6 months to correct

Question 26

Which retainers are required for patients with treated C2D2 malocclusions?

Answer 26

Usually combination of bonded and thermoplastic

-> due to risk of deep OB and rotated laterals relapsing

Question 27

What can cause issues with stability of treated C2D2 malocclusion?

Answer 27

Continued (future) facial growth

Question 28

Why should deep OB be treated whilst the patient is still growing?

Answer 28

Allows patient to adapt to vertical change
-> treated using URA with FABP

Question 29

When should a C2D2 be referred to a specialist?

Answer 29

If other dental anomalies

If orthognathic surgery required

If deep OB