Class 2 Div 2 Malocclusions Flashcards
What is the definition of a C2D2 malocclusion?
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
What is the incidence of the different incisor relationships ?
C1- 60%
C2D1- 15-20%
C2D2- 5-18%
C3- 3-8%
What are the AP skeletal features of a C2D2?
Usually mild to moderate Class 2 (can be 1/3)
How is vertical discrepancy ascertained?
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
What are the vertical skeletal features of C2D2?
Vertical height is reduced- reduced FPMA
Forward rotational pattern of growth
Prominent chin- progenia
What are the features of ST in patients with C2D2?
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)
What are the dental features of C2D2?
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
What is the issue with U2 cingulum being poorly formed in patients with C2D2?
Lack of occlusal stop means OB is more likely to be increased
-> must be normalised by treatment to prevent relapse
What ways can soft tissue become traumatised from deep OB in C2D2 patients?
Damage to palate from lowers- may be interdigitation
Damage to labial mucosa from retroclined upper
If traumatic OB- patient will score 4f on IOTN
Which dental anomalies are often seen in patients with C2D2?
Impacted canines
Microdontia
-> this can influence canine eruption pattern as lateral not as prominent to be used in eruption of canine
What do treatment options for patients with C2D2 depend on?
Severity
Dental health- OH must be satisfactory
Age and motivation of patient
Patient concerns
What are the treatment options for treating a patient with C2D2 malocclusion?
Accept
Growth modification- if mild/moderate and still growing
Camouflage
Orthognathic surgery
When may the option to accept C2D2 malocclusion be selected?
Acceptable aestehtics
Patient not concerned or suitable
OB is not traumatic
When is the time of the growth spurt in males and females?
Males- 14 (+/- 2 years)
Females 12 (+/- 2 years)
How is a twin block modified in order to correct a C2D2 into C2D1 which can be then treated with fixed appliances?
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)
What may be used in conjunction with modified twin block in patients with C2D2?
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)
What is camouflage treatment?
Accepting the underlying skeletal base relationship and aiming to treat to class 1 incisor relationship
-> suitable for mild/moderate C2D2
Why must extraction be planned carefully when carrying out fixed appliance treatment in C2D2 patients with crowding?
Space closure is difficult to achieve due to low angle
What are the requirement for stable correction of C2D2 malocclusion?
Overbite reduction
Correction of inter- incisal angle (reduction)
-> prevent relapse
How is Inter-incisal angle reduced?
Palatal root torque upper incisors
Proclination of lower incisors
What are the requirements/risk of upper incisor torquing?
Requires adequate cancellous bone levels
Risk- greater level of root resorption
When is orthognathic surgery considered for patients with C2D2 malocclusion?
If too severe- discrepancy in AP, V, T planes
If patient is no longer growing
If patient has concerns over profile
What are the stages in orthognathic surgery for patients with C2D2 malocclusions?
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
How long can decompensation in pre-orthognathic surgery ortho take?
18 months
