Question 21

Question 1

class 2 div 1 everything need to know

Answer 1

• Class II – lower incisal edges lie posterior to the cingulum plateau of the upper incisors
  o Division I – upper incisors are proclined or of average inclination with an increased overjet
   Requires treatment due to increased risk of trauma
   Aetiology
• Skeletal pattern – class II, retrognathic mandible
• Soft tissues – incompetent lips, lower lip trap
• Dental factors – increased OJ, incisors proclined or average, habitually parted lips may lead to gingival drying and exacerbation of pre-existing gingivitis
• Habits – digit or lip sucking – must be controlled by reinforcement or a habit breaker appliance
  o Proclination of upper anteriors
  o Retroclination of lower anteriors
  o Localised AOB or incomplete OB
  o Narrow upper arch +/- unilateral posterior crossbite
   Management
  1. Accept malocclusion
  2. Attempt growth modification
  a. Headgear – restrain growth of maxilla
  b. Functional appliance – twin-block used during growth to restrain maxillary growth and promote mandibular growth. Mostly dentoalveolar changes, some skeletal
  3. Simple tipping of teeth using a URA – retrocline anterior teeth using a Roberts retractor
  4. Camouflage – fixed appliance
  5. Orthognathic surgery – carried out when growth is complete and there is a severe skeletal discrepancy. Usually mandibular advancement, sometimes maxillary impaction. Fixed appliances throughout

Question 2

class 2 div 2 everything you need to know

Answer 2

o Division II – upper incisors are retroclined and the overjet is minimal or may be increased
 Aetiology
* Skeletal – AP class II, reduced FMPA
* Soft tissue – high resting lower lip line, marked labio-mental fold
* Dental – retroclined upper centrals, upper 2s often crowded, deep OB, UE canines, peg laterals

 Management
1. Accept malocclusion
2. Growth modification – functional appliance (modified twin block) during growth
3. Camouflage – accept underlying skeletal relationship and correct to class I incisor relationship using fixed appliances. Stability requires OB reduction and correction of inter-incisal angle
4. Orthognathic treatment

Question 3

class 3 everything need to know

Answer 3

• Class III – lower incisal edges lie anterior to the cingulum plateau of upper incisors. The overjet is reduced or reversed
  o Aetiology
   Skeletal – class III, small maxilla, large mandible, bilateral crossbites
   Dental – class III incisors, reverse OJ, reduced OB or AOB, crossbites, dentoalveolar compensation
  o Management – growth tends to be unfavourable as mandibular growth continues for longer. Wait until growth has stopped
  1. Accept and monitor
  2. Interceptive Tx with URA – procline upper incisors or correct anterior crossbite, good OB will maintain stability
  3. Growth modification – in growing patient to reduce mandibular growth and encourage maxillary growth
  a. Functional appliance – reverse twin block
  b. Protraction headgear +/- rapid maxillary expansion
  c. Temporary anchorage devices
  4. Camouflage – accept underlying skeletal pattern and correct incisors (procline UI’s, retrocline LI’s, correct OJ), favourable if growth stopped, extractions required
  5. Orthognathic surgery