Class II Div 1 Flashcards
What is the BSI definition of Class II div 1 incisor relationship?
- Lower incisor edges lie posterior to the cingulum plateau of the upper incisors
- There is an increased overjet
- Upper central incisors are proclined or of average inclination
What is the percentage of Class II div 1 malocclusions?
- 15-20%
Why are we so concerned about treating Class II div 1 cases?
- Concerns about aesthetics
- Concerns about dental health
What are the dental health concerns of class II div1 malocclusion?
- Prominent incisors at risk of trauma esp if incompetent lips
- OJ >9mm twice as likely to suffer trauma
What is the IOTN of OJ >9mm?
- 5a
What A/P skeletal pattern is Class ii div 1 associated with and what type of mandible is this due to?
- Usually Class II skeletal pattern
- Commonly due to retrognathic mandible (can be maxillary protrusion but less common)
In class ii div1 cases what is the Overjet likely to be due to?
- Skeletal pattern
- Tooth inclination
- Combo of both
Does class ii div 1 cases have an association wirh vertical skeletal pattern?
- Found in association with a range of vertical skeletal patterns
Does class ii div 1 cases have an association with transverse skeletal pattern?
- No association
On a lateral ceph what is the normal SNA value? What does this denote?
81 +/- 3
- Relationship of Sella, Nasion and A point
- Shows AP position of maxilla relative to cranial base
- Increased shows protrusion
- Decreased shows retrusion
On a lateral ceph what is the normal SNB value? What does this denote?
78 +/- 3
- Relationship of Sella, Nasion and B point
- Shows AP position of mandible relative to cranial base
On a lateral ceph what is the normal ANB value an what does tis represent?
3 +/- 2
= SNA - SNB
- If ANB angle is reduced pt has Class III skeletal base
- If ANB angle is increased pt has Class II skeletal base
What is the normal MxP/MnP value and what does this represent?
27 +/- 4
- Maxillo-mandibular plane angle
What is the normal Ul/MxP value and what does it represent?
109 +/- 6
- Upper incisors relative to the maxillary plane
- If increased then upper incisors are proclined
- If decreased upper incisors retroclined
What is the normal Ll/MnP value and what does this represent?
- 93 +/- 6
- Lower incisors relative to the mandibular plane
- If increased incisors are proclined
- If decreased incisors are retroclined
What are the normal LAFH/TAFH values?
- 55%
- State whether it is increased or decreased or average
Why are lips incompetent?
- Due to prominence of incisors
- and/or underlying skeletal pattern
What is the purpose of trying to correct lip incompetence?
- Achieve an anterior oral seal
What are the txt options to achieve an anterior oral seal?
1 - Lip to lip seal by activity of circum-oral musculature
- Mandible postured to allow lips to meet
2 - Lower lip drawn up behind upper incisors
- Tongue placed forwards between incisors to lower lip
3 - Combo of these two options
What are the dental factors of Class ii div 1 malocclusion that we need to be aware of?
- Increased overjet (incisors proclined or average)
- Overbite variation
- See goof alignment, crowding or spacing
- Molar relationship
- Habitually parted lips may lead to drying of gingiva and exacerbation of any pre-existing gingivitis
What sucking habits can lead to class ii div 1 malocclusion?
- Thumb
- Fingers
- Blanket
- Lip
- Combination
What are the occlusal features of sucking habit?
- Proclination of upper anteriors
- Retroclination of lower anteriors
- Localised AOB or incomplete OB
- Narrow upper arch (may see unilateral posterior crossbite)
What are the habit txt principles (3 of them)?
Stop habit
– Reinforcement
– Removable appliance habit breaker
– Fixed appliance habit breaker
* Allow spontaneous improvement
* Treat residual malocclusion if required
What are the 5 management options for Class ii div1 maloclusions?
- Accept
- Attempt growth modification
- Simple tipping of teeth
- Orthodontic Camouflage
- Orthognathic surgery
When we choose to accept a class ii div 1 malocclusion what dentally are we accepting?
- Mildy increased OJ
- Sig OJ but pt not unhappy
- Be careful as txt options may be more difficult in the future
- Give advice regarding a mouthgaurd due to increased chance of trauma
What is a functional appliance?
“Functional appliances utilize, eliminate, or
guide the forces of muscle function, tooth
eruption and growth to correct a
malocclusion
- Used mostly for class ii div 1 cases
What are the two options we have when attempting growth modification?
- Headgear where try and restrain growth of maxilla horizontally and/or vertically
- Functional appliance
What are some types of removable functional appliance?
- Tooth borne (Twin block or Activator/bionator)
- Soft tissue born (Frankel FR II)
What type of fixed functional appliance do we have?
- Herbst fixed functional appliance
What are the aims of functional appliances?
- Produce restraint of maxillary growth and encourage mandibular growth
- Success depend on favorable growth (useful during growth spurt) and enthusiastic pt
What is the therapeutic effect of functional appliances on dento-alveolar and skeletal?
- Mostly dento-alveolar changes
- Minor degree of skeletal changes
What is the dento-alveolar change that occur during functional appliance therapy?
- Distal movement upper dentition
- Mesial movement lower dentition
- Retroclination of upper incisors
- Proclination of lower incisors
What is the little skeletal change observed in functional appliance therapy?
- RCT’s indicate that degree of
maxillary restraint and mandibular
growth is usually small (1-2mm) - Significant variation in response
What are your options for when to use a functional appliance?
- During growth and if poss during pubertal growth spurt
1 - Early use about yrs old with a 2 phase txt
2 - Later use in late mixed or early permanent dentition with a 1 phase txt
What are the possible disadvantages of early txt with functional appliance therapy?
- Early skeletal effects from functional appliance or headgear therapy not maintained long term
- 2 phase txt so txt time increased
- Research shows little difference in results for early txt and those who waited until permanent dentition
What are the potential benefits of early txt for functional appliances>
- Improve appearance earlier (teasing & potential
psychological benefit)
– Reduce risk of trauma
– Often better compliance with appliance wear
What is the URA appliance for retroclining anterior teeth?
Active: Roberts retractor
0.5mm in tubing
* Retention: Adams cribs 6/6
0.7mm HSSW
* Anchorage: Stops mesial to
3/3?
* Baseplate: Flat anterior biteplane
What is an option for adult dentition with increased OJ and class II molars?
- Camouflaged by fixed appliances
- XLA premolar upper arch to create space for OJ reduction
- Creates class III molar relationship but reduces OJ and looks better
2 - Non XLA OJ reduction which allows for molar correction , distal movement of U6s aided by XLA of U7s
When is orthognathic surgery considered?
- When growth is complete
- Skeletal discrepancy is severe in A/P and / or vertical direction
What does orthognathic surgery involve?
- Mandibular surgery but may also involved maxillary
- Fixed appliances before / during / after surgery
