Class II Div 1 Flashcards
(41 cards)
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
