Class 2 Division 1 Malocclusion

Question 1

what is the BSI definition of class 2 division 1 malocclusion

Answer 1

lower incisor edges lie posterior to the cingulum plateau of the upper incisors. there is an increased overjet and the upper centrals are proclined or of average inclination

Question 2

why would you treat class 2 div 1

Answer 2

aesthetic concerns
trauma if incompetent lips or overjet >9mm

Question 3

what is the AP skeletal pattern like for class 2 div 1

Answer 3

class 2 AP skeletal base (sometimes class 1)
retrognathic mandible more common than prognathic maxilla

Question 4

what can cause an overjet

Answer 4

skeletal pattern
tooth inclination
combination of both
lower lip trap

Question 5

why would the lips be incompetent

Answer 5

prominence of incisors
underlying skeletal pattern

Question 6

how would someone with incompetent lips achieve an oral seal

Answer 6

by muscle activity
mandible postured to allow lips to meet
lower lip drawn up behind the upper incisors
tongue placed forwards between incisors to lower lip

Question 7

what are the dental factors of class 2 div 1 malocclusion

Answer 7

increased overjet
variable overbite
crowding/spacing/or good alignment
molar relationship
dry gingiva if parted lips

Question 8

what kind of sucking habits could a patient have

Answer 8

thumb
fingers
blanket
lip
combination
non-nutritive sucking habit

Question 9

what are the occlusal features of class 2 div 1

Answer 9

proclination of upper anteriors
retroclination of lower anteriors
localised AOB or incomplete OB
narrow upper arch

Question 10

what are the treatment principles of habits

Answer 10

stop habit - reinforcement, appliances
allow spontaneous improvement
treat residual malocclusion if required

Question 11

what are the management options for class 2 div 1

Answer 11

accept
attempt growth modification
simple tipping of teeth
camouflage
orthognathic surgery

Question 12

when would you accept a class 2 div 1

Answer 12

mildly increased overjet
significant overjet but not unhappy

Question 13

what advice is given to a patient if they choose to accept a class 2 div 1

Answer 13

wear mouthguard for sports

Question 14

what are the ways of growth modification

Answer 14

headgear
functional appliance

Question 15

what is the function of headgear

Answer 15

restrain growth of maxilla horizontally/vertically by using the top of the skull as anchorage

Question 16

what does a functional appliance do

Answer 16

utilise, eliminate or guide the forces of muscle function, tooth eruption and growth to correct a malocclusion

Question 17

give an example of a functional appliance

Answer 17

twin block (removable)

Question 18

what are the aims of a functional appliance

Answer 18

produce restraint of maxillary growth and encourage mandibular growth

Question 19

what does the success of a functional appliance depend on

Answer 19

favourable growth and enthusiastic patient

Question 20

what are the dento-alveolar changes with a functional appliances

Answer 20

distal movement of uppers
mesial movement of lowers
retroclination of upper incisors
proclination of lower incisors

Question 21

what degree of skeletal change can be made with a functional appliance

Answer 21

1-2mm

Question 22

when is a functional appliance used

Answer 22

during growth
early = 10yrs old
late = late mixed/early permanent

Question 23

what are the advantages of using a functional appliance in early stages

Answer 23

improve appearance earlier
reduce trauma risk
better compliance

Question 24

what are the disadvantages of using a functional appliance in early stages

Answer 24

skeletal effects not maintained
treatment time increased - 2 phases (functional and fixed)

Question 25

when is a URA not used

Answer 25

mild class 2 or class 1
overjet is due to proclined and spaced incisors
overbite is favourable

Question 26

what is the appliance design for retroclining anterior teeth

Answer 26

active = roberts retractor 0.5mm tubing
retention = adams clasps on 6s 0.7mm HSSW
anchorage = stops mesial to canines
baseplate = flat anterior biteplane

Question 27

what is the goal of camouflaging a class 2 div 1 and how is it achieved

Answer 27

reducing the overjet
upper arch extractions to give space

Question 28

when is orthognathic surgery carried out

Answer 28

when growth is complete

Question 29

what cases would get orthognathic surgery

Answer 29

skeletal discrepancy is severe in AP or vertical direction