Class II Division 1 Malocclusion

Question 1

The diagnosis of a Class II Div 1 malocclusion
is based on the

Answer 1

incisor relationship

Question 2

Definition of class II div 1 malocclusion

Answer 2

Lower incisor edges are palatal to the
cingulum plateau of the upper incisors and the
upper incisors are proclined or of average
inclination, with an increased overjet

Question 3

overjet is … and normal in mm is …

Answer 3

Horizontal relationship
between the upper incisors
and lower incisors
 2 - 4 mm

Question 4

incidence is .. hence common/uncommon?

Answer 4

20-30 percent of all malocclusions (UK)
common

Question 5

proportion of class II div 1 that have skeletal base

Answer 5

II (if skeletal base I think possible habit?)

Question 6

significance of class II div 1

Answer 6

 Poor dental appearance
 Facial profile often poor

Question 7

increased risk of

Answer 7

upper incisor trauma – over 40% risk with overjets 9mm+

Question 8

often associated with

Answer 8

deep overbite and possible palatal trauma

Question 9

what is the IOTN

Answer 9

Index of orthodontic treatment need
 Used in N.Ireland since 2014 to decide which
cases are severe enough to warrant treatment
under the NHS
 Has been used in rest UK for many years

Question 10

how does it work?

Answer 10

 IOTN DHC grades 1 – 5
 series of criteria
 IOTN AC grade 1 – 10
 series of 10 photographs

Question 11

IOTN and II/i - dental health component

Answer 11

— Grade 2 = OJ 4 – 6mm with competent lips
 mild crowding

— Grade 3 = OJ 4 - 6mm with incompetent lips
 moderate crowding

— Grade 4 = OJ >6 – 9mm
 severe crowding
 mild hypodontia or supernumeraries
 deep traumatic OB

— Grade 5 = OJ 9mm +
 impacted teeth
 supernumerary teeth

Question 12

aetiology of class II/i

Answer 12

 Growth - AP skeletal discrepancy ( > 70% of
cases)- Mandibular retrognathia

 Habits eg. thumb sucking

 Soft Tissues - lower lip maintains proclination

 Dental factors – maxillary crowding

Question 13

EO features of II/i (mild)

Answer 13

mandible relatively behind the maxilla

Question 14

EO features of II/i (severe)

Answer 14

severity of discrepancy can be disguised by a prominent chin point

lower vertical facial proportions often reduced (reduced MMA)

Question 15

ceph values

Answer 15

upper incisors are proclined (>109 degrees)

ANB > 4 degrees

(ANB= SNA-SNB)- sna is a measure of maxillary AP position, SNB is a measure of mandibular AP position

Question 16

IO features (inclination, overjet, overbite)

Answer 16

 proclined or average upper incisors
 overjet increased
 overbite increased

Question 17

IO features (buccal segments and crowding)

Answer 17

class II buccal segments
crowding

Question 18

treatment of II/i - why?

Answer 18

Improved dentofacial appearance
 Improved self-esteem – reduce teasing
 Improved psychosocial wellbeing
 Reduction in trauma
 Improved function / reduce lip incompetence
 ? improved speech

Question 19

aims of treatment II/i

Answer 19

 Improve facial profile
 Reduce overjet (OJ)
 Reduce overbite (OB)
 Relieve crowding and align arches
 Correct centre-lines
 Deal with impacted / ectopic / supernumerary
/ missing teeth as appropriate
 Produce a stable result / retain result

Question 20

What functional appliances are there

Answer 20

 Functional appliances
- (Andresen, MOA or most commonly Clarke Twin-Block, +/- FA)

 Upper removable appliances
- normally to facilitate transition between functional and fixed phase
- occasionally as complete Tx (historical)

 Fixed appliances
-often in conjunction with functional appliances +/- extractions
- Or with class II correctors eg. PowerScope (AO)

 Headgear
- used less and less frequently

 Orthodontic mini-implants
- to improve anchorage balance – becoming more popular

 Surgical orthodontic treatment
- Non-growing patients

 New developments
- Invisalign® with class 2 elastics

Question 21

Treatment: no skeletal discrepancy

Answer 21

Fixed appliance only
(occasionally URA)

Question 22

Treatment: mild sk discrep

Answer 22

Functional / Fixed

Question 23

 Moderate: sk discrep

Answer 23

Functional / URA / Fixed

Question 24

Severe sk discrep

Answer 24

Surgery + Fixed – possibly try
functional aged 12/13 to reduce
discrepancy – key is informed
consent

Question 25

Treatment: Functional appliances- indications

Answer 25

 Age 10-13
 Mild to moderate skeletal discrepancies

Question 26

functional- complete treatment-

Answer 26

for well aligned arches

Question 27

functional- 2 stage treatment-

Answer 27

functional to reduce overjet
2nd stage of fixed +/- extractions

Question 28

types of functional appliances

Answer 28

 Activator (Andresen)
 Bionator
 Twinblock lower arch block slides along slope of upper arch block and forwards

Question 29

twinblock

Answer 29

lower arch block slides along slope of upper arch block and forwards

Question 30

URAs- and class II/i

Answer 30

1. extract upper 4s
2. retract canines
3. retract incisors

Question 31

overbite and overjet relationship important how in relation to II div i and URAs

Answer 31

increased overbite prevents full overjet reduction therefore first reduce the overbite to normalthen reduce the overjet

Question 32

treatment of II i with URA and overbite reduction

Answer 32

anterior biteplane incorporated into URAs
start overbite reduction early (during canine retraction)

Question 33

palatal finger spring retractor do what

Answer 33

retract canines/ premolars

Question 34

palatal finger spring retractors work how
(crib what tooth, diameter springs? activate by how much?)

Answer 34

crib 6s
activate by 1/2 width of canine or premolar
0.5mm springs

Question 35

buccal canine retractor do what

Answer 35

reatract canines (to relieve crowding/ reduce overjet)

Question 36

buccal canine retractors work how - crib, what springs, activate by how much

Answer 36

crib 6s
0.7mm springs
activate by 1/3 width of canine

Question 37

roberts retractor do what

Answer 37

retract incisors (class II div 1)

Question 38

roberts retractors work how (crib etc. )

Answer 38

 Crib 6s
 0.5 mm labial bow supported by SS tube
 should lie just behind incisal edges when passive

Question 39

fixed appliances benefits

Answer 39

 Excellent tooth control, now treatment of choice

Question 40

Fixed appliances

Answer 40

Mild (to moderate) skeletal discrepancies

Crowded upper / lower arches

Question 41

preparation for fixed?

Answer 41

 Extract
– upper premolars –
to provide space for overjet reduction.
– If lower crowding then consider upper 4’s & lower 5’s –
to improve anchorage balance

Question 42

may need what for fixed appliances

Answer 42

 May need headgear / orthodontic mini implants

Question 43

fixed appliances are commonly used when

Answer 43

 Commonly used after initial phase of functional.

Question 44

cases not suitable for removable appliances are

Answer 44

bodily movement etc

Question 45

overjet reduction: fixed vs URA- with regards with upper incisor angulation

Answer 45

URA- tipping only
Fixed- bodily movement

Question 46

what is anchorage demanding with fixed appliances in class II div 1

Answer 46

bodily retraction

Question 47

what teeth to extract for better anchorage balance?

Answer 47

 Usually extract upper 4s, provide better
anchorage balance than upper 5’s*

Question 48

consider banding/bonding what teeth to improve anchorage balance?

Answer 48

upper 7s

Question 49

what might also be needed to help anchorage balance

Answer 49

headgear or orthodontic mini implants now also an option

Question 50

anchorage balance is needed for what purpose in Tx of II/i

Answer 50

to carry out initial phase of functional Tx

Question 51

Orthognathic surgery what skeletal discrepancy and what patients

Answer 51

severe class II skeletal discrepancy and in patients too old for functional appliances

Question 52

what procedure is needed before mandibular advancement (+/- maxillary procedure)

Answer 52

fixed appliances to align and coordinate individual arches

Question 53

typical treatment plan for II/i

Answer 53

2 phase treatment-
phase 1 - functional appliance
phase 2 fixed appliance

Question 54

Prognosis

Answer 54

ask functional appliance patients to continue wearing appliances for a period of time

Question 55

Stability

Answer 55

enhanced by lower lip control of upper incisors

Question 56

rarely stable?

Answer 56

advancement of the lower incisors in attempt to reduce the overjet

Question 57

common malocclusion

Answer 57

class II div i

Question 58

main treatment aim II/i

Answer 58

overjet reduction

Question 59

best timing for treatment II/i

Answer 59

late mixed or early permenant dentitions, functional appliances freq used

Question 60

if lower crowding present in upper or lower arches?

Answer 60

fixed appliances

Question 61

severe skeletal discrepancies are classed as

Answer 61

> 10mm

Question 62

severe skeletal discrepancies are

Answer 62

difficult to fully treat with functional appliances

Question 63

significant skeletal discrepancies in non growing patients require

Answer 63

surgery