Class II Division 1 Malocclusion Flashcards
The diagnosis of a Class II Div 1 malocclusion
is based on the
incisor relationship
Definition of class II div 1 malocclusion
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
overjet is … and normal in mm is …
Horizontal relationship
between the upper incisors
and lower incisors
2 - 4 mm
incidence is .. hence common/uncommon?
20-30 percent of all malocclusions (UK)
common
proportion of class II div 1 that have skeletal base
II (if skeletal base I think possible habit?)
significance of class II div 1
Poor dental appearance
Facial profile often poor
increased risk of
upper incisor trauma – over 40% risk with overjets 9mm+
often associated with
deep overbite and possible palatal trauma
what is the IOTN
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
how does it work?
IOTN DHC grades 1 – 5
series of criteria
IOTN AC grade 1 – 10
series of 10 photographs
IOTN and II/i - dental health component
— 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
aetiology of class II/i
Growth - AP skeletal discrepancy ( > 70% of
cases)- Mandibular retrognathia
Habits eg. thumb sucking
Soft Tissues - lower lip maintains proclination
Dental factors – maxillary crowding
EO features of II/i (mild)
mandible relatively behind the maxilla
EO features of II/i (severe)
severity of discrepancy can be disguised by a prominent chin point
lower vertical facial proportions often reduced (reduced MMA)
ceph values
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
IO features (inclination, overjet, overbite)
proclined or average upper incisors
overjet increased
overbite increased
IO features (buccal segments and crowding)
class II buccal segments
crowding
treatment of II/i - why?
Improved dentofacial appearance
Improved self-esteem – reduce teasing
Improved psychosocial wellbeing
Reduction in trauma
Improved function / reduce lip incompetence
? improved speech
aims of treatment II/i
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
What functional appliances are there
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
Treatment: no skeletal discrepancy
Fixed appliance only
(occasionally URA)
Treatment: mild sk discrep
Functional / Fixed
Moderate: sk discrep
Functional / URA / Fixed
Severe sk discrep
Surgery + Fixed – possibly try
functional aged 12/13 to reduce
discrepancy – key is informed
consent
Treatment: Functional appliances- indications
Age 10-13
Mild to moderate skeletal discrepancies
functional- complete treatment-
for well aligned arches
functional- 2 stage treatment-
functional to reduce overjet
2nd stage of fixed +/- extractions
types of functional appliances
Activator (Andresen)
Bionator
Twinblock lower arch block slides along slope of upper arch block and forwards
twinblock
lower arch block slides along slope of upper arch block and forwards
URAs- and class II/i
- extract upper 4s
- retract canines
- retract incisors
overbite and overjet relationship important how in relation to II div i and URAs
increased overbite prevents full overjet reduction therefore first reduce the overbite to normalthen reduce the overjet
treatment of II i with URA and overbite reduction
anterior biteplane incorporated into URAs
start overbite reduction early (during canine retraction)
palatal finger spring retractor do what
retract canines/ premolars
palatal finger spring retractors work how
(crib what tooth, diameter springs? activate by how much?)
crib 6s
activate by 1/2 width of canine or premolar
0.5mm springs
buccal canine retractor do what
reatract canines (to relieve crowding/ reduce overjet)
buccal canine retractors work how - crib, what springs, activate by how much
crib 6s
0.7mm springs
activate by 1/3 width of canine
roberts retractor do what
retract incisors (class II div 1)
roberts retractors work how (crib etc. )
Crib 6s
0.5 mm labial bow supported by SS tube
should lie just behind incisal edges when passive
fixed appliances benefits
Excellent tooth control, now treatment of choice
Fixed appliances
Mild (to moderate) skeletal discrepancies
Crowded upper / lower arches
preparation for fixed?
Extract
– upper premolars –
to provide space for overjet reduction.
– If lower crowding then consider upper 4’s & lower 5’s –
to improve anchorage balance
may need what for fixed appliances
May need headgear / orthodontic mini implants
fixed appliances are commonly used when
Commonly used after initial phase of functional.
cases not suitable for removable appliances are
bodily movement etc
overjet reduction: fixed vs URA- with regards with upper incisor angulation
URA- tipping only
Fixed- bodily movement
what is anchorage demanding with fixed appliances in class II div 1
bodily retraction
what teeth to extract for better anchorage balance?
Usually extract upper 4s, provide better
anchorage balance than upper 5’s*
consider banding/bonding what teeth to improve anchorage balance?
upper 7s
what might also be needed to help anchorage balance
headgear or orthodontic mini implants now also an option
anchorage balance is needed for what purpose in Tx of II/i
to carry out initial phase of functional Tx
Orthognathic surgery what skeletal discrepancy and what patients
severe class II skeletal discrepancy and in patients too old for functional appliances
what procedure is needed before mandibular advancement (+/- maxillary procedure)
fixed appliances to align and coordinate individual arches
typical treatment plan for II/i
2 phase treatment-
phase 1 - functional appliance
phase 2 fixed appliance
Prognosis
ask functional appliance patients to continue wearing appliances for a period of time
Stability
enhanced by lower lip control of upper incisors
rarely stable?
advancement of the lower incisors in attempt to reduce the overjet
common malocclusion
class II div i
main treatment aim II/i
overjet reduction
best timing for treatment II/i
late mixed or early permenant dentitions, functional appliances freq used
if lower crowding present in upper or lower arches?
fixed appliances
severe skeletal discrepancies are classed as
> 10mm
severe skeletal discrepancies are
difficult to fully treat with functional appliances
significant skeletal discrepancies in non growing patients require
surgery
