class 2 div 1 malocclusion Flashcards
definition
lower incisor edges lie posterior to the cingulum plateau of the upper incisors
increased OJ
U central incisors proclined or of average inclination
incidence
15-20% (most common malocclusion)
why treat?
aesthetics
dental health
- prominent incisors at risk of trauma esp if incompetent lips
- OJ >9mm x2 as likely to suffer trauma - IOTN 5a
broad categories of aetiology/features
skeletal pattern
STs
dental factors
habits
AP skeletal pattern
usually associated with a class 2 skeletal pattern
commonly due to a retrognathic mandible
- maxillary protrusion less common
do see with skeletal class 1
v rarely see with skeletal class 3 but possible - could be purely due to STs e.g. lip trap
skeletal pattern - vertical
found in association with a range of vertical skeletal patterns
decreased vertical = increased OB
increased vertical = decreased OB/AOB
skeletal pattern - transverse
no particular association with transverse problems
could have buccal segment CB due to maxillary contraction
what is incompetent lips
don’t sit together at rest without muscular activity
what are incompetent lips often due to?
prominence of incisors and/or underlying skeletal pattern
what ST factor can be an etiological factor in increased OJ?
L lip trap
- proclination Us
- retroclination Ls
what is the consequence of incompetent lips when swallowing?
special effort is needed to achieve an anterior oral seal
methods of achieving an anterior oral seal
1 - lip to lip seal by activity of circum-oral musculature
2 - mandible postured forward to allow lips to meet
3 - L lip drawn up behind U incisors,
4 - tongue placed forwards between incisors to meet L lip - tends to contribute to increased OB
5 - combination of these
dental factors
- increased OJ (incisors proclined or average?)
- common to have spaced U anteriors if proclined
- molars usually class 2 but crowding could alter this
- habitually parted lips
/ - OB varies
- can see good alignment, crowding or spacing
consequences of habitually parted lips
drying of gingiva and exacerbation of any pre-existing gingivitis
rolled gingival margins- inflamed
U lip not covering U gingival margin
non-nutritive sucking habits
thumb fingers blanket lip combination
what does the effects of a sucking habit depend on?
- duration and intensity
- if >6hrs per day will have occlusal effects*
occlusal features of a sucking habit
proclination of U incisors
retroclination of L incisors
localised AOB or incomplete OB
narrow upper arch (may see unilateral posterior CB)
why does a sucking habit result in a narrow upper arch?
- tongue in low position due to thumb - (tongue help shapign upper arch width)
- maxilla constricts due to action of buccinator
habit treatment principles
stop before age 9
allow spontaneous improvement - <9yrs would hope for improvement
tx residual malocclusion if required
methods of stopping sucking habit
- positive reinforcement
- bitter nail varnish
- gloves
- removable appliance habit breaker (good for pt who wants to help themselves)
- fixed appliance habit breaker (palatal arch with goalposts at front - stops thumb going into mouth)
management options
- accept
- attempt growth modification
- simple tipping of teeth (URA)
- camouflage
- orthognathic surgery
indications to accept
- mildly increased OJ
- significant OJ but not unhappy and not keen on tx
discussion to have with pt/parent re accept
- will any tx options be more difficult in future?
- risk of trauma
- advice re mouthguard for contact sports
what is growth modification and when can it be done?
you apply significant force to the skeletal bases to try and improve the underlying skeletal discrepancy
while still growing
- girl 12 +/- 2
- boy 14 +/- 2
how does headgear and EO traction work
- try and restrain growth of the maxilla horizontally and/or vertically
- use cranium as anchor, bands attach to URA
- up and backward pull for upper dentition
- distalise U molar, retract UI
spring loaded and facebow (500g force)
why do you need extremely good pt cooperation for headgear?
wear at least 14 hours per day
how does a functional appliance work?
“utilise, eliminate or guide the forces of muscle function, tooth eruption and growth to correct a malocclusion”
what malocclusion is functional appliances mostly used for?
class 2 div 1
what other malocclusions can fct appliances be used for?
class 2 div 2 class 3 (but limited use)
describe the growth modification effect of fct appliances
- mandible postured down and forwards
- aim to restrain max growth and encourgae mand growth
therapeutic effect of fx app.
- mostly dento-alveolar changes
- distal movement of upper dentition
- mesial movement of lower dentition
- retrocclination of UI
- proclination of LI - minor degree of skeletal changes
- RCT’s indicate that degree of max restraint and mand growth is usually small (1-2mm)
- significant variation in response - skeletal 27%, dental 73%
how should the registration for a functional appliance be taken?
with the teeth as close to edge to edge as possible
2 main types of fct appliance
removable or fixed
removable fct appliance
tooth-borne - twin block (most common) - activator/bionator soft-tissue borne - Frankel II - buccal shields and wire frame which fits around teeth without clasping onto teeth
fixed functional appliance
Herbst - capping bonded onto surface of teeth, connecting rod between upper and lower which postures mandible forward
twin block design
midline palatal screw to allow expansion - usually needed to keep pace with lower arch
**labial bow **- if proclination and spacing
speech often an issue - persistence
get lat open bite - resolves in a few months e.g. just wear block at night
what is the success of a twin block dependent on?
favourable growth and enthusiastic patient
why should a fct appliance be used during growth?
teeth move more easily
more compliant
can harness effect of favourable growth if they have it
two options for timing of a fct appliance
early use about 10yo (2 phase tx)
- have to withdraw tx for transition from mixed to permanent (2yrs)
- then use fixed for fine realignment
later use - 12-14 yo late mixed or early permanent dentition (1 phase tx)
disadvantages of early fct appliance tx
- early skeletal effects from fct appliance or headgear therapy not maintained in long term
- overall tx time increased, 2 phase tx
* early fct appliance plus retention * fixed app in early permanent dentition - research shows little if any difference in results between those treated early and those who waited until permanent dentition
advantages of early fct appliance tx
improve appearance earlier (teasing and potential psychological benefit)
reduce risk of trauma
often better compliance with appliance wear
when are the only times URAs (simple tipping) would really be used?
v mild class 2 or class 1
OJ due to proclined and spaced incisors
OB favourable
and then only after a specialist assessment
URA design to retrocline anterior teeth
active component - Roberts retractor, 0.5mm HSSW in tubing
retention - Adams clasps 0.7mm HSSW
anchorage - stops mesial to 3s (have already been retracted)
baseplate - FABP
when is camouflage useful?
- if haven’t worn fct well enough/are too old for a fct
- malocclusion is not severe
- main concern is position of teeth
what does camouflage usually involve?
fixed appliances
if goal is to reduce the OJ may need U arch extractions to give space (or distal movement)
txing an increased OJ and class 2 molars - camouflage
- ext method - ext U 4s, bring anteriors back ( with unfavourbale molar forward movement)
- non-ext method - distalise molars to class 1 (aided by ext of U7s - but would want 8 in good position to come down and replace 7 when tx completed)
when would orthognathic surgery be indicated?
growth complete and profile concerns
- F 18-19 yrs
- M 20-21 yrs
severe skeletal discrepancy in AP and/or vertical direction
what does orthognathic surgery usually involve?
mandibular surgery but may also involve maxillary surgery
- maxillary impaction
- mandibular advancement e.g. bilateral sagittal split osteotomy
what appliance is usually required as well as orthognathic surgery?
fixed - before , during and after
rectangular SS arch wires with printable hooks - run elastics to fine tune occlusion and keep teeth in correct place
class 2 elastic
correct a class 2 occlusion
class 3 elastic
correct a class 3 occlusion
