orthodontics Flashcards
what is IOTN?
index of orthodontic treatment need - measure impact of malocclusion on individuals dental health + psychosocial wellbeing
1 (least need) - 5 (greatest need)
dental health + aesthetic component
what is PAR?
peer assessment rating - quantitively measures malocclusion + efficacy of treatment
4 ways to modify growth
- functional appliance
- headgear
- temporary anchorage devices
- palatal implants
mode of action for removable appliances?
tipping
what is a flat anterior bite plane used for?
overbite reduction
what is an expansion appliance used for?
widen maxilla
what is a cover plate used for?
after exposure surgery - for 2 weeks
what is a space maintainer?
maintains space after early tooth loss for a prosthesis/successor
3 types of retainers post ortho
- essix
- hawley - full time 3/12 then nights
- fixed/bonded
what is a functional appliance?
removable or fixed using forces generated by stretching of muscles, fascia +/- periodontist to alter skeletal + dental relationships
what functional appliance is usually used for class II malocclusions?
twinblock
OJ>6mm
when is appropriate for use of functional appliance?
when actively growing
f = 11-13 years m = 12-14 years
3 components of skeletal diagnosis
- classification
- FMPA
- Lower face height
what would an obtuse nasolabial angle suggest?
poor lip support - extractions to be avoided
measurements for mild, moderate + severe crowding?
mild = <4mm moderate = 4-8mm severe = >8mm
which cusps of molars normally occlude with each other?
upper buccal cusp, buccal to lower
risks of leaving impacted teeth?
cyst formation
root reosorption
risks of exposing impacted teeth?
root damage, crown damage, ankylosis
inevitable amount of induce inflammatory root resorption after orthodontic?
1-2mm
over what period of time for elastic recoil PDL fibres remodel?
~1y
4 main risk to explain when gaining consent for orthodontic treatment
- pain
- root resorption
- decalcification
- relapse/retention
examples of soft tissue/habits that change occlusal classfication
- lip trap = II
- large tongue = III
- active lowerlip = II
- digit sucking = II
movement made by fixed appliances?
bodily movement
what physics law does orthodontic anchorage use?
newtons 3rd law
6 ways to create space?
- leeway space
- distal movement
- arch expansion
- incisor proclamation
- inter proximal stripping
- extractions
when should teeth be extracted?
1-2 weeks before appliance placement
is GA justified for orthodontic extraction?
no
a in IOTN
overjet
h in IOTN
hypodontia
I in IOTN
impedance
m in IOTN
reverse overjet
p in IOTN
clefts
s in IOTN
submerged
c in IOTN
crossbites
d in IOTN
displacement
e in IOTN
open bite
factors affecting teeth resorption risk with fixed appliance
distance moved existing resorption pipette shaped roots/thin roots previous trauma asthma
normal measurement for overbite
40%
normal amount of incisor showing on smiling
75-100%
how to describe overbite
% + complete/incomplete
components of intra-oral ortho assessment
OH, periodontal status incisor, canine, molar relationship overjet + overbite centreline discrepancies crowding cross bite/displacements
reasons to take radiograph for ortho assessment
pathology suspected
skeletal discrepancies
developmental - uneurpted teeth/submerged/impacted
aesthetic rating qualifying for NHS treatment
6 or above
nemonic for order of IOTN
MOCDO
m=missing = h o = overjet = a c = cross bite = c d = displacement = d o = overbite
which premolars extracted for severe crowding
4s
5s for less
what is SNA
position of maxilla relative to anterior cranial base
what is SNB
position of mandible relative to anterior cranial base
what is ANB
relative position of maxilla to mandible
benefits of ortho
function relieve impaction - resorption/cysts reduce perio/caries reduce trauma risk psychological
when should upper 6s be extracted?
8-10yrs
when should lower 6s be extracted?
8-10yrs - 7s bifurcate 9/9.5
biology of tooth movement
force applied, bone layed down where PDL under tension, resorbed in areas of PDL compression
normal angle for nasolabial angle
90-110
3 indications for taking lateral cephalogram
skeletal discrepancy
anterior-posterior movement of incisors is planed
monitoring of growth
3 options for skeletal problems
orthodontic camouflage
growth modification
surgery
when might you retain poor prognosis 6s
retain until 7s erupted if severe overjet or anterior crowding - space maintenance
what is vertical subsigmoid osteotomy used to achieve?
setback on mandible
what is a sagittal split osteotomy used to achieve?
advance or pushback mandible or asymmetry
IAN complication
most common surgery
most common maxillary surgery
le fort 1 osteotomy
orthodontic treatment done before orthographic surgery is called what
decompensation - may make worse to start with
prevalence of cleft lip/palate
1/700 Caucasians
syndrome often associated with cleft lip/palate
treacher collins
