Extractions in Orthodontics Flashcards
4 reasons space creation is needed
relieve crowding
correct incisor relationship- overjet, overbite
correct molar relationship
compensate for skeletal discrepancies
5 methods by which space is created
Extractions Growth- functional appliance Interdental enamel reduction Distal movement Expansion
8 reasons teeth may be extracted
caries/pulp pathology trauma infra-occlusion ectopic permanent teeth supernumerary teeth hypodontia preparation for alveolar bone graft- centre line shift
Define overjet
horizontal distance between upper and lower anteriors
usually 1-3mm
define overbite
vertical overlap of the upper incisors over the lower incisors >30% covered
Define the term ‘functional applaince’
appliances which alter forces of muscle function, tooth eruption and growth to correct a malocclusion
Fixed or removable
works by posturing the mandible forwards in growing patients
Which type of malocclusion does a functional appliance correct
Class II
correct an increased over jet
What is the most common fixed appliance used
twin block
List 3 techniques in which distal movement can be achieved
headgear
non-compliance distaliser
Implants (TAD)
When would headgear be used?
when little space is require - 2-3mm each side- as extraction would cause too much space
in addition to extraction if more space is required
How does headgear work?
pull posterior teeth back using the back of the head as anchorage
What is required for headgear to be effective?
Patient compliance
How does a non-compliance distaliser work?
Maxillary molar distaliser
growing and non-growing patients
no compliance needed
What does TAD stand for and how does it work?
Temporary anchorage device
miniscrews placed in alveolar bone under LA which can be used to provide orthodontic anchorage
these are removed at the end of the treatment
When would it be useful to use TADs?
when large/difficult tooth movement are required
2 methods expansion can be created and describe them
Quadhelix- expand dental arches, fixed slow expansion appliance,
RME- Rapid maxillary expansion by opening midline suture, fixed, patient can adjust
How does expansion work in orthodontics?
Widens maxilla/expand arches
open midline suture and expand upper arch
What is interdental enamel reduction and how is this carried out?
removing enamel mesidal and distal of teeth to create space
with an abrasive strip
What should teeth be treated with following interdental enamel reduction?
F-
What does the term ectopic teeth mean
eruption disturbance
tooth does not follow its usual course
Define hypodontia
Congenitally missing teeth
Define centre line shift
midline of upper and lower do not meet- either to left or right
Define infra-occlusion, what causes it and which teeth are mainly affected
Teeth that are fixed in position whilst remaining teeth continue to erupt due to ankylosis of the tooh
mainly affects primary molars
Define ankylosis and why is this a problem
Fusion of the tooth to bone preventing eruption and orthodontic movement
Define supernumerary teeth and which teeth are most commonly affected
Duplications of teeth
2nd lateral incisor (mesiodens)
molars and premolars
Define transitional incisor crowding
transition from primary to permanent dentition- incisor crowding in mixed dentition
which tooth is most likely to be ectopic?
3’s
Which age should 3’s be palpable and what should be done if not palpable?
9
if not palpable at 10- x rays
What technique is used in a radiograph for ectopic teeth?
parallax–S.L.O.B
Which teeth are most likely to be infra-occluded?
D’s and E’s
Which teeth are most likely to be congenitally missing?
5’s so extract E’s
Which teeth would most likely extracted to correct centre line shift?
C’s
3 reasons why A’s and B’s would be extracted
trauma
ectopic permanent tooth
caries
5 reasons why C’s would be extracted
caries trauma ectopic permanent tooth correct centre line shift transition incisor crowding
Which tooth is most likely to be extraced if transitional incisor crowding?
C’s
4 reasons D’s may be extracted
caries
infra-occlusion
ectopic permanent tooth
hypodontia
5 reasons E’s may be extracted
caries infra-occluded impacted 6's hypodontia- missing 5's ectopic 5 so extract E
Which permanent teeth are mainly extracted for ortho?
premolars –4’s
Which permanent tooth would be extracted to correct an overjet?
4’s
If U6 is extracted why would you consider extracting L6?
to prevent over eruption of the L6
3 reasons why a 6 maybe extracted for ortho and not premolars
heavily restored
MIH- hypoplastic
poor long term prognosis- extensive caries
What can occur of 6’s are extracted too early and what age would this be?
mainly for lower arch
<8
premolar may drift distally into this space, rotate or tilt
and then long need for fixed appliances
what can occur is 6’s are extracted too late and what age would this be?
> 10
7 may be in later stages of eruption and may then tip mesially and rotate and may not come forward enough
what are disadvantages of extraction treatment (ortho)?
affects TMJ
what does non-extraction treatment cause?
poor stability
What is extraction choice based on?
crowding/overjet
