Orthodontics Flashcards
name four possible orthodontic treatment options for growing patients
growth modification
functional appliances
headgear
RME or reverse pull facemask
what are the three main risks of orthodontic treatment
relapse
root resorption
decalcification
name three benefits of orthodontic treatment
improve function
improve appearance
reduce risk of trauma
what are the two ages where orthodontic assessments can be made
brief at 9 years old
comprehensive at 11/12
name andrew’s six keys
molar relationship
crown anulation
crown inclination
no rotations
no spaces
flat occlusal planes
what three planes is the facial skeleton considered in
AP
transverse
vertical
what can a lip trap induce
proclination of upper incisors
what does a hyperactive lower lip cause and why is this relevant for the end of treatment
can retrocline lower incisors
indicates likely instability at end of treatment
what aspect of malocclusion is a tongue thrust commonly associated with
anterior open bite
name five features of a digit sucking habit
proclined upper anteriors
retroclined lower anteriors
AOB
narrow upper arch
posterior crossbite
when would you be concerned about an anterior crossbite and want to intercept
if there is mandibular displacement
name three unfavourable outcomes of mandibular displacement
lower incisors become mobile
labial gingival recession of lower incisors
tooth surface loss on labial surface of lower anteriors and palatal surface of upper anteriors
what is the value of degree of upper incisors to the maxillary plane
109 degrees
what is the value of degree of lower incisors to mandibular plane
93 degrees
what is the SNA angle related to
the maxilla to the anterior cranial base
what is the SNB angle related to
the mandible to the anterior cranial base
what is it called when dento-alveolar structures disguise underlying skeletal discrepancy
dento-alveolar compensation
what is the frankfort plane
orbitale to porion
what is the mandibular plane
menton to gonion
what is the normal value of FMPA
27 degrees
name 5 causes of local causes of malocclusion
variation in tooth number
variation in tooth size
abnormality of position
soft tissue abnormality
local pathology
name the four types of supernumerary teeth
conical
tuberculate
supplemental
odontome
name Three causes of a primary tooth being retained
absent successor
supernumerary
ectopic successor
what are the two options for management of a retained primary tooth with an absent successor
retain primary tooth for as long as possible if good prognosis
extract deciduous tooth to encourage space closure
should you compensate extraction of primary teeth
no
what is the only teeth you should contemplate balancing in the deciduous dentition
Cs
what should you consider when there is early loss of Ds or Es
space maintainers
name three factors that impact the rate at which space closes after tooth loss
age
degree of crowding
arch (mandible loses space quicker)
where do premolars develop in relationship to the deciduous tooth
right above/ below it
will not be able to palpate
if a premolar is ectopic where is it more likely to sit
palatally
as a GDP what should you do if you find a tooth that is ankylosed and infra-occluded below the level of the contact points of adjacent teeth
extract and space maintain if permanent successor
as a GDP what should you do if a deciduous tooth is infra-occluded with no permanent successor
refer early (hypodontia patient)
keep infra-occluded tooth to do a crown
take out tooth to close the space
what is a transposition
interchange in the position of two teeth
what s a soft tissue cause of midline diastema
low labial frenum
what two habits are associated with AOB
tongue thrust
digit sucking habit
what occurs in areas where bone is compressed
bone is resorbed
what occurs in areas where bone is under tension
bone is deposited
what can functional appliances achieve in a class II
retroclination of upper
proclination of lower
mesial migration of lower teeth
distal migration of upper teeth
what forces are required for a tipping movement
35g - 60g
what do light forces achieve when applied to the teeth
multinucleate cells absorb bone directly and there is hyperaemia in the PDL
what do moderate forces achieve when applied to the teeth
force exceeds the capillary blood pressure and creates a cell free zone on pressure side
resorption at hyalinisation occurs at reduced rate
what is it called when the force exceeds the capillary blood pressure and creates area of no cells on pressure side
hyalinisation
what occurs when there is excessive pressure applied to the teeth
there are unwanted side effects like pain and necrosis and root resorption
this can lead to anchorage loss and loss of vitality of the tooth
what degree of tooth movement per month is optimal
1mm
why may cleft lip and palate occur independently from one another
the upper lip and anterior part of palate have different embryological origins from the posterior palate and they fuse at separate times
what are the three main site of secondary cartilage formation in the mandible
condylar cartilage
coronoid cartilage
symphyseal cartilage
what two areas of secondary cartilage disappear before/ around time of birth
coronoid and symphyseal
what secondary cartilage in the mandible continues growth until age 20
condylar
how does the vault of the skull form
intramembranous ossification
how does the base of the skull form
endochondral ossification
by which means do the mandible and maxilla form
intramembranously
what is a primary abnormality
defect in the structure of an organ traced back to anomaly in development
what is secondary abnormality
interruption of normal development of organ that can be traced back to influences such as infection, trauma ect
what is agenesia
absence of organ due to failed development during embryonic period
what is a syndrome
group of anomalies that can be traced back to common origin
name two syndromes that can be atributed to maxillary hypoplasia
Apert’s syndrome
Achondroplasia
name two syndromes that can be atributed to mandibular problems
Treacher Collins syndrome
Turner’s syndrome
name three aetiologies of cleft lip/ palate
monozygotic twins
familial pattern
smoking
at birth, cartilaginous growth centres remain between which bones
sphenoidal and occipital
nasal septum
what are the three sites of facial growth
sutures
synchondroses
surface deposition
how does growth at sutures occur
growing structures separating the bone
new bone forms in sutures when the bones are pushed apart
how does growth occur at synchondroses
new cartilage forms in the centre of synchondroses and the cartilage at the periphery is turned into bone
how does growth occur at surface deposition
new bone is deposited beneath the periosteum over surface of cranial and facial bones
so they maintain their shape - resorption also occurs
what is the term for a change in position of bone due to remodelling
cortical drift
how does growth occur in the cranial vault
bone growth at sutures
surface deposition
what causes bone growth in the forehead after neural growth ceases
accommodation of air sinuses
how does growth occur in the cranial base
endochondral ossification
surface remodelling
how is the maxilla displaced in relation to anterior cranial base
forwards and downwards
at what age does growth at the maxilla and mandible slow
maxilla - 7 years
mandible - 17
in what planes does growth slow in both jaws - from first to last
width
length
height
how can growth be used to facilitate orthodontic treatment outcome
use of functional appliances
use of rapid maxillary expansion
use of protraction headgear
overbite reduction
what is a growth rotation due to
imbalance in growth of anterior and posterior face height
what does a backwards growth rotation lead to
long face (anterior open bite)
what does a forwards growth rotation lead to
short face (deep bite)
name four errors in cephalometry
magnification/ distortion
non-linear fields
quality of image
landmark definition and location
what do movements of teeth in the eruptive phase occur in response to
positional changes of neighbouring crowns
growth of mandible and maxilla
resorption of deciduous tooth roots
what is the first stage in the intra-osseous tooth eruption
root formation by proliferation of epithelial sheath and continues with production of dentine and pulp
what is the second stage in the intra-osseous tooth eruption
movements of the developing tooth - in occlusal direction
what is the third stage of intra-osseous tooth eruption
reduced enamel epithelium fuses with oral epithelium
what is the eruption pathway comprised of
area resulting from blood vessels decreasing in number and nerve fibres breaking into pieces
what is the first phase in the extra-osseous eruption of teeth
penetration of tooths crown tip through epithelial layers
what is the second phase in the extra-osseous tooth eruption
crown moves through mucosa in occlusal direction until contacting opposing tooth
what is the last phase in the extra-osseous eruption of teeth
muscle forces (tongue, cheeks, lips) help to determine final tooth position
what do teeth move in response to in the post-eruptive phase
increases in height of growing alveolar bone and jaws
attrition and abrasion
name three roles of the dental follicle
initiates resorption of bone overlying the teeth
facilitates connective tissue degradation to produce eruption pathway
provides traction forces in the PDL
in what position do the permanent incisors develop compared to their deciduous counterparts
palatal/ lingual
how is space created in the jaws anteriorly
intercanine space gained through lateral growth of jaws
upper incisors erupt into wider arc and more proclined
what is leeway space in the upper arch
the C D and E width is 1.5mm more than 3 4 and 5 width
what is leeway space in the lower arch
the C D and E width is 2.5mm more than the 3 4 and 5
what are 5 management options of an impaction of FPM
wait - 90% self correct
orthodontic separator
attempt to distalise the first molar
extract E and space maintain
distal disking of E
name three reasons central incisors may fail to erupt
supernumeraries
trauma to primary tooth
congenital absence (rare)
what are the four management options of an unerupted permanent incisor when there is a supernumerary tooth present
XLA supernumerary teeth and primary incisor
Space maintain
monitor for 12 months
if the above fails - expose and apply orthodontic traction with gold chain
how is early loss of a C managed
balance
how is early loss of an E managed
space maintainer as major space loss
more space loss in upper than lower
what are the components for a URA as a space maintainer
Adams clasps
labial bow
extend acrylic around teeth to prevent unwanted mesial drift
what is the guidelines for treatment of FPM of poor prognosis
do not routinely remove upper FPM if removing lower (and vice versa)
refer for orthodontic and paediatric assessment combined
look for position of 7 as well as the bifurcation (mesially tilted is favourable)
what would be the components for a URA to correct posterior unilateral crossbite
adams clasps (no retentive component across midline)
Active component - Hyrax screw
posterior bite plane to disclude teeth
what would be the components for a URA to correct an anterior crossbite
A - Z-spring
R - adams clasp and the anterior tooth you are not moving
A - only moving one tooth
B - PMMA
name four digit habit breakers
positive reinforcement
bitter tasting nail varnish
glove on hand
habit breaker appliance
name 2 ways a habit breaker appliance for digit habits could be constructed
one piece baseplate with single goal post
expansion screw and 2 goal posts if wanting to include maxillary expansion treatment
what should you check clinically when a patient appears with an anterior cross bite
is patient displacing mandible anteriorly (wear on lingual of lowers and labial of uppers)
mobility of lower incisor
tooth wear
gingival recession
how would you manage a tooth that has ankylosed and infra-occluded below the level of contact points of adjacent teeth and there is a permanent successor
extract and space maintain
how would you manage a patient with an infra-occluded tooth where there is no permanent successor
refer as URGENT as now a hypodontia patient
keep infra-occluded tooth to do a crown on
take tooth out to space close or maintain space for prosthesis
how should you clinically assess when canines are going to erupt
palpate at 9 and 11 years
mobile Cs
angulation of lateral incisors
name three risks of doing nothing with an ectopic maxillary canine
permanent canine fails to erupt
root resorption of adjacent teeth
cyst formation around canine
what are the three risks of doing nothing with an infra-occluded primary when the permanent successor is present
permanent successor becomes ectopic
primary tooth becomes inaccessible for XLA
caries and periodontal disease
give three treatment options for Class III malocclusions
RME to enhance maxillary growth
functional appliance - reverse twin block
camouflage with URA
what are treatment options for class II malocclusions
functional appliances - twin block
headgear
what are the components of a twin block that means it will treat class II malocclusion
expansion of upper palate - gives space for teeth to be moved back into position
upper and lower pieces of twin block meet so mandible is placed more forward
further eruption of rear teeth to complete treatment
removal of which premolar will give more space
although 5s are larger than 4s there is usually mesial drift of 6s so removing 4s is better
what two molar relationships are considered acceptable
class I
full unit class II
what is mild crowding
0-4mm
what is moderate crowding
5-8mm
what is severe crowding
more than 8mm
how can space be created in spacing cases
derotating teeth
uprighting teeth
molar distalisation (head gear)
expansion
incisor proclination
extraction
