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3rd year lectures key points Flashcards

1
Q

AP class 1

A

mandibular base 2-3mm behind maxillary base

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2
Q

AP class 2

A

maxilla more than 3mm in front of mandible

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3
Q

AP class 3

A

maxilla less than 2-3mm in front of mandible (mandible may be in front)

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4
Q

tx for skeletal discrepancies

A

growing pts - growth mod

completed growth - orthognathic surgery

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5
Q

aims of tx

A

stable
fct
aesthetic

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6
Q

risks

A

decalcification
relapse
root resorption

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7
Q

benefits

A 
fct
aesthetics
dental health
reduce risk of trauma
facilitate other dental tx
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8
Q

why ortho assess?

A

determine if any malocclusion present
identify any underlying causes
decide if tx indicated

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9
Q

when assess?

A

brief at 9yrs - interceptive ortho
comprehensive 11-12yrs - when 3s and 4s erupt
when older pts first present
if a malocclusion develops later in life

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10
Q

ideal occlusion - Andrews 6 keys

A 
molar relationship
crown angulation
crown inclination
no rotations
no spaces
flat occlusal plane (no curve of Spee)
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11
Q

normal occlusion

A

more common than ideal

minor deviations that do not contribute an aesthetic or fct problem

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12
Q

malocclusions

A

more significant deviations from the ideal that may be considered unsatisfactory (aesthetically or fct)
may require tx but pt factors may influence decision

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13
Q

PMH

A

allergy - Ni or latex
epilepsy - if not well-controlled avoid URA
drugs - some induce e.g. gingival overgrowth
imaging - delay tx until had scans

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14
Q

PDH

A

freq attendance
prev tx
cooperation
trauma - RR

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15
Q

dentoskeletal relationships

A

teeth on individual skeletal bases which are attached to the cranial base

  • maxilla - maxillary teeth and alveolus
  • mandible - mandibular teeth and alveolus
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16
Q

ideal FMPA

A

meet at occipuit

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17
Q

lateral skeletal assessment ref line

A

mid sagittal plane

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18
Q

assessing skeletal pattern

A

visual

palpate skeletal bases

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19
Q

effect of lip trap

A

may procline U incisors

may lead to relapse of OJ if persists at end of tx

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20
Q

effect of hyperactive L lip

A

may retrocline L incisors

indicates likely instability at end of tx

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21
Q

lips

A

competent/incompetent
trap
lower lip activity

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22
Q

which type of tongue thrust may cause a relapse of AOB?

A

endogenous

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23
Q

tongue thrust associated with

A

AOB

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24
Q

angulation of U incisors to Frankfort plane

A

110 degrees

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25
angulation of L incisors to mandibular plane
90 degrees
26
types of tooth movement
``` physiological - tooth eruption - mesial drift - U better orthodontic - from externally generated forces ```
27
tooth eruption stages
``` pre-eruptive tooth movement intra-osseous eruption mucosal penetration pre-occlusal eruption post-occlusal eruption ```
28
pre-eruptive tooth movement
small random movement | rocks in crypt
29
intra-osseous eruption
when roots begin to form slow 1mm/3m to 1mm/3yrs
30
mucosal penetration
fast | 1-2mm per month
31
pre-occlusal eruption
slow | stops when tooth hits something hard - when PDL begins to form
32
post-occlusal eruption
v slow
33
tooth eruption theories
``` root elongation alveolar bone remodel PDL formation apical blood flow important PTH receptor gene ```
34
interceptive tx
utilise tooth eruption to minimise impact of a developing malocclusion
35
interceptive tx - ectopic U C
remove c - 10-13yrs | permanent teeth can be encouraged ti erupt if extract primary tooth at correct stage - 1/2 to 2/3 root development
36
prevalence of ectopic U3
1-2%
37
when should you palpate for U3?
9-10yrs | buccal sulcus
38
things to assess when looking at ectopic U3
height closeness to midline - doesn't overlap adjacent incisor by >1/2 - angle between vertical and canine ideally <30 degrees
39
physiological basis of tooth movement ortho
if external force applied to tooth - will move as bone around it remodels bony remodelling mediated by PDL - if ankylosed/no PDL will not move (will cause movement of other healthy teeth) cementum much more resistant to resorption than bone - but some RR after ortho expected OBs and OCs - appliances transmit force to PDL and bone - phagocytosed by macrophages when stop functioning
40
theories for ortho tooth movement
differential pressure theory Piezoelectric pressure theory mechano-chemical pressure theory
41
differential pressure theory
force = tension areas - deposition compression areas - resorption
42
Piezoelectric pressure theory
Piezoelectric currents generated when crystalline structures such as bone are deformed compression side more +, tension side more - - OB and OC get preferentially recruited to certain sides
43
mechano-chemical pressure theory
mechanical stress release of neuropeptides from nerve endings stimulate FBs, endothelial cells and alv bone FBs also comm with OBs and OCs alv bone and PDL remodelling = tooth movement
44
force for tooth movement - tipping
35-60g
45
force for tooth movement - bodily movement
150-200g
46
force for tooth movement - intrusion
10-20g
47
force for tooth movement - extrusion
35-60g
48
force for tooth movement - rotation
35-60g
49
force for tooth movement - torque
50-100g
50
what movement do fixed appliances produce?
bodily movement
51
intrusion
pressure on supporting structures | resorption of bone
52
extrusion
tension in supporting structures | bone deposition
53
functional appliances mechanism by which they work
skeletal changes 30% - growth of mandible, restraint of maxilla dentoalveolar changes 70% - facial musculature stretched which generates forces transmitted to teeth and alveolus - retroclination U teeth - proclination L teeth
54
light force
``` hyperaemia within PDL OB and OC appear resorption of LD from pressure side apposition of osteoid on tension side remodelling of socket - frontal resorption PD fibres reorganise gingival fibres appear not to become reorganised but remain distorted slow tooth movement ```
55
mod force
occlusion of PDL vessels on pressure side hyperaemia of PDL vessels on tension side cell-free areas on pressure side (hyalinisation) - no cells, not dead but nothing going on so can't resorb period of stasis increased endosteal vascularity undermining resorption increased OC activity = get OC coming in and nibble from below sudden movement of tooth CLUNK - tooth may become slightly loose healing of PDL - reorganisation and remodelling
56
rotation
need a force couple - 2 forces in opp directions
57
excessive force
``` necrosis undermining resorption resorption of root surfaces pain permanent change ```
58
factors affecting response to ortho force
magnitude duration age anatomy
59
deleterious effects of ortho forces
``` pain and mobility pulpal changes RR loss of alveolar bone support relapse ```
60
rotational relapse
tend to rotate again due to supercrestal fibres | fibres will gradually move the tooth back after the appliance is removed
61
aetiology of skeletal variation
genetic | env - MM, mouth breathing, head posture
62
class 1 ceph
SNA 81 +/- 3 SNB 78 +/- 3 ANB 3 +/- 2
63
class 2 ceph
SNA usually average but may be increased if maxilla prognathic SNB usually decreased ANB >5 degrees
64
class 3 ceph
expect SNA decreased if maxilla deficient SNB often average but may be increased if mandible prognathic ANB <1 degree or negative
65
dento-alveolar compensation
dento-alveolar structures may disguise underlying skeletal discrepancy forces from STs - incline teeth towards a position of ST balance
66
Frankfort plane clinical
lower orbital rim to superior border of EAM
67
where do FMPA normally meet clinically?
EOP
68
vertical facial proportions clinical landmarks
glabella subnasale soft tissue menton
69
vertical facial clinical proportions
50%
70
Frankfort plane ceph
orbitale to porion
71
mandibular plane ceph
menton to gonion
72
FMPA degree
27 +/- 4
73
vertical facial proportions ceph landmarks
nasion ANS menton
74
vertical facial ceph proportions
45, 55
75
vertical jaw relationship - long facial height
``` LAFH >55% FMPA >31 degrees steeply inclined mandibular plane backward mandibular growth rotation AOB tendency ```
76
vertical jaw relationship - short facial type
``` LAFH <55% FMPA <23 degrees tendency to parallelism of jaws forward mandibular growth rotation deep overbite tendency ```
77
mandibular displacement
inter-arch width discrepancy causes posterior teeth to meet cusp to cusp mandible forced to deviate to one side to achieve position of inter-cuspation - association with TMD - one reason why you would treat it
78
transverse jaw discrepancies: arch width discrepancies
disproportion of M and M arches maxillary arch too narrow is the most common causes buccal CBs often exaggerated by AP discrepancies
79
transverse dento-alveolar compensation
small maxilla - upper molars tend to flare outwards due to forces of tongue moulding to compensate
80
facial asymmetry causes
dental cause | true mandibular asymmetry
81
arch size discrepancies - DA disproportion
discrepancy between size of teeth and jaws crowding - small jaws, normal teeth (most common) - macrodontia spacing - large jaws, normal teeth - microdontia
82
aetiology of malocclusion
skeletal dental STs other e.g. habits
83
local causes of malocclusion
``` variation in tooth number variation in tooth size/form abnormalities of tooth position ST abnormalities local pathology ```
84
variation in tooth number
``` supernumeraries hypodontia variation of timing - retained primary - early loss primary - unscheduled loss of permanents ```
85
supernumeraries
tooth/tooth-like entity which is additional to normal series
86
where are most supernumeraries located?
80% in anterior maxilla
87
prevalence of supernumeraries
1% in primary | 2% in permanent
88
types of supernumerary
conical tuberculate supplemental odontome
89
conical supernumerary
``` most common anterior maxilla small, peg shaped close to midline, mesiodens may erupt (extract) tend not to prevent eruption/cause impaction but may displace adjacent teeth parallax ```
90
supplemental supernumeraries
normal morphology at end of a tooth series often extract
91
tuberculate supernumeraries
tend not to erupt - often associated with a failure of eruption cause impaction of teeth paired barrel-shaped usually extracted one of main causes of failure of eruption of permanent upper incisors
92
odontome
mass of P, D, E can prevent eruption of teeth compound/complex
93
hypodontia prevalence
4-6%
94
retained primary tooth
difference >6m between shedding of contralateral teeth | radiograph
95
why are primary teeth retained?
``` absent successor ectopic successor/dilacerated infra-occluded primary molars - trauma/idiopathic dentally delayed - may be medical causes pathology/supernumerary ```
96
retained primary tooth - absent successor
maintain primary tooth for as long as possible (if good prognosis) or extract early - encourage spontaneous space closure
97
infra-occluded primary molar
``` tooth fails to achieve/maintain its occlusal relationship with adjacent teeth - MRs not same height often corrects temp ankylosis percussion sound ```
98
infra-occluded primary molar - prevalence
common 1-9%
99
slight infra-occluded primary molar
between occlusal surface and IP contact, <2mm
100
mod infra-occluded primary molar
within occluso-gingival margins of IP contact
101
severe infra-occluded primary molar
below IP contact point - likely extract
102
management of infra-occluded primary molar - successor present
usually self-correct so keep under review consider extraction if - contact points going subgingival - root formation of successor near completion
103
infra-occluded primary molar management - successor absent
depends on potential of crowding - retain if good condition (onlay) - or extract and plan space management
104
early loss of primary teeth - localisation of crowding depends on:
which tooth extracted when tooth extracted pts inherent crowding
105
balancing ext
ext from opp side of same arch | minimise midline shift
106
compensating ext
extract from opposing arch of same side | maintain occ relationship
107
early loss of primary canines
consider balancing ext | as can get midline shift
108
when does the early loss of primary teeth have most effect?
when primary teeth extracted early - little effect if extracted late more space loss in U>L marked space loss in crowded pts minimal/no space loss in spaced dentitions
109
compensating extractions if early loss of FPMs
U6 extracted - don't compensate | L6 extracted - may need to compensate - depends on occlusal stops
110
when should the prognosis of FPMs be assessed if considered ext?
age 8-9yrs
111
balancing extractions if early loss of FPMs
consider if premolar crowding
112
factors influencing impact of loss of 6s
``` age at loss - U less important - L bifurcation development in 7s - too late - poor space closure - too early - distal drift of 5s crowding - U potentially rapid space loss - L best results if crowded. if spaced/aligned - spaces malocclusion ```
113
loss of permanent central incisor
maintain space - centre lines reimplant
114
variation in tooth size/form
``` macrodontia microdontia abnormal form - aesthetics - pulp chamber morphology ```
115
abnormalities of tooth position
ectopic | transpositions
116
ectopic first molars
``` <5% U arch more common reversible <8yrs manage - separator - attempt to distalise 6 - extract E ```
117
incidence of ectopic canines
1-3% pop | 80% palatal
118
what are ectopic canines associated with?
small/absent U laterals
119
assessment of canines
``` clinical - palpation - inclination of 2 - mobility of c/2 - colour of c/2 radiographic - 2 - parallax ```
120
tx options for ectopic canines
extract c - interceptive retain 3 and observe surgical and ortho (surgical) extraction
121
reasons for ectopic upper centrals
dilacerated (trauma) | supernumerary
122
local abnormalities of STs
digit sucking frenum tongue thrust
123
transposition
interchange in position of 2 teeth
124
true transposition
apices in wrong place
125
pseudo transposition
only crowns crossed
126
treatment of transposition
extract one then close space accept (correct) if pseudo
127
labial frenum
may cause median diastema tx - ortho - frenectomy
128
why shouldn't you start tx straight after someone stops a non-nutritive sucking habit
might get some spontaneous correction
129
tongue thrust
may cause AOB endogenous e.g. Down syndrome macroglossia exogenous e.g. incompetent lips, struggle to get a seal to swallow
130
local pathology
caries cysts tumours
131
what does ectomesenchyme form?
P D C PDL
132
how do the flat bones of the skull form?
IM ossification
133
how does the base of the skull form?
endochondral ossification
134
IM bone formation
bone deposited directly into primitive mesenchymal tissues needle like bone spicules progressively radiate from primary ossification centres to periphery vault of skull maxilla most of mandible
135
endochondral bone formation
hyaline cartilage precursor centres of ossification base of skull get islands of cartilage remaining to allow growth
136
vault of skull growth
IM ossification in 3rd month in several centres fontanelles - anterior closes 2 years - posterior closes 1 year growth occurs at fibrous sutures in response to ICP growth continues until 7 but some of the sutures remain open until adulthood
137
embryonic facial cartilages
M and M develop IM, but develop adjacent to pre-existing cartilaginous skeletons - nasal capsule and Meckels cartilage 6 weeks associated but don't form it
138
when does ossification of face and skull occur?
about 7-8 weeks
139
mandibular processes
condylar unit angular unit - in response to MP and masseter coronoid unit - in response to temporalis alveolar unit - only forms if teeth are developing body - forms in response to IAN
140
3 main sites of secondary cartilage formation in the mandible
condylar - disappears long before birth coronoid - growth continues here until about 20yrs symphyseal end of each half of bony mandible - disappears just after birth appear 12-14 weeks IUL
141
development of M and M
both IM but are preceded by a cartilaginous facial skeleton
142
what precedes the mandible?
meckels cartilage
143
what precedes the primary skeleton of the upper face?
nasal capsule
144
primary abnormality
defect in structure/part of an organ that can be traced back to an anomaly in its development - spina bifida, cleft lip, CHD
145
secondary abnormality
interruption of normal development of an organ that can be traced back to other influences - teratogenic agents: infection (rubella virus), chemical (thalidomide/lithium) - trauma, amniotic bands
146
is a congenital abnormality always inherited?
no
147
deformation
anomalies that occur due to outer mechanical effects on existing structures
148
agenesia
absence of an organ due to failed development during embryonic period
149
sequence
single factor results in numerous secondary effects
150
syndrome
group of anomalies that can be traced back to a common origin
151
facial syndromes arising from early problems with facial development (1-8 wks)
``` env - foetal alcohol syndrome genetic multifactorial - hemifacial microsomia - Treacher collins syndrome (mandibulofacial dysostosis) - clefts ```
152
FAS
``` high maternal alcohol intake day 17 microcephaly short palpebral fissures short nose low nasal bridge long and thin upper lip deficient philtrum small midface small mandible mild mental retardation ```
153
hemifacial microsomia
``` 3D progressive facial asymmetry high arched palate malformed pinna ear tags unilateral mandibular and zygomatic arch hypoplasia normal intellect clinical spectrum of severity deafness, cardiac and renal problems ```
154
TC - mandibulofacial dysostosis
``` AD deformity of first and second branchial arches anti-mongoloid slant palpebral fissures coloboma of lower lid hypoplastic/missing zygomatic arches hypoplastic mandible deformed pinna, conductive deafness ```
155
CLP aetiology
``` genetic env - smoking - alcohol - anti-epileptics ```
156
dental features CLP
``` cleft lip that crosses over alveolus causes dental anomalies impacted teeth crowding hypodontia supernumeraries hypoplastic teeth caries ```
157
achondroplasia
problem with EC ossification defects in long bones, short limbs = dwarfism defects in base of skull, retrusive middle 1/3 of face, depressed nasal bridge
158
crouzon's (CF dysostosis)
``` AD premature closure of cranial sutures esp C and L proptosis mild hypertelorism retrusion and vertical shortening of midface prominent nose class 3 distraction osteogenesis ```
159
Apert's (acrosyndactyly)
``` AD premature closure of almost all cranial sutures maxillary hypoplasia class 3, AOB Parrot's beak nose syndactyly of fingers and toes CP association conductive deafness ```
160
differences between neonatal and adult skull
face small compared to cranium eyes large ears low set forehead upright and bulbous face appears broad nasal region vertically shallow, nasal floor close to inferior orbital rim - in adult mid face expands and nasal floor descends
161
growth of the cranial vault
expands in response to growing brain until age 7 growth at sutures - deposition in response to raised ICP shape modified by surface resorption/deposition after neural growth ceases forehead continues to expand due to pneumatisation of air sinuses
162
where does post-natal growth occur?
sutures synchondroses - in cartilage surface deposition
163
post-natal growth - sutures
periosteal lined contact areas | flat bones grow laterally and bone deposited where sutures are
164
post-natal growth - synchondroses
islands of cartilage remaining between bones forming base of skull in secondary cartilage of condyle and in cartilage of nasal septum spheno-occipital synchondrosis cartilage divides and areas pushed apart, turns to bone further away from the synchondroses
165
post-natal growth - surface deposition
over surfaces of cranial and facial bones, beneath the covering periosteum
166
growth of the cranial base
lateral growth completed by 3 years sphenoethmoidal synchondrosis fuses at 6-7 yrs, after this the anterior CB is relatively stable and is used as baseline growth ceases at SOS 12-15yrs and fusion by 20yrs
167
post-natal growth of maxilla
downwards and forwards growth at sutures, between maxilla and skull surface deposition mainly posteriorly and resorption anteriorly and inferiorly
168
post-natal growth of mandible
downwards and forwards growth at condyle surface resorption anteriorly and lingually with deposition posteriorly and laterally
169
timing of stopping of facial growth - M and M
order M and M growth stops: width, length, height width growth completed before pubertal growth spurt length growth continues throughout puberty - girls slows to adult rate 2-3yrs after 1st period - boys around 18yrs vertical height continues longest, declines to adult rate around 17-18 girls, early 20s boys
170
sec difference in adolescent growth spurt
girls 1-2years earlier | for tx to coincide with growth spurt need to start earlier in girls
171
growth rotations
forwards - short face downwards and backwards - long face AOB crowding of lower labial segment in late teens/early 20s - growth rotation
172
adult facial growth
v variable slowly throughout life tendency to increased overall length and prominence of nose and chin and ears
173
general direction of growth
downwards and forwards | but variations with growth rotations
174
which skeletal problems can a lat ceph be used for?
AP and vertical | 2D so can't use for transverse problems
175
analysis of lat ceph
relationship between jaws and cranial base relationship between jaws position of teeth relative to jaws ST profile
176
nasion
most anterior point of frontonasal suture
177
gonion
most posterior inferior point on mandibular angle
178
pogonion
most anterior point on mandibular symphysis
179
menton
most inferior point on mandibular symphysis
180
porion
upper midpoint on EAM
181
orbitale
most anterior inferior point on IO rim
182
ACB on lat ceph
sella-nasion | doesn't change after age 7 so can use as ref point
183
A and B
hard tissue - deepest concavity
184
AP - class 1 ANB
2-4
185
AP - ANB what can ortho be done on
8 to -3
186
vertical MMPA angle
27
187
vertical MMPA what can ortho be done on
17-37
188
Ui/MxP
109 +/- 6
189
Li/MnP
93 +/- 6
190
Ui/Li
135 +/- 10
191
rule of thumb for angles you can achieve with braces
U 120 | L 80
192
max movement with surgery
can only move M/M back/forward by 10mm | - if need >10mm do bimaxillary procedure
193
interceptive ortho - diastema
wait until Cs erupt | <2.5mm should close
194
ugly duckling stage
6 yrs 96% have diastema | canine crowns on distal of lateral roots
195
causes of UE central incisors
supernumeraries trauma/dilaceration other pathology v unusual to be congenitally missing
196
UE central incisors due to supernumeraries management
``` usually palatal 1 - remove deciduous and supernumeraries 2 - expose/bond 3 - create space 4 - monitor >1.5yrs 80% will erupt over 16m ```
197
what does the effect of early loss of primary teeth depend on?
crowding age arch anteriorly spacing so ok posteriorly causes crowding as 6s come forward
198
early loss of primary c's
balance to prevent centre line shift
199
tx of anterior CB
``` tend to tx early (2s through) z-spring 3 Adams clasps - need one at front PBP so occlusion doesn't interfere ```
200
extracting L FPM
need to compensate | don't balance
201
extracting U FPM
don't compensate - don't get over eruption in lower arch
202
ideal time for ext of FPMs
``` 7s furcation forming - less likely to get severe mesial tipping (8s present) class 1 mod L crowding mild/mod U crowding U space closure much better ```
203
when should you treat a posterior unilateral CB?
if displacement on closure | - distance between centre lines
204
tx of a unilateral posterior CB
PBP - disocclude 6m would get correction turn screw x2 per week reciprocal anchorage
205
when should habits be stopped by?
9yrs (within 3yrs of eruption)
206
retained primary teeth
extract
207
U canines development
palatal migrate and lie labial and distal to root apex of U laterals 90% palpable by 11yrs - if can't then radiograph
208
slightly enlarged canine roots
palatally placed
209
diagnosis of infra-occluded primary teeth
percussion (hollow) visually radiograph (best)
210
tx of infra-occluded primary teeth
successor present and mild (2mm or less) - observe 1yr | no successor - extract as likely to get worse
211
consequences of leaving infra-occluded primary tooth
hard to keep clean | further submerged = harder to extract
212
management of ectopic U C's
extract c's 11-12yrs - if 3 not past midline of 2 - 90% success - if 3 encroaching on 1 (significantly past 2) - 60% success ensure enough space
213
causes of a reverse OJ
dental e.g. retroclined uppers skeletal e.g. class 3 both
214
comprehensive tx
full correction of malocclusion Andrew's 6 keys class 1 canines, incisors, molars
215
compromise tx
correct certain aspects accepting others | e.g. accept buccal CB with no displacement - no fct problem
216
stages of tx planning
``` plan around L arch (LLS stable - just incisors) - plan everything around lower incisors tx in lower build U arch around L - canines must be class 1 molar relationship - class 1 or full unit class 2 ```
217
crowding assessment
measure space available and space required | overlap technique
218
space required in L arch - mild
0-4mm NE - stripping E5s
219
space required in L arch - mod
5-8mm E5s (5mm) E4s (6,7,8mm)
220
space required in L arch - severe
8+ mm | E4s
221
stripping
``` metal sandpaper IP enamel reduction can get up to 3mm - 12 surfaces c to c - take off 0.5mm ```
222
extracting L4 or L5
extract L4 - less mesial drift only take out 5s if at mild end of crowding - won't get enough space if severe L4 is 7mm wide so get 14mm space if ext both - if all the space needed need to reinforce anchorage (HG) - usually front teeth come back 50% and back teeth forward 50%
223
if you ext in L arch what should you do in U?
E in U arch t get a MR class 1 (avoid class 3)
224
if you don't ext in L arch what should you do in U?
``` 1 - ext U arch - MR class 2 2 - distalise UBS with headgear (MR class 1) ```
225
tx options
``` accept malocclusions E only URA functionals +/- ext fixed +/- ext complex tx - ortho and restorative - ortho and orthognathic surgery ```
226
limitations
effects almost purely dentoalveolar and tooth movement | only remain stable where forces in equilibrium

Ortho (21 decks)

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