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BDS3 CDS > ortho 2 > Flashcards

ortho 2 Flashcards

1
Q

3 phases of tooth eruption

A

pre eruptive
eruption - intra-osseous and extra-osseous
post eruption

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2
Q

what are the fibres formed at the periphery of the eruption pathway, that guide the tooth into the oral cavity called

A

gubernacular cord

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3
Q

describe the intra-osseous eruptive phase

A

root formation - proliferation of epithelial root sheath then dentine and pulp formation

movement of developing tooth occlusally or incisally - slow, several months

formation of gubernacular cord - links tooth follicle to gingiva

reduced enamel epithelium rises with oral epithelium to form junctional epithelium

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4
Q

describe the extra-osseous eruption phase

A

penetration of crown tip ruptures epithelium - fast, 1-2 weeks

formation of attached gingivae

crown moves through mucosa until contacts opposing tooth - slow, several months

environmental factors determine final position (forces from cheeks, lips, tongue)

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5
Q

describe the post eruptive phase of eruption

A

movement after tooth reaches occlusal plane

  • response to growing alveolar bone and jaws
  • response to attrition and abrasion - compensating for wear
  • tooth wear of proximal surface leads to mesial drift
  • over eruption due to loss of opposing teeth
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6
Q

give a cause of mesial drift

A

tooth wear of proximal surface

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7
Q

3 roles of the dental follicle

A

initiate resorption of overlying bone

creates eruption pathway via connective tissue degradation

promotes alveolar bone growth

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8
Q

what is interceptive ortho

A

any procedure that will reduce or eliminate developing malocclusion

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9
Q

when is the correct time to extract deciduous tooth to encourage permanent teeth to erupt

A

one half to two thirds root development of permanent tooth

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10
Q

what age can you treat ectopic upper permanent canines by extracting the cs

A

10-13

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11
Q

where in relation to the primary incisors to permanent incisors develop

A

palatal/lingual

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12
Q

Additional space is required to accommodate the larger anterior teeth of the permanent dentition, how is this space gained

A

lateral growth of jaws increases inter canine width
upper incisors erupt more proclined
lee way space

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13
Q

what is the leeway space in upper arch

A

1-1.5mm

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14
Q

what is the leeway space in lower arch

A

2-2.5mm

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15
Q

how to calculate leeway space

A

primary c d e - permanent 3 4 5 = leeway space

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16
Q

when does a diastema usually close

A

by 12 when the 3s have erupted

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17
Q

management options of ectopic 6 stuck beneath e

A

if <7 years wait 6 months and review
orthodontic separator
distalise 1st molar
extract E
file down distal of E

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18
Q

causes of unerupted central incisors

A

trauma to primary tooth causing dilaceration of permanent

supernumeraries

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19
Q

management of unerupted central incisors

A

remove primary teeth and supernumeraries

maintain/create space

monitor for 12 months if less than 9

if 9+ or still not erupted, expose and ortho traction

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20
Q

impact of early loss of deciduous teeth

A

localised crowding

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21
Q

what factors influence the effect of crowding after early loss of deciduous tooth

A

crowding already present
age
which arch
which tooth

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22
Q

reason for balancing extraction

A

maintain position of centre line

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23
Q

reason for compensating extraction

A

maintain buccal occlusion

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24
Q

loss of which deciduous tooth requires balancing extraction

A

C

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25
Q

why should you consider a space maintainer after early loss of an E

A

major space loss of don’t - 6 will drift mesially
more so in upper than lower

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26
Q

design a passive URA that will maintain space

A

Adams clasp 0.7mm HSSW on UL6 and UR6
southend clasp 0.7mm HSSW
baseplate with acrylic serenaded around teeth to prevent mesial drift
+/- mesial stop 0.6mm HSSW on individual tooth

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27
Q

example of a fixed space maintainer

A

band and loop

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28
Q

when is the most ideal result gained when extracting 6s of poor prognosis

A

7s bifurcation is calcifying
8s are present
moderate crowding
class 1

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29
Q

4 rules for extracting 6s

A

if extracting lower, take upper - compensate

don’t need to compensate an upper 6 extraction

don’t balance with a sound tooth

don’t balance if well aligned or spaced

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30
Q

What do we tell the patient when we fit a removable appliance ?

A

Wear Full-time

Keep teeth and appliance clean - 2x daily minimum and every time after eating. (Can be worn for eating but remove for tooth brushing.)

Use a daily fluoride mouthwash

Avoid sugary food and drinks especially carbonated drinks

Avoid hard, sticky foods

May want to remove for some sports

initially speech will be affected

excess saliva

eating might feel awkward

teeth being moved might be painful.

Advise whom to Contact if patient has any problems

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31
Q

describe an URA design suitable for crossbite correction

A

hyrax screw or coffin spring
post bite plane
Adams class 0.7mm HSSW on 4s and 6s

over correct

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32
Q

URA design for anterior cross bite

A

z spring for tooth behind Lower incisors 0.5mm HSSW

Adams clasps 0.7mm HSSW on 4s and 6s

posterior bite plane

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33
Q

management of digit habit

A

bitter nail polish
positive reinforcement
glove on hand
habit breaker appliance - deterrents such as goal posts

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34
Q

how to know if pt is wearing appliance

A

did they wear into surgery
ask them
still excess salivation or speech affected
are active components now passive
signs of wear on appliance, palate and gingiva

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35
Q

what should you check for when assessing ant.cross bite

A

gingival recession
mobility of lower incisor
tooth wear
displacement

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36
Q

what is the aetiology of an infra occluded tooth

A

ankylosis of primary tooth
surrounding alveolar bone continues to grow
primary tooth left behind

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37
Q

how do you diagnose infra-occluding teeth

A

percussion
check for mobility
radiographs

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38
Q

when radiographically assessing an infra occluded tooth, give 3 things to check for

A

ankylosis of tooth - no PDL space
presence or absence of successor
root resorption

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39
Q

treatment of infra-occluded tooth below contact point

A

extract and maintain space

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40
Q

Please provide an URA to maintain space UL5

A

Adams clasps UR6 and UL6 (0.7mm HSSW) Southend clasp UR1,UL1 (0.7mm HSSW)
extend baseplate distal to UL4 OR Consider wire stop

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41
Q

where does development of canines begin

A

high and palatal

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42
Q

when do you start palpating and assessing position of upper canines

A

9 - should be palpable by 11

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43
Q

what effect do ectopic upper canines have on lateral incisors

A

root resorption

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44
Q

what circumstances is extraction of c most successful - 3

A

pt between 10 and 13
canine distal to midline of upper lateral incisor
sufficient space is available

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45
Q

risks of doing nothing with ectopic maxillary canines

A

becomes more ectopic
root resorption of adjacent teeth
failure to erupt

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46
Q

ortho interceptive treatment options for class 3

A

maxillary protraction head gear +/- RME (rapid maxillary expansion)
reverse twin block

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47
Q

why treat OJ early

A

trauma risk
appearance - bullying
more difficult when pt stops growing

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48
Q

when is anterior cross bite treated by ortognathic surgery and when is it treated with orthodontics

A

orthognathic - skeletal cause
orthodontics - dental cause

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49
Q

objective of ortho

A

to produce an occlusion that is stable, functional and aesthetic

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50
Q

what is compromise treatment

A

correct certain aspects and accept others e.g. accept buccal cross bite with no displacement

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51
Q

which arch is ortho treatment planned around

A

plan around lower arch and decide lower treatment
then build upper arch around lower

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52
Q

when examining a pt upper and lower arches for orthodontic assessment what do you check for

A

crowding
angulation of incisors
angulation of canines
centrelines

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53
Q

when orthodontically assessing teeth in ICP, what do you assess

A

incisor relationship
canine and molar relationship
OJ
OB
centrelines

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54
Q

how do you measure space available and space required when assessing crowding

A

space available = measure arch length anterior to first permanent molar

space required = measure every tooth width anterior to first permanent molar and add together

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55
Q

for what degree of crowding in lower arch do you extract 5s

A

mild to moderate
0-4mm
5-8mm

if taking lower extract upper

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56
Q

for what degree of crowding in lower arch do you extract 4s

A

moderate to severe crowding
5-8mm
8+mm

if taking lower extract upper

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57
Q

what incisor and canine relationship is the aim of ortho

A

class 1

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58
Q

what molar relationship is the aim in ortho

A

class 1 OR full unit class 2

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59
Q

limitations of ortho

A

prone to relapse if forces are not balanced between occlusion, periodontal structures and soft tissues

movement limited by shape and size of alveolar process

effects are purely dento alveolar and tooth movement - little skeletal effect

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60
Q

when are functional appliances and overbite reduction most successful

A

if used during adolescent growth spurt

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61
Q

main constituent of stainless steel

A

iron 72%

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62
Q

stainless steel constituents

A

iron - 72%
chromium - 18%
nickel - 8%
titanium - 1.7%
carbon - 0.3%

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63
Q

what is iron combined with to form steel

A

carbon

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64
Q

property chromium gives to steel

A

corrosion resistance

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65
Q

what properties do nickel give to SS

A

corrosion resistance and strength

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66
Q

why is titanium added to SS

A

to prevent precipitation of chromium carbides at grain boundaries
carbon preferably binds to titanium over chromium

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67
Q

how to make HSSW

A

work hardening - drawing metal In cold state through series of dies of successively smaller diameter

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68
Q

what are active components

A

components that will be moving teeth with application of force

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69
Q

what is retention in a URA

A

resistance to displacement forces

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70
Q

what is anchorage

A

resistance to unwanted tooth movement

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71
Q

what is the function of a baseplate in a URA

A

connect components

anchorage

retention

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72
Q

diameter of wire used for active components

A

0.5mm HSSW

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73
Q

diameter of wire for Adams clasps and retentive components

A

0.7mm HSSW

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74
Q

what component can you utilise to correct an over bite

A

FABP

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75
Q

advantages of removable ortho - 4

A

less specialised training requires
tipping of teeth
anchorage
OH easy to maintain

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76
Q

disadvantages of removable ortho - 4

A

can be removed by pt
only 1-2 teeth at a time
rotations are difficult to correct
less precise control

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77
Q

purpose of tagging ends of Adams clasp

A

to add mechanical retention

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78
Q

what additional component is added to buccally placed active components to increase their strength and rigidity

A

0.5mm internal diameter tubing - example, buccal canine retractor

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79
Q

describe a URA for 12 in anterior cross bite

A

12 z spring 0.5mm HSSW
16 26 14 24 Adams clasp HSSW 0.7mm
posterior bite plane

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80
Q

active component that could be utilised to retract buccally placed canines

A

buccal canine retractors o.5mm with o.5mm ID tubing

81
Q

component that would correct overbite in pt
pt also has OJ of 6mm

A

flat anterior bite plane OJ plus 3mm

82
Q

steps in fitting a URA

A

check correct patient
check correct design
inspect design
check integrity of wire work
insert and check for blanching or trauma
check posterior retention - flyover then arrow head
check anterior retention
activate appliance
demo pt insertion and removing
review app. 4-6 weeks

83
Q

what info will you give to a pt after fitting a URA

A

big and bulky feel
affect speech for short time
salivation
discomfort or ache
wear 24/7 inc meal times and sleep
remove after meal and clean
remove for contact sports
avoid hard or sticky foods
cautious with hot and cold
non compliance increases treatment time
emergency contact

84
Q

Appliance that can be used to reduce 6mm OJ of 11 12 21 22 and OB

A

Roberts retractor - o.5mm HSSW with o.5mm ID tubing
0.7mm mesial stops on 13 and 23

16 and 26 Adams clasp

FABP OJ+3mm - need to reduce gradually

85
Q

URA appliance design to expand upper arch

A

midline palatal screw
adams clasp on 16 26 14 24
PBP

86
Q

why is facial growth important

A

size shape and position of jaws determines tooth position and therefor malocclusion

can utilise growth to predict changes and correct

87
Q

what are thew two phases of life in utero

A

embryonic 1-8 weeks
foetal 8 weeks to term

88
Q

when are all the limbs and organs formed in utero

A

first 2 months

89
Q

when is the incidence of deformities that lead to miscarriage highest

A

first 8 weeks - embryonic

90
Q

how many Carnegie stages is the embryonic period divided into

A

23

91
Q

describe the first stage - first day of embryonic life

A

fertilised oocyte
male and female pronucleus
formation of zygote

92
Q

ascribe stage 2 of embryonic life

A

separation and formation of blastomeres

93
Q

what happens in stage 3 of embryogenesis

A

segmentation

embryonic and abembryonic poles

94
Q

what happens after the primitive groove is formed

A

embryo with somites and neural groove formation

95
Q

which cell migration is important in development of face

A

neural crest

96
Q

how does the neural tube dorm

A

neural folds fuse to form neural tube at end of week 3

97
Q

the neural tube fuses at the end of week 3, failure to fuse will lead to what?

A

spina bifida

98
Q

the neural tube develops into the brain and spinal cord, what will failure to develop lead to

A

anencephaly - cerebral hemispheres and cranial vault absent

99
Q

neural crest cells develop along the neural groove and then undergo migration to differentiate into many cell types such as…

A

spinal and autonomic ganglia

Schwann cells

adrenal medulla

100
Q

where is the ectomesenchyme derived from

A

neural crest

101
Q

what does ectomesenchyme contribute to

A

branchial arch cartilage

bone and connective tissue proper

dental tissues - pulp dentine cement and PDL

102
Q

where are pulp dentine cementum and PDL derived from

A

ectomesenchyme

103
Q

when does formation of the face occur in utero

A

first 8 weeks

104
Q

defects of the face are closely related to defects where else

A

anterior brain

105
Q

what cells form the majority of the face

A

migrating neural crest cells

106
Q

what occurs when there is failure of fusion between the palatine processes or facial processes

A

cleft formation

107
Q

why do cleft lip and alveolus occur independently of cleft palate and vice versa

A

the upper lip and anterior palate have different embryological origins to posterior palate and fuse at different times

108
Q

where are mandibular and maxillary processes derived from

A

first pharyngeal arch

109
Q

where is the operculum and sinus cervicalis derived from

A

2nd pharyngeal arch

110
Q

the skull can be divided into two parts. what are the two parts

A

neurocranium - protective case of brain

viscerocranium - skeleton of face

111
Q

give examples of intramembranous bones

A

vault of skull
maxilla
most of mandible

112
Q

how is intramembranous bone formed

A

bone is deposited directly into primitive mesenchymal tissue

bone spicules form which radiate from primary ossification centres to periphery

progressive bone formation leads to fusion of adjacent bony centres

113
Q

how is endochondral bone formed

A

bones are preceded by a hyaline cartilage

several centres of ossification which eventually fuse

114
Q

which bones are formed by endochondral ossification

A

base of skull

115
Q

where do cartilaginous growth centres remain at birth

A

between spend and occipital bones

nasal septum

116
Q

intramembranous ossification is incomplete at birth and there are widening left on the vault of cranium. what are these called and what are their function

A

fontanelles - allow flexibility during birth

117
Q

when does the ant. and post. fontanelle close

A

anterior - 2 years
posterior - 1 year

118
Q

why does growth continue to occur at fibrous sutures until about 7

A

intracranial pressure

119
Q

maxilla and mandible develop adjacent to preexisting cartilaginous skeletons, what is the name of these?

A

maxilla - develops adjacent to nasal capsule

mandible - develops adjacent to meckels cartilage

120
Q

describe the growth of the mandible

A

develops adjacent to pre existing mockers cartilage

develops as several units responding to different stimuli - condylar, angular, coronoid, body and alveolar unit

3 main secondary sites of cartilage formation - condylar, coronoid and symphyseal

coronoid disappears before birth, condylar growth continues until 20, midline symphysis uses a few months after birth

121
Q

what are the 5 units of mandible in development

A

body
angular
alveolar
coronoid
condylar

122
Q

what does the body unit of mandible form in response to

A

IAN

123
Q

what does the coronoid unit of mandible form in response to

A

temporalis muscle development

124
Q

when does the alveolar unit of mandible form

A

only when there are teeth developing

125
Q

what does the angular unit of mandible form in response to

A

in response to lateral pterygoid and masseter

126
Q

what are the 3 main sites of secondary cartilage formation in the mandible at each end of mandible halves

A

condylar cartilage - grows until 20
coronoid cartilage - disappears before birth
symphyseal - midline symphysis fuses after birth

127
Q

briefly describe prenatal growth of the face - 5

A

ossification of skull and face commences 7-8weeks

neurocranium incases brain, viscerocranium skeleton of face

the vault of skull is formed intramembranously

base of skull is formed by endochondral ossification

maxilla and mandible formed intramembranously but are preceded by cartilaginous facial skeleton

128
Q

what cartilage is the primary skeleton of upper face

A

nasal capsule

129
Q

what cartilage precedes the mandible

A

meckels cartilage

130
Q

what is a primary abnormality and give an example

A

defect in the structure of an organ or part of an organ that can be traced back to an anomaly in development

cleft lip

spina bifida

131
Q

what is a secondary abnormality and give an example

A

interruption in the normal development of an organ that can be traced back to other influences

trauma

infection - rubella virus

thalidomide

132
Q

what is a deformation

A

anomalies that occur due to outer mechanical effects on existing structures

133
Q

what is agenesia

A

absence of an organ due to failed development during embryonic period

134
Q

what is a sequence abnormality - give example

A

single factor resulting in numbers secondary effects

pierre robin sequence - underdeveloped mandible

135
Q

what is a syndrome and give example

A

group of abnormalities that can be traced to a common origin

trisomy 21 in downs syndrome

136
Q

3 facial syndromes related to maxillary hypoplasia

A

aperts syndrome - acrosyndactyly

croutons syndrome - craniofacial dysotosis

doses syndrome

137
Q

3 facial syndromes related to mandibular problems

A

teacher Collins - mandibulofacial dysostosis

pierre robin sequence

hemifacial microsomia

138
Q

give an example of facial syndrome that arises from environmental cause

A

foetal alcohol syndrome

139
Q

characteristics of foetal alcohol syndrome

A

indistinct philtrum and thin upper lip

short palpebral fissures

microcephaly

short nose and low nasal bridge

micrognathia - small mandible

mild mental retardation

140
Q

characteristics of hemifacial microsomia

A

unilateral mandibular hypoplasia - spectrum

zygomatic arch hypoplasia

malformed pinna

deafness

141
Q

what causes treacher collins

A

deformity of 1st and 2nd pharyngeal arches

142
Q

what are the characteristics of treacher collins syndrome - mandibulofacial dystosis

A

anti-mongoloid slant palpebral fissure

colomboma of lower lid outer third

hypoplastic or missing zygomatic arches

hypoplastic mandible with antigonial notch

deformed pinna and conductive deafness

143
Q

incidence of cleft L and P

A

1:700 births

144
Q

when does cleft lip and cleft palate abnormality occur

A

cleft lip day 28-38

cleft palate day 42-55

145
Q

3 genetic causes of cleft lip and palate

A

monozygotic twins

familial pattern

syndromes

146
Q

3 environmental causes of cleft lip and palate

A

social deprivation
smoking
alcohol

147
Q

3 dental features of cleft lip and palate

A

impacted teeth
crowding
hypodontia

148
Q

what is achondroplasia

A

problem with endochondrial ossifications

defects in long bones - short limbs

149
Q

characteristics of achondroplasia

A

short limbs - dwarfism

base of skull defects - retrusive mid third of face depressed nasal bridge, frontal bossing (prominent forehead)

150
Q

what causes crouzons syndrome (craniofacioal dystosis)

A

premature closure of cranial sutures - coronal and lambdoid

151
Q

characteristics of crouzons syndrome (craniofacial dystosis)

A

proptosis - shallow orbits

orbital dystopia

retrusion and vertical shortening of mid face

prominent nose

class 3 and narrow spaced teeth

152
Q

what is cranial synostosis

A

early closure of cranial sutures

153
Q

what is the cause of aperts syndrome - acrosyndactyly

A

premature closure of almost all sutures

154
Q

characteristic of aperts syndrome/acrosyndactyly

A

proptosis - bulging eyes

hypertelorism - increased distance between orbits

maxillary hypoplasia

parrots beak nose

class 3 occlusion, AOB

155
Q

acrosyndactyly/aperts affects the face by premature closure of almost all cranial sutures, where else does aperts affect

A

syndactyly of fingers and toes

156
Q

3 differences between adult and child face

A

infant has small face compared to cranium
eyes are large and ears low set
forehead upright and bulbous

157
Q

3 sites of facial growth

A

sutures
synchondroses
surface deposition

158
Q

what is a suture

A

fibrous joint between intramembranous bones that fuse when growth is complete

159
Q

where are synchondroses found

A

midline of sphenoid, occipital and ethmoid bones

160
Q

what is a synchondrosis

A

a cartilage based growth centre - growth occurs in both directions
peripheral cartilage turns to bone while new cartilage forms in middle

161
Q

what is the process of bone deposition and resorption known as

A

bone remodelling

162
Q

what is the change in position of a bone due to remodelling known as

A

drift

163
Q

how many fontanelles are present at birth

A

6

164
Q

growth of cranial vault occurs in response to the expanding brain until what age

A

7

165
Q

2 ways growth occurs in cranial vault

A

bone growth at sutures

external and internal surface remodelling of bone

166
Q

2 ways growth occurs in cranial base

A

endochondral ossification

surface remodelling

167
Q

large cranial base angle is associated with what skeletal class

A

class 2

168
Q

class 3 is associated with what size of cranial base angle

A

small angle

169
Q

where does sutural growth of maxilla take place

A

mid palatine suture
zygomatic and frontal bone sutures

170
Q

how does the mandible grow in terms of direction

A

down and forward

171
Q

how does the mandible grow to accommodate permanent dentition

A

condylar cartilage

surface remodelling - resorption anterior and lingual and deposition posterior and lateral

172
Q

when does growth of the mandible accelerate significantly

A

during pubertal growth spurt

173
Q

when does the maxilla growth start to slow

A

7

174
Q

put in order of which growth of mandible and maxilla slows first - height, width, length

A

width - slows first
length
height

175
Q

what treatment would an orthodontist use growth to facilitate - 4

A

functional appliance
rapid maxillary expansion
protraction headgear
overbite reduction

176
Q

what causes growth rotations

A

imbalance in growth of anterior and posterior face heights

177
Q

what growth rotation leads to development of deep bite

A

forward

178
Q

what growth rotation can lead to AOB

A

backwards

179
Q

3 ways to measure facial growth changes

A

lateral cephalometry
casts of face
3D photogrammetry

180
Q

indications for lateral cephalogram - 3

A

aid diagnosis of skeletal discrepancy
treatment planning
to monitor progress of treatment e.g. functional appliance

181
Q

position pf head and occlusion for lateral cephalogram

A

Frankfurt plane parallel to floor

RCP

182
Q

how is head kept steady in cephalostat

A

ear rods
nasion support

183
Q

what is a lateral cephalogram

A

standardised radiograph of face and base of skull

184
Q

what is cephalometry

A

analysis and interpretation of lateral cephalograms

185
Q

why are lateral cephalographs used for ortho treatment

A

they are reproducible - set distance

186
Q

what do you analyse when interpreting a lateral ceph. - 4

A

relationship between jaws and cranial base
relationship between upper and lower jaw
teeth position relative to jaw
soft tissue profile

187
Q

what angle measures maxilla in relation to mandible anteroposteriorly

A

ANB

188
Q

what angle measures antero posterior position of mandible and maxilla in relation to base of skull

A

SNB - mandible
SNA - maxilla

189
Q

what angle measures the position of mandible relative to maxilla vertically

A

FMPA

190
Q

normal SNA

A

81 +/-3

191
Q

normal SNB

A

79 +/-3

192
Q

normal ANB

A

3 +/-2

193
Q

normal FMPA

A

27 +/-4

194
Q

normal LAFT/TAFH ratio

A

55%

195
Q

UI-Mx and LI-Md measure the angulation of teeth to maxilla and mandible - what are their normal values

A

UI Mx 109 +/-6
LI Md 93 +/-6

UI/LI is 135

196
Q

ANB in class 1

A

2-4*

197
Q

ANB in class 2

A

mild 4-6*
mod 6-8*
sev >8*

198
Q

class 3 ANB

A

mild 0-2*
mod -3-0*
sev <-3*

BDS3 CDS (11 decks)

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