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BDS4 CDS > Orthodontics > Flashcards

Orthodontics Flashcards

1
Q

what can be used for parallax

A

horizontal parallax - two periapical radiographs
vertical parallax - an opt and occlusal

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2
Q

how does parallax work

A

need two images taken when the x-ray beam has changed direction
vertical - going from occlusal to OPT beam moves upwards - if tooth moves upwards - palatally placed
horizontal - two PAs, if move right and tooth moves right, palatally placed
SLOB - same lingual (palatal) opposite buccal

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3
Q

why do we take occlusal radiographs

A

to look for pathology in upper anterior region of maxilla
to confirm prescence of unerupted teeth
root resorption
to aid location of unerupted teeth - parallax

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4
Q

why do we take periapical radiographs

A

to investigate periapical infection
to check if a tooth is ankylosed
to check for root resorption
to aid location of unerupted teeth - parallax

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5
Q

why do we take bitewing radiographs

A

caries diagnosis
prognosis of tooth
alveolar bone levels

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6
Q

why do we take lateral ceph

A

aid diangosis - skeletal discrepancy
treatment planning
progress monitoring
research purposes

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7
Q

what position should the patient be in for lateral ceph and why are these useful

A

with frankfort plane horizontal and teeth in RCP, it is standardised and reproducible

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8
Q

what lines are seen on a lateral ceph

A

sella-nasion
frankfort - ponion to orbitale
maxillary plane - anterior nasal spine to posterior nasal spine
mandibular plane - menton to gonion

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9
Q

what analysis is commonly used for lateral ceph

A

eastmans analysis

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10
Q

what does the SNA and SNB line show in a lateral ceph and what are standard values

A

the antero-postero relationship of the maxilla (A) and the mandible (B) to the skeletal base. SNA - 81, SNB - 78

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11
Q

on a lateral ceph, what shows the relationship of the maxilla to the mandible

A

antero-postero - ANB
vertical - FMPA

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12
Q

what are the standard ANB values for each skeletal AP class

A

class 1 - 3-5
class 2 - more than 5, 8+ is severe
class 3 - less than 2, -3 is severe

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13
Q

what are the standard FMPA values for average, increased and decreased vertical class

A

average - 27 degrees
increased - above 27, above 32 mod
decreased - less than 27, below 22 mod

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14
Q

what should the inclination of the incisors be in relation to mandible and maxilla and what are the limits of camouflage

A

upper incisors - 109 ± 6
lower incisors - 93± 6
above these no.s - proclined
below these no.s - retroclined
uppers cannot be proclined past 120
lowers cannot be retroclined past 80

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15
Q

what measurements help to decided whether camouflage would be sufficient or if surgery would be required

A

ANB above 8 or below -3
FMPA above 37 or below 17
upper incisor above 120 or lower incisor below 80

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16
Q

why might we want to treat class 2 div 1

A

aesthetics - patients concerned, bullying
dental health - twice as likely to have trauma if OJ larger than 9mm

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17
Q

what skeletal pattern is often seen with class 2 div 1

A

AP - class 2, mandible behind maxilla, retrognathic mandible
vertical - variable, increased - AOB or decreased - large overbite

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18
Q

what soft tissue features are seen with class 2 div 1

A

lip trap - exacerbating proclination of uppers and retroclination of lowers
incompetent lips - incomplete closure of lips, increased risk of trauma

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19
Q

what habits are associated with class 2 div 1 and what are features of this

A

non-nutritive sucking habit
posterior cross bite - narrow upper arch
proclination of uppers
retroclination of lowers
anterior open bite

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20
Q

how is a sucking habit treatment

A

enforce that treatment cannot commence until habit stops - reinforcement, habit breaker - either URA or fixed
if stopped before 9 - spontaneous repositioning
after this, roots have completed growth so unlikely to get spontaneous
treat residual malocclusion

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21
Q

what management options are available for class 2 div 1

A

accept
enhance growth modification
simple tipping of teeth
camouflage
orthognathic surgery

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22
Q

what appliances can be used for growth modification

A

functional appliance - twin block
head gear

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23
Q

how does headgear work

A

restricts horizontal and/or vertical growth of maxilla to allow mandible to come forwards

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24
Q

how does a functional appliance work

A

utilize, eliminate or guide the force of muslce function, tooth eruption and growth to correct malocclusion

postures mandible downwards and forwards, stretches and activates masticatory muscles, mesialise mandible and distalise maxilla. restraint maxillary growth and enhance mandibular growth

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25
Q

what are therapeutic effects of functional appliance

A

minor skeletal change - any growth occured wouldve happened anyway. mostly dento-alveolar movement
distal movement of upper molars
mesial movement of lower molars
retroclination of upper anteriors
proclination of lower anteriors

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26
Q

what might be a design of a twin block functional URA

A

labial bow to retract upper incisors, midline palatal screw to expand upper arch, adams clasp for retention

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27
Q

when would a functional appliance be used

A

should be used during growth
can be used in early years - age 10 - can prevent trauma, compliance is better, but done in 2 phases as have to come back when secondary molars, not efficient and can get relapse
older ages - 12 - one phase of treatment, no relapse, easier, but risk of trauma, less compliant

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28
Q

what is the risk of using only ura to correct class 2 div 1

A

could tip the teeth back into class 2 div 2

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29
Q

when is camouflage appropriate

A

too old for functional, or had functional but compliance poor - can be used to mask skeletal difference if it is moderate

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30
Q

when is orthognathic surgery used

A

when growth is complete and AP or vertical skeletal relationship is severe

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31
Q

what is involved in orthognathic surgery for class 2 div 1

A

mandibular advancement and/or maxillary impaction
fixed ortho before, during and after treatment

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32
Q

what is the definition of hypodontia and severe hypodontia

A

congenital absence of one or more teeth, severe - 6 or more

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33
Q

what teeth are more commonly missing in hypodontia

A

upper and lower 5s
upper lateral incisors
lower incisors
last in series

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34
Q

what are the two types of hypodontia

A

syndromic - is a symptom of another syndrome - anhydrotic etodermal dysplasia, cleft palate
non-syndromic - mutations in at least 3 genes, familial or sporadic

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35
Q

how might hypodontia patients present

A

delayed eruption, unusual eruption pattern, retained primary teeth

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36
Q

what other problems are associated with hypodontia

A

microdontia, malformation of other teeth, impaction, delayed eruption, crowding or malocclusion

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37
Q

what are features of anhydrotic ectodermal dysplasia

A

effects all ectodermal tissue - hair, skin, sweat glands, teeth - sparse hair, dry wrinkly skin

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38
Q

what problems can hypodontia cause

A

spacing, over eruption, inadequate function, poor aesthetics

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39
Q

what treatment options are available for hypodontia patients

A

accept, ortho alone, restorative alone, ortho and restorative combined treatment

40
Q

when missing upper laterals, what treatment options are available

A

open space - extract premolar, pull canine back and then restore with implant, denture, bridge
close space - use ortho to close space and leave it or can intrude canine and extrude premolar then alter shape of teeth with composite and bleach to make it look more like lateral - space closure plus

41
Q

what must treatment for hypodontia achieve

A

satisfy aesthetic expectation, satisfy functional expectation, least invasive

42
Q

what is the aetiology of class 2 div 1

A

skeletal - maxillary prognathism, mandibular retrognathism

dental - proclination of uppers

soft tissues - lip trap, NNS habit, tongue thrust

43
Q

why is treatment required in class 2 div 1

A

OJ more than 9mm - IOTN 5a
high risk of trauma to incisors
aesthetics of concern to patient

44
Q

what is the incisor definition of class 2 div 2

A

lower incisor edge lies posterior to upper incisor cingulum plateau, overjet is reduced or reversed, upper incisors are retroclined

45
Q

what is the most common AP class seen in class 2 div 2

A

class 2 - ANB increased, more than 4

46
Q

what vertical discrepancy is seen in class 2 div 2

A

reduced FMPA and reduced LFH

47
Q

what are the soft tissue components seen in class 2 div 2

A

lower lip line is higher - entraps central incisors causing retroclination.
mentalis muscle is tight along chin - increases retroclination of lower incisors

48
Q

what is the aetiology of class 2 div 2

A

skeletal - prognathic maxilla, retrognathic mandible

dental - increased overbite, retroclination of incisors, upper laterals have poorly developed cingulums, shortened crown height of laterals - missing lower lip and in lower lip trap

soft tissues - high lower lip line, tight mentalis muscle

49
Q

what is the need for treatment in class 2 div 2

A

traumatic over bite - gingival stripping - 4f

50
Q

what are the treatment options for class 2 div 2

A

accept - non-traumatic overbite, patient not concerned

growth modification - functional appliance

URA - mild malocclusion, used to reduce overbite

fixed appliance - camouflage if underlying skeletal pattern is mild

orthognathic surgery - outwith growth potential

51
Q

what functional appliance can be used in class 2 div 2

A

modified from one used in div 1. want to procline upper incisors. ELSA design - expansion and spring - expand upper arch and spring to push upper incisors forward

52
Q

what dental anomaly is commonly seen class 2 div 2

A

ectopic or impacted canines - have a long route eruption, utilise lateral incisors to ensure correct eruption - but if they are small, more likely to go wrong

53
Q

what are the features of a class 3 incisor relationship

A

incisor - lower incisor edge lies anterior to cingulum plateau of upper incisors

AP - class 3, ANB less than 2
vertical - FMPA can be increased or reduced, LAFH can be increased or reduced
transverse - asymmetry - crossbite can cause deviation

54
Q

what is the aetiology of a class 3 relationship

A

genetics plays large factor

environmental factor - cleft lip and palate, acromegaly

skeletal - mandibular prognathism, maxillary retrognathism

dental - reduced overbite, anterior crossbite, buccal crossbite, dentoalveolar compensation

55
Q

how is the complexity of class 3 decided

A

number of teeth involved in anterior crossbite
presence of anterior open bite
skeletal discrepancy involved - ANB less than 0

56
Q

when is a class 3 treated

A

aesthetic concerns
functional problems - unable to eat and speak
dental health concerns - gingival stripping, attrition, displacement on closing TMD problems

57
Q

what treatment options are available for class 3

A

accept
growth modification - reverse twin block, restrict mandibular growth and encourage maxillary growth

URA - posterior bite plane, spring or screw plate to procline uppers over bite

fixed - procline uppers, retrocline lowers and correct OJ

orthognathic surgery

58
Q

what is role of GDP in class 3

A

identify and classify, refer to specialist
produce URA when requested

59
Q

what is the aetiology of the unerupted maxillary incisors

A

unerupted supernumerary preventing eruption
retained primary incisor
early loss of primary incisor
trauma to primary causing dilaceration of permanent root
crowding
ectoptic position of tooth germ

60
Q

what systemic conditions are associated with unerupted

A

downs syndrome, turners syndrome, cleft lip and palate, rickets

61
Q

how can an unerupted incisor be recognised

A

pattern of eruption - symmetrical - should appear within 6 months of condralateral
eruption pattern is out of sequence

62
Q

how can an un erupted maxillary incisor be treated

A

accept - unlikely, poor aesthetics, risk of crown resorption
monitor - if less than 9 years old, apex open and chance for spontaneous eruption
if apex closed - surgical exposure and ortho gold chain and apply traction

63
Q

what is the risk of leaving unerupted canines

A

root resorption of adjacent teeth
resorption of canine crown
ankylosis of tooth
cyst formation around crown
loss of deciduous and restorative options much more complicated when older

64
Q

when might surgical removal of an unerupted canine be indicated

A

canine is not alignable
root resorption of adjacent teeth is clear
no risk of damage during procedure
patient is happy with appearance and doesnt want orthodontic treatment

65
Q

what would indicate that canines are not alignable

A

too close to the midline
too high up - near the apical third of the incisors
the angle to the midsagittal plane is more than 55 degrees

66
Q

what are the treatment options for unerupted canines

A

accept and do nothing
surgical removal
surgical exposure and fixed orthodontic treatment
autotransplantation

67
Q

what are the benefits of ortho treatment

A

improved aesthetics - dental and facial, can improve QoL
improved function - mainly mastication if severe malocclusion
improved dental health

68
Q

what is the IOTN and what is it used for

A

index of treatment need = to assess the need for treatment depending on the impact on dental health

69
Q

what is the acronym used for IOTN

A

M - missing or impacted - risk of resorption or cyst formation
O - overjet - risk of trauma
C - crossbite - risk of tooth wear and recession
D - displacement of contact points - crowding or spacing, risk of caries
O - overbite - risk of gingival stripping

70
Q

what are the most common risk of ortho treatment

A

relapse, root resorption, decalcification, periodontal health

71
Q

name other less common risks of tx

A

soft tissue trauma, loss of vitality, enamel loss/tooth wear, allergy

72
Q

what is relapse and what are the highest risk for relapse

A

the return of features of the original malocclusion following correction
high risk - lower labial segment, closure of spaced dentition (midline diastema), correction of rotation, reduced overjet but incompetent lips, reduced periodontal support

73
Q

name diff types of retainers and their benefits

A

fixed bonded - compliance is not a problem, good for areas of high chance of relapse
essix - vacuum formed clear plastic, good aesthetics, well tolerated - should be worn daily for a week then overnight use
hawley - poor aesthetics but doesnt have to be removed for eating

74
Q

what are complications with a bonded retainer

A

can de-bond without patient knowing, one tooth can then relapse
de-bonding can then act as plaque trap
difficult to clean and OH must be good to prevent calculus build up and periodontal disease
requires a lot of upkeep - fixing them and patient will have to pay

75
Q

what is root resorption and what is normal root resorption

A

shrinking of the root, gets smaller
inevitable with tooth movement - 1mm of resorption after 2 year tx

76
Q

what are risk factors for root resorption

A

root shape - blunt, pippette shape, short
previous dental trauma
habits - nail biting
large movements, long treatment, torque or intrusion

77
Q

how should cases of high risk of root resorption be managed

A

screen for risk prior to treatment
if high risk - tx might not be completed fully, limit movements
monitor 6 months into tx with radiograph to check for root resorption
only radiographs after that is if unaccounted for mobility

78
Q

what is decalcification

A

loss of calcium from mineralised tooth surface, it is the beginning of dental decay and can appear as a white spot, can be prevented by good OH and fluoride and it is reversible. if not adresed can lead to caries

79
Q

how can decalcification be prevented

A

careful case selection - patients should not have treatment if high caries rate or poor OH
OHI - complete regime of brushing with F- tp, interdental brushes twice a day, also brush with normal toothbrush after every meal, use of F- mouth wash once a day, but not after brushing, spit dont rinse
diet advice - low sugar snacks, no fizzy drinks or juice, sugar limited to meal times
fluoride - high strength fluoride toothpaste, fluoride varnish, fluoride mouthwash, fluoride supplement

80
Q

what are the risks to periodontal health with orthodontic treatment

A

gingivitis - most common, poor plaque control around gingival margin
gingival recession - if thin biotype, shrinks back from gum, sensitivity
periodontal disease - uncommon, should be stable and have excellent OH prior to tx

81
Q

how does tooth movement occur with fixed appliance

A

light continuous force causes frontal resorption
pressure side - force acting upon it, hyperaemia of PDL, activates osteoclasts, causes bone resorption of lamina dura, allows PDL to move through
tension site - hyperaemia of PDL causes osteoblasts on this side, bone deposition and osteoid formed
remodelling of the socket and PDL reorganisation

82
Q

what is the first step in the ortho emergency competence

A

describe the orthodontic appliance being used and what is is used for

83
Q

what is the second step in the ortho emergency competence

A

patient safety - account for all the missing components
if unaccounted for and you are concerned - referral to A+E for chest x-ray to ensure it hasnt been inhaled - risk of lung perforation

84
Q

what is acrylic creep and how is it solved

A

when you take a new impression of a patient midway through tx, the URA will be altered to this cast, but some acrylic can seep between appliance and cast causing creep and appliance will no longer fit the patient
solved by either using the original working cast if still available
or by taking an impression with the appliance in situ - when poured up the appliance will sit flush on the model

85
Q

in what scenarios can acrylic creep be a problem

A

fractured adams clasp and requiring a new component
fractured south end clasp - requiring new component

86
Q

how is a fractured adams clasp treated - completely fractured off

A

if beginnning of treatment - new appliance
if nearing end of treatment - smooth wire, check for hard edges and try in. If adequately retentive - leave
if not retentive - need new component. take imps of appliance in situ, send to lab asking for new adams clasp component

87
Q

if a southend clasp is fractured at the flyover between central and lateral, how is it treated

A

too close to acrylic to soldier - flammable
cut at midpoint then bend back on itself - c clasp - retentive enough
if happened at start of treatment - new appliance

88
Q

how are debonds of a fixed retainer treated

A

if just one debonded - smooth down with high speed and remove composite, check under wire for bacteria + caries
check wire work + ensure wire is flush and passive against tooth
etch, bond tooth and place composite back over wire - light cure

multiple debonds - wire has now become active - not fit for purpose. explain to patient why, remove rest of wire and composite. offer patient new one if within your scope, offer thermoplastic retainer in meantime. if nothing - ensure patient knows risk of relapse and get them to sign consent form

debonded on 3 and wire distorted. explain to patient why you cant rebond it - risk of tooth movement. cut it at distal to 2, smooth it off. provide thermoplastic retainer and tell patient to go to orthodontist for new one if required - risk of relapse on 3 if not

89
Q

how would you treat wire slippage on a fixed appliance

A

slipped through on one side and short at the other. retentive tag at side it is short to prevent further slippage. cut it at other side to prevent trauma and retentive tag. tell patient to make an appt with orthodontist

90
Q

how would you treat a URA that has been shattered extra orally

A

advise patient not to glue it back together, and dont wear it in its current state.
cant make new one as unsure of prescription. provide a thermoplastic retainer to freeze treatment and prevent relapse. make patient aware if they dont wear it, risk of relapse.
make appt with orthodontist

91
Q

how would you treat a fractured adams clasp at arrowhead

A

can be soldered if facilities available - not close to acrylic
if not - modify it
cut it from baseplate, turn it back on its self to make a single arrowhead
or replace entire clasp - impression with appliance in situ

92
Q

how would you fix a fractured transpalatal arch

A

needs to be removed
secure it first - floss around it and get patient to hold it
use high speed diamond bur with lots of water to remove it nearest the bands
get patient to make appt with orthodontist asap

93
Q

how do you deal with brackets debonded from a fixed appliance

A

if circular wire - bracket will spin round it. risk of inhalation so needs to be removed. remove ligatures and give the patient the bracket - tell them to see orthodontist asap
if rectangular wire - bracket will just move side to side. doesnt need to be removed as no risk of inhalation. show the patient how to move the bracket for OH. tell them to make appt with orthodontist

94
Q

how to deal with ura adams clasp fractured at acrylic

A

cant be soldered - flammable
cut adams clasp at corner of bridge
squeeze arrowhead - single arrowhead
or replace whole component - imps with URA in situ

95
Q

how to deal with mobile molar band

A

GI cement has failed
cut wire between 5 and 6
remove band - give it to patient/parent
make retentive tag after 5
tell patient to make appt with orthodontist

96
Q

how to deal with multiple missing brackets

A

ask how it happened - ensure story matches injury, no doubts for child protection
trauma stamp

remove wire - not doing anything
remove any loose brackets
give to patient
keep secure brackets
check for mobility - splint any mobile teeth - can use brackets for it
tell patient to make appt with orthodontist

97
Q

how to deal with fracture in midline of southend clasp

A

could be soldered but too bulky - will rub
turn back on itself and squeeze to create 2 c clasps

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