Orthodontics Flashcards

(97 cards)

1
Q

what can be used for parallax

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

why do we take bitewing radiographs

A

caries diagnosis
prognosis of tooth
alveolar bone levels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

why do we take lateral ceph

A

aid diangosis - skeletal discrepancy
treatment planning
progress monitoring
research purposes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what analysis is commonly used for lateral ceph

A

eastmans analysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

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

A

antero-postero - ANB
vertical - FMPA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what management options are available for class 2 div 1

A

accept
enhance growth modification
simple tipping of teeth
camouflage
orthognathic surgery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what appliances can be used for growth modification

A

functional appliance - twin block
head gear

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

how does headgear work

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
what are therapeutic effects of functional appliance
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
26
what might be a design of a twin block functional URA
labial bow to retract upper incisors, midline palatal screw to expand upper arch, adams clasp for retention
27
when would a functional appliance be used
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
28
what is the risk of using only ura to correct class 2 div 1
could tip the teeth back into class 2 div 2
29
when is camouflage appropriate
too old for functional, or had functional but compliance poor - can be used to mask skeletal difference if it is moderate
30
when is orthognathic surgery used
when growth is complete and AP or vertical skeletal relationship is severe
31
what is involved in orthognathic surgery for class 2 div 1
mandibular advancement and/or maxillary impaction fixed ortho before, during and after treatment
32
what is the definition of hypodontia and severe hypodontia
congenital absence of one or more teeth, severe - 6 or more
33
what teeth are more commonly missing in hypodontia
upper and lower 5s upper lateral incisors lower incisors last in series
34
what are the two types of hypodontia
syndromic - is a symptom of another syndrome - anhydrotic etodermal dysplasia, cleft palate non-syndromic - mutations in at least 3 genes, familial or sporadic
35
how might hypodontia patients present
delayed eruption, unusual eruption pattern, retained primary teeth
36
what other problems are associated with hypodontia
microdontia, malformation of other teeth, impaction, delayed eruption, crowding or malocclusion
37
what are features of anhydrotic ectodermal dysplasia
effects all ectodermal tissue - hair, skin, sweat glands, teeth - sparse hair, dry wrinkly skin
38
what problems can hypodontia cause
spacing, over eruption, inadequate function, poor aesthetics
39
what treatment options are available for hypodontia patients
accept, ortho alone, restorative alone, ortho and restorative combined treatment
40
when missing upper laterals, what treatment options are available
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
what must treatment for hypodontia achieve
satisfy aesthetic expectation, satisfy functional expectation, least invasive
42
what is the aetiology of class 2 div 1
skeletal - maxillary prognathism, mandibular retrognathism dental - proclination of uppers soft tissues - lip trap, NNS habit, tongue thrust
43
why is treatment required in class 2 div 1
OJ more than 9mm - IOTN 5a high risk of trauma to incisors aesthetics of concern to patient
44
what is the incisor definition of class 2 div 2
lower incisor edge lies posterior to upper incisor cingulum plateau, overjet is reduced or reversed, upper incisors are retroclined
45
what is the most common AP class seen in class 2 div 2
class 2 - ANB increased, more than 4
46
what vertical discrepancy is seen in class 2 div 2
reduced FMPA and reduced LFH
47
what are the soft tissue components seen in class 2 div 2
lower lip line is higher - entraps central incisors causing retroclination. mentalis muscle is tight along chin - increases retroclination of lower incisors
48
what is the aetiology of class 2 div 2
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
what is the need for treatment in class 2 div 2
traumatic over bite - gingival stripping - 4f
50
what are the treatment options for class 2 div 2
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
what functional appliance can be used in class 2 div 2
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
what dental anomaly is commonly seen class 2 div 2
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
what are the features of a class 3 incisor relationship
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
what is the aetiology of a class 3 relationship
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
how is the complexity of class 3 decided
number of teeth involved in anterior crossbite presence of anterior open bite skeletal discrepancy involved - ANB less than 0
56
when is a class 3 treated
aesthetic concerns functional problems - unable to eat and speak dental health concerns - gingival stripping, attrition, displacement on closing TMD problems
57
what treatment options are available for class 3
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
what is role of GDP in class 3
identify and classify, refer to specialist produce URA when requested
59
what is the aetiology of the unerupted maxillary incisors
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
what systemic conditions are associated with unerupted
downs syndrome, turners syndrome, cleft lip and palate, rickets
61
how can an unerupted incisor be recognised
pattern of eruption - symmetrical - should appear within 6 months of condralateral eruption pattern is out of sequence
62
how can an un erupted maxillary incisor be treated
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
what is the risk of leaving unerupted canines
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
when might surgical removal of an unerupted canine be indicated
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
what would indicate that canines are not alignable
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
what are the treatment options for unerupted canines
accept and do nothing surgical removal surgical exposure and fixed orthodontic treatment autotransplantation
67
what are the benefits of ortho treatment
improved aesthetics - dental and facial, can improve QoL improved function - mainly mastication if severe malocclusion improved dental health
68
what is the IOTN and what is it used for
index of treatment need = to assess the need for treatment depending on the impact on dental health
69
what is the acronym used for IOTN
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
what are the most common risk of ortho treatment
relapse, root resorption, decalcification, periodontal health
71
name other less common risks of tx
soft tissue trauma, loss of vitality, enamel loss/tooth wear, allergy
72
what is relapse and what are the highest risk for relapse
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
name diff types of retainers and their benefits
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
what are complications with a bonded retainer
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
what is root resorption and what is normal root resorption
shrinking of the root, gets smaller inevitable with tooth movement - 1mm of resorption after 2 year tx
76
what are risk factors for root resorption
root shape - blunt, pippette shape, short previous dental trauma habits - nail biting large movements, long treatment, torque or intrusion
77
how should cases of high risk of root resorption be managed
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
what is decalcification
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
how can decalcification be prevented
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
what are the risks to periodontal health with orthodontic treatment
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
how does tooth movement occur with fixed appliance
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
what is the first step in the ortho emergency competence
describe the orthodontic appliance being used and what is is used for
83
what is the second step in the ortho emergency competence
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
what is acrylic creep and how is it solved
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
in what scenarios can acrylic creep be a problem
fractured adams clasp and requiring a new component fractured south end clasp - requiring new component
86
how is a fractured adams clasp treated - completely fractured off
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
if a southend clasp is fractured at the flyover between central and lateral, how is it treated
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
how are debonds of a fixed retainer treated
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
how would you treat wire slippage on a fixed appliance
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
how would you treat a URA that has been shattered extra orally
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
how would you treat a fractured adams clasp at arrowhead
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
how would you fix a fractured transpalatal arch
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
how do you deal with brackets debonded from a fixed appliance
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
how to deal with ura adams clasp fractured at acrylic
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
how to deal with mobile molar band
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
how to deal with multiple missing brackets
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
how to deal with fracture in midline of southend clasp
could be soldered but too bulky - will rub turn back on itself and squeeze to create 2 c clasps