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ortho Flashcards

1
Q

general benefits and risks of orthodontic treatment (7/6)

A

benefits:
- improved function/speech/mastication
- improved aesthetics
- psychological benefits
- (possibly) improved cleansability
- (possibly) improved dental awareness
- (possibly) decreased occlusal anomalies affecting perio
- (possibly) decreased trauma risk
risks:
- root resorption
- demineralisation
- periodontal attachment loss
- loss of vitality
- soft tissue trauma
- retention indefinitely

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2
Q

what can increase the risk of root resorption with orthodontic treatment? (4)

A
  • resorbed, blunted or pipette-shaped roots
  • previous trauma
  • excessive force applied
  • prolonged treatment time
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3
Q

how much root resorption is expected with orthodontics?

A

~1mm over a 2 year period

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4
Q

what may increase the risk of loss of vitality with orthodontics? (2)

A
  • excessive force or speed of movement
  • previous trauma to teeth
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5
Q

why might someone be referred for orthodontic treatment? (5)

A
  • facial appearance/severe skeletal issues
  • functional issues
  • increased/traumatic overbite
  • moderate-severe crowding
  • adverse growth or soft tissue pattern
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6
Q

where might you refer a patient for orthodontic treatment and how do you choose? (2)

A
  • specialist practice for simpler cases, private and NHS
  • hospital for severe cases (IOTN 4/5, multidisciplinary)
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7
Q

what are the different hospital orthodontic clinics that you might refer to? (5)

A
  • orthognathic
  • orthodontic-restorative
  • orthodontic-paediatric
  • orthodontic-oral surgery
  • cleft clinic
    (all are multidisciplinary team management)
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8
Q

which patients qualify for NHS orthodontic treatment? (4)

A
  • <18yo
  • IOTN 4/5 or 3 with AC 6+
  • dentally fit
  • motivated to wear appliances
    (only one course covered by NHS)
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9
Q

at what age would you refer for orthognathic surgery?

A

adults, after pubertal growth spurt
(may refer earlier for assessment)

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10
Q

at what age would you refer for cleft or craniofacial abnormalities?

A

ASAP if not already under a MDT/cleft team

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11
Q

at what age would you refer for growth modification and what features may these pts have? (up to 9 features)

A
  • 9-10yo in females, 12-13yo in males
    features:
  • severe class III
  • class II with severe teasing or trauma risk
  • delayed eruption of permanent incisors
  • impacted/UE FPMs or poor prognosis
  • marked mandibular displacement
  • anterior crossbite affecting perio
  • hypodontia
  • ectopic canines, pathology
  • MH (for monitoring)
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12
Q

at what age would you refer for orthodontic camouflage?

A

when child has permanent dentition
(also for class II growth modification)

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13
Q

what habits may you ask about in the orthodontic assessment and why? (3)

A
  • digit sucking - AOB, needs to stop
  • parafunction - can increase risk of RR and breaking appliance
  • chewing items - can increase risk of RR and breaking appliance
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14
Q

what factors are important regarding digit sucking? (3)

A
  • hours per day (>6)
  • current/previous, when did they stop?
  • manner/strength of force
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15
Q

what extraoral features should be included in orthodontic assessment? (9)

A
  • AP plane = I/II/III
  • vertical height = increased or decreased
  • transverse plane = acceptable symmetry or not
  • lips = competency, length, smile line, lips to E line
  • NL angle
  • LM fold
  • chin
  • TMJ
  • mandibular displacements
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16
Q

how can AP class be assessed clinically? (2)

A
  • Kettle’s method
  • zero Meridian line
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17
Q

how do soft tissue points A and B relate in a class I AP patient?

A

point A is 2-4mm anterior to point B

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18
Q

how can vertical facial height be assessed clinically? (2)

A
  • facial thirds
  • FMPA
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19
Q

how can the transverse plane be assessed clinically? (2)

A
  • rule of fifths
  • midline (glabella, philtrum, pogonion)
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20
Q

what is the average value for NL angle?

A

90-110º

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21
Q

what is the average height of the smile line?

A

showing from 75% of upper incisors to 100% with 2mm gingiva

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22
Q

what is a consonant smile arc?

A

when the incisal edges of the upper incisors and the top of the lower lip are parallel when smiling

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23
Q

what intraoral features should be included in orthodontic assessment of each arch separately? (8)

A
  • teeth present/missing from mouth
  • caries, restorations
  • OH
  • soft tissues
  • arch form (U/V/square) and symmetry
  • crowding or spacing (in mm)
  • inclination/angulation
  • rotations
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24
Q

list the 5 anterior occlusal features to be assessed

A
  • incisor relationship
  • overjet
  • overbite
  • centrelines
  • crossbites +/- displacements
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25
Q

list the 5 posterior occlusal features to be assessed

A
  • right canine relationship
  • left canine relationship
  • right molar relationship
  • left molar relationship
  • crossbites +/- displacements
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26
Q

what is average overjet in mm?

A

2-4mm

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27
Q

what descriptors may be used for overjet?

A

increased, average, decreased

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28
Q

what is average overbite?

A

upper incisors covering the incisal third of the lower incisors (2-4mm)

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29
Q

what descriptors may be used for overbite?

A
  • increased, decreased, open bite
  • complete to tooth/palate/gingiva, incomplete
  • +/- traumatic
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30
Q

why is it important to check for mandibular displacements?

A

may make malocclusion (crossbites and class III) appear worse than it actually is

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31
Q

give a standard DPT radiographic report template (7)

A

1 DPT, diagnostically acceptable
2 no gross pathology
3 normal bony outlines
4 charting of teeth
5 general dental condition, restorations, radiolucencies/caries
6 root morphology and crown to root ratios
7 alveolar bone levels

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32
Q

what features are assessed with a lateral cephalogram for orthodontics? (5)

A
  • skeletal base (ANB)
  • vertical proportions (MMPA, LFH)
  • incisor inclinations
  • interincisal angle
  • soft tissues
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33
Q

give the average Caucasian cephalometric values and standard deviations (8)

A
  • SNA = 81 +/- 3º
  • SNB = 78 +/- 3º
  • ANB = 3 +/- 2º
  • UI inclination = 109 +/- 6º
  • LI inclination = 93 +/- 6º
  • interincisal angle 135 +/- 10º
  • MMPA = 27 +/- 5º
  • LFH = 55 +/- 2%
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34
Q

what are the average Caucasian SNA, SNB and ANB angles?

A
  • SNA = 81 +/- 3º
  • SNB = 78 +/- 3º
  • ANB = 3 +/- 2º
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35
Q

what are the average Caucasian upper and lower incisor inclinations and interincisal angle?

A
  • UI inclination = 109 +/- 6º
  • LI inclination = 93 +/- 6º
  • interincisal angle 135 +/- 10º
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36
Q

what are the average Caucasian MMPA and LFH?

A
  • MMPA = 27 +/- 5º
  • LFH = 55 +/- 2%
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37
Q

for what reasons is a lateral cephalogram taken? (4)

A
  • diagnosis
  • pre-treatment record
  • monitor treatment progress or growth
  • research
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38
Q

what categories is orthodontic aetiology separated into? (3)

A
  • skeletal
  • soft tissue
  • dentoalveolar and local
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39
Q

what might be part of your treatment plan in orthodontics? (6)

A
  • prevention - OHI, diet advice
  • growth modification, orthodontic camouflage or orthognathic surgery
  • removable or fixed appliances, functional appliances
  • anchorage considerations
  • any extractions
  • retention, stability/growth
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40
Q

what is MOCDO?

A
  • acronym to help assess a patient’s IOTN
  • Missing teeth
  • Overjet
  • Crossbite
  • Displacement of contact points
  • Overbite
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41
Q

what is included in the M part of MOCDO?

A
  • missing teeth
  • 5h (hypodontia >1 tooth/Q)
  • 5s (submerging deciduous tooth)
  • 5i (impacted)
  • 4h (hypodontia 1 tooth/Q maximum)
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42
Q

what does 5h mean in the IOTN?

A

extensive hypodontia with restorative implications, >1 tooth per quadrant

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43
Q

what does 4h mean in the IOTN?

A

less extensive hypodontia needing orthodontics pre-restorative tx or space closure (1 tooth/Q maximum)

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44
Q

how is hypodontia graded by the IOTN?

A

h = hypodontia
- 5h if >1 tooth/Q
- 4h if 1 tooth/Q max

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45
Q

what does 5s mean in the IOTN?

A

submerging deciduous tooth

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46
Q

what does 5i mean in the IOTN?

A

impeded eruption/impacted

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47
Q

how is positive overjet graded by the IOTN?

A

a = overjet
- 5a = >9mm
- 4a = 6.1-9mm
- 3a = 3.6-6mm with incompetent lips
- 2a = 3.6-6mm with competent lips

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48
Q

how is reverse overjet graded by the IOTN?

A

b = reverse overjet
- 5m = >3.5mm with masticatory or speech difficulty
- 4b = >3.5mm
- 3b = 1.1-3.5mm
- 2b = 0.1-1mm

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49
Q

how is crossbite graded by the IOTN?

A

c = crossbite
- 4c = xbite with >2mm discrepancy between RCP and ICP
- 4l = posterior lingual crossbite with no functional occlusal contact in 1 or both buccal segments
- 3c = xbite with 1.1-2mm discrepancy
- 2c = xbite with up to 1mm discrepancy

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50
Q

how is crowding graded by the IOTN?

A

d = contact point displacement (single worst)
- 4t = PE, tipped, impacted against adjacent teeth
- 4x = supplemental teeth
- 4d = >4mm
- 3d = 2.1-4mm
- 2d = 1.1-2mm

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51
Q

what does 4x mean in the IOTN?

A

supplemental teeth

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52
Q

how is overbite graded by the IOTN?

A

e = lateral or anterior open bite
- 4e = >4mm
- 3e = 2.1-4mm
- 2e = 1.1-2mm
f = increased overbite
- 4f = increased and complete OB with gingival/palatal trauma
- 3f = increased and complete OB
- 2f = increased >3.5mm

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53
Q

are impacted maxillary canines more likely to be buccally or palatally placed?

A

palatally (85%)

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54
Q

predisposing factors to maxillary impacted canines (7)

A
  • long path of eruption
  • displacement of crypt
  • absence of guidance from lateral (micro/hypodontia)
  • crowding
  • syndromes, CLP
  • pathology and supernumeraries
  • early maxillary trauma
    (retained C is an indicator, not a factor)
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55
Q

possible effects of maxillary impacted canines (2)

A
  • root resorption (incisors especially)
  • cystic change
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56
Q

after what age is root resorption due to maxillary impacted canines unlikely to occur?

A

14yo

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57
Q

what is considered delayed eruption of maxillary canines (RCS)?

A
  • females = 12.3yo
  • males = 13.1yo
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58
Q

what should be included in your clinical assessment of maxillary impacted canines and why? (7)

A
  • palpate from 10yo - presence, symmetry/location
  • mobility of C and adjacent teeth - root resorption
  • colour of C and lateral - resorption, necrosis, disguising
  • vitality of teeth - prognosis
  • inclination of 2 and 4 - location of 3
  • space available - for E+B
  • wear of C and L3 overeruption - disguising
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59
Q

what features on a DPT are used to assess maxillary impacted canine(s) prognosis and what are the optimum values? (3)

A
  • height - ideally crown of 3 is within coronal third of tooth roots
  • inclination - 0-15º
  • proximity to midline - apex of 3 over eruption space
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60
Q

what radiographs may you take for parallax of maxillary impacted canines?

A
  • LCPA + USO or another LCPA
  • DPT + LCPA or USO
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61
Q

general treatment options for maxillary impacted canines (5)

A

1 interceptive extraction of C (10-13yo)
2 surgical expose and bond (open or closed) +/- space creation
3 surgical extraction of 3 and disguise another tooth/prosthetic replacement
4 autotransplantation
5 no treatment and monitor

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62
Q

describe interceptive extraction of C for maxillary impacted canine (3)

A
  • 10-13yo (mixed dentition)
  • wait 1 year for any spontaneous eruption before E+B
  • favourable position of 3
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63
Q

describe surgical E+B for maxillary impacted canine, open or closed (4)

A
  • +/- space creation which may allow spontaneous eruption
  • open = faster and no FAs immediately, better bond BUT must be a growing pt with low canine
  • closed = can be done of non-growing pt with high canine BUT poor moisture control and longer active tx time
  • must erupt into keratinised gingiva
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64
Q

into what type of tissue must a maxillary impacted canine erupt into and why?

A
  • keratinised gingiva
  • otherwise periodontal pocketing and need for a gingival graft
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65
Q

when might you do surgical extraction of a maxillary impacted canine? (3)

A
  • unfavourable position for eruption
  • MH contraindicates E+B
  • acceptable aesthetics without 3
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66
Q

describe autotransplantation for maxillary impacted canines (3)

A
  • done if adequate space and bone in arch for 3
  • best prognosis with 50-70% of root formed
  • may obstruct other teeth movements (must remain in situ until transplantation)
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67
Q

when may you choose to monitor maxillary impacted canine(s) (4)

A
  • no/unlikely to cause root resorption
  • normal follicle size (<3mm)
  • difficult to remove (high) and would not affect prosthetic replacement if left in situ
  • 4-2 tooth contact achievable
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68
Q

define relapse

A

tendency of a treated malocclusion to return to the original features of the malocclusion after correction

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69
Q

what types of malocclusions/corrections have a high risk of relapse? (10)

A
  • space closure
  • rotations
  • bimaxillary proclination
  • orthognathic surgery >5-6mm in maxilla, >8mm in mandible
  • LLS movement >2mm from neutral zone
  • excess arch expansion
  • unfavourable STs
  • persistent habits
  • periodontal disease
  • AOB with adverse growth rotation
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70
Q

aetiology of spacing (8)

A
  • soft tissue:
    – macroglossia
    – flaccid lips
  • local dental:
    – hypodontia
    – microdontia
    – “loss” of tooth - displaced, trauma, pathology, morphology (gemination, fusion, etc)
    – unerupted tooth for any reason
  • habits:
    – digit sucking
    – tongue thrust
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71
Q

aetiology of median diastema (7)

A
  • physiological (closes with eruption of 3s)
  • hypodontia
  • microdontia
  • persistent low fraenal attachment
  • racial/FH - esp Afrocaribbean
  • mesiodens (pathology, supernumerary)
  • proclined ULS (habits, perio)
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72
Q

management of spacing (4)

A
  • investigate for any unerupted teeth, supernumeraries, pathology, habits
  • stop habits, remove pathology
  • mild = non-orthodontic space closure or accept
  • orthodontic treatment if pt wishes (not covered by NHS) - collect, redistribute or close space with permanent retention
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73
Q

when would you intercept for a median diastema in a child?

A

> 3mm pre-canine eruption with insufficient space for laterals

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74
Q

how long should you retain a space before restoring with RBBs?

A

at least 3-6 months (9 months if space opened)

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75
Q

what are the different types of crowding?

A
  • primary = dentoalveolar disproportion (genetic)
  • secondary = early loss of primary tooth (environmental)
  • tertiary = late lower incisor crowding
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76
Q

factors in late lower incisor crowding (3)

A
  • mesial migration of teeth with age
  • forward growth of jaws (low levels in adulthood but never stops)
  • presence and position of third molars
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77
Q

how is crowding classified?

A
  • mild = <4mm
  • moderate = 4-8mm
  • severe = >8mm
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78
Q

aetiology of crowding (4)

A

(DENTAL mainly)
- dentoalveolar disproportion
- early loss of primary teeth (space loss)
- displacement of teeth (esp 3 and 5)
- anomalies in tooth number or morphology = supernumerary

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79
Q

possible consequences of crowding on other teeth

A
  • increased caries and perio risk
  • impaction
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80
Q

what may cause tooth impaction/failure of eruption? (5)

A
  • gingival fibromatosis
  • retained primary tooth (ankylosis)
  • crowding
  • supernumerary
  • trauma or developmental dilaceration
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81
Q

name some syndromes which may be associated with supernumerary teeth (3)

A
  • Gardner’s
  • CLP
  • Down’s
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82
Q

which teeth are more commonly affected by macrodontia? (2)

A

U1, L5

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83
Q

how may unerupted displaced teeth be managed? (2)

A
  • mild = extraction of primary tooth with spontaneous eruption
  • severe = E+B or removal
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84
Q

how may mild crowding be treated? (3)

A

(does not qualify for NHS tx)
- EO traction/molar distalisation with headgear or TAD
- interproximal stripping of lower incisors (adults, 0.5mm/contact)
- arch expansion with FAs (ideally only with xbites)

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85
Q

when is molar distalisation used for mild crowding and what issues are associated?

A
  • for ≤ 1/2 unit class II
  • safety issues, pt preference, poor compliance
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86
Q

how may moderate/severe crowding be managed?

A

extractions (but caution if deep bite)

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87
Q

define crossbite

A

transverse discrepancy in tooth relationship

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88
Q

how is crossbite classified?

A
  • lower teeth relative to the upper teeth
    – buccal = buccal cusps of lowers lateral to uppers
    – lingual/scissors bite = buccal cusps lingual to palatal cusps
    – anterior (incisors), reverse OJ if multiple incisors involved
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89
Q

aetiology of crossbite (7)

A
  • skeletal:
    – discrepancy in dental base width
    – secondary to gross AP discrepancy
    – genuine dental base/arch asymmetry (unilateral, no displacement)
  • soft tissue:
    – low tongue position (bilateral buccal)
    – increased cheek pressure (hourglass arch)
  • dental:
    – crowding -> tooth displacement from arch
    – cusp-to-cusp relationship causing deflection and tilting or displacements
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90
Q

give examples of genuine dental base/arch asymmetry (2)

A
  • CLP surgical repair = scarring, restriction = buccal crossbite
  • mandibular growth disturbance
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91
Q

how may gross AP discrepancy lead to crossbite?

A
  • marked class II = lingual crossbite (especially in premolar area)
  • marked class III = buccal crossbite
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92
Q

what may cause a low tongue position? (3)

A
  • digit sucking
  • mouth breathing
  • increased lower face height
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93
Q

treatment for lingual crossbite (2)

A
  • FAs with cross elastics
  • +/- surgery if severe skeletal issue
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94
Q

treatment for unilateral buccal crossbite with displacement

A

expansion of upper arch (prevents cusp-to-cusp relationship)

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95
Q

treatment for unilateral buccal crossbite with no displacement (2)

A
  • dental asymmetry = orthodontics +/- expansion
  • base asymmetry = investigate why, growth issues may need surgery
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96
Q

management of bilateral buccal crossbite with aligned arches

A

accept (but rare)

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97
Q

treatment of bilateral buccal crossbite needing alignment (2)

A
  • mild/moderate = orthodontics +/- expansion
  • severe = surgery
98
Q

specific methods of treating buccal crossbites (3)

A
  • conventional methods = URA (screw plate, coffin spring) or FAs (quadhelix, cross-elastics, heavy AWs)
  • RME
  • localised = Z or T springs, unilateral screw plate
99
Q

describe rapid maxillary expansion (RME) briefly (4)

A
  • cemented appliance = heavy force to wedge midpalatal suture apart + buccal tilting of teeth
  • 12-14yo (fuses at 14yo)
  • permanent dentition (456 bilateral)
  • for bilateral buccal expansion for crossbite
100
Q

specific methods of treating anterior crossbites (2)

A
  • FAs
  • URA (Z spring or anterior sectional screw plate)
101
Q

factors to consider when treating anterior crossbite (5)

A
  • skeletal severity
  • displacements
  • incisor inclination
  • OJ
  • OB (stability)
102
Q

average age of eruption for upper and lower permanent canines

A
  • lower = 9-10yo
  • upper = 11-12yo
103
Q

average age of eruption of upper and lower central and lateral incisors

A
  • lower incisors = 6-8yo
  • upper incisors = 7-9yo
104
Q

define normal occlusion, malocclusion and functional occlusion

A
  • normal = minor deviations from ideal that do not constitute aesthetic or functional issues
  • malocclusion = appreciable deviation from the ideal causing aesthetic or functional issues
  • functional occlusion = occlusion free of interferences to smooth gliding movements of the mandible with no pathology
105
Q

what are Andrew’s six keys for an ideal occlusion?

A
  • correct molar relationship (usually class I unless asymmetric extractions, good interdigitation)
  • correct crown angulation (mesially)
  • correct crown inclination (labiolingual tilt)
  • no rotations
  • tight contacts
  • flat occlusal plane (ie no deep overbite or anterior open bite)
106
Q

define class I incisor relationship

A

incisal edge of lower central incisor occludes with or lies immediately below cingulum plateau of upper central incisor

107
Q

define class II div 1 incisor relationship

A
  • lower incisor edges lie posterior to middle palatal third or cingulum plateau of upper central incisors
  • upper incisors proclined or average inclination with increase in overjet
108
Q

define class II div 2 incisor relationship

A
  • lower incisor edges lie posterior to middle palatal third or cingulum plateau of upper central incisors
  • retroclined upper central incisors with normal/increased overjet
109
Q

define class III incisor relationship

A

lower incisor edges lie anterior to cingulum plateau of upper central incisors and OJ is reduced/reversed

110
Q

define class I molar relationship (Angle’s and Andrew’s)

A
  • Angle’s = MB cusp of U6 should occlude with anterior buccal groove of L6
  • Andrew’s = MB cusp of U6 should occlude with anterior buccal groove of L6 AND DB cusp should be in contact with L7
111
Q

define class II molar relationship

A

U6 MB cusp is mesial to the L6 buccal groove
(may be fractions of a unit)

112
Q

define class III molar relationship

A

U6 MB cusp is distal to the L6 buccal groove
(may be fractions of a unit)

113
Q

define class I canine relationship

A

U3 occludes directly in the embrasure space between the L3 and L4

114
Q

define class II canine relationship

A

U3 occludes mesial to the embrasure space between the L3 and L4
(may be fractions of a unit)

115
Q

define class III canine relationship

A

U3 occludes distal to the embrasure space between the L3 and L4
(may be fractions of a unit)

116
Q

what is point A and point B on a lateral cephalogram?

A
  • point A = deepest concavity on maxilla
  • point B = deepest concavity of mandible
117
Q

what are the landmarks for assessing vertical facial “thirds”?

A
  • upper face height = glabella to soft tissue nasion
  • lower face height = subnasale to soft tissue menton
    (usually exclude uppermost facial third - trichion to glabella)
118
Q

what is Frankfort’s plane?

A

horizontal plane from orbitale (inferior orbital margin) to tragus of ear (upper border of EAM)

119
Q

what is FMPA?

A
  • Frankfort-mandibular planes angle
  • where Frankfort plane intersects the line of the lower border of the mandible
120
Q

what is the S-N line on a lateral cephalogram?

A
  • line from sella point (middle of sella turcica) and nasion (junction between frontal bone and nasal bone)
  • represents cranial base
121
Q

what is a fraenum?

A

small fold of tissue that secures or restricts the motion of a mobile tissue

122
Q

define gemination of tooth bud

A

incomplete division of a single tooth bud

123
Q

define twinning of tooth bud

A

complete division of a single tooth bud

124
Q

define fusion of teeth

A

union of dentine of two teeth from two tooth buds

125
Q

define concrescence of teeth

A

union of cellular cementum of two teeth from two tooth buds

126
Q

define anodontia

A

complete developmental absence of teeth

127
Q

define hypodontia

A

developmental failure of ≤6 teeth, other than the third molars

128
Q

define oligodontia

A

absence of more than six teeth in primary, permanent or both dentitions

129
Q

what are supplemental teeth?

A

developmental extra copies of teeth due to lamina dura extension

130
Q

what is the difference between active and passive appliances?

A
  • active = bring about tooth movement
  • passive = maintain position of teeth (eg space maintainers, retainers)
131
Q

what is deflection (removable appliances)?

A

amount of activation the operator puts into a spring

132
Q

what is retention (removable appliances)?

A

means by which appliances resist displacement (stay in the mouth)

133
Q

what meant by “active component” (removable appliances)?

A

means by which forces are applied to teeth to bring about the required movement, eg springs, bows, screws

134
Q

what is anchorage and the factors affecting it?

A
  • resistance to unwanted tooth movement
  • dependent on surface area of root in the bone and type of tooth movement
135
Q

define anterior open bite

A

no overlap of incisors when the posterior teeth are in occlusion

136
Q

define posterior open bite

A

space between the posterior teeth when the teeth are in occlusion

137
Q

what is retention (after orthodontic treatment)?

A

maintenance of intra-arch relationships (alignment of teeth) and inter-arch relationships (static and dynamic occlusion)

138
Q

what is a retainer?

A

passive orthodontic appliances that maintain the position of teeth after orthodontic treatment

139
Q

define torque

A

controlled movement of root with little or no movement of the crown in the opposite direction

140
Q

at what age and which dentition will failure of eruption of upper permanent incisors present?

A

7-9yo, mixed dentition

141
Q

what is considered delayed eruption for upper permanent incisor(s)? (3)

A
  • contralateral incisor erupted >6 months earlier
  • lower incisors are erupted >1 year earlier
  • significant deviation from normal eruption sequence (eg laterals before centrals)
142
Q

issues with failure of eruption of upper permanent incisors (2)

A
  • poor aesthetics
  • decreased self esteem and social interaction
143
Q

aetiology of unerupted permanent upper central incisors (7)

A

local:
- early loss of primary teeth +/- space loss
- prolonged retention of primary teeth
- ULS crowding
- previous trauma to primary teeth
- localised pathology (supernumerary, odontome, cyst)
- CLP
systemic:
- systemic conditions causing multiple supernumeraries

144
Q

what are the two most common causes of unerupted permanent upper central incisors?

A
  • physical obstruction (supernumerary or odontome)
  • trauma to primary dentition +/- dilaceration
145
Q

which 3 teeth are most commonly impacted?

A

8s > U3s > U1s

146
Q

general management principles of unerupted permanent upper central incisors (5)

A
  • provision of adequate space in arch –> spontaneous eruption +/or appliances
  • remove obstructions (supernumerary, odontome) –> usually spontaneous eruption (up to 18 months)
  • +/- surgical exposure +/- traction
  • incisor removal at some point if significantly dilacerated, ankylosed
  • autotransplantation of developing (lower) premolar
147
Q

what radiographs may be taken to assess an unerupted permanent upper central incisor?

A
  • LCPA +/- USO for presence and parallax, anomalies
  • lateral ceph = location, assessment (height, inclination)
  • CBCT (esp for treatment planning dilacerations)
148
Q

how much space is needed in the arch to allow an unerupted permanent upper central incisor to erupt?

A

9mm (average)

149
Q

what side of the tooth will most likely be bonded to for E+B of unerupted permanent upper central incisor?

A

palatal (favourable direction, reduce risk of fenestration of attachment)

150
Q

pros and cons of autotransplantation for unerupted permanent upper central incisors

A
    • = physiological with preserved periodontium
    • = poor morphology, extensive restorative work required, occlusal interferences
      – may also have rapid root resorption and premature loss of transplanted tooth
151
Q

at what age is removal of a supernumerary more likely to cause spontaneous eruption with permanent upper central incisors?

152
Q

pt (3) and dental (4) factors affecting treatment of unerupted permanent upper central incisor(s)

A
  • MH affecting ortho or surgery
  • age - spontaneous eruption?
  • potential compliance for treatment (future ortho)
  • retained primary tooth (extract)
  • position and stage of development of impacted incisor (low and immature is best)
  • nature of any physical obstruction and degree of displacement (tubercular and odontome worse)
  • any unfavourable root formation (dilacerations)
153
Q

potential risks of treatment for unerupted permanent upper central incisors (4)

A
  • failure of eruption
  • ankylosis
  • external root resorption
  • poor gingival aesthetics
154
Q

possible management options of ankylosis of permanent upper central incisor (5)

A
  • composite build up for minor infraocclusion
  • repositioning of ankylosed incisor (surgical)
  • extraction and space closure
  • decoronation (growing pt, to preserve bone)
  • extract and replace with prosthesis (nearing growth completion)
155
Q

aetiology of class I malocclusion

A
  • mild skeletal base
  • favourable soft tissues (except bimaxillary proclination with flaccid lips)
  • mainly dental:
    – tooth-arch size discrepancy or other dental anomalies
    – environmental (premature loss, growth disturbances)
156
Q

aetiology of class II div 1 incisor relationship

A

skeletal:
- AP relationship - usually class II with retrognathic mandible
- variable VD

ST: (mediated by skeletal + anterior oral seal)
- incompetent lips –> lip trap, tongue contacts lower lip for seal, increased circumoral muscle activity
- tight lower lip = retroclined LLS

digit sucking habit leads to:
- increased OJ (proclined ULS, decreased LLS)
- asymmetrical AOB or decreased + incomplete OB
- crossbite (small UA)
- non-coincident centrelines

157
Q

consequences of digit sucking (5)

A
  • proclined upper incisors, retroclined lower incisors = increased OJ
  • asymmetrical AOB or decreased, incomplete OB
  • narrow upper arch
  • crossbite (buccal unilateral with displacement)
  • non-coincident centrelines
158
Q

aetiology of class II div 2 incisor relationship

A

skeletal:
- usually MILD class II base
- usually decreased VD (lack of occlusal stop)
- anticlockwise growth rotation

ST:
- high lower lip line
- tight lips (bimaxillary retroclination)

dental:
- retroclined teeth = crowding
- poorly developed cingulum = increased overbite +/- trauma

159
Q

aetiology of class III incisor relationship

A

skeletal:
- usually class III with large mandible/prognathia
- variable VD
- variable growth patterns

ST:
- if lip seal achievable = dentoalveolar compensation

dental:
- narrow UA with broad LA –> UA crowded, buccal crossbites

160
Q

characteristic features you may see in class II div 1 patients (2)

A
  • lip trap
  • ULS gingivitis (lip incompetence)
161
Q

characteristic features you may see in class II div 2 patients (5)

A
  • lingual crossbite of first premolar, hourglass upper arch
  • small proclined lateral incisors
  • impacted 3s
  • marked labiomental fold
  • well-developed masseters
162
Q

characteristic features you may see in class III patients (2)

A
  • broad well-aligned lower arch
  • unfavourable growth pattern
163
Q

factors affecting management of a malocclusion (7)

A
  • malocclusion and severity
  • facial profile
  • aetiology
  • future growth (age, sex)
  • likely stability
  • compliance
  • pt wishes
164
Q

aetiology of posterior lateral open bite (5)

A
  • increased VD (usually extension of AOB)
  • early loss of FPM
  • submerging buccal segments
  • primary failure of eruption or arrest of eruption
  • unilateral condylar hyperplasia
165
Q

management options for class I malocclusion (2)

A
  • accept (esp if unfavourable STs and not motivated)
  • dependent on malocclusion features:
    – eg AOB = URA + discourage habits in mixed dentition, HG to intrude molars, surgery
    – often FAs
166
Q

management options for class II div 1 malocclusion on mild skeletal II (2)

A
  • accept
  • FAs +/- XTNs (orthodontic camouflage)
167
Q

management options for class II div 1 malocclusion on moderate/severe skeletal II (4)

A
  • accept
  • growth modification (twin block, GD) - 1-3 years before peak growth with prolonged retention until growth complete +/- FAs
  • orthodontic camouflage with FAs - permanent dentition
  • ortho + orthognathic surgery (ANB >8º or VD issues) - adult growth, mandibular advancement, segmental maxillary setback, bimaxillary surgery
168
Q

management for class II div 2 malocclusion on mild skeletal II (2)

A
  • accept
  • FAs +/- XTNs (orthodontic camouflage) - but caution with XTNs as it may increase OB and hard to close spaces in pts with decreased LFH
169
Q

management options for class II div 2 malocclusion on moderate/severe skeletal II (4)

A
  • accept
  • growth modification - convert to div 1 then twin block, HG, 1-3 years before peak growth with prolonged retention until growth complete +/- FAs
  • orthodontic camouflage with FAs (less likely)
  • ortho + orthognathic surgery - convert to div 1 then bilateral sagittal split
170
Q

management options for class III malocclusion on mild skeletal III (5)

A
  • accept
  • accept and align if pt happy and minimal OB
  • procline ULS if upright with adequate OB (mixed dentition before eruption of U3s) +/- extraction of lower Cs (moves LLS back) - but 3s must not be too low (risks RR of 2s)
  • procline ULS and retrocline LLS, as above
  • URA in mixed dentition to correct a simple anterior crossbite
171
Q

management for class III malocclusion on moderate/severe skeletal III (4)

A
  • accept
  • growth modification with reverse pull HG +/- maxillary expansion
  • orthodontic camouflage
  • ortho + orthognathic surgery (ANB <-4º, LI <83º) - caution with extractions
172
Q

list different active components that may be used with removable appliances (8)

A

(applies force to teeth)
- palatal finger spring
- Z spring
- T spring
- coffin spring
- buccal canine retractor
- Robert’s retractor
- labial bow (more retentive)
- screw-type appliances

173
Q

list the different retentive components that may be used with removable appliances (3)

A

(resists displacement)
- Adams clasp
- Southend clasp
- fitted labial bow

174
Q

how much are palatal and buccal active components activated by and how often?

A
  • palatal = 3mm (thinner wire)
  • buccal = 1mm (thicker wire)
  • monthly usually = 1-2mm of movement/month
175
Q

describe a palatal finger spring (2)

A
  • moves teeth in the line of the arch
  • 0.5mm coiled wire with perpendicular guard wire
176
Q

describe a Z spring (2)

A
  • incisor/canine proclination (+/- posterior buccal capping)
  • 0.5mm wire with two coils
177
Q

describe a T spring (2)

A
  • moves premolars buccally (needs good retention +/- posterior buccal capping)
  • 0.5mm wire
178
Q

describe a coffin spring (2)

A
  • historically used for upper arch expansion
  • 1.25mm wire
179
Q

describe a buccal canine retractor (2)

A
  • retracts buccally placed canines (but better to use fixed appliances)
  • 0.7mm wire
180
Q

describe a Robert’s retractor (2)

A
  • decreases a large OJ
  • 0.5mm flexible bow with tubing and trimmed base plate (hard to repair)
181
Q

describe a fitted labial bow (3)

A
  • used more so for retention (eg Hawley retainer)
  • 0.7mm bow across upper 2-2 with U loops
  • requires proclined upper incisors (to engage)
182
Q

describe a screw-type appliances (3)

A
  • base plate split to move individual/groups of teeth +/- posterior capping
  • buccal expansion, segment/tooth movement, distal movement of molars, etc
  • requires good pt cooperation (1-2 turns/week)
183
Q

describe an Adams clasp (2)

A
  • retentive component
  • 0.7mm wire with arrowheads engaging MB and DB undercuts of molars or premolars (or Ds)
184
Q

describe a Southend clasp (2)

A
  • retentive component
  • 0.7mm wire fitted around labial gingival margins of the upper central incisors
185
Q

what is the function of the baseplate in an URA? (3)

A
  • supports wire components
  • contributes to anchorage
  • +/- bite planes to open the bite
186
Q

describe the different types of anchorage (3)

A
  • simple = pitting against a single small tooth
  • compound = pitting a group of teeth against ≥1 tooth (eg FAs, base plates)
  • reciprocal = two groups pitted against each other equally (eg bilateral expansion, closing midline diastema)
187
Q

pros and cons of removable appliances (5/6)

A

+:
- easy cleaning
- easy adjustment
- increased anchorage with palate
- cannot apply excess force
- can shorten FA treatment time

-:
- only tipping movements
- retention and anchorage can be difficult
- requires pt cooperation and skill
- good technician needed
- affects speech
- poorly tolerated in lower arch

188
Q

situations where you might use an URA (5)

A
  • decrease OB in growing children
  • EO traction
  • arch expansion
  • space maintainer
  • passive retainer
189
Q

general instructions for removable appliances (3)

A
  • constant wear
  • remove for cleaning, contact sports, +/- eating
  • saliva pooling will stop eventually and will adapt to speech
190
Q

how do edgewise brackets and the straight wire technique work? (4)

A
  • edgewise brackets have pre-adjusted AVERAGE prescriptions built into slots (varies per tooth)
  • this allows a single straight wire to give the correct average tooth positions (increased ease)
  • progress from thinner, more flexible wires to thicker rectangular wires to engage the slot prescriptions
  • +/- added bends for specific patient
191
Q

what is the function of elastomeric modules and wire ligatures (FAs)?

A

secure the arch wire into the bracket slots

192
Q

describe differences between NiTi and SS arch wires

A

(may also have TMA and CoCr)
- NiTi = shape memory, high spring back, low stiffness
- SS = low spring back, high stiffness, low friction, cheap

193
Q

what are the four general stages of fixed appliance treatment?

A

1 straighten/align teeth = derotating, cross bites
2 levelling the occlusion, decreasing curve of Spee = intrusion/extrusion, intermaxillary elastics, HG
3 space closure
4 finishing = final bends to individual pt

194
Q

what are the 3 different types of wire bends and what are they for?

A
  • 1st order = horizontal plane for B-L/in-out and for rotations
  • 2nd order = vertical plane for M-D tilt, intrusions/extrusions
  • 3rd order = twisting the wire for torquing
195
Q

pros and cons of fixed appliance treatment (2/6)

A

+:
- precise bodily movement
- less dependent on cooperation

-:
- excellent OH needed - risks decalcification
- changes to diet
- mucosal trauma
- pt cooperation needed with elastics/HG
- staining of modules
- risk of iatrogenic damage (RR)

196
Q

pros and cons of ceramic fixed appliances (1/5)

A

+ = better aesthetics

-:
- high friction
- brittle
- risk of TW on opposing teeth
- increased risk of debonding
- modules still stain, AW visible

197
Q

pros and cons of lingual fixed appliances (1/5)

A

+ = better aesthetics

-:
- bespoke with increased chairside time
- special pliers and training needed
- speech impeded
- lingual ulcers
- increased failure rate and hard to repair

198
Q

pros and cons of invisalign removable appliances (2/4)

A

+:
- removable = easy to clean
- aesthetic

-:
- attachments and appliance affects speech
- initial training and costs
- pt cooperation
- not for complex cases

199
Q

how do functional appliances work?

A

uses forces of the muscles of mastication to move teeth

200
Q

describe the effects of functional appliances (decrease OJ) (up to 11)

A

1/3 skeletal:
- redirect condylar growth
- possible glenoid fossa remodelling
- accelerate growth spurt
- restrict maxillary growth, affect maxillary sutures

2/3 dental:
- retrocline upper incisors
- procline lower incisors
- controlled eruption of teeth
- HG effect = rolling/tipping back of maxillary teeth

ST:
- correct lip traps, swallowing pattern, holding soft tissues away for expansions

201
Q

when should functional appliances be used? (3)

A
  • mixed dentition (except Herbst) during growth spurt
  • reasonably favourable growth pattern
  • moderate-severe skeletal pattern
202
Q

when should a patient be referred for growth modification and at what age should treatment be carried out?

A
  • refer ~11yo (1-3 years pre-growth spurt)
  • female = 10-13yo
  • male = 11-14yo
203
Q

how does intermaxillary traction work with correcting class II div 1 malocclusion (functional appliance)? (2)

A
  • mesial force on mandible against the muscles of mastication pulling distally
  • distal force transferred to the maxilla as the arches are splinted together
204
Q

pros and cons of functional appliances generally (6/3)

A

+:
- eliminates abnormal muscle function
- better aesthetics/facial profile (usually)
- improved psychosocial state
- decreased trauma risk (decreased OJ)
- removable = easy to clean
- less chairside time than FAs

-:
- needs growing pt, growth-dependent
- increases overall treatment time, FAs still needed usually
- needs pt compliance

205
Q

list different types of functional appliances (5)

A
  • Andresen/activator
  • Bionator
  • Clark/twin block
  • Frankel
  • Herbst (fixed)
206
Q

describe the Andresen/activator appliance (3)

A
  • upper and lower arches fit into a single acrylic block, in a predetermined postured position
  • labial bow retention with capping (can decrease OB)
  • large, bulky, made to be loose (poorly tolerated)
207
Q

describe the bionator appliance (2)

A
  • wire base activator with a labial bow extended into wire “shields” buccally (holds cheeks away)
  • better tolerated than Andresen
208
Q

describe the Clark/twin block appliance (4)

A
  • SEPARATE upper and lower appliances which lock together into a postured position on closing
  • slanted bite blocks, clasps, labial bow
  • interferes less with normal function, more comfortable and aesthetic so better tolerated
  • not great for deep OB (buccal blocks may increase OB)
209
Q

describe the Frankel appliance (2)

A
  • no longer used (complex to make, bulky, poorly tolerated)
  • single unit similar to Andresen but has acrylic screens to relieve soft tissue forces
210
Q

describe the Herbst appliance (3)

A
  • fixed, arches splinted together with cemented framework using a pin and tube apparatus
  • less reliant on compliance
  • can have masticatory issues, soft tissue trauma or breakage/distortion
211
Q

what is orthodontic camouflage?

A

accepting the skeletal relationship but correcting the incisor relationship

212
Q

when is orthodontic camouflage appropriate? (4)

A
  • permanent dentition
  • small ANB (mild/moderate skeletal relationship)
  • no habits
  • little dentoalveolar compensation
213
Q

pros and cons of orthodontic camouflage (4/2)

A

+:
- any age
- no surgery
- +/- extractions
- fixed or removable appliances

-:
- mild cases only
- profile remains the same

214
Q

what is orthognathic surgery?

A

movement of one or both jaws into a different position to correct a skeletal discrepancy +/- FAs

215
Q

give some examples of orthognathic surgery (4)

A
  • mandibular advancement
  • segmental maxillary setback
  • bilateral sagittal split
  • bimaxillary osteotomy
216
Q

when is orthognathic surgery appropriate? (4)

A
  • non-growing pts
  • severe skeletal discrepancy ANB >8º or <-4º or craniofacial deformity
  • unfavourable aesthetics, abnormal function
  • adverse growth patterns
217
Q

risks of orthognathic surgery (6)

A
  • surgical risks
  • risk of IDN damage
  • TMJ and swallowing issues
  • risk to ophthalmic, auditory systems
  • risks of GA
  • relapse risk if movements >5-6mm in maxilla or >8mm in mandible
218
Q

which arch is considered first in treatment planning for orthodontics? why?

A

lower arch - LLS cannot be moved too far outside current position otherwise will be unstable (neutral zone)

219
Q

what factors affect which tooth is extracted? (5)

A
  • prognosis (poorer)
  • location
  • tooth position (esp ectopic teeth)
  • amount of crowding (4s give more space than 5s)
  • alignment of opposing arch
220
Q

what extraction patterns are usually used for the treatment of each malocclusion?

A
  • class I = same teeth U/L
  • class II div 1 = same OR further forward in the upper to decrease OJ OR only upper teeth (well-aligned lower)
  • class II div 2 = as for div 1, but with caution as may be hard to close spaces and retroclined upper incisors
  • class III = same OR further forward in the lower arch OR only lower arch
    (caution in cases with orthognathic surgery)
221
Q

why are premolars usually extracted for orthodontic space? (2)

A
  • middle of arch (can relieve crowding anteriorly or posteriorly)
  • similar crown forms, similar contact points
222
Q

when might you extract first premolars vs second premolars?

A
  • 4s = severe crowding, near the site of crowding, preventing the U3 from buccal exclusion
  • 5s = mild/moderate crowding, poor condition or displaced; alters anchorage balance (6 drifts)
223
Q

why might removing poor prognosis FPMs be undesirable in orthodontics? (2)

A
  • increased treatment times and complicated mechanics = increased risk of iatrogenic issues
  • extracting too late means the 7 does not close space well
224
Q

when should poor prognosis FPMs be removed? (7)

A
  • 10-11yo (before the 3/5/7 erupt) = allows reasonable spontaneous space closure
    – L7 calcified at bifurcation with 15-30º angle
    – presence of L8
  • lower 6s often need compensation
  • if 7s already in occlusion (12yo+) then need FAs for space closure
    – upper gap will close space reasonably
    – lower gap will not, L7 tilts and rotates
225
Q

why are 7s not often extracted for orthodontics? (2)

A
  • too far back to relieve crowding
  • unpredictable effect on 8s (so no point)
226
Q

why are 8s not often extracted for orthodontics? (2)

A
  • too late for use in adolescents
  • may be removed pre-orthognathic surgery
227
Q

why are canines not often extracted for orthodontics?

A

needed for occlusion

228
Q

why are incisors not often extracted for orthodontics? (2)

A
  • aesthetics
  • lower incisors extraction = crowding of ULS and increased OJ and indefinite retention needed (NEVER in teens)
229
Q

approximately when does maxillary and mandibular growth reach adult levels generally?

A
  • maxillary = 15yo in F, 17yo in M
  • mandibular = 17yo in F, 19yo in M
230
Q

how is orthodontics in adults different? (6)

A
  • negligible growth
  • decreased blood supply and turnover, slower tissue reorganising = slower reaction, needs increased/permanent retention
  • decreased periodontal attachment = needs lighter forces, accelerates recession
  • missing and heavily restored teeth = tilting, migration, alveolar bone “necking”, anchorage and bonding issues
  • less able to adapt to occlusal discrepancies
  • increased likelihood of relapse of molar extrusion
231
Q

give the recommended retention regimes (4)

A
  • treat all cases as high risk for relapse
  • 3 months URA for 1-2 teeth = 3 months full time retainer wear
  • Hawley or VFR for 3-6 months full-time then 6-12 months night time
  • wear as long as pt wants teeth to be straight
232
Q

describe a Hawley retainer (2)

A
  • acrylic base plate, Adams cribs and fitted labial bow
  • expensive, palatal coverage and visible but allows occlusal settling
233
Q

describe a vacuum-formed retainer (VFR) (3)

A
  • full occlusal coverage 7-7
  • cheap, quick, well tolerated and better control of incisor alignment but no occlusal settling
  • may add pontics (Essix retainer)
234
Q

describe a fixed retainer

A
  • multistranded SS wire bonded with composite to lingual/palatal surfaces of 3-3
  • well-tolerated, less reliant on compliance
  • expensive and time consuming to place, technique sensitive, difficult OH, failure and maintenance
235
Q

what three things are needed for orthodontic tooth movement to occur?

A
  • PDL
  • bone
  • appropriate force
236
Q

describe the pressure-tension hypothesis (4)

A
  • orthodontic force causes tooth to shift within the PDL after a few seconds
  • compression to 1/3 of width = OCs migrate and resorb bone (frontal resorption) within days
  • tension with stretched PDL fibres = increased OBs and fibroblasts = lay down osteoid and fibre remodelling
  • acute and chronic inflammatory processes
237
Q

what are the properties of ideal orthodontic forces? (4)

A
  • light (<capillary pressure) - to prevent sterile necrosis and undermining resorption = pain, RR, mobility
  • continuous >6hrs/day
  • prolonged over several months
  • controlled ~1mm/month
238
Q

why is orthodontic movement faster in children? (4)

A
  • increased physiological movement (eruption)
  • more cellular PDL, increased proportion of OBs
  • faster cellular response
  • increased PDL width in newly-erupted teeth = can use increased force
239
Q

what is the rationale behind retention following orthodontics? (4)

A
  • gingival and periodontal fibres reorganise for about a year and bone remodelling
  • post-tx growth, late lower incisor crowding
  • maturational changes = decreased intercanine width and arch length
  • soft tissues and habits may not be changed
    (NHS tx not offered twice)
240
Q

what may be done to increase the stability of derotations? (3)

A
  • overcorrect by 10%
  • derotate early in treatment with FA (retention period during treatment)
  • pericision/circumferential supracrestal fibrectomy (esp maxillary)

BDS5 (5 decks)

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