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
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
3
Q
how much root resorption is expected with orthodontics?
A
~1mm over a 2 year period
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
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
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)
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)
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)
9
Q
at what age would you refer for orthognathic surgery?
A
adults, after pubertal growth spurt
(may refer earlier for assessment)
10
Q
at what age would you refer for cleft or craniofacial abnormalities?
A
ASAP if not already under a MDT/cleft team
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)
12
Q
at what age would you refer for orthodontic camouflage?
A
when child has permanent dentition
(also for class II growth modification)
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
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
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
16
Q
how can AP class be assessed clinically? (2)
A
- Kettle’s method
- zero Meridian line
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
18
Q
how can vertical facial height be assessed clinically? (2)
A
- facial thirds
- FMPA
19
Q
how can the transverse plane be assessed clinically? (2)
A
- rule of fifths
- midline (glabella, philtrum, pogonion)
20
Q
what is the average value for NL angle?
A
90-110º
21
Q
what is the average height of the smile line?
A
showing from 75% of upper incisors to 100% with 2mm gingiva
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
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
24
Q
list the 5 anterior occlusal features to be assessed
A
- incisor relationship
- overjet
- overbite
- centrelines
- crossbites +/- displacements
25
list the 5 posterior occlusal features to be assessed
- right canine relationship
- left canine relationship
- right molar relationship
- left molar relationship
- crossbites +/- displacements
26
what is average overjet in mm?
2-4mm
27
what descriptors may be used for overjet?
increased, average, decreased
28
what is average overbite?
upper incisors covering the incisal third of the lower incisors (2-4mm)
29
what descriptors may be used for overbite?
- increased, decreased, open bite
- complete to tooth/palate/gingiva, incomplete
- +/- traumatic
30
why is it important to check for mandibular displacements?
may make malocclusion (crossbites and class III) appear worse than it actually is
31
give a standard DPT radiographic report template (7)
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
32
what features are assessed with a lateral cephalogram for orthodontics? (5)
- skeletal base (ANB)
- vertical proportions (MMPA, LFH)
- incisor inclinations
- interincisal angle
- soft tissues
33
give the average Caucasian cephalometric values and standard deviations (8)
- 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%
34
what are the average Caucasian SNA, SNB and ANB angles?
- SNA = 81 +/- 3º
- SNB = 78 +/- 3º
- ANB = 3 +/- 2º
35
what are the average Caucasian upper and lower incisor inclinations and interincisal angle?
- UI inclination = 109 +/- 6º
- LI inclination = 93 +/- 6º
- interincisal angle 135 +/- 10º
36
what are the average Caucasian MMPA and LFH?
- MMPA = 27 +/- 5º
- LFH = 55 +/- 2%
37
for what reasons is a lateral cephalogram taken? (4)
- diagnosis
- pre-treatment record
- monitor treatment progress or growth
- research
38
what categories is orthodontic aetiology separated into? (3)
- skeletal
- soft tissue
- dentoalveolar and local
39
what might be part of your treatment plan in orthodontics? (6)
- prevention - OHI, diet advice
- growth modification, orthodontic camouflage or orthognathic surgery
- removable or fixed appliances, functional appliances
- anchorage considerations
- any extractions
- retention, stability/growth
40
what is MOCDO?
- acronym to help assess a patient's IOTN
- Missing teeth
- Overjet
- Crossbite
- Displacement of contact points
- Overbite
41
what is included in the M part of MOCDO?
- missing teeth
- 5h (hypodontia >1 tooth/Q)
- 5s (submerging deciduous tooth)
- 5i (impacted)
- 4h (hypodontia 1 tooth/Q maximum)
42
what does 5h mean in the IOTN?
extensive hypodontia with restorative implications, >1 tooth per quadrant
43
what does 4h mean in the IOTN?
less extensive hypodontia needing orthodontics pre-restorative tx or space closure (1 tooth/Q maximum)
44
how is hypodontia graded by the IOTN?
h = hypodontia
- 5h if >1 tooth/Q
- 4h if 1 tooth/Q max
45
what does 5s mean in the IOTN?
submerging deciduous tooth
46
what does 5i mean in the IOTN?
impeded eruption/impacted
47
how is positive overjet graded by the IOTN?
a = overjet
- 5a = >9mm
- 4a = 6.1-9mm
- 3a = 3.6-6mm with incompetent lips
- 2a = 3.6-6mm with competent lips
48
how is reverse overjet graded by the IOTN?
b = reverse overjet
- 5m = >3.5mm with masticatory or speech difficulty
- 4b = >3.5mm
- 3b = 1.1-3.5mm
- 2b = 0.1-1mm
49
how is crossbite graded by the IOTN?
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
50
how is crowding graded by the IOTN?
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
51
what does 4x mean in the IOTN?
supplemental teeth
52
how is overbite graded by the IOTN?
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
53
are impacted maxillary canines more likely to be buccally or palatally placed?
palatally (85%)
54
predisposing factors to maxillary impacted canines (7)
- 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)
55
possible effects of maxillary impacted canines (2)
- root resorption (incisors especially)
- cystic change
56
after what age is root resorption due to maxillary impacted canines unlikely to occur?
14yo
57
what is considered delayed eruption of maxillary canines (RCS)?
- females = 12.3yo
- males = 13.1yo
58
what should be included in your clinical assessment of maxillary impacted canines and why? (7)
- 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
59
what features on a DPT are used to assess maxillary impacted canine(s) prognosis and what are the optimum values? (3)
- height - ideally crown of 3 is within coronal third of tooth roots
- inclination - 0-15º
- proximity to midline - apex of 3 over eruption space
60
what radiographs may you take for parallax of maxillary impacted canines?
- LCPA + USO or another LCPA
- DPT + LCPA or USO
61
general treatment options for maxillary impacted canines (5)
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
62
describe interceptive extraction of C for maxillary impacted canine (3)
- 10-13yo (mixed dentition)
- wait 1 year for any spontaneous eruption before E+B
- favourable position of 3
63
describe surgical E+B for maxillary impacted canine, open or closed (4)
- +/- 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
64
into what type of tissue must a maxillary impacted canine erupt into and why?
- keratinised gingiva
- otherwise periodontal pocketing and need for a gingival graft
65
when might you do surgical extraction of a maxillary impacted canine? (3)
- unfavourable position for eruption
- MH contraindicates E+B
- acceptable aesthetics without 3
66
describe autotransplantation for maxillary impacted canines (3)
- 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)
67
when may you choose to monitor maxillary impacted canine(s) (4)
- 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
68
define relapse
tendency of a treated malocclusion to return to the original features of the malocclusion after correction
69
what types of malocclusions/corrections have a high risk of relapse? (10)
- 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
70
aetiology of spacing (8)
- 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
71
aetiology of median diastema (7)
- physiological (closes with eruption of 3s)
- hypodontia
- microdontia
- persistent low fraenal attachment
- racial/FH - esp Afrocaribbean
- mesiodens (pathology, supernumerary)
- proclined ULS (habits, perio)
72
management of spacing (4)
- 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
73
when would you intercept for a median diastema in a child?
>3mm pre-canine eruption with insufficient space for laterals
74
how long should you retain a space before restoring with RBBs?
at least 3-6 months (9 months if space opened)
75
what are the different types of crowding?
- primary = dentoalveolar disproportion (genetic)
- secondary = early loss of primary tooth (environmental)
- tertiary = late lower incisor crowding
76
factors in late lower incisor crowding (3)
- mesial migration of teeth with age
- forward growth of jaws (low levels in adulthood but never stops)
- presence and position of third molars
77
how is crowding classified?
- mild = <4mm
- moderate = 4-8mm
- severe = >8mm
78
aetiology of crowding (4)
(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
79
possible consequences of crowding on other teeth
- increased caries and perio risk
- impaction
80
what may cause tooth impaction/failure of eruption? (5)
- gingival fibromatosis
- retained primary tooth (ankylosis)
- crowding
- supernumerary
- trauma or developmental dilaceration
81
name some syndromes which may be associated with supernumerary teeth (3)
- Gardner's
- CLP
- Down's
82
which teeth are more commonly affected by macrodontia? (2)
U1, L5
83
how may unerupted displaced teeth be managed? (2)
- mild = extraction of primary tooth with spontaneous eruption
- severe = E+B or removal
84
how may mild crowding be treated? (3)
(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)
85
when is molar distalisation used for mild crowding and what issues are associated?
- for ≤ 1/2 unit class II
- safety issues, pt preference, poor compliance
86
how may moderate/severe crowding be managed?
extractions (but caution if deep bite)
87
define crossbite
transverse discrepancy in tooth relationship
88
how is crossbite classified?
- 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
89
aetiology of crossbite (7)
- 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
90
give examples of genuine dental base/arch asymmetry (2)
- CLP surgical repair = scarring, restriction = buccal crossbite
- mandibular growth disturbance
91
how may gross AP discrepancy lead to crossbite?
- marked class II = lingual crossbite (especially in premolar area)
- marked class III = buccal crossbite
92
what may cause a low tongue position? (3)
- digit sucking
- mouth breathing
- increased lower face height
93
treatment for lingual crossbite (2)
- FAs with cross elastics
- +/- surgery if severe skeletal issue
94
treatment for unilateral buccal crossbite with displacement
expansion of upper arch (prevents cusp-to-cusp relationship)
95
treatment for unilateral buccal crossbite with no displacement (2)
- dental asymmetry = orthodontics +/- expansion
- base asymmetry = investigate why, growth issues may need surgery
96
management of bilateral buccal crossbite with aligned arches
accept (but rare)
97
treatment of bilateral buccal crossbite needing alignment (2)
- mild/moderate = orthodontics +/- expansion
- severe = surgery
98
specific methods of treating buccal crossbites (3)
- conventional methods = URA (screw plate, coffin spring) or FAs (quadhelix, cross-elastics, heavy AWs)
- RME
- localised = Z or T springs, unilateral screw plate
99
describe rapid maxillary expansion (RME) briefly (4)
- 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
specific methods of treating anterior crossbites (2)
- FAs
- URA (Z spring or anterior sectional screw plate)
101
factors to consider when treating anterior crossbite (5)
- skeletal severity
- displacements
- incisor inclination
- OJ
- OB (stability)
102
average age of eruption for upper and lower permanent canines
- lower = 9-10yo
- upper = 11-12yo
103
average age of eruption of upper and lower central and lateral incisors
- lower incisors = 6-8yo
- upper incisors = 7-9yo
104
define normal occlusion, malocclusion and functional occlusion
- 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
what are Andrew's six keys for an ideal occlusion?
- 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
define class I incisor relationship
incisal edge of lower central incisor occludes with or lies immediately below cingulum plateau of upper central incisor
107
define class II div 1 incisor relationship
- 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
define class II div 2 incisor relationship
- 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
define class III incisor relationship
lower incisor edges lie anterior to cingulum plateau of upper central incisors and OJ is reduced/reversed
110
define class I molar relationship (Angle's and Andrew's)
- 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
define class II molar relationship
U6 MB cusp is mesial to the L6 buccal groove
(may be fractions of a unit)
112
define class III molar relationship
U6 MB cusp is distal to the L6 buccal groove
(may be fractions of a unit)
113
define class I canine relationship
U3 occludes directly in the embrasure space between the L3 and L4
114
define class II canine relationship
U3 occludes mesial to the embrasure space between the L3 and L4
(may be fractions of a unit)
115
define class III canine relationship
U3 occludes distal to the embrasure space between the L3 and L4
(may be fractions of a unit)
116
what is point A and point B on a lateral cephalogram?
- point A = deepest concavity on maxilla
- point B = deepest concavity of mandible
117
what are the landmarks for assessing vertical facial "thirds"?
- 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
what is Frankfort's plane?
horizontal plane from orbitale (inferior orbital margin) to tragus of ear (upper border of EAM)
119
what is FMPA?
- Frankfort-mandibular planes angle
- where Frankfort plane intersects the line of the lower border of the mandible
120
what is the S-N line on a lateral cephalogram?
- line from sella point (middle of sella turcica) and nasion (junction between frontal bone and nasal bone)
- represents cranial base
121
what is a fraenum?
small fold of tissue that secures or restricts the motion of a mobile tissue
122
define gemination of tooth bud
incomplete division of a single tooth bud
123
define twinning of tooth bud
complete division of a single tooth bud
124
define fusion of teeth
union of dentine of two teeth from two tooth buds
125
define concrescence of teeth
union of cellular cementum of two teeth from two tooth buds
126
define anodontia
complete developmental absence of teeth
127
define hypodontia
developmental failure of ≤6 teeth, other than the third molars
128
define oligodontia
absence of more than six teeth in primary, permanent or both dentitions
129
what are supplemental teeth?
developmental extra copies of teeth due to lamina dura extension
130
what is the difference between active and passive appliances?
- active = bring about tooth movement
- passive = maintain position of teeth (eg space maintainers, retainers)
131
what is deflection (removable appliances)?
amount of activation the operator puts into a spring
132
what is retention (removable appliances)?
means by which appliances resist displacement (stay in the mouth)
133
what meant by "active component" (removable appliances)?
means by which forces are applied to teeth to bring about the required movement, eg springs, bows, screws
134
what is anchorage and the factors affecting it?
- resistance to unwanted tooth movement
- dependent on surface area of root in the bone and type of tooth movement
135
define anterior open bite
no overlap of incisors when the posterior teeth are in occlusion
136
define posterior open bite
space between the posterior teeth when the teeth are in occlusion
137
what is retention (after orthodontic treatment)?
maintenance of intra-arch relationships (alignment of teeth) and inter-arch relationships (static and dynamic occlusion)
138
what is a retainer?
passive orthodontic appliances that maintain the position of teeth after orthodontic treatment
139
define torque
controlled movement of root with little or no movement of the crown in the opposite direction
140
at what age and which dentition will failure of eruption of upper permanent incisors present?
7-9yo, mixed dentition
141
what is considered delayed eruption for upper permanent incisor(s)? (3)
- contralateral incisor erupted >6 months earlier
- lower incisors are erupted >1 year earlier
- significant deviation from normal eruption sequence (eg laterals before centrals)
142
issues with failure of eruption of upper permanent incisors (2)
- poor aesthetics
- decreased self esteem and social interaction
143
aetiology of unerupted permanent upper central incisors (7)
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
what are the two most common causes of unerupted permanent upper central incisors?
- physical obstruction (supernumerary or odontome)
- trauma to primary dentition +/- dilaceration
145
which 3 teeth are most commonly impacted?
8s > U3s > U1s
146
general management principles of unerupted permanent upper central incisors (5)
- 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
what radiographs may be taken to assess an unerupted permanent upper central incisor?
- LCPA +/- USO for presence and parallax, anomalies
- lateral ceph = location, assessment (height, inclination)
- CBCT (esp for treatment planning dilacerations)
148
how much space is needed in the arch to allow an unerupted permanent upper central incisor to erupt?
9mm (average)
149
what side of the tooth will most likely be bonded to for E+B of unerupted permanent upper central incisor?
palatal (favourable direction, reduce risk of fenestration of attachment)
150
pros and cons of autotransplantation for unerupted permanent upper central incisors
- + = 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
at what age is removal of a supernumerary more likely to cause spontaneous eruption with permanent upper central incisors?
8-9yo
152
pt (3) and dental (4) factors affecting treatment of unerupted permanent upper central incisor(s)
- 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
potential risks of treatment for unerupted permanent upper central incisors (4)
- failure of eruption
- ankylosis
- external root resorption
- poor gingival aesthetics
154
possible management options of ankylosis of permanent upper central incisor (5)
- 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
aetiology of class I malocclusion
- 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
aetiology of class II div 1 incisor relationship
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
consequences of digit sucking (5)
- 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
aetiology of class II div 2 incisor relationship
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
aetiology of class III incisor relationship
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
characteristic features you may see in class II div 1 patients (2)
- lip trap
- ULS gingivitis (lip incompetence)
161
characteristic features you may see in class II div 2 patients (5)
- lingual crossbite of first premolar, hourglass upper arch
- small proclined lateral incisors
- impacted 3s
- marked labiomental fold
- well-developed masseters
162
characteristic features you may see in class III patients (2)
- broad well-aligned lower arch
- unfavourable growth pattern
163
factors affecting management of a malocclusion (7)
- malocclusion and severity
- facial profile
- aetiology
- future growth (age, sex)
- likely stability
- compliance
- pt wishes
164
aetiology of posterior lateral open bite (5)
- 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
management options for class I malocclusion (2)
- 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
management options for class II div 1 malocclusion on mild skeletal II (2)
- accept
- FAs +/- XTNs (orthodontic camouflage)
167
management options for class II div 1 malocclusion on moderate/severe skeletal II (4)
- 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
management for class II div 2 malocclusion on mild skeletal II (2)
- 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
management options for class II div 2 malocclusion on moderate/severe skeletal II (4)
- 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
management options for class III malocclusion on mild skeletal III (5)
- 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
management for class III malocclusion on moderate/severe skeletal III (4)
- accept
- growth modification with reverse pull HG +/- maxillary expansion
- orthodontic camouflage
- ortho + orthognathic surgery (ANB <-4º, LI <83º) - caution with extractions
172
list different active components that may be used with removable appliances (8)
(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
list the different retentive components that may be used with removable appliances (3)
(resists displacement)
- Adams clasp
- Southend clasp
- fitted labial bow
174
how much are palatal and buccal active components activated by and how often?
- palatal = 3mm (thinner wire)
- buccal = 1mm (thicker wire)
- monthly usually = 1-2mm of movement/month
175
describe a palatal finger spring (2)
- moves teeth in the line of the arch
- 0.5mm coiled wire with perpendicular guard wire
176
describe a Z spring (2)
- incisor/canine proclination (+/- posterior buccal capping)
- 0.5mm wire with two coils
177
describe a T spring (2)
- moves premolars buccally (needs good retention +/- posterior buccal capping)
- 0.5mm wire
178
describe a coffin spring (2)
- historically used for upper arch expansion
- 1.25mm wire
179
describe a buccal canine retractor (2)
- retracts buccally placed canines (but better to use fixed appliances)
- 0.7mm wire
180
describe a Robert's retractor (2)
- decreases a large OJ
- 0.5mm flexible bow with tubing and trimmed base plate (hard to repair)
181
describe a fitted labial bow (3)
- 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
describe a screw-type appliances (3)
- 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
describe an Adams clasp (2)
- retentive component
- 0.7mm wire with arrowheads engaging MB and DB undercuts of molars or premolars (or Ds)
184
describe a Southend clasp (2)
- retentive component
- 0.7mm wire fitted around labial gingival margins of the upper central incisors
185
what is the function of the baseplate in an URA? (3)
- supports wire components
- contributes to anchorage
- +/- bite planes to open the bite
186
describe the different types of anchorage (3)
- 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
pros and cons of removable appliances (5/6)
+:
- 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
situations where you might use an URA (5)
- decrease OB in growing children
- EO traction
- arch expansion
- space maintainer
- passive retainer
189
general instructions for removable appliances (3)
- constant wear
- remove for cleaning, contact sports, +/- eating
- saliva pooling will stop eventually and will adapt to speech
190
how do edgewise brackets and the straight wire technique work? (4)
- 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
what is the function of elastomeric modules and wire ligatures (FAs)?
secure the arch wire into the bracket slots
192
describe differences between NiTi and SS arch wires
(may also have TMA and CoCr)
- NiTi = shape memory, high spring back, low stiffness
- SS = low spring back, high stiffness, low friction, cheap
193
what are the four general stages of fixed appliance treatment?
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
what are the 3 different types of wire bends and what are they for?
- 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
pros and cons of fixed appliance treatment (2/6)
+:
- 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
pros and cons of ceramic fixed appliances (1/5)
+ = better aesthetics
-:
- high friction
- brittle
- risk of TW on opposing teeth
- increased risk of debonding
- modules still stain, AW visible
197
pros and cons of lingual fixed appliances (1/5)
+ = better aesthetics
-:
- bespoke with increased chairside time
- special pliers and training needed
- speech impeded
- lingual ulcers
- increased failure rate and hard to repair
198
pros and cons of invisalign removable appliances (2/4)
+:
- removable = easy to clean
- aesthetic
-:
- attachments and appliance affects speech
- initial training and costs
- pt cooperation
- not for complex cases
199
how do functional appliances work?
uses forces of the muscles of mastication to move teeth
200
describe the effects of functional appliances (decrease OJ) (up to 11)
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
when should functional appliances be used? (3)
- mixed dentition (except Herbst) during growth spurt
- reasonably favourable growth pattern
- moderate-severe skeletal pattern
202
when should a patient be referred for growth modification and at what age should treatment be carried out?
- refer ~11yo (1-3 years pre-growth spurt)
- female = 10-13yo
- male = 11-14yo
203
how does intermaxillary traction work with correcting class II div 1 malocclusion (functional appliance)? (2)
- mesial force on mandible against the muscles of mastication pulling distally
- distal force transferred to the maxilla as the arches are splinted together
204
pros and cons of functional appliances generally (6/3)
+:
- 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
list different types of functional appliances (5)
- Andresen/activator
- Bionator
- Clark/twin block
- Frankel
- Herbst (fixed)
206
describe the Andresen/activator appliance (3)
- 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
describe the bionator appliance (2)
- wire base activator with a labial bow extended into wire "shields" buccally (holds cheeks away)
- better tolerated than Andresen
208
describe the Clark/twin block appliance (4)
- 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
describe the Frankel appliance (2)
- no longer used (complex to make, bulky, poorly tolerated)
- single unit similar to Andresen but has acrylic screens to relieve soft tissue forces
210
describe the Herbst appliance (3)
- 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
what is orthodontic camouflage?
accepting the skeletal relationship but correcting the incisor relationship
212
when is orthodontic camouflage appropriate? (4)
- permanent dentition
- small ANB (mild/moderate skeletal relationship)
- no habits
- little dentoalveolar compensation
213
pros and cons of orthodontic camouflage (4/2)
+:
- any age
- no surgery
- +/- extractions
- fixed or removable appliances
-:
- mild cases only
- profile remains the same
214
what is orthognathic surgery?
movement of one or both jaws into a different position to correct a skeletal discrepancy +/- FAs
215
give some examples of orthognathic surgery (4)
- mandibular advancement
- segmental maxillary setback
- bilateral sagittal split
- bimaxillary osteotomy
216
when is orthognathic surgery appropriate? (4)
- non-growing pts
- severe skeletal discrepancy ANB >8º or <-4º or craniofacial deformity
- unfavourable aesthetics, abnormal function
- adverse growth patterns
217
risks of orthognathic surgery (6)
- 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
which arch is considered first in treatment planning for orthodontics? why?
lower arch - LLS cannot be moved too far outside current position otherwise will be unstable (neutral zone)
219
what factors affect which tooth is extracted? (5)
- prognosis (poorer)
- location
- tooth position (esp ectopic teeth)
- amount of crowding (4s give more space than 5s)
- alignment of opposing arch
220
what extraction patterns are usually used for the treatment of each malocclusion?
- 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
why are premolars usually extracted for orthodontic space? (2)
- middle of arch (can relieve crowding anteriorly or posteriorly)
- similar crown forms, similar contact points
222
when might you extract first premolars vs second premolars?
- 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
why might removing poor prognosis FPMs be undesirable in orthodontics? (2)
- increased treatment times and complicated mechanics = increased risk of iatrogenic issues
- extracting too late means the 7 does not close space well
224
when should poor prognosis FPMs be removed? (7)
- 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
why are 7s not often extracted for orthodontics? (2)
- too far back to relieve crowding
- unpredictable effect on 8s (so no point)
226
why are 8s not often extracted for orthodontics? (2)
- too late for use in adolescents
- may be removed pre-orthognathic surgery
227
why are canines not often extracted for orthodontics?
needed for occlusion
228
why are incisors not often extracted for orthodontics? (2)
- aesthetics
- lower incisors extraction = crowding of ULS and increased OJ and indefinite retention needed (NEVER in teens)
229
approximately when does maxillary and mandibular growth reach adult levels generally?
- maxillary = 15yo in F, 17yo in M
- mandibular = 17yo in F, 19yo in M
230
how is orthodontics in adults different? (6)
- 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
give the recommended retention regimes (4)
- 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
describe a Hawley retainer (2)
- acrylic base plate, Adams cribs and fitted labial bow
- expensive, palatal coverage and visible but allows occlusal settling
233
describe a vacuum-formed retainer (VFR) (3)
- 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
describe a fixed retainer
- 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
what three things are needed for orthodontic tooth movement to occur?
- PDL
- bone
- appropriate force
236
describe the pressure-tension hypothesis (4)
- 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
what are the properties of ideal orthodontic forces? (4)
- light (6hrs/day
- prolonged over several months
- controlled ~1mm/month
238
why is orthodontic movement faster in children? (4)
- 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
what is the rationale behind retention following orthodontics? (4)
- 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
what may be done to increase the stability of derotations? (3)
- overcorrect by 10%
- derotate early in treatment with FA (retention period during treatment)
- pericision/circumferential supracrestal fibrectomy (esp maxillary)
other bds5 things
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