12. Orthodontics

Question 1

Ortho Rx

1. 3 aims
2. 5 advantages
3. 5 risks/disadvantages
4. 3 indications
5. 5 contraindications
6. 3 limitations of ortho

Answer 1

1. Restore stability, function, aesthetics
2. Improve function, appearance, dental health, reduce risk of trauma, facilitate other dental treatment
3. Decalcification, relapse, root resorption, perio attachment loss, loss of vitality, gingival recession, pain and discomfort, soft tissue trauma, length of treatment, appearance during treatment
4. Significant functional/aesthetic malocclusion, good attendance/motivation, psychological impact
5. Uncontrolled epilepsy, poorly controlled diabetes, bisphosphonates, poor attendance/motivation, poor dental/oral hygiene
6. Effects purely dento-alveolar and tooth movement, little effect on skeletal pattern, tooth movement limited by shape and size of alveolar processes, teeth will only remains stable in neutral position

Question 2

Occlusion

1. Definition of ideal occlusion
2. List Andrews six keys
3. Definition of normal occlusion
4. Definition of malocclusions
5. Definition of overjet
6. Normal overjet
7. Definition of overbite
8. Normal overbite
9. 5 types of overbite
10. Definition of crossbite
11. 2 types of cross bite

Answer 2

1. Anatomically perfect occlusion - gold standard by which occlusal irregularities and treatment may be judged
2. Correct molar relationship, correct crown angulation, correct crown inclination, absence of rotations, tight proximal contacts (absence of spaces), flat occlusal plane
3. Acceptable variation from ideal, usually minor deviations that do not constitute an aesthetic or functional problem
4. More significant deviations from the ideal that may be considered aesthetically or functionally unsatisfactory
5. Extent of horizontal overlap of maxillary central incisors over mandibular central incisors (distance between upper and lower incisors in the horizontal plane)
6. 1.5-2.5mm
7. Extent of vertical overlap of maxillary central incisors over mandibular central incisors (overlap of incisors in the vertical plane)
8. 1/3-1/2 of lower incisors covered
9. Complete, incomplete, deep, open, traumatic, normal
10. Deviation from the normal bucco-lingual position
11. Lingual (lower teeth too lingual) or buccal (lower teeth too buccal)

Question 3

BSI classification definitions

1. Class I
2. Class II division 1
3. Class II division 2
4. Class III

Answer 3

1. Incisal edges of lower incisors occlude with/lie immediately below the cingulum plateau of upper central incisors
2. Incisal edges of lower incisors lie posterior to the cingulum plateau of upper incisors. The upper incisors are proclined/of average inclination. There is an increase in overjet
3. Incisal edges of lower incisors lie posterior to the cingulum plateau of upper incisors. The upper incisors are retroclined. The overjet is usually minimal/may be increased
4. Incisal edges of lower incisors lie anterior to the cingulum plateau of upper incisors. The overjet is reduced/reversed

Question 4

Class II/1

1. Usually associated with which skeletal classification
2. Normal cause
3. Associated soft tissue features
4. 5 treatment options

Answer 4

1. Skeletal class II or class I
2. Mandibular retrognathia
3. Incompetent lips, hyperactive lower lip
4. Accept, growth modification (twin-block), URA (Roberts retractor + FABP), fixed appliances, orthognathic surgery

Question 5

Class II/2

1. Usually associated with which skeletal classification
2. Normal cause
3. Associated soft tissue features
4. 5 treatment options

Answer 5

1. Skeletal class II or class I
2. Mandibular retrognathia
3. Reduced FMPA/LAFH, progenia, hyperactive lower lip, accentuated labio-mental fold
4. Accept, growth modification (modified twin block), camouflage (URA), fixed appliances, orthognathic surgery

Question 6

Class III

1. 1. Usually associated with which skeletal classification
2. Normal cause
3. Associated dental features
4. 5 treatment options

Answer 6

1. Class III or class I
2. Maxillary hypoplasia or mandibular protrusion
3. Reduced overbite
4. Accept, interceptive URA, growth modification (reverse twin block, FRIII), camouflage, orthognathic surgery, fixed appliances

Question 7

Molar and Canine Relationships

1. Describe Angle’s classification
2. Describe canine relationship

Answer 7

1. Class I - neutron-occlusion - MB cusp of U6 occludes with MB groove of L6
Class II - disto-occlusion - MB cusp of L6 occludes distal to class I position (post-normal)
Class III - mesio-occlusion - MB cusp of L6 occludes mesial to class I position (pre-normal)

2. Class I - cusp of U3 occludes with embrasure of L3 and L4. Mesial slope of U3 is continuous with distal slope of L3
Class II - cusp of U3 occludes mesial to class I position
Class III - cusp of U3 occludes distal to class I position

Question 8

Skeletal Base classification

1. Definition of each skeletal base

Answer 8

Class I - maxilla 2-3mm in front of mandible
Class II - maxilla >3mm in front of mandible
Class III - maxilla <2mm in front of mandible or maxilla behind mandible

Question 9

EO Exam

1. 5 key features
2. How to assess AP relationship clinically
3. How to assess vertical relationship clinically
4. How to assess transverse relationship clinically
5. Key features of TMJ
6. Key features of lip assessment

Answer 9

1. AP relationship, vertical relationship, transverse relationship, TMJ, lips
2. Visual, palpate skeletal bases
3. FMPA, AFH
4. Asymmetry, mid-sagittal reference line
5. Path of closure, deviation
6. Competent/incompetent, lip trap, lower lip activity (if too high, may retrocline incisors), smile line, habits, speech, oral seal

Question 10

IO Exam

1. 5 features
2. 2 techniques for crowding assessment

Answer 10

1. OH and perio health, crowding/spacing/rotations, inclination/angulation of teeth, tooth shape/size, tongue (thrusts, habits, swallowing), OJ, OB, centre line, BSI, MR, canine relationship
2. Space required vs space available, overlap technique

Question 11

Treatment aims

1. 4 aims of treatment
2. 3 categories of crowding and treatment options for lower crowding
3. Treatment options for upper crowding

Answer 11

1. Class I BSI, MR, canine; Andrews six keys, plan around LLS, build upper around lower
2. Mild (0-4mm) - non-extraction stripping, XLA5, moderate (4-8mm) - XLA5, XLA4, severe (8+mm) - XLA4
3. If lower extraction - compensating extraction for MR class I; non-extraction - upper extraction (MR class II), distalise UBS with headgear (MR class I)

Question 12

Malocclusions

1. 8 normal AP cephalometric values
2. Class I, class II and class III cephalometric values for SNA, SNB, ANB
3. 2 normal vertical cephalometric values
4. 2 features of long face type
5. 2 features of short face type

Answer 12

1. SNA - 81±3
SNB - 78±3
ANB - 3±2
FMPA - 27±4
UI/MxP - 109±6
LI/MnP - 93±6
Ui/Li - 135±10
Li-APo - 0-2mm

2. Class I - SNA 81±3, SNB 78±3, ANB 3±2
   Class II - SNA usually average, SNB usually decreased, ANB >5
   Class III - SNA usually decreased, SNB usually average, ANB <1
3. FMPA - 27±4
   LAFH - 50/50 clinical (45/55 radiographically)
4. Increased FMPA, increased LAFH
5. Decreased FMPA, decreased LAFH

Question 13

Ectopic teeth management

Give management options for an ectopic:

1. Central incisor
2. First molar
3. Third molar
4. Canine
5. When to palpate canine and what to do if no buccal bulge

Answer 13

1. Surgical exposure, remove supernumerary, bonding gold chain, ortho, bonded retainer
2. Attempt to distalise 6, otherwise extract e
3. Extract if symptomatic
4. XLAc, retain c and observe, surgical exposure and orthodontic alignment, extract, transplant
5. 9yrs old; radiograph to localise, refer if appropriate

Question 14

Tooth Movement

1. List 6 types of orthodontic tooth movement and the ideal forces associated with them
2. 4 factor responsible for affecting response to orthodontic forces

Answer 14

1. Tipping/tilting (35-60g), bodily movement (150-200g), intrusion (10-20g), extrusion (35-60g), rotation (35-60g), torque (50-100g)
2. Magnitude, duration, age, anatomy

Question 15

Orthodontic Forces

1. Give some key features of light ortho forces
2. Give some key features of moderate ortho forces
3. Give some key features of excessive ortho forces

Answer 15

1. PDL hyperaemia, osteoclastogenesis and osteoblastogenesis, resorption of lamina dura from pressure side, apposition of osteoid on tension side, socket remodelling, periodontal fibres reorganise, gingival fibres remain distorted
2. Occlusion of vessels of PDL on pressure side, hyperaemia of vessels of PDL on tension side, cell-free areas on pressure side (hyalinisation), period of stasis, increased endosteal vascularity (undermining resorption), relatively rapid movement of tooth with bone deposition on tension side, PDL healing (reorganisation and remodelling)
3. Necrosis, undermining resorption, resorption of root surfaces, pain, permanent change

Question 16

Orthodontic appliances

1. Indication for removable appliances
2. How removable appliances work
3. 5 indications for fixed appliances
4. 4 components of fixed appliances
5. Advantage of fixed appliances
6. 3 palatal components of fixed appliances and what they are used for

Answer 16

1. Correct/camouflage minor malocclusions
2. Tilt/tip teeth
3. Correct/camouflage mild to moderate skeletal discrepancies, alignment of teeth, correct rotations, centreline correction, reduce OJ and OB, space closure/creation, vertical movement of teeth (intrusion/extrusion)
4. Brackets, bands, arch wires, auxillaries
5. Can move teeth by 3D movement, fixed so good compliance
6. Quadhelix - expansion of arch
   Removable palatal arch with nance button - anchorage
   Transpalatal arch - anchorage, retention

Question 17

Retention

1. Definition
2. 4 features with high relapse rates
3. 2 main types of retainers, with 3 indications for 1 type

Answer 17

1. Maintaining final tooth position with a passive orthodontic appliance
2. Diastema/space closure, rotations, palatally ectopic canines, proclamation of lower incisors, AOB
3. Removable - thermoplastic pressure-formed or Hawley
   Fixed - space closure, proclanation of LLS, correction of rotations

Question 18

IOTN

1. Function
2. What are the 2 components
3. What acronym can be used to help identify the worst occlusal feature

Answer 18

1. Indicate the need for ortho Rx
2. DHC - indicates need for treatment
   AC - scale of photographs showing different levels of dental attractiveness
3. MOCDOO - missing teeth, overjet, crossbite, displacement of contact points, overbite, other

Question 19

Growth

1. What are the 2 main bones of the skull that form in utero
2. How does the skull vault form
3. How does the base of the skull form
4. How do the maxilla and mandible develop and what is unique about how they develop
5. What are 5 units of the mandible and why do 4 of these develop
6. What are 3 sites of secondary cartilage formation and when do they disappear

Answer 19

1. Neurocranium, viscerocranium
2. Intramembranous ossification
3. Endochondral ossification
4. Intramembranously, but preceded by cartilaginous facial skeleton (nasal capsule, Meckel’s cartilage)
5. Condylar, angular (medial pterygoid and masseter), coronoid (temporalis), alveolar (if teeth are developing), body (IAN)
6. Condylar cartilage (continues until 20yrs old), coronoid cartilage (disappears after birth), symphyseal cartilage (disappears before birth)

Question 20

Facial syndromes

1. Give 3 features of foetal alcohol syndrome
2. Give 3 features of hemifacial microsomia
3. Give 3 features of Treacher Collins syndrome (mandibulofacial dysostosis)
4. Give 3 features of achondroplasia
5. Give 3 features of Crouzon’s syndrome (craniofacial dysostosis)
6. Give 3 features of Apert’s syndrome (acrosyndactyly)

Answer 20

1. Short palpebral fissures, short nose, long (thin) upper lip, indistinct philtre, small mid face and mandible, varying degrees of mental deficiency
2. 3D progressive facial asymmetry, unilateral mandibular hypoplasia, zygomatic arch hypoplasia, high arched palate, malformed pinna, normal intellect
3. AD condition, anti-mongloid slant palpebral fissures, coloboma of outer third of lower eyelid, hypoplastic/aplastic zygomatic arches, hypo plastic mandibular with antiphonal notch, deformed pinna, conductive deafness
4. AD condition, problems with endocohodral ossification, defects in long bones (short limbs/stature) and base of skull, retruded middle third of face, frontal bossing, depressed nasal bridge
5. AD condition, premature closure of cranial sutures (coronal, lambdoid), proptosis, orbital hysteria, mild hypertelorism, recursion and vertical shortening of mid face, prominent nose, class III malocclusion, narrow spaced teeth
6. AD condition, premature closure of almost all cranial sutures, exophthalmos, hypertelorism, maxillary hypoplasia, class III occlusion, AOB, narrow spaced teeth, Parrot’s beak nose, narrowed high-arched palate, conductive deafness, syndactyly of fingers and toes

Question 21

Clefts

1. Give 3 causes of clefts
2. Give 3 members of a cleft MDT
3. What do cleft palates affect primarily
4. What do cleft lips and palates primarily affect
5. How are clefts classified
6. Give 4 key implications of clefts
7. Give 5 dental implications of clefts
8. Describe the standard surgical journey for a cleft patient

Answer 21

1. Environmental (smoking, alcohol, anticonvulsants, social deprivation) and genetic (syndromes, FH)
2. Orthodontics, cleft surgeon, ENT, psychologists, CNS, geneticist
3. Speech
4. Teeth, speech, growth
5. LAHSHAL classification
6. Aesthetics, hyper-nasal speech, dental, hearing/airway problems, cardiac anomaly, Apert’s syndrome
7. Missing teeth, impacted teeth, crowding (usually maxilla), class III growth pattern, caries, aesthetics (low lip line)

8. 3mths - lip closure
6-12mths - palate closure
8-10yrs - alveolar bone graft
12-15yrs - definitive ortho
18-20yrs - orthographic surgery ± aesthetic revision surgery

Question 22

Interceptive Ortho

1. Give 5 indications for interceptive ortho
2. When is the ideal time to extract 6s
3. How can anterior crossbones be treated interceptively
4. How can posterior crossbones be treated interceptively
5. Give 4 dental features of digit sucking habits
6. List 5 IO forces that can dislodge appliances

Answer 22

1. Impacted 6s, potential crowding, early loss of deciduous teeth, carious 6s, crossbites, transpositions, habits
2. Beginning of calcification of bifurcation of 7, 5s and 8s all present, class I, average/reduced OB, moderate lower crowding, mild-moderate upper crowding
3. URA with z-spring + FABP
4. URA with midline palatal screw + PBP
5. Proclined upper incisors, retroclined lower incisors, localised AOB/incomplete OB, narrowed upper arch ± unilateral posterior crossbite
6. Gravity, muscles (tongue), speech, mastication, active components

Question 23

URA

1. Describe the lab prescription for a URA
2. Give the definition of each section and give the appropriate wire diameter where appropriate
3. For the last section of the lab prescription, name the material that is used to make It and give 3 functions of this component
4. List 5 active components and what they would be used for

Answer 23

1. Aim
Active components
Retention
Anchorage
Baseplate

2. Active component - any component that uses forces to try to move teeth. 0.5mm HSSW
   Retention - resistance to displacement forces. 0.7mm HSSW
   Anchorage - resistance to unwanted tooth movement
   Baseplate
3. Self-cure PMMA. Connector, anchorage, retention through adhesion-cohesion
4. Palatal fingerspring (retract canines)
   Z-spring (correct anterior crossbite + FABP)
   Buccal canine retractor (retract and distalise canine)
   Roberts retractor (reduce OB and retrocline upper incisors + FABP)
   Midline screw (expand arch, correct crossbite + PBP)

Question 24

URA 2

1. List the key features to check when fitting a URA for the first time
2. List the key patient instructions when fitting a URA for the first time

Answer 24

1. Check it’s for right patient
   Check design of URA matches prescription
   Check for sharp areas
   Check for any pre-existing damage
   Try in and check for trauma/blanching
   Check posterior retention (Adams clasps – check for flush flyover and arrowhead engages undercuts)
   Check anterior retention
   Activate appliance for 1mm movement per month
   Demonstrate to patient how to get it in and out
   Get patient to demonstrate they can put it in and take it out
   Review every 4-6 weeks to reactivate for 1mm movement per month
2. URA is big and bulky, will get used to it
   Practice reading out loud for speech
   Excess salivation but only for first 24 hours
   Might be achy and mild discomfort – means it is working
   Avoid hard and sticky foods
   Be careful with hot foods and hot drinks
   Wear all the time
   Take out if doing contact/active sports
   Take out and clean after every meal
   Poorer compliance = longer treatment
   Emergency contacts – if something breaks off, get in touch

Question 25

Adult ortho 1. Give 3 indications for adult ortho 2. Give 5 key differences between adult and child ortho and describe the importance and relevance of these 3. Name 3 groups of aesthetic appliances

Answer 25

1. Improve dental appearance, adjunctive to restorative treatment, adjunctive to periodontal treatment, part of orthognathic surgery 2. Lack of growth (accept skeletal discrepancy or surgery required), presence of perio disease (reduce anchorage value of teeth if periodontally involved), missing/heavily restored teeth, physiological factors (reduced cell turnover, slower initial movement - light forces), adult motivation (often well motivated - may want aesthetic appliances) 3. Lingual appliances, aligner technology, short-term ortho