Orthodontic Assessment

Question 1

Why is orthodontic assessment carried out?

Answer 1

To determine if any malocclusion is present
Identify underlying causes to these
Decide if treatment is indicated

Question 2

When is orthodontic assessment carried out?

Answer 2

Brief examination often at 9
Comprehensive examination when premolars and canines erupt 11-12
When older patients first present
If a malocclusion develops later in life

Question 3

What is the ideal occlusion?

Answer 3

Gold standard by which occlusal irregularities and treatment may be judged
Rarely found naturally

Question 4

What are Andrews 6 keys?

Answer 4

I - Molar relationship
II - Crown angulation
III - Crown inclination
IV - No rotations
V - No spaces
VI - Flat occlusal planes

Question 5

Describe the molar relationship in ideal occlusion

Answer 5

The distal surface of the disto-buccal cusp of the upper first permanent molar occludes with the mesial surface of the mesio-buccal cusp of the lower second permanent molar

Question 6

Describe a normal occlusion

Answer 6

More common than ideal occlusion
Have minor deviations that aren’t an aesthetic or functional problem
May requires treatment, but patient factors may influence decision

Question 7

Give examples of conditions that are a contra-indication to orthodontic treatment

Answer 7

Allergy - Ni or Latex - rarely a problem
Epilepsy
Drugs causing gingival hyperplasia and inflammation
Imaging - cannot have if getting MRI etc

Question 8

What habits can influence tooth position?

Answer 8

Thumb sucking
Lower lip sucking
Tongue thrust
Chewing finger nails

Question 9

What should be checked in an extra-oral examination?

Answer 9

Skeletal bases
Soft tissues
TMJ

Question 10

Why should the patient be compared to the parent?

Answer 10

For malocclusions and growth potential
Especially in class III malocclusion

Question 11

Why are skeletal bases important?

Answer 11

Slight movement in skeletal bases can result in malocclusion

Question 12

How do you clinically assess APs

Answer 12

Visual assessment
Palpate skeletal bases

Question 13

Describe a Class I occlusion in AP skeletal assessment

Answer 13

Maxilla 2-3mm in front of mandible

Question 14

Describe a class II occlusion in AP skeletal assessment

Answer 14

Maxilla more than 3mm in front of mandible

Question 15

Describe a class III occlusion in AP skeletal assessment

Answer 15

Mandible in front of maxilla

Question 16

Describe an average vertical skeletal assessment

Answer 16

Frankfort and mandibular planes meet at the back of the head

Question 17

How may vertical assessment conclude?

Answer 17

Average
Increased FMPA angle
Reduced FMPA angle
(Frankfort - Mandibular Plane Angle)

Question 18

How is lateral skeletal assessment carried out?

Answer 18

Mid sagittal reference line

Question 19

How may soft tissues influence tooth position?

Answer 19

Lips - competent/incompetent, lower lip level, lower lip activity
Tongue - position, habitual and swallowing
Habits - thumb, digit sucking
Speech - lisping

Question 20

What are competent lips?

Answer 20

Lips that meet at rest with a relaxed mentalis muscle

Question 21

What does a lip trap do

Answer 21

May procline upper incisors
May lead to relapse of overjet if persists at the end of treatment

Question 22

Describe a hyperactive lower lip

Answer 22

May retrocline lower incisors
INdicates likely instability at end of treatment

Question 23

How can tongue position affect swallowing?

Answer 23

Tongue thrust on swallowing can be associated with an anterior open bite
Can be endogenous or adaptive
May cause repulse of AOB at the end of treatment if endogenous

Question 24

What are the occlusal features of a sucking habit?

Answer 24

Proclined ion of upper anteriors
Retroclination of lower anteriors
Localised AOB or incomplete OB
Narrow upper arch may lead to a unilateral posterior crossbite

Question 25

What should be checked for in TMJ examination?

Answer 25

Mandibular displacement Discrepancy in RCP and ICP

Question 26

What should be checked in an intra-oral examination?

Answer 26

Oral hygiene and periodontal health Count the teeth from the back Teeth of poor prognosis Assess crowding/spacing/rotations Assess inclination and angulation Palpate for canines if not erupted Note teeth of abnormal shape/size

Question 27

What are the main checks of an intra-oral examination?

Answer 27

Teeth present Oral hygiene Quality of teeth

Question 28

What should be checked in the lower arch?

Answer 28

Degree of crowding Presence of rotations Inclination of canines - mesial, upright, distal Angulation of incisors to mandibular plane - upright, proclined, retroclined

Question 29

What should be checked in the upper arch?

Answer 29

Degree of crowding Presence of rotations Inclination of canines - mesial, upright, distal Angulation of incisors to Frankfort plane - upright, proclined, retroclined

Question 30

Describe the normal angulation of incisors to Frankfort plane

Answer 30

Frankfort plane to long axis of upper incisor is about 110º

Question 31

What should be checked while teeth are in occlusion?

Answer 31

Incisor relationship Overjet Overbite/open bite Molar relationship Canine relationship Cross bites Centre lines

Question 32

What are the different classes of incisor relationship?

Answer 32

Class I Class II div 1 Class II div 2 Class III Overjet, overbite, centrelines

Question 33

What is incisor relationship class I?

Answer 33

The lower incisor edges occlude with or lie immediately below the cingulum plateau of the upper central incisors

Question 34

What is incisor relationship class II?

Answer 34

The lower incisors edges lie posterior to the cingulum plateau of the upper incisors

Question 35

What is incisor relationship class II div 1?

Answer 35

The upper incisors are proclined or of average inclination and there is an increase in overjet

Question 36

What is incisor relationship class II div 2?

Answer 36

The upper central incisors are retroclined The overjet is usually minimal or may be increased

Question 37

What is incisor relationship class III?

Answer 37

The lower incisor edges lie anterior to the cingulum plateau of the upper incisors The overjet is reduced or reversed

Question 38

What radiographs are commonly taken in orthodontic assessment?

Answer 38

OPT Maxillary anterior occlusal Lateral cephalogram

Question 39

What other special investigations may be taken?

Answer 39

Vitality tests Study models Photographs