Interceptive Orthodontics 2

Question 1

What should be assessed in anterior cross bites?

Answer 1

Displacement
Mobility of lower incisors
Tooth wear
Gingival recession

Question 2

What active component is used to correct an anterior open bite?

Answer 2

Z-spring (double cantilevered spring) 0.5mm HSSW

Question 3

How stable are cross bite corrections?

Answer 3

Anterior - may cause overbite
Posterior - 50% relapse

Question 4

Why should cross bites be treated early?

Answer 4

To maximise potential for spontaneous correction while there is still eruptive potential for incisors (8-10 years)
To prevent effects on skeletal development which could lead to permanent skeletal change if habit persists

Question 5

What teeth are commonly infra-occluded why?

Answer 5

In 10% of people
Lower more than upper
Possibly due to permanent absent successors

Question 6

Describe the aetiology of infra-occluding teeth

Answer 6

Ankylosis of primary tooth
Surrounding alveolar bone continues to grow
Primary tooth gets left behind

Question 7

How is an infra-occluding tooth diagnosed?

Answer 7

Percussion
Check for mobility
Radiographs (PA or OPT)

Question 8

What should radiographs be assessed for in infra-occluding teeth?

Answer 8

Presence/absence of successor
Ankylosis of primary tooth (no PDL space/no clear lamina dura)
Root resorption of primary

Question 9

What should you do with infra-occluding teeth if the permanent successor is present?

Answer 9

Monitor for 6-12 months
Extract if primary tooth is below the interproximal contact point
Consider extraction if root formation of successor is near completion
If extracted - maintain space - most important in upper arch

Question 10

What should you do with infra-occluding teeth if the permanent successor is present?

Answer 10

Monitor for 6-12 months
Extract if primary tooth is below the interproximal contact point
Consider extraction if root formation of successor is near completion
If extracted - maintain space - most important in upper arch

Question 11

What are the risks of doing nothing to an infra-occluded tooth?

Answer 11

Permanent successor can become more ectopic
Infra-occlusion worsens with tipping of adjacent teeth - primary tooth becomes inaccessible for extraction
Caries and periodontal disease

Question 12

What should you do with an infra-occluding tooth if the permanent successor is absent?

Answer 12

Tx plan depends on degree of crowding, degree of infra-occlusion and any other malocclusion features
Retain primary if in good condition and only extract if below interproximal contact point

Question 13

Describe normal development of upper canines

Answer 13

Development starts high and palatally
Migrates and lies labial and distal to the root apex of upper laterals
90% are palpable by 11 years
Mobile symmetry of Cs
Angulation of lateral incisors

Question 14

When should eruption of upper canines be assessed?

Answer 14

9-10 years onwards
Radiograph if unable to palpate by 11 years

Question 15

What are the consequences of ectopic maxillary canines?

Answer 15

Resorption of:
Central incisors in 15%
Lateral incisors up to 66.7%
Most root resorption occurs before age 13

Question 16

How are ectopic maxillary canines intercepted?

Answer 16

Extraction of the Cs

Question 17

When is extraction of Cs for ectopic maxillary canines most successful?

Answer 17

Patient aged 10-13
Canine is distal to the midline of the upper lateral
There is sufficient space available

Question 18

What are the risks of doing nothing for ectopic maxillary canines?

Answer 18

Permanent successor can become more ectopic
Permanent canine then fails to erupt
Risk of root resorption of canine crown
Risk of cyst formation around canine
Permanent canine can become ankylosed

Question 19

How should a reverse OJ be assessed?

Answer 19

Assess whether the patient can achieve an edge-edge relationship
Assess if the mandible displaces on closing

Question 20

What are the interceptive treatment options for a class III occlusion?

Answer 20

Growth modification:
Enhance maxillary growth and/or reduce mandibular growth - protraction headgear and possible rapid maxillary expansion or functional appliances such as reverse twin block

Or camouflage with URA

Question 21

When is growth modification in class III occlusion most successful?

Answer 21

Skeletal I or only mild class III
Maxillary retrusion
Anterior displacement on closing
Average or reduced lower face height
Patient 8-10 years

Question 22

When is growth modification in class III occlusion most successful?

Answer 22

Skeletal I or only mild class III
Maxillary retrusion
Anterior displacement on closing
Average or reduced lower face height
Patient 8-10 years

Question 23

When does a patient need to wear protraction headgear?

Answer 23

14+ hours a day

Question 24

When is bone anchored maxillary protraction used and what is the success rate?

Answer 24

Bollard Implants
Used in the late mixed dentition
90% success rate

Question 25

What is the success rate of protractions headgear?

Answer 25

70%

Question 26

Why should an increased OJ be treated early?

Answer 26

Risk of trauma - incompetent lips
Appearance
More difficult to achieve correction once patient has stopped growing

Question 27

What are the different IOTN scores for increased OJs?

Answer 27

> 6mm = 4a - need for treatment
9mm = 5a - high need for treatment

Question 28

What are the interceptive treatment options for a class II occlusion?

Answer 28

Growth modification - functional appliances and headgear to restrain maxillary growth and promote mandibular growth