class III

Question 1

What is the BSI definition of Class III malocclusion

Answer 1

Lower incisor edge occludes anterior to the cingulum plateau of the upper incisors
The overjet is reduced or reversed

Question 2

What is the incidence of Class III malocclusion?

Answer 2

3-7% in the UK
Higher incidence in Asia

Question 3

Describe the AP skeletal aetiology of Class III malocclusion

Answer 3

It could be due to a small maxilla, large mandible (most common), or a combination of both

Question 4

What are the dental features of Class III malocclusion?

Answer 4

Class III incisor relationship
Class III molar relationship (not always)
Tendency to reverse overjet
Reduced overbite
Cross bites

Question 5

Why is it important to treat a Class III malocclusion?

Answer 5

For aesthetics
Dental health reasons eg - attrition, gingival recession, mandibular displacement
Function eg - speech and mastication

Question 6

What factors increase the difficulty in treating Class III malocclusion?

Answer 6

Larger number of teeth in anterior crossbite
Skeletal element in aetiology
Greater AP discrepancy
Presence of an AOB

Question 7

What are the management options for Class III malocclusion?

Answer 7

Accept/monitor
Intercept early with URA
Growth modification
Camouflage
Combined orthognathic/orthodontic treatment

Question 8

When is interceptive treatment suitable for Class III malocclusion?

Answer 8

If class III incisors have developed due to early contact on permanent incisors, or for correcting a lateral incisor crossbite if permanent canines are high above lateral roots

Question 9

What is the purpose of a chin cup in orthodontics?

Answer 9

A functional appliance used to tip the lower incisors lingually and rotate the mandible down and back.
Not used anymore

Question 10

Explain the use of protraction headgear in orthodontics

Answer 10

Protracts the maxilla and corrects class III malocclusion
It requires a cooperative patient to wear the headgear for approximately 14 hours a day.
Most effective when used in early mixed dentition and may be combined with rapid maxillary expansion

Question 11

What are Bollard implants used for in orthodontics?

Answer 11

Used in late mixed and permanent dentition to provide anchorage for orthodontic treatment
They are inserted in the infrazygomatic crest and lower canine region
Mucoperiosteal flaps need to be raised for their insertion and removal

Question 12

Define orthodontic camouflage

Answer 12

An approach in orthodontics where the underlying skeletal base relationship is accepted, and the focus is on moving the teeth to achieve a class I incisor relationship

Question 13

When is orthodontic camouflage a good treatment option in a class III?

Answer 13

It is suitable for patients with mild to moderate class III skeletal base, average or increased overbite, and little or no dentoalveolar compensation

Question 14

What is the extraction pattern for camouflage in orthodontics?

Answer 14

Extracting further back in the upper arch and further forward in the lower arch
The classic pattern is to extract the upper 5s and lower 4s, but the extraction pattern may vary based on dental health and individual patient need

Question 15

Describe the aims of camouflage in orthodontics

Answer 15

Procline the upper incisors
Retrocline the lower incisors
Correct the overjet

Question 16

What are the warnings of camouflage as a treatment option?

Answer 16

It is important not to fully correct the malocclusion if the patient is still growing
Lower arch extraction are generally avoided to preserve future treatment options

Question 17

What is orthognathic surgery in orthodontics?

Answer 17

A surgical procedure that involves the manipulation of the mandible and/or maxilla to achieve optimal dentofacial aesthetics and function
Typically performed on patients who have aesthetic or functional concerns, and their growth is completed
The surgery can address moderate to severe skeletal discrepancies

Question 18

Who are the members of the multidisciplinary team involved in orthognathic surgery?

Answer 18

Orthodontist
Maxillofacial surgeon
Technician
Psychologist

Question 19

What are the typical timeframes for orthognathic treatment?

Answer 19

Presurgical orthodontics (approximately 18 months) to level, align, coordinate, and decompensate the teeth
Orthognathic surgery to reposition the jaws, either the mandible alone or both the mandible and maxilla
Post-surgical orthodontics (approximately 6 months) is performed to fine-tune the occlusion and achieve optimal results

Question 20

What alignment of teeth is often seen in class III?

Answer 20

Maxilla often crowded
Mandible often aligned or spaced

Question 21

What dentoalveolar compensation is commonly seen in class III?

Answer 21

Proclined upper incisors
Retroclined lower incisors

Question 22

Describe the soft tissue aetiology of a class III

Answer 22

Soft tissue not usually involved in aetiology
Tongue proclines the upper incisors
Lower lip retroclines the lower incisors

Question 23

What is a GDP’s role in a class III malocclusion?

Answer 23

Identify class III malocclusion
Refer to hospital service or specialist practitioner
URA treatment - anterior crossbite correction