Class III Malocclusion Flashcards

Questions and Answers

What is the definition of Class III malocclusion?

The lower incisor edge occludes anterior to the cingulum plateau of the upper incisors.

How common is Class III malocclusion in Caucasians?

3% of Caucasians

What are the features of Class III malocclusion?

Skeletal features, soft tissue features, occlusal and dento-alveolar features, facial growth factors.

What skeletal class is usually associated with skeletal features?

Usually Class III Signup and view all the answers

What happens to the size of the maxilla and mandible in Class III malocclusion?

Large mandible or small maxilla, or a combination of both. Signup and view all the answers

Is the anterior cranial base short or long in individuals with Class III malocclusion?

Short Signup and view all the answers

What are the lateral skeletal features in Class III malocclusion?

Narrow upper arch and broad lower arch. Signup and view all the answers

What are the consequences of having a narrow upper arch and broad lower arch?

Crossbites. Signup and view all the answers

What do soft tissues tend to do to compensate for skeletal relationships in Class III?

Tip teeth. Signup and view all the answers

Why do anterior crossbites occur in individuals with Class III malocclusion?

Because of Class III incisors. Signup and view all the answers

What causes posterior crossbites in Class III malocclusion?

Narrow upper arch and broad lower arch. Signup and view all the answers

With a Class III condition, what does the anterior and posterior crossbite indicate?

Mandibular displacement. Signup and view all the answers

Where may wear occur due to Class III malocclusion?

On labial surfaces of upper incisors. Signup and view all the answers

Where may gingival recession occur in Class III malocclusion?

On lower incisors. Signup and view all the answers

What areas may experience crowding or spacing in Class III malocclusion?

Narrow upper arch - Crowding; Broad lower arch - Aligned/Spaced. Signup and view all the answers

On average, how much more do individuals with Class III malocclusion grow and at what age?

2 mm more from age 11 to the end of growth. Signup and view all the answers

Is the growth in Class III malocclusion favorable compared to Class II?

Favorable in Class II and unfavorable in Class III. Signup and view all the answers

Can adverse growth in Class III be compensated for compared to Class II?

Less compensation due to more bone behind the upper incisors. Signup and view all the answers

Should you be pessimistic about future growth in Class III?

Yes, you can't predict it. Signup and view all the answers

When do we usually treat Class III malocclusion?

Later rather than early. Signup and view all the answers

What is an exception to the treatment timing for Class III?

Mild Class III with a mandibular displacement. Signup and view all the answers

Why should mild Class III with mandibular displacement be treated early?

To avoid damage to teeth and the periodontium. Signup and view all the answers

What are the three categories of treatment for Class III?

Mild class III - procline upper incisors; Moderate class III - procline uppers and retrocline lowers; Marked - combined orthodontics and orthognathic jaw surgery. Signup and view all the answers

What are favorable features for predicting successful correction of Class III?

Mild Class III, forward mandibular displacement, little or no dento-alveolar compensation, normal or increased overbite. Signup and view all the answers

Why is forward mandibular displacement favorable in treatment?

Some correction can come from the condyles dropping back into the fossae. Signup and view all the answers

When should treatment for moderate Class III start and how does the appliance move the teeth?

Later; via bodily movement. Signup and view all the answers

When should treatment for marked skeletal Class III start and why?

When growth has stopped; we want to prevent later growth from undoing treatment. Signup and view all the answers

Study Notes

Class III Malocclusion Overview

Defined by lower incisor edge occluding anterior to upper incisors' cingulum plateau.
Approximately 3% prevalence in Caucasians.

Features of Class III Malocclusion

Includes skeletal, soft tissue, occlusal, and dento-alveolar features.
Influenced by facial growth factors.

Skeletal Features

Often categorized as class III skeletal pattern.
Characterized by a large mandible or small maxilla or a combination.
Short anterior cranial base is common.

Lateral Skeletal Features

Upper arch tends to be narrow due to size limitations.
Lower arch is broad as it generally maintains larger dimensions.
Consequences include the presence of crossbites.

Dento-Alveolar Compensation

Soft tissues adapt by tipping teeth to adjust for skeletal relationships.
Upper incisors become proclined while lower incisors are retroclined.

Crossbite Tendencies

Anterior crossbites arise due to class III incisor relationships.
Posterior crossbites occur from narrow upper arches opposing broad lower arches.

Mandibular Displacement

Anterior and posterior crossbites are associated with forward mandibular displacement from edge-to-edge occlusion.

Wear and Recession

Labial surfaces of upper incisors may experience wear.
Gingival recession can occur on lower incisors.

Crowding and Spacing

Narrow upper arches often lead to crowding.
Broad lower arches may be aligned or spaced.

Facial Growth Patterns

Individuals with skeletal class III grow about 2 mm more on average from ages 11 until the end of growth.
Growth is considered favorable in class II but unfavorable in class III.

Compensation for Adverse Growth

Less compensation possible for adverse growth in class III compared to class II due to skeletal structure limitations.

Treatment Timing and Prognosis

Pessimism about future growth is warranted; treatment is usually postponed, with exceptions for mild cases with mandibular displacement.
Treatment of mild class III early can prevent dental and periodontal damage and is relatively quick.

Treatment Categories

Mild Class III: Procline upper incisors, typically using a removable appliance (URA).
Moderate Class III: Procline uppers and retrocline lowers using fixed appliances (FAs).
Marked Class III: Combines orthodontic treatment with orthognathic surgery.

Predictive Features for Successful Correction

Mild class III with forward mandibular displacement is more favorable.
Low or no dento-alveolar compensation may lead to instability post-treatment, whereas normal/increased overbite promotes stability.

Favorable Positions for Correction

Forward mandibular displacement allows some correction through condyle repositioning.
Slightly more edge-edge starting positions facilitate simpler corrections.

Treatment Considerations for Moderate Class III

Treatment should begin later, focusing on bodily tooth movement with fixed appliances.

Marked Skeletal Class III Treatment

Surgical treatment starts when growth has ceased to prevent changes from later growth.
Patient dissatisfaction with both dental and facial aesthetics is a significant factor in initiating treatment.

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Description

This quiz focuses on the essential definitions and features of Class III malocclusion. It includes key skeletal characteristics, prevalence in different populations, and other relevant clinical details. Perfect for dental students and professionals looking to enhance their understanding of orthodontic classifications.