Class III Malocclusion Flashcards

Questions and Answers

What are the components in a class III malocclusion?

Skeletal pattern

Incisal relationship

Molar relationship

All of the above (correct)

What is the skeletal pattern of a class III malocclusion?

Mandible is protruded/in line in relation to the maxilla.

What is the technique used to diagnose skeletal patterns?

Bimanual palpation technique.

What is the definition of a class III incisal relationship?

The lower incisal edge meets anterior to the cingulum plateau of the palatal surface of the upper incisors. Signup and view all the answers

What is the definition of a class III molar relationship?

The mesio-buccal cusp of the upper first molar lies distal to the mesiobuccal groove of the lower molar. Signup and view all the answers

What is the aetiology of a class III malocclusion?

Skeletal, soft tissue, dentoalveolar, and other factors. Signup and view all the answers

What are the skeletal factors that cause a class III malocclusion?

Retrusive maxilla and protrusive mandible. Signup and view all the answers

What are the soft tissue factors that cause a class III malocclusion?

Soft tissues do not play a primary role but may act as a compensatory factor in dentition. Signup and view all the answers

What are the dento-alveolar factors that cause a class III malocclusion?

Fewer teeth in the maxillary arch, narrow upper arch, broad lower arch, and possible pseudo class III. Signup and view all the answers

What are the main other factors that cause a class III malocclusion?

Genetics and syndromes of the head and neck. Signup and view all the answers

What are the components needed in diagnosing a class III patient?

Thorough history, extraoral, intraoral, and radiographs. Signup and view all the answers

What are the important factors when recording history when diagnosing a class III patient?

Significant skeletal discrepancies, family history, and history of surgical correction. Signup and view all the answers

What are the three hard tissue factors that need to be assessed?

Antero-posterior, vertical, and transverse. Signup and view all the answers

What is used to assess the antero-posterior skeletal relationship?

Bi-manual palpation. Signup and view all the answers

What is used to assess the vertical skeletal relationship?

Profile and frontal view assessments. Signup and view all the answers

What is used to assess the transverse skeletal relationship?

View from above and behind. Signup and view all the answers

What are the two components that need to be examined in intra-oral examination?

Intra-arch and inter-arch. Signup and view all the answers

What is intra-arch assessment?

Estimation of the degree of crowding or spacing within each arch. Signup and view all the answers

What is inter-arch assessment?

Examination of incisor relationship, overjet, overbite, centrelines, molar relationship, crossbites and displacements. Signup and view all the answers

What are the intra-oral features of class III malocclusion?

Class III incisal relationship, overjet, overbite, shifted centrelines, class III molar relationship, crossbites, and displacements. Signup and view all the answers

How to measure displacement?

By asking the patient to bite edge to edge and measuring the reverse overjet and centrelines after displacement. Signup and view all the answers

Why must displacements be treated?

To prevent incisal wear, attrition at sites of premature contact, TMJ disorders, and strain on periodontal attachments. Signup and view all the answers

What are the radiographs used for diagnosis of a class III malocclusion?

Orthopantomogram (OPG), Lateral Cephalogram, and possibly upper standard occlusal. Signup and view all the answers

What are the indications for treatment of a class III malocclusion?

Cross-bite, expected future growth pattern, aesthetics, and reported functional problems. Signup and view all the answers

What are the components in the assessment before treatment in class III malocclusion?

Age, patient concern, treatment difficulty, and amount of dento-alveolar compensation. Signup and view all the answers

What are the treatment options for class III malocclusion?

Interceptive treatment Signup and view all the answers

What treatment can be provided to early treatment timing?

Interceptive treatment. Signup and view all the answers

What are the indications for interceptive treatment?

Anterior crossbite, posterior crossbite with displacement, risk of trauma, or dehiscence. Signup and view all the answers

What are the problems with early interceptive treatment?

Poor stability, poor compliance, and negatively affecting growth. Signup and view all the answers

What are the components in the URA?

Active component (T-spring), retention (Adams clasps and C-clasp), baseplate (with posterior capping), and anchorage. Signup and view all the answers

When can camouflage be used for treating class III malocclusion?

In a patient with mild to moderate skeletal III pattern and a good overbite. Signup and view all the answers

What are the techniques for dental camouflage?

Using upper and lower fixed appliances, extractions, and possibly upper arch expansion. Signup and view all the answers

What treatment do late treatment timing patients need?

Orthognathic surgery and possibly camouflage. Signup and view all the answers

When is orthognathic surgery indicated?

When facial profile is a concern. Signup and view all the answers

Can you start camouflage and then go for surgery?

False Signup and view all the answers

Study Notes

Class III Malocclusion Overview

Class III malocclusion is characterized by a skeletal pattern where the mandible is positioned forward relative to the maxilla.
Patients often exhibit a reduced overjet and an incisal relationship where the lower incisors meet anterior to the palatal cingulum of the upper incisors.

Components of Class III Malocclusion

Skeletal Factors: Includes a retrusive maxilla, protrusive mandible, or a combination of both.
Incisal Relationship: Lower incisal edges are positioned ahead of the upper incisors leading to a reverse overjet.
Molar Relationship: Mesio-buccal cusp of the upper first molar is located distal to the lower molar's mesiobuccal groove.

Diagnostic Techniques

Bimanual Palpation: A technique for establishing skeletal patterns by placing fingers in the concavities of the maxilla and mandible, assessing relative positioning of points A and B.

Aetiology of Class III Malocclusion

Involves skeletal, soft tissue, dentoalveolar, and genetic components affecting the dental structure and overall morphology.
Skeletal Factors: Often include a combination of a hypoplastic maxilla and a prognathic mandible.
Dentoalveolar Factors: Can manifest as fewer teeth in maxillary arches, narrow upper arches, bilateral crossbites, and uneven tooth positioning affecting occlusion.

Radiographic Diagnosis

Essential radiographs include Orthopantomogram (OPG), lateral cephalogram, and optionally upper standard occlusal views.

Treatment Considerations

Different timing in treatments:
- Early Treatment: Often involves interceptive approaches before significant skeletal growth causes further complications.
- Intermediate Treatment: Focuses on growth modification when the patient is still growing but may require different strategies than camouflage.
- Late Treatment: Involves orthognathic surgery and fixed appliances, with camouflage usually not viable.

Treatment Options

May include jaw repositioning techniques, dental camouflage using fixed appliances, or orthognathic surgery for severe cases.
Common soft tissue compensations can include proclining and retroclining adjacent teeth to adjust the bite without changing skeletal relationships.

Intraoral Examination Features

Key assessments include incisor relationships, overjet, overbite, centrelines, molar relationships, and displacement monitoring.
Clinical observation can identify potential crossbites and disruptions in occlusal harmony.

Indications for Treatment

Presence of significant skeletal discrepancies, aesthetic concerns, functional problems, and potential growth dynamics may indicate the need for treatment.
Awareness of patient’s history and concerns regarding aesthetics and functionality is crucial in planning.

Interceptive Treatments

Active Removable Appliances (URA): Focus on correcting crossbites, managing overcrowding, or addressing incisor positioning while the patient is still growing.
Can lead to significant improvements and stability in occlusion if done at the appropriate growth stage.

Orthognathic Surgery

Typically indicated for patients with pronounced skeletal discrepancies who are no longer growing.
Procedures can dramatically change facial profiles and improve life quality by allowing for more functional occlusion.

Prognosis

Good prognosis for stability if the upper and lower teeth can be aligned properly with careful treatment timing and monitoring.
Early intervention often leads to improved long-term outcomes with less risk of requiring more extensive surgeries later on.

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Description

Test your knowledge on Class III malocclusion with these flashcards. Each card covers essential components such as skeletal patterns, incisal relationships, and the bimanual palpation technique. Perfect for dental students wanting to sharpen their understanding of orthodontics.