Questions and Answers
What is Class II Div 1 malocclusion?
Lower molar distally positioned relative to upper molar. Proclined upper incisors, increased OJ. Can be half cusp or full cusp.
What are the soft tissue characteristics of Class II malocclusion?
Retrognathic mandible and increased overjet. Common traits include a lip trap and lip incompetence.
What is the aetiology of Class II div 1?
Dental, skeletal, combination.
What are the dental causes of Class II malocclusion?
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What are the skeletal causes of Class II malocclusion?
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What can a combination of dental and skeletal issues cause?
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How does the lateral cephalometric angle indicate a Class II relationship?
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What are different jaw growth patterns?
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How do we diagnose Class II extraorally?
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How do we determine which jaw is at fault in a Class II profile?
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If Class II is due to mandibular retrognathism, what should we do with photos?
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Why do we need to assess CO-CR in patients with Class II?
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How do we see if there are transverse discrepancies in Class II patients?
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What is the usual transverse discrepancy for Class II patients?
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Should we correct Class II malocclusions in the deciduous dentition?
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Why should Class II patients during mixed dentition wear a mouthguard?
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When may we do treatment for Class II during mixed dentition?
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Study Notes
Class II Malocclusion Overview
- Class II Div 1 malocclusion characterized by lower molar positioned distally to upper molar, proclined upper incisors, and increased overjet.
- Can present as half cusp or full cusp relationships.
Soft Tissue Characteristics
- Features retrognathic mandible and increased overjet, leading to lip traps and upper lip curling.
- Classically presents with lip incompetence, where the lower lip rests on the palatal surface of upper incisors.
- Often associated with retroclination of lower incisors or proclination of upper incisors.
Aetiology of Class II Div 1
- Causes categorized into dental, skeletal, or a combination.
Dental Causes
- Early loss of primary teeth can lead to malocclusion.
- Tooth-arch discrepancies and pathological tooth loss contribute to the condition.
- Habits such as thumb sucking may exacerbate malocclusion.
Skeletal Causes
- Maxillary protrusion indicated by increased size and SNA value with normal mandibular relationship.
- Mandibular retrusion shows normal maxillary size (SNA) with decreased mandibular size.
- Combination cases can occur, leading to both dental and skeletal influences.
A Combination of Factors
- For example, the early loss of upper primary teeth results in mesial drift of maxillary first molars, creating a dental Class II malocclusion.
- Retrospective mandibular positioning may lead to a skeletal Class II facial pattern.
Lateral Cephalometric Analysis
- SNA assesses maxilla's position relative to cranial base.
- SNB reflects mandibular positioning, with an ANB angle of 4 or more indicating Class II relationship.
Jaw Growth Patterns
- Horizontal growth leads to deep bite while vertical growth can result in open bite.
- Neutral patterns correspond primarily to dental malocclusions.
Extraoral Diagnosis
- Diagnosis involves evaluating profile, facial type, nasolabial angle, and lip competence.
- Tissue type assessment is also crucial for a comprehensive evaluation.
Determining Jaw Fault
- Convex profiles indicate potential jaw issues; assess maxillary projection relative to a vertical line from the glabella.
- Profile photos used to analyze jaw positions further.
Profile Photo Assessment for Mandibular Retrognathism
- Patients asked to bite forward for profile photos to understand if mandibular advancement is necessary.
- Improvement in protrusion indicates the best treatment option; otherwise, evaluate the underlying aetiology.
Assessing CO-CR Discrepancy
- Class II patients with mandibular retrusion may exhibit a habit of biting forward.
- Severity of skeletal discrepancies often manifests in excessive overjet in habitual occlusion.
Detecting Transverse Discrepancies
- Patients instructed to bite in an edge-to-edge position to check for post crossbite.
- Correction may require maxillary expansion if included in treatment plans.
Typical Transverse Discrepancy
- Class II patients typically exhibit a 3-5mm transverse discrepancy between maxilla and mandible despite seemingly normal posterior dentition.
Treatment in Deciduous Dentition
- Early treatment during mixed dentition is generally not beneficial for preventing future Class II malocclusions.
- Appliance therapy is not recommended at this developmental stage, though discouraging digit sucking is advised.
Mouthguard Use
- Mouthguards are recommended for Class II patients during sports activities to protect protruded anterior teeth from injury.
Treatment Considerations During Mixed Dentition
- Timing for treatment during mixed dentition requires careful consideration based on specific patient conditions and growth patterns.
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Description
This quiz covers key concepts related to Class II malocclusions, including the characteristics and definitions of various types such as Class II Division 1. It will help you understand the implications of these dental misalignments and their impact on soft tissue. Suitable for dental students and professionals alike.
