Questions and Answers
What is the definition of Class II division 1 malocclusions?
The lower incisor edges lie posterior to the cingulum plateau of the upper incisors.
What is always present in Class II division 1 malocclusions?
Increased overjet.
What is the prevalence of Class II division 1 malocclusions?
15 - 20%.
What are the four aetiological factors of Class II division 1 malocclusions?
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What is the skeletal pattern (anthro-posterior relationship) of Class II division 1 malocclusions?
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What is the Skeletal pattern (vertical relationship) of Class II division 1 malocclusions?
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What is the main dental factor for Class II division 1 malocclusions?
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How does crowding lead to Class II division 1 malocclusions?
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What are the dental features of Class II division 1 malocclusions?
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What position do teeth normally lie in?
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How does the lower lip affect the eruption of upper teeth?
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What are the reasons for the lower lip being unable to control the eruption of upper teeth?
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How does the muscular tone of the lip affect the eruption of upper teeth?
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What is the thumb-sucking habit that causes Class II division 1 malocclusions?
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Why are Class II division 1 malocclusions treated?
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What are the treatment options for Class II division 1 malocclusions?
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What must you do when accepting a Class II division 1 malocclusion?
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What is the purpose of headgear?
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What is orthognathic treatment?
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Who are the best candidates for growth modification?
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What two changes do functional appliances cause?
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What are the properties of the dental changes caused by functional appliances?
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What are the properties of the skeletal changes caused by functional appliances?
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Study Notes
Class II Division 1 Malocclusions
- Class II division 1 malocclusions defined by lower incisor edges being posterior to the cingulum plateau of upper incisors.
- Prevalence of Class II division 1 malocclusions ranges from 15% to 20% of the population.
Key Characteristics
- Increased overjet is a consistent feature; upper incisors may be proclined or average in inclination.
- Malocclusion can be caused by skeletal, dental, soft tissue factors, and habits.
Aetiological Factors
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Skeletal Factors:
- Predominantly skeletal Class II, often associated with retrognathic mandible (80% of cases).
- Mild cases may present as skeletal Class I.
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Dental Factors:
- Crowding is the primary dental issue; can lead to labial positioning of upper incisors.
- Features include increased overjet, buccal occlusion class II, variations in overbite, and potential spacing due to non-crowding.
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Soft Tissue Factors:
- The lower lip influences upper incisor position through its resting position.
- Incompetent lips due to increased vertical dimension can exacerbate proclination of upper incisors.
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Habits:
- Thumb sucking leads to proclination of upper teeth and retroclination of lower incisors, further increasing overjet and potentially causing open bite.
Treatment Considerations
- Treatment is indicated for aesthetics, increased trauma risk (overjet greater than 9 mm), and psychological well-being.
- Options include acceptance (for mild cases), growth modification, headgear, camouflage, or orthognathic surgery.
Growth Modification
- Functional appliances utilize forces from oral musculature to enact dental and skeletal changes—commonly includes removable and fixed types.
- Best candidates for growth modification are well-motivated, actively growing with moderate to severe anterior-posterior discrepancies.
Functional Appliance Properties
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Dental Changes:
- 70% of changes noted include the retroclination of upper incisors and proclination of lower incisors, effectively removing Class II relationship.
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Skeletal Changes:
- Approximately 30% of changes observed, including some mandibular growth and minimal restraint on maxillary growth.
Key Functional Appliances
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Twin Block Appliance:
- Composed of two sections, provides forward jaw posturing and can expand the upper arch.
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Headgear:
- Applied force to restrict maxillary growth while allowing mandibular catch-up growth; typically required for 14 hours a day.
Camouflage Treatment
- Established when treating mild to moderate skeletal Class II patterns by working around the underlying Class II relationship, which may involve extractions.
Orthognathic Treatment
- Involves jaw surgery in conjunction with fixed appliances, primarily used for adults with completed growth, severe skeletal discrepancies, or poor facial aesthetics.
Conclusion
- Class II division 1 malocclusions showcase a range of dental, skeletal, and soft tissue characteristics, requiring careful evaluation for appropriate treatment planning.
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Description
Explore the characteristics and aetiological factors of Class II Division 1 malocclusions. This quiz covers skeletal, dental, and soft tissue influences, as well as prevalence rates in the population. Test your knowledge on this common dental issue.
