Longitudinal evaluation of growth changes in Class II division 1 subjects

Area of Science:

• Orthodontics
• Craniofacial Growth
• Pediatric Dentistry

Background:

• Class II division 1 malocclusion is a common dental anomaly.
• Understanding its skeletal origins is crucial for early diagnosis and treatment.
• Previous studies have yielded varied results on the specific skeletal contributions.

Purpose of the Study:

• To compare skeletal growth patterns between Class II division 1 and Class I female subjects from age 7 to 14.
• To identify early indicators of Class II malocclusion.
• To determine the primary skeletal discrepancies contributing to Class II division 1 malocclusion.

Main Methods:

• Longitudinal data from the Ohio State University Growth Study.
• Tensor analysis for yearly growth rate and direction assessment.
• Comparison of cephalometric variables including cranial base, maxilla, mandible, and facial heights.

Main Results:

• No significant difference in cranial base dimensions between groups.
• Class II subjects exhibited a normal maxilla-cranial base relationship (S-N-A).
• Significantly retrusive mandible (S-N-B, S-N-Pog), shorter mandibular length (Ar-Gn, Go-Gn), and increased mandibular plane angle in Class II subjects.
• Reduced posterior to anterior facial height ratio (PFH/AFH) during puberty.
• Persistent maxillo-mandibular discrepancy (A-N-B) and increased convexity (A-N-Pg) from age 7 through puberty.

Conclusions:

• Class II division 1 malocclusion in females is primarily due to mandibular skeletal retrusion or combined horizontal/vertical mandibular abnormalities, not maxillary protrusion.
• These skeletal differences are detectable early (age 7) and persist through puberty.
• Early detection of mandibular skeletal discrepancies is possible, guiding timely orthodontic intervention.