Sagittal lip positions in different skeletal malocclusions: a cephalometric analysis

Area of Science:

• Orthodontics
• Cephalometrics
• Facial analysis

Background:

• Soft tissue analysis is crucial for establishing cephalometric norms.
• Previous studies have not focused on sagittal lip position in the Northeast Chinese adult population.

Purpose of the Study:

• To establish soft tissue cephalometric norms for sagittal lip position in Northeast Chinese adults.
• To compare lip positions across different skeletal malocclusions.
• To compare Northeast Chinese lip positions with other populations.

Main Methods:

• Lateral cephalometric radiographs were analyzed using five established reference lines (Steiner, Ricketts, Burstone, Sushner, Holdway).
• Linear distances between lip tips and reference lines were measured.
• Statistical analysis included descriptive statistics, coefficient of variation, and Tukey's post hoc test.

Main Results:

• Significant differences in sagittal lip positions were observed among skeletal malocclusions.
• The S2 line was most consistent for skeletal classes I and II; the B line for skeletal class III.
• Northeast Chinese adults exhibited more protrusive upper and lower lips compared to skeletal class I and III, and retrusive upper lips and protrusive lower lips in skeletal class III compared to skeletal class I and II.

Conclusions:

• Sagittal lip position is associated with skeletal malocclusion patterns.
• The Northeast Chinese population presents with protrusive lips compared to Caucasians.
• Optimal reference lines for sagittal lip analysis vary by skeletal malocclusion.