Soft and hard tissue changes in Class III patients treated by bimaxillary surgery

Area of Science:

• Orthodontics and Dentofacial Orthopedics
• Surgical Orthodontics
• Cephalometric Analysis

Background:

• Class III malocclusion often requires complex treatment involving orthognathic surgery.
• Understanding the correlation between hard and soft tissue changes is crucial for predictable treatment outcomes.
• Bimaxillary surgery, involving both upper and lower jaw movements, is a common approach for severe Class III cases.

Purpose of the Study:

• To assess treatment outcomes in Class III patients undergoing bimaxillary surgery.
• To evaluate the correlation between hard tissue movements and resultant soft tissue changes.
• To identify reliable hard tissue predictors for soft tissue changes in bimaxillary surgery.

Main Methods:

• A cephalometric study was conducted on 17 non-growing, dentate Class III subjects.
• Measurements focused on hard tissue landmarks and corresponding soft tissue changes.
• Correlation analysis was performed in both horizontal and vertical dimensions.

Main Results:

• Orthognathic profiles were achieved through maxillary advancement and mandibular setback.
• Strong horizontal correlations were observed between lower lip, chin landmarks, and superior labial sulcus/Point A.
• Soft tissue to hard tissue movement ratios approached 1:1 for the lower lip and chin.
• Vertical correlations were strong in the lower lip and chin, but less so for nasal base and upper lip areas.

Conclusions:

• Bimaxillary surgery effectively corrects Class III profiles.
• Predictable soft tissue changes can be anticipated, particularly in the lower lip and chin.
• Hard tissue predictors are identified to aid in surgical planning for Class III bimaxillary surgery.