Soft tissue changes after a mandibular osteotomy for symmetric skeletal class III malocclusion

Area of Science:

• Oral and Maxillofacial Surgery
• Orthodontics
• Plastic Surgery

Background:

• The soft tissue profile is a critical determinant of esthetic outcomes following orthognathic surgery.
• Skeletal class III malocclusion often necessitates surgical intervention like sagittal split ramus osteotomy (SSRO) to correct mandibular prognathism.

Purpose of the Study:

• To evaluate soft tissue profile changes in the subnasal and submental regions.
• To assess these changes more than one year after isolated sagittal split ramus osteotomy (SSRO).
• To analyze the correlation between hard and soft tissue movements and their impact on facial esthetics.

Main Methods:

• Lateral cephalograms were obtained from 22 patients with mandibular prognathism before and after isolated SSRO.
• Soft and hard tissue landmarks were analyzed to quantify positional changes.
• Specific facial angles (labiomenton, stomions, naso-labial) were measured and correlated with skeletal and soft tissue displacements.

Main Results:

• Subnasal and submental soft tissues showed significant posterior movement relative to hard tissues (85-96%).
• Soft tissue B point and chin movements closely mirrored hard tissue displacement (96-99%).
• Changes in labiomenton, stomions, and naso-labial angles were influenced by skeletal movement and soft tissue width.

Conclusions:

• Soft tissue changes following SSRO are substantial and vary depending on the specific facial region.
• Accurate prediction of esthetic results requires consideration of the complex interplay between hard and soft tissues.
• Naso-labial angle modifications can occur even with isolated mandibular surgery, highlighting the importance of comprehensive analysis.