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Soft-tissue thickness changes following bimaxillary surgery in skeletal class II malocclusion
Hao Chen1,2, Dirk-Melle Beek3, Frank Baan4
1Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, Guangdong Engineering Research Center of Oral Restoration and Reconstruction, Guangzhou Key Laboratory of Basic and Applied Research of Oral Regenerative Medicine, Guangzhou Medical University, Huangsha Avenue 39, Liwan District, Guangzhou, Guangdong, 510150, China.
Bimaxillary surgery in Class II patients causes significant soft-tissue thinning, especially in the lower lip. This thinning should be considered during surgical planning and patient communication for better outcomes.
Area of Science:
- Orthognathic Surgery
- Craniofacial Anatomy
- Radiographic Analysis
Background:
- Bimaxillary surgery is a common treatment for skeletal Class II malocclusion.
- Understanding soft-tissue changes is crucial for predicting aesthetic outcomes.
- Limited data exists on region-specific soft-tissue thickness changes after bimaxillary advancement.
Purpose of the Study:
- To evaluate regional facial soft-tissue thickness changes after bimaxillary surgery in skeletal Class II patients.
- To assess the association between these changes, skeletal movement, and patient-related factors.
Main Methods:
- Retrospective cohort study of 89 skeletal Class II patients undergoing bimaxillary advancement without genioplasty.
- Voxel-based superimposition of preoperative and postoperative CBCT scans (16.7 ± 5.3 months post-op).
- Measurement of skeletal displacement and overlying soft-tissue thickness at key facial landmarks (A, Sd, Id, B, Pog, Me).
Main Results:
- Significant soft-tissue thinning observed at A, Id, B, and Pog.
- No significant changes in soft-tissue thickness at Sd and Me.
- Thinning at A and Id correlated with greater sagittal advancement (r = -0.650, p<0.001; r = -0.338, p=0.001).
- Downward vertical movement at B was associated with less thinning (r = 0.240, p=0.023).
- Thickness changes were not associated with age, sex, or CBCT interval.
Conclusions:
- Bimaxillary surgery in Class II patients without genioplasty leads to region-specific soft-tissue thinning, notably affecting the lower lip.
- Postoperative soft-tissue thinning is a critical factor to consider in surgical planning and patient consultations.
