Three-dimensional evaluation of stability after bimaxillary orthognathic surgery for skeletal class III malocclusion in patients with cleft lip and palate.

BACKGROUND

Using three-dimensional reconstruction technology, we evaluated postoperative jawbone stability in patients with cleft lip and palate and skeletal Class III malocclusion following bimaxillary surgery-maxillary advancement via LeFort I osteotomy and mandibular retraction via bilateral sagittal split osteotomy.

METHODS

Twenty patients with cleft lip and palate who underwent bimaxillary surgery due to maxillary hypoplasia were selected for the study. Computed tomography (CT) images were collected at preoperative (T0), immediate postoperative (T1), and postoperative follow-up (T2) time points. The spatial distances (A-C, A-F, A-S, B-C, B-F, B-S) of points A (subspinale) and B (supramental) from the baseline coronal (C), horizontal (F), and sagittal (S) planes, as well as the spatial angles of the angles SNA, SNB, and ANB, were measured in the three periods after three-dimensional reconstruction utilizing Mimics21 software. Compare the changes in the three periods.

RESULTS

1. All indicators from T0 to T1 showed statistically significant changes, P < 0.05.2. From T1 to T2, the average B-C increased by 2.25 mm, the average B-F decreased by 2.64 mm, the angle SNB increased by 1.25° on average, and the angle ANB decreased by 1.12° on average. All these changes were statistically significant (P < 0.05). However, the changes in the distance A-F, A-C, and the angle SNA were not statistically significant, P > 0.05.3. From T0 to T2, the average A-C increased by 3.16 mm, the average A-F increased by 1.81 mm, the average B-C decreased by 3.56 mm, the angle SNA increased by 2.77° on average, SNB decreased by 2.53° on average, and the angle ANB increased by 6.22° on average. All these changes were statistically significant (P < 0.05). The changes in A-S, B-F, and B-S were not statistically significant (P > 0.05).

CONCLUSION

Bimaxillary surgery is an effective method for correcting skeletal Class III malocclusion in patients with cleft lip and palate. The planned surgical movement of the mandible via bilateral sagittal split osteotomy (BSSO) with setback allows for compensatory reduction in the required maxillary advancement during LeFort I osteotomy. This approach may potentially reduce the extent of anteroposterior relapse in the maxilla.