Differences in the stability of the lesser and greater maxillary segments after cleft orthognathic surgery: A retrospective study using 3D analysis.

The aim of this study was to determine whether significant differences in postoperative stability exist between the lesser and the greater maxillary segments after cleft orthognathic surgery in patients with and without residual alveolar cleft. A retrospective study of orthognathic patients with unilateral cleft was conducted. The patients were divided into two groups according to maxillary status before surgery, with group 1 comprising single-piece maxilla and group 2 comprising two-piece maxilla. Four maxillary points were used for intra- and intergroup comparisons of movements and relapses between the two maxillary segments. In total, 24 patients were included. The intragroup comparison showed significant differences in vertical relapses between lesser and greater segments in both group 1 (anterior, p = 0.004 and posterior, p = 0.01) and group 2 (posterior, p = 0.013). With regard to intergroup comparison, the lesser segments in the two groups differed in transverse movements (anterior, p = 0.048) and relapses (posterior; p = 0.04), while the greater segments differed in transverse movements (anterior, p = 0.014 and posterior, p = 0.019), with significant differences in relapses anteriorly (vertical, p = 0.031 and sagittal, p = 0.036) and posteriorly (transverse, p = 0.022). Maxillary changes following cleft orthognathic surgery showed significant differences between the lesser and the greater segments. These findings imply that 3D images should be used to assess each maxillary segment separately with regard to planning and outcome evaluation.

Are We Correctly Measuring Mandibular Stability After Surgery-First Approach? A Comparative Study Based on Novel 3-Dimensional Measurements.

Using traditional measures to assess mandibular stability after the surgery-first approach (SFA) may produce inaccurate results because unlike the conventional orthodontic-first approach (OFA), the main dental movements occur after surgery in SFA, which produce unavoidable mandibular movements, especially in cases with postsurgical premature dental contact. As these movements are part of the surgical-orthodontic plan, they should not be considered an actual relapse. In this study, to avoid postsurgical dental movement effects, the authors used the relationship between proximal and distal mandibular segments to evaluate stability after SFA. Four easily located points on computerized tomography/cone-beam computerized tomography reconstructed 3-dimensional images were used to calculate 4 measurements between proximal and distal mandibular segments across the osteotomy line in two matched groups of patients (SFA and OFA) at 3 different time points (before, immediately after, and 1 year after the surgery). A high level of skeletal stability was found in the SFA group, with changes 1 year after surgery not exceeding 0.5 mm. The SFA was as skeletally stable as OFA, and the mandibular counterclockwise rotation after surgery was related to the planned dental movements and not the instability of the surgery itself. To avoid the illusion of this preplanned relapse, stability should be measured as a relation between proximal and distal mandibular segments, across the osteotomy and fixation line, and not as a relation between maxillary and mandibular landmarks or between the mandible and facial planes as classically described.