# Condylar Changes Following Mandibular Setback Using Manual Guidance
## 4 Discussion
Similarly, our study found that patients with mandibular asymmetry (more than a 3 mm difference between the right and left setback amount) showed significant anterior movement between T0 and T1 (\(p=0.003\): Table 3). However, there was no significant difference during follow-up (\(p>0.05\): Table 3). Interestingly, when comparing the preoperative condylar position, mandibular asymmetry did not appear to have an impact on the condylar position at 6 months postoperatively (\(p>0.05\): Table 3). In contrast, [PERSON] et al. [33] observed a posterior-lateral-inferior displacement of the condyle after SSRO in patientswith asymmetry and mandibular pragnathism. They reported significant differences in the condylar position along all three axes when comparing results preoperatively and one week postoperatively, as well as one week and seven months postoperatively. The duration of time required for recovery to the preoperative condylar position after orthognathic surgery has varied in previous studies, ranging from 6 months [15; 17] to 3 years [34]. [PERSON] et al. [30] reported a trend of condyles returning to their preoperative position over time, which was consistent with the findings of this study (Table 2), demonstrating a common pattern of condylar displacement after surgery. The present study revealed significant positional changes between T0 and T2 only in the \(y\)-axis (\(p<0.05\): Table 2). The condyles generally move in a certain direction after surgery and gradually recover towards the preoperative position, but the extent and duration of recovery may vary depending on the surgical approach and patient-specific factors. In this study, the voxel-based registration method, a comparatively new technique, was utilized. This method involves aligning CT images acquired at two different time points through a mathematical algorithm that relies on the grayscale variation of voxels [35; 36]. It offers superior accuracy and reduces the likelihood of human error compared to that with landmark-based registration, since the superimposition of CT scans is automated and does not necessitate the repeated selection of reference points [21; 36; 37]. The current study acknowledges several limitations. Firstly, the follow-up period in this investigation was confined to 6 months. Although significant recovery towards the original condylar position was observed in our study, this period may have been inadequate for the full recovery of condylar position in the \(y\)-axis, as shown in Table 2. Future studies with extended follow-up durations are needed to observe the long-term changes in condylar position after surgery. Secondly, the present study did not evaluate the effects of different fixation materials on postoperative condylar position and soft tissue changes. All patients in this study received a bioabsorbable mesh for mandibular fixation in SSRO. For a comprehensive comparison, future research should consider including an additional group that receives a traditional metal plate or screw fixation. Thirdly, our sample predominantly consisted of bimaxillary surgeries, with a relatively small number of single-jaw cases. Incorporating a larger number of single-jaw surgeries would enhance our understanding of the potential differences in condylar position changes between single-jaw and bimaxillary surgeries. Lastly, while this study was retrospective in nature, a prospective study design, potentially with a pre-determined sample size based on power calculations, would permit a more controlled and robust analysis of condylar position changes following mandibular setback surgery. We strongly advocate for such future studies to validate and expand upon our findings.