# Condylar Changes Following Mandibular Setback Using Manual Guidance
## 4 Discussion  
This study's objective was to examine condylar position alterations after mandibular setback surgery using manual guidance in patients with mandibular prognathism and to assess the impact of patient age, sex, the type of orthognathic surgery, the extent of mandibular setback, and the degree of asymmetry on these changes. Our results revealed that the condyle moved significantly in an anterior-lateral-inferior direction between T0 and T1 and in a posterior-medial-superior direction between T1 and T2, indicating a tendency to return to its original position (\(p<0.05\), Table 2). There were no significant changes in the anterior-posterior and medial-lateral directions between T0 and T2, but a statistically significant inferior displacement was observed until 6 months postoperatively (\(p<0.05\), Table 2). Furthermore, there were statistically significant differences in positional changes between T0 and T1, but no significant differences between T0 and T2 (Table 2). The average changes in the condyle position between T0 and T1 and T0 and T2 were comparable to or smaller than those observed in a previous study [19] that used manual guidance with metal plates for mandibular fixation. The difference from that study to our current study was the use of bioabsorbable plates for mandibular fixation in SSRO. Orthognathic surgery typically employs metal plates and screws. Despite the conventional perception that bioabsorbable plates are weaker than metal plates, there is a growing trend towards using bioabsorbable plates, which is primarily driven by the patient's preferences. Multiple studies have confirmed the usefulness and skeletal stability of bioabsorbable plates [20; 23; 24]. Bioabsorbable plates offer benefits such as not requiring secondary surgery for removal, eliminating the risk of metal corrosion, reducing stress shielding, and radiolucency [25; 26]. Condylar displacement following orthognathic surgery is influenced by several factors, including the type of surgery (single- or two-jaw), the extent of mandibular setback, the degree of mandibular asymmetry, and the fixation method [13; 14; 15; 17; 20; 27; 28; 29; 30; 31; 32; 33]. However, the direction of condylar displacement is not consistent across these factors. A previous study [27] has reported posterior-lateral-superior displacement of the condyle during single-jaw surgery and posterior-medial-inferior displacement during two-jaw surgery. However, another study [28] has reported similar condylar movement regardless of the type of surgery. Additionally, many papers have noted anterior-lateral-inferior displacement of the condyle in patients who underwent SSRO for mandibular prognathism [15; 17]. In our study, we found that the anterior-posterior direction of condylar positional changes showed opposite movement between T0 and T1 depending on the type of surgery, but the difference was not statistically significant (\(p>0.05\)). However, statistically significant differences in condylar movement were observed in the anterior-posterior direction between T1 and T2 according to the type of surgery. (\(p=0.037\): Table 3). The extent of mandibular setback is an important factor that can affect condylar displacement after surgery [15; 31; 32; 33]. However, a previous study [29] found that changes in condylar position are not significantly influenced by the extent of mandibular setback. Similarly, in our study, we found that the amount of setback did not have a significant impact on postoperative or follow-up condylar position (\(p>0.05\): Table 3). Interestingly, when comparing condylar position between T0 and T2, we observed that patients who underwent mandibular setbacks of \(>\)8 mm showed a significant downward condylar position at T2 compared to that at T0 (\(p=0.021\): Table 3). [PERSON] et al. [30] reported a significant increase in intercondylar distance due to lateral condylar movement in patients with asymmetry and mandibular prognathism.