# Condylar Changes Following Mandibular Setback Using Manual Guidance
## 2 Materials and Methods  
This retrospective study was conducted with the approval of the Institutional Review Board of Gangneung-Wonju National University Dental Hospital (GWNUDH-IRB2022-A001). The study involved 28 patients (11 men and 17 women) with mandibular prognathism, with a mean age of 22 years (age range: 17-28 years), and 56 condyles in total were analyzed (Table 1). All patients underwent mandibular setback surgery by a single surgeon between 2014 and 2021. All patients did not have any specific TMJ symptoms. Of the 28 patients, 5 underwent mandibular surgery only, while 23 underwent bimaxillary surgery. The average mandibular setback was 8.21 mm. \begin{table}
\begin{tabular}{c c c c} \hline
**Patient** & **Age (Years)/** & & **Right Mandibular** & **Left Mandibular** \\
**(No.)** & **Sex** & **Surgery Type** & **Setback (mm)** & **Setback (mm)** \\ \hline
1 & 21/F & Bimaxillary surgery & 8.5 & 7.5 \\
2 & 24/F & Bimaxillary surgery & 9 & 13 \\
3 & 23/M & Bimaxillary surgery & 6 & 7 \\
4 & 23/M & Bimaxillary surgery & 8 & 4 \\
5 & 18/F & Bimaxillary surgery & 2 & 6 \\
6 & 28/F & Bimaxillary surgery & 8 & 10 \\
7 & 28/M & Bimaxillary surgery & 12 & 9 \\
8 & 21/F & Bimaxillary surgery & 7 & 7 \\
9 & 19/F & Mandibular surgery & 5 & 10 \\
10 & 23/F & Bimaxillary surgery & 1 & 9 \\
11 & 21/M & Mandibular surgery & 8 & 5 \\
12 & 19/M & Mandibular surgery & 11 & 11 \\
13 & 25/M & Bimaxillary surgery & 6 & 12 \\
14 & 22/F & Bimaxillary surgery & 7 & 11 \\
15 & 28/M & Bimaxillary surgery & 4.5 & 7.5 \\
16 & 23/F & Bimaxillary surgery & 6 & 4 \\
17 & 19/F & Bimaxillary surgery & 10 & 8 \\
18 & 27/M & Bimaxillary surgery & 9 & 12 \\ \hline \end{tabular}
\end{table} 
Table 1: Information of the included patients. The patients had undergone conventional bilateral SSRO with the placement of a bioabsorbable mesh (OsteotransMX(r) Tairon, Osaka, Japan) and 3 to 5 mm long bioabsorbable screws in each segment for mandibular fixation. LeFort I osteotomy of the maxilla was additionally performed in patients requiring bimaxillary surgery. Intraoperatively, the mandibular condyle was manually positioned using the conventional methods; the condyle was elevated to its highest point, pressure was released to identify the stable condyle position, and these steps were repeated until a consistent, reproducible position was achieved, before the proximal segment was slightly advanced within 2 mm. Postoperatively, intermaximillary fixation was implemented for a duration of 3 to 5 days based on the patient's occlusion. Subsequently, it was transitioned to a rubber guiding, in accordance with our protocol, which was followed by mouth opening exercises. As described in a previous report [12], the nasion was set to point (0,0,0), with three axes passing through this point: the line parallel to the Frankfurt horizontal plane (FH plane) was the \(x\)-axis, perpendicular to the FH plane was the \(y\)-axis, and parallel to the FH plane and perpendicular to the \(x\)-axis was the \(z\)-axis (Figure 1a). In this three-dimensional coordinate system, the coordinate point of the center of the mandibular condyle head was set as follows (Figure 1b). 1. Frontal (medial to lateral) plane: As initially described, the center of the condylar head was identified as the point placed in the middle of the lateral and medial poles of the condyle. 2. Sagittal (anterior to posterior) plane: The center of the condylar head was determined by identifying the midpoint between the most anterior and most posterior aspects of the condylar head on sagittal sections. 3. Axial (superior to inferior) plane: In the axial plane, the center of the condylar head was identified by locating the midpoint between the most superior and most inferior aspects of the condylar head based on the axial sections.