Skeletal stability after mandibular setback surgery: comparisons among unsintered hydroxyapatite (u-HA) / poly-L-lactic acid (PLLA) plate, PLLA plate and titanium plate

Purpose: The purpose of this study is to compare the time-course changes in condylar long axis and skeletal stability after sagittal split ramus osteotomy (SSRO) with unsintered hydroxyapatite (u-HA) / poly-L-lactic acid (PLLA) plate, PLLA plate versus titanium plate. Patients and Methods: Of 60 Japanese patients diagnosed of mandibular prognathism, 20 underwent SSRO with u-HA/PLLA plate system and 20 underwent SSRO with PLLA plate system, while the other 20 underwent SSRO with conventional titanium plate system. The time-course changes in condylar long axis and skeletal stability were assessed by axial, frontal, and lateral cephalograms. Results: Titanium group was significantly larger than uHA/PLLA group in the change of right condyle angle between initial and 1 month (P=0.0105), intercondylar axes angle between 1 and 3 months (P=0.0013). PLLA group was significantly larger than titanium group (P=0.0043) and u-HA/PLLA group (P=0.0002) in the change of ramus inclination between 1 and 3 months; however, there were no significant differences between the three groups in the other measurements in each time interval. Conclusion: This study suggested that there were no significant differences in postoperative time-course changes among u-HA/PLLA plate system, PLLA plate system and conventional titanium plate system.