Skeletal Stability after Two-Jaw Surgery in Patients with Mandibular Prognathism

Comparison of Titanium and Resorbable PLLA Miniplate Osteosynthesis

Abstract

The skeletal stability after Le Fort I osteotomy and bilateral sagittal split osteotomy was evaluated on lateral cephalograms in 108 patients with mandibular prognathism with/without facial asymmetry. The subjects were divided into two groups based on the types of used osteosynthesis systems and the usefulness of a resorbable poly-L-lactide (PLLA) osteosynthesis system for bone fixation in orthognathic surgery was examined. Group A consisted of 37 patients in whom the titanium osteosynthesis system was used for bone fixation and group B consisted of 71 patients in whom the PLLA osteosynthesis system was used for bone fixation at the bilateral border of piriform aperture and the titanium osteosynthesis system was used at the zygomatic process of maxilla. Lateral cephalograms were taken before surgery, immediately after surgery, and at least six months after surgery. Changes in the positions ofpoint A, the incisal edge of the upper central incisor (U1), the incisal edge of the lower central incisor (L1), and point B were examined. The postoperative changes of the maxilla and mandible were less than 1mm on cephalograms except the vertical change at L1 in group B. There was no statistical difference in the postoperative skeletal stability between the two groups. In both groups, the tendency to relapse was greater in cases in which large movements of maxilla and/or mandible occurred during surgery. It can be concluded that the PLLA osteosynthesis system is considered to be clinically useful since the system does not have to be removed and maintains the postoperative skeletal stability.