Abstract
The purpose of this study was to examine the biomechanical stability on the in vitro model of bilateral sagittal split ramus osteotomy of the mandible (BSSRO). BSSRO was performed on the polyurethane mandible (Mandible teeth clip, SYNBONE® #8311, SYNBONE AG, Switzerland) by 2 types (angle or parallel) of osteotomy lines with or without bone obstruction. The split rami were fixed by 6 types of osseointegration materials with various designs described as follows: titanium straight locking plate with 4 holes, titanium straight non-locking plate with 4 holes, unsintered hydroxyapatite/poly-L-lactic acid (uHA/PLLA) mesh with 6 holes, uHA/PLLA mesh with 4 holes, uHA/PLLA box with 4 holes, and uHA/PLLA straight plate with 4 holes. The displaced length was measured by 50N and 130N linear compressive load on the bilateral lower first molars with 10mm/min, and those data were statistically analyzed.
The angle osteotomy line was less displaced than the parallel one, and the osteotomy model with bone obstruction was less displaced than that without bone obstruction. In the osteotomy model without bone obstruction, uHA/PLLA mesh fixation showed the least displacement, then titanium plate and uHA/PLLA plate showed less displacement in sequence. In the osteotomy model with bone obstruction, only uHA/PLLA mesh fixation sustained the split mandible. The other plates were fractured by 130N load, which was an approximate value of the occlusal force one month after orthognathic surgery.
These results suggest that the uHA/PLLA mesh with 6 holes fixation can be more stabilized in the osseointegration method than titanium plate fixation for bilateral sagittal split ramus osteotomy of the mandible in certain conditions.
