Biodegradable self-reinforced poly-L/DL-lactide plates and screws in bimaxillary orthognathic surgery: short term skeletal stability and material related failures.

Biodegradable self-reinforced poly-L/DL-lactide plates and screws were used for osteosynthesis in 10 consecutive cases of bimaxillary procedures with simultaneous genioplasties, without postoperative rigid intermaxillary fixation. During surgery, data were gathered concerning failure of the osteosynthesis material. Clinical examination was carried out weekly until the sixth postoperative week. Cephalometric analysis of standardized cephalograms was performed to evaluate the short-term skeletal stability pattern, which was compared with similar reports in the literature. Six weeks postoperatively, all jaws were clinically stable and there was no clinical evidence of foreign body reactions. For the whole group (n = 10), the mean maxillary advancement at point A was 2.9 mm with a mean postoperative relapse of 0.0 mm. The mean advancement at point B was 2.8 mm with a mean additional advancement postoperatively of 1.1 mm. The mean vertical surgical displacement at point A was directed inferiorly with a value of 1.8 mm and a relapse of -0.4 mm. At point B the corresponding values were 1.9 mm and -0.4 mm. In the Angle Class III group (n = 4), the mean advancement at A was 5.9 mm with an additional postoperative advancement of 0.3 mm. In the Angle Class II group (n = 6), mean advancement at point B was 4.0 mm, with an additional postoperative advancement of 1.1 mm. In the group with short face deformity (n = 3), the mean inferior movement in ANS was 6.6 mm with a relapse of -0.2 mm. At menton the vertical surgical movement was 13.0 mm with a relapse of -0.2 mm. None of the plates, which were bent at room temperature, broke. The screw heads broke or had an insufficient fit in the bone in 12 of 305 (3.9%) screws. It can be concluded that the tested system of biodegradable self-reinforced poly-L/DL-lactide screws and plates has a small material-related failure rate, and that their application in orthognathic surgery leads to a predictable short-term skeletal stability pattern which is comparable to the 'gold standard' of titanium plates and screws.