A computer study of biodegradable plates for internal fixation of mandibular angle fractures

Purpose: This computer-based study was performed to determine the suitabili ty of small biodegradable plate systems for mandibular angle fractures. Materials and Methods: In a 3-dimensional computer model of the mandible, f racture mobility and plate strain were calculated for bite forces applied o n 13 bite points on the dental arch. The angle fracture was fixed with 2 po lylactide (PLA) midiplates or with 2 PLA maxiplates. The first plate was po sitioned buccally on the external oblique ridge. Two positions of the secon d plate were studied: halfway up the height of the mandible or on the lower border. Maximum fracture mobility was set at a limit of 150 mum to enable undisturbed fracture healing. Maximum plate strain was set at the yield str ain of PLA. Results: Fixation with the PLA maxiplates, with the second plate positioned halfway up the height of the mandible, resulted in fracture mobility below the set limit for all bite points. For the other PLA fixation strategies, fracture mobility exceeded the set Limit. Fixation with the second plate po sitioned halfway up the height of the mandible generally resulted in less f racture mobility than with the plate positioned on the lower border. The yi eld strain of PLA was not exceeded in any of the fixation strategies. Conclusions: Based on the computer model. 2 PLA maxiplates are suitable for fixation of mandibular angle fractures. One plate should be positioned buc cally on the external oblique ridge, and the other should be positioned hal fway up the height of the mandible. (C) 2001 American Association of Oral a nd Maxillofacial Surgeons.