Comparative biomechanical study on three miniplates osteosynthesis systems for stabilisation of low condylar fractures of the mandible.

Open reduction and fixation of low condylar fractures of the mandible can be achieved by many osteosynthesis systems that differ in size, shape, and site of placement according to the surgical approach. We investigated the maximum load and rigidity of 4 osteosynthesis systems: the standard double 4-hole straight miniplates, the inverted y-miniplate (with and without self-drilling screws), and the TriLock Delta condyle trauma plate. The standard double 4-hole straight miniplate osteosynthesis achieved the best fixation and resistance in view of a mean (SD) maximum load of 539.8 (100.2)N, followed by the inverted y-miniplate with the self-drilling screws (246.5 (23.8)N), the inverted y-miniplate with standard screws (242.4 (27.2)N), and finally the TriLock Delta plate (167.4 (39.2)N). Analysis of the slope of the force-displacement diagram from 80N to 100N in each group showed that the TriLock Delta miniplate had the highest values for rigidity (17.3 (5.1)N/μm), followed by the inverted y-miniplate groups with self-drilling screws (14.1 (6.4)N/μm), and with standard screws (12.6 (2.5)N/μm). The double 4-hole straight miniplate osteosynthesis had the lowest rigidity (8.7 1.4)N/μm). Despite the significant difference in the maximum load between the double 4-hole miniplates and other investigated osteosynthesis patterns, all groups had sufficient load for the fixation of low condylar fractures of the mandible when postoperative bite forces and the slowly increasing voluntary clenching during healing were considered.