Biomechanical evaluation of two plating configurations for critical-sized defects of the mandible in dogs

OBJECTIVE To compare the biomechanical behavior of mandibular critical-sized defects stabilized with 2 plating configurations under in vitro conditions resembling clinical situations. SAMPLE 24 mandibles harvested from 12 adult canine cadavers. PROCEDURES 8 mandibles were kept intact as control samples. A critical-sized defect was created in 16 mandibles; these mandibles were stabilized by use of a single locking plate (LP [n = 8]) or an LP combined with an alveolar miniplate (LMP [8]). Mandibles were loaded in cantilever bending in a single-load-to-failure test with simultaneous recording of load and actuator displacement. Stiffness, yield, and failure properties were compared among groups. Mode of failure was recorded. Radiographic evidence of tooth root and mandibular canal damage was quantified and compared between groups. RESULTS Stiffness and yield loads of single LP and LMP constructs were < 30% of values for intact mandibles, and failure loads were < 45% of values for intact mandibles. There were no consistent biomechanical differences at failure between single LP and LMP constructs, but the LMP construct had greater stiffness and strength prior to yield. Frequency of screw penetration of teeth and the mandibular canal was significantly greater for LMP than for single LP constructs. CONCLUSIONS AND CLINICAL RELEVANCE Both fixation methods were mechanically inferior to an intact mandible. The LMP construct was mechanically stronger than the LP construct but may not be clinically justifiable. Addition of an alveolar miniplate provided additional strength to the construct but resulted in more frequent penetration of tooth roots and the mandibular canal.