Dentistry and Oral Surgery Service, William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California-Davis, Davis, CA.
Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA.
Am J Vet Res. 2022 Jun 29;83(8):ajvr.22.03.0043. doi: 10.2460/ajvr.22.03.0043.
To evaluate the biomechanical properties of the mandibles of cats with experimentally created osteotomies simulating oblique ramus fractures, which were stabilized with malleable L-miniplates with either locking screws [locking construct (LC)] or nonlocking screws [nonlocking construct (NLC)], compared with those for intact mandibles.
20 mandibles from 10 adult cat cadavers.
A block study design was adopted to allocate the mandibles of each cadaver to 2 of the 3 test groups (LC, NLC, or intact mandible). Mandibles within each cadaver were allocated systematically to a test group. For mandibles assigned to an LC and an NLC, a complete oblique osteotomy was performed from the mid rostral aspect of the ramus in a caudoventral direction. All mandibles were loaded in a single-load-to-failure test through cantilever bending. Load and actuator displacement were recorded simultaneously. Mode of failure and radiographic evidence of damage to tooth roots and the mandibular canal were evaluated. Biomechanical properties were compared among the groups.
No iatrogenic tooth root damage was evident, but all mandibles with an LC and an NLC had evidence of screw invasion into the mandibular canal. Plated mandibles had significantly less stiffness and bending moment than intact mandibles. Stiffness was not significantly different between the LC and the NLC; the NLC had a greater bending moment at failure than the LC. The pre-yield stiffness of plated mandibles decreased when the number of screw holes overlapping the mandibular canal increased.
The use of a malleable L-miniplate in a caudal mandibular fracture model is feasible. Both the LC and the NLC were inferior mechanically to intact mandibles. Type of construct used did not affect the construct stiffness significantly in tested mandibles.
评估模拟斜行下颌骨骨折的猫下颌骨的生物力学特性，这些下颌骨采用可弯曲的 L 型迷你板进行固定，其中带有锁定螺钉[锁定结构（LC）]或非锁定螺钉[非锁定结构（NLC）]，与完整下颌骨进行比较。
10 只成年猫尸体的 20 个下颌骨。
采用块研究设计将每个尸体的下颌骨分配到 3 个测试组（LC、NLC 或完整下颌骨）中的 2 个。在每个尸体中，下颌骨系统地分配到一个测试组。对于分配给 LC 和 NLC 的下颌骨，从髁突的中前部分以向尾侧的斜向进行完全斜行截骨。所有下颌骨均通过悬臂弯曲进行单载荷至失效试验。同时记录负载和执行器位移。评估失效模式和牙根及下颌管的放射学损伤证据。比较各组之间的生物力学特性。
没有明显的医源性牙根损伤，但所有具有 LC 和 NLC 的下颌骨都有螺钉侵入下颌管的证据。有板的下颌骨的刚度和弯矩明显小于完整的下颌骨。LC 和 NLC 之间的刚度没有显著差异；NLC 在失效时的弯矩大于 LC。当重叠下颌管的螺钉孔数量增加时，有板下颌骨的预屈服刚度降低。
在低位下颌骨骨折模型中使用可弯曲的 L 型迷你板是可行的。LC 和 NLC 在机械性能上均劣于完整的下颌骨。在测试的下颌骨中，使用的结构类型对结构刚度没有显著影响。
