牙种植体骨感知外周神经机制的动物实验

An animal study of peripheral neurophysiologic mechanism in osseoperception phenomena of dental implant

目的研究种植体周围骨组织内是否存在功能性神经感受器，并探讨种植体外周神经反馈通路重建的程度及其影响因素。方法取比格犬3只，每只犬拔牙8颗，即刻或延期植入9枚种植体（包括1枚休眠种植体）。3只犬共植入27枚种植体，种植体共分5组：即刻种植＋延期负重组、即刻种植＋早期负重组、延期种植＋早期负重组、延期种植＋延期负重组，以上每组6枚种植体；另设休眠种植体组3枚种植体。种植体完成修复后负重3～6个月。采用肌电图仪行电生理实验，分别给予各组种植体以电刺激，在下牙槽神经附近记录感觉神经动作电位（sensory nerve action potential，SNAP）的潜伏期和波幅，设同侧下颌尖牙为对照。处死动物后获取带有种植体的下颌骨标本，采用免疫组织化学染色方法行组织学观察。结果种植体及天然牙受电刺激时，均可记录到SNAP。天然牙SNAP波幅为（44．04±6．23）μV，明显高于各种植体SNAP波幅（P〈0．01）；天然牙与各种植体之间SNAP潜伏期的差异无统计学意义（P〉0．05）。组织学观察可见种植体周围骨组织内存在神经末梢样结构以及粗大神经束，但神经纤维数量较少，部分神经纤维与种植体界面直接接触。结论种植体周围骨组织内存在功能性神经感受器，其数量少于天然牙；不同种植手术方式及负重时间对种植体周围骨组织内神经反馈通路的重建无明显影响。

Objective To investigate the existence of functional neuroreceptors in peri-implant bone tissue and to test the peri-implant neural feedback pathway reconstruction and its influential factors. Methods Three beagle clogs were involved in this study. After the extraction of 3 premolars and 1 molar of the bilateral mandible, 27 implants were placed immediately or delayed. The implants were loaded for 3-6 months, then sensory nerve action potential（SNAP） tests were performed. The stimulating electrode was connected to the implant or natural tooth. The recording electrode was fixed near the inferior alveolar nerve （IAN） to record the latency period and amplitude of SNAP. The specimens with peri-implant bone tissues were taken and examined by immunohistochemistry. Results SNAP of IAN could be recorded following stimulations to natural teeth and implants. The differences in SNAP amplitudes between natural teeth [ （44. 04±6. 23） μV] and all implant groups were statistically significant （P 〈0. 01 ）. Free nerve endings and nerve tract were found in the peri-implant bone tissue, but much less than those in periodontal membrane. Some nerve fibers were directly connected with implant surface. Conclusions Functional neuroreeeptors, though much less than that of natural tooth, exist in peri-implant bone tissue. Surgical methods and loading time do not have obvious influences on peri-implant neural feedback pathway reconstruction.