钛镍记忆合金牵张装置增高牙槽嵴对咀嚼肌的影响

Effect of Alveolar Ridge Augmentation with TiNi-SMA Distractor on the Masticatory Muscles

目的:通过组织学观察,研究钛镍记忆合金牵张装置增高牙槽嵴对咀嚼肌的影响。方法:!重20～30kg健康成年杂种犬18只,3只为对照组,其余随机分为3组,每组5只。拔除所有犬双侧下颌前磨牙及第一磨牙,1个月后在实验组犬的一侧下颌骨植入钛镍记忆合金丝加工成的S形牵张装置。牵张器就位后骨块即开始牵张升起,术后一周增高量达7.5～11.5mm,其后无明显变化。分别在牵张后1、3、6个月处死5只实验犬和1只对照犬。取双侧嚼肌、颞肌、翼内肌、翼外肌进行组织学和超微结构分析。结果:!1个月时牵张侧各咀嚼肌纤维见少量淋巴细胞渗出。3个月组部分颞肌、嚼肌、翼内肌纤维扭曲、横纹消失,偶见肌纤维溶解,线粒体肿胀。6个月时各咀嚼肌肌纤维排列整齐,粗细均匀,肌节完整,肌横纹清晰,线粒体正常。结论:钛镍记忆合金牵张装置增高牙槽嵴是一种安全可靠的方法,对咀嚼肌的影响是轻微、可逆的。

Objective： To study the effect of alveolar ridge augmentation with TiNi-SMA distractor on the masticatory muscles. Methods： 18 dogs weighing 20-30 kg, were extracted bilateral premolars and the first molar. 3 were selected as control group. The rest 15 dogs were randomly divided into 3 experiment groups, 5 dogs in each. One month later, the TiNi-SMA distractor were buried into one side mandible of all experiment dogs. The bone segments were lifted up immediately after the insertion of the distractors, and the height achieved 7.5-11.5 mm one week later and no more changes were observed since then. 5 experiment dogs and one control dog were sacrificed respectively at 1, 3 and 6 months. The bilateral masseter muscle, temporal muscle, lateral pterygoid muscle and medial pterygoid muscle were harvested and processed for histological and TEM（Transmission Electron Microscope） evaluation. Results： No abnormal changes were observed in control group. In experiment group of one month,in experimental side the myofihrils dilated slightly, a few of inflammatory cells were observed. More histological changes were found in experiment group of 3 months, such as the wrench and deformation of muscular fibers, the dissolution of partial myofihril, the swelling of mitochondria. In experiment group of 6 months, no obvious changes of masticatory muscles were observed comparing with control group. Conclusion： The TiNi-SMA distractor used to elevate alveolar ridge is safe, and its harmness on masticatory muscles is slight and reversible.