纤维桩长度和牙槽骨高度对上颌中切牙抗折性能的影响

背景：纤维桩具有与天然牙本质接近的弹性模量，在受外力时能够与根管壁保持广泛面接触，与牙本质形成一同质的整体，使应力沿根管壁均匀传导，减少根折的发生。 目的：观察牙槽骨高度和纤维桩长度对上颌中切牙抗折性能的影响。 方法：将48颗离体上颌中切牙随机分为6组，每组8颗。A，B，C组牙槽骨距离釉质牙骨质界的距离为2 mm，纤维桩长度分别为5，7，9 mm；D，E，F组牙槽骨距离釉质牙骨质界的距离为5 mm，纤维桩长度分别为5，7，9 mm。截冠、根管治疗、纤维桩树脂核及铸造金属全冠修复后，将试样牙置于电子万能试验机上，与牙体长轴呈45？的加载方向，以1 mm/min的加载速度，持续加载至试样牙发生折裂。记录折裂时的加载强度和折裂模式。 结果与结论：牙槽骨高度对试样牙的抗折性能有显著影响（F=560.943，P＜0.05）；纤维桩长度对试样牙的抗折性能没有显著影响（P＞0.05）。牙槽骨高度正常各组试样牙断裂模式多为可修复性断裂模式，牙槽骨高度降低各组试样牙断裂模式多为不可修复性断裂模式，差异有显著性意义（χ2=5.689，P ＜0.05）。说明在牙槽骨高度降低的情况下，增加纤维桩的长度不能提高牙齿的抗折性能。

Effect of alveolar bone height and fiber post length on the fracture resistance of endodontically treated maxillary central incisors

BACKGROUND：The elastic modulus of the fiber post is close to that of the dentine, so it can form a homogeneous whole and share the masticatory force, which can ease the stress concentration of dentine and prevent from tooth fracture. OBJECTIVE：To investigate the effect of alveolar bone height and fiber post length on the fracture resistance of endodontical y treated maxil ary central incisors. METHODS：Forty-eight human maxil ary central incisors were assigned randomly to six groups （n=8） of three different post insertion depths （5, 7, 9 mm） and two alveolar bone levels （2 and 5 mm） from the cement-enamel junction. Al of them were restored by glass fiber posts with composite resin core and cast metal crown. The samples were loaded in a testing machine with a crosshead speed of 1 mm/min at a 45＆#176; angle to the long axis of the tooth on the palatal surfaces until tooth fracture occurred. The maximum load and failure mode were recorded. RESULTS AND CONCLUSION：Alveolar bone height had a significant influence on the fracture resistance （F=560.943, P〉0.05）, but fiber post length did not have a significant influence on it （P〉0.05）. Significant differences were found between the normal and resorbed alveolar bone groups in the number of repairable fracture patterns （χ2=5.689, P〈0.05）. Under the circumstance of lowered alveolar bone height, lengthening fiber post cannot enhance fracture resistance of the teeth.