机械力学评价不同长度石英纤维桩的抗折强度

背景：桩长度是影响桩冠固位的主要因素,目前有关桩长度对修复体机械力学影响的意见不一致。目的：比较不同长度石英纤维桩在树脂类黏结剂黏结条件下修复体抗折强度的差异。方法：将正常人离体上颌中切牙30颗随机分成对照组、8mm石英纤维桩组及5mm石英纤维桩组,每组10颗。其中后2组截冠并分别预备5mm和8mm桩道,以树脂黏结剂黏固石英纤维桩,复合树脂恢复核形态,金属全冠修复;对照组不截冠,牙体预备后即行金属全冠修复。将3组牙垂直栽种于自凝塑料模块中,以力学实验机加力杆于牙冠腭侧切1/3与中1/3交界处与牙长轴成130°加载,加载速度为1mm/min,记录失败点力值及折裂模式。结果与结论：5,8mm石英纤维桩组抗折强度均低于对照组（P〈0.01）,前2组抗折强度差异无显著性意义,但在理论上各组均能承受成人咀嚼过程中产生的平均咬合力。5,8mm石英纤维桩组断裂模式主要以桩折为主,可进行再修复;对照组主要以根颈斜折为主,不利于再次修复。表明在树脂类黏结条件下,5mm石英纤维桩与8mm石英纤维桩的抗折强度无差异,牙体折裂模式也相近。

Mechanical evaluation of fracture resistance of different length quartz fiber-reinforced composite posts

BACKGROUND： Post length is the main influential factor in post retention. Scholars have different opinions about the mechanical effect on the prostheses with different post length.OBJECTIVE： Under the situation of the resin adhesive, to compare the fracture strength of prostheses with different length quartz fiber-reinforced composite posts.METHODS： Thirty extracted human maxillary central incisors were selected and divided into three groups of 10 samples in each group. One group was control group, and the other two groups in which crowns sectioned were treated with post way of 5 mm and 8 mm, respectively. Both of them were restored by quartz fiber posts with composite resin core and cast stainless steel crown. The control group was endodontically treated with teeth which were restored with stainless steel crown. All posts were bonded with resin adhesive. The boosting rod of mechanical test machine was put in the junction of cut 1/3 and middle 1/3. All posts were set in the palatal side with loading at angle of 130° to the long axis of root at 1 mm/min speed, The maximum load and failure mode were recorded.RESULTS AND CONCLUSION： 5 mm length quartz fiber post resulted in no significantly difference in fracture strength with 8 mm length quartz fiber post. The fracture strength of control group was higher than that of quartz fiber post groups （P 〈 0.01）. But in theory, all groups could endure masticator force. Both two groups with quartz fiber post mainly underwent post fracture, and the control group mainly underwent cervical oblique fracture. The shorter posts could make it possible to restore the shorter roots under the compensation function of resin adhesive. Quartz fiber posts and composite cores had lower possibility of root fracture and better aesthetic capability; they could become the effective choices for aesthetic restoration.