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背景:牙体组织剩余量与纤维树脂桩核修复体的抗折强度密切相关。目的:采用体外应力分析方法比较不同牙体残余量对纤维树脂桩核修复体抗疲劳强度的影响。方法:将36颗离体人下颌单根管前磨牙随机均分为4组,进行牙根管预备与填充后,A组平齐基准平面横断磨除冠部牙体;B组,牙冠近远中斜形损耗,远端牙本质领圈高度2 mm,逐渐减少到近中端时牙本质领圈高度为0 mm;C组,牙冠横行缺失,留2 mm健康牙本质;D组,保留完整冠部牙体组织。各组常规桩道预备后进行黏结处理,将Para post fiber lux玻璃纤维桩置入桩道内,采用动态力学加载设备对试件进行加载。结果与结论:4组荷载力值大小为D组>C组>B组>A组,组间两两比较差异有显著性意义(P<0.05)。实验样本折裂形式大致可分为牙冠斜行折裂、牙颈部横行折裂、牙颈部斜行折裂及牙根折裂等4种。A组发生牙颈部横行折裂7颗、牙颈部斜行折裂2颗;B组发生牙冠斜行折裂4颗、牙颈部斜行折裂5颗;C组发生牙颈部斜行折裂6颗、牙根中部折裂3颗;D组发生牙颈部斜行折裂7颗、牙根中部折裂2颗。表明当牙体残余量较多时,牙齿受到的咬合应力也会从颈缘转移到根部,整体水平也随着减低,纤维树脂桩核修复体的强度也会随着增强,因此在临床实践中应尽可能多保存牙体组织。
BACKGROUND: The residual volume of dental tissue is closely related to the flexural strength of fiber-reinforced plastic post-core restoration. OBJECTIVE: To compare the effect of different residual amount of teeth on the fatigue strength of fiber post-core restoration with in vitro stress analysis. Methods: Thirty-six mandibular single premolar premolars were randomly divided into four groups. After root canal preparation and filling, the coronal group A Distal oblique loss, the distal dentin collar height 2 mm, gradually reduced to near the end when the dentin collar height is 0 mm; C group, crowns missing, leaving 2 mm healthy dentin; D group, Retain the complete crown tooth tissue. Each group of conventional lanes was prepared and then bonded. Para post fiber lux fiberglass piles were placed in the lanes, and the specimens were loaded with dynamic mechanical loading equipment. RESULTS AND CONCLUSION: The load values of four groups were D group> C group> B group> A group. There was significant difference between the two groups (P <0.05). The fracture types of the experimental samples can be roughly divided into four kinds: oblique oblique fracture, transverse fracture of the dental neck, oblique fracture of the cervical and cervical teeth, and root fracture. In group A, there were 7 teeth with transverse dehiscence and 2 teeth with oblique deformity. There were 4 oblique bends in group B and 5 oblique bends in group B. In group C, Oblique fracture 6, fracture 3 in the middle of the root; group D occurred in 7 cases of oblique cervical teeth, root fracture 2. It shows that when the residual amount of tooth is large, the occlusal stress will also be transferred from the cervical margin to the root, the overall level also decreases with the increase of the strength of the fiber post resin core restoration body, so in clinical practice Save as much body tissue as possible.