纤维树脂桩核修复体力学性能与不同牙体剩余量的关系

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。中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程

Relationship between mechanical properties of fiber resin post-core system and different dental remaining tissues

BACKGROUND:The dental remaining tissue is closely related to fracture resistance ability of the fiber resin post. OBJECTIVE:To compare the effect of different dental remaining tissues on fatigue resistance of the fiber resin post using in vitro stress analysis method.METHODS:A total of 36 single rooted mandibular premolars were randomly divided into four groups. Upon finishing standardized root canal therapy, tooth preparation was performed on all four groups. Group A: transverse grinding of the crown on datum plane. Group B: coronal oblique distal, middle and proximal defects with the dentin collar height of 2 mm at the distal end, and dentin collar height of 0 mm when gradually reduced to the proximal end. Group C: transverse missing of dental crown, leaving healthy dentin with 2 mm. Group D: retention of complete dental tissues on the dental crown. Routine bonding treatment was performed after the preparation in each group, and the Para post fiber lux glass fiber post was then implanted. Dynamic mechanical loading equipment was used to analyze the fracture resistance value of the four groups. RESULTS AND CONCLUSION:The loading value was as follows: Group D > Group C > Group B > Group A, and significant differences were found between two groups (P < 0.05). The four model fracture forms were as follows: coronal oblique fracture, dental cervix transverse fracture, tooth cervical oblique fracture and root fracture. In the Group A, there were seven cases of dental cervix transverse fracture and two cases of oblique fracture. In the Group B, there were four cases of coronal oblique fracture and five cases of oblique fracture of dental cervix. In the Group C, there were six cases of oblique fracture of dental cervix and three cases of root fracture. In the Group D, there were seven cases of oblique fracture of dental cervix and two cases of root fracture. The result explains that the occlusal stress will be transferred from cervix to the root when there are enough remaining dental tissues; overall levels reduce, and the strength of fiber post increases. Therefore, it is suggested clinically to save as much dental tissues as possible.