摘要
目的探讨根管壁切削程度与牙根强度的关系及应力分布的变化规律。方法用抗压实验测试3组根管壁厚度分别为1.00mm、0.75mm和0.50mm的15对试件的最大断裂载荷,并与原始根管的基线试件比较。三维有限元分析根管壁厚度分别为常规预备后(根管壁厚1.2mm)及过度扩大致剩余根管壁厚度为基准模型的75%、50%和25%时的应力大小和分布。结果抗压实验中1.00mm、0.75mm和0.50mm组的牙根最大断裂载荷分别为(4432.41±563.59)、(4137.43±680.29)和(3749.87±554.17)N,载荷强度随根管壁面积的减小而下降。有限元分析表明,如果根管壁厚度下降较多,根管壁的应力大小和分布均会发生明显改变。结论在临床根管治疗操作中,应以彻底去除根管壁感染物质为标准,尽量避免对牙体硬组织的过度切削。
Objective To investigate the correlation between the extent of cutting of the root canal wall and the root fracture strength and the stress distribution. Methods Fifteen pairs of root sections were into 3 groups with canal wall thickness of 1.00 mm, 0. 75 mm and 0. 50 mm respectively. The maximum load was tested required for fracture for each group through fracture test in a universal testing machine, and compared with that for the original canal. The stress and its distribution of the root with normal wall thickness （ 1.2 mm） and roots with 75%, 50% and 25% respectively of the normal wall thickness were examined by three-dimensional finite analysis. The maximum Von Mises stress of the root of each model was calculated. Results The mean fracture strengths of the groups with canal wall thickness of 1.00 mm, 0. 75 mm and 0. 50 mm were （4 432.41 ± 563.59） N, （4 137.43 ± 680. 29 ） N and （3 749. 87 ± 554. 17 ） N respectively. The maximum load of fracture resistance is a linear function of the root canal wall thickness（ r =0. 972 ,P 〈 0. 001 ）. The three-dimensional finite analysis revealed that the enlargement of root canal diameter brought on increase of stress of root canal wall, and the stress and its distribution altered with further decrease of the wall thickness. The stress of lateral loading was greater than that of vertical loading. Conclusions The results suggests that clinical root canal treatment should be designated to remove just the infected tissue and avoid over-cutting of the hard tissue.
出处
《中华口腔医学杂志》
CAS
CSCD
北大核心
2006年第11期661-663,共3页
Chinese Journal of Stomatology
基金
"十五"国家科技攻关计划基金资助项目(2004BA720A23)
关键词
根裂
抗裂载荷
三维有限元分析
Root fracture
Fracture strength
Three-dimension finite analysis
