根管峡部牙本质的结构与矿物质含量及显微硬度的研究

Study of root canal isthmus dentin structure and mineral content and microhardness

目的对比研究有无根管峡部单根前磨牙根部牙本质的结构、矿物质含量及显微硬度的差异。方法收集有根管峡部的单根前磨牙30颗(实验组)和无根管峡部的单根前磨牙30颗(对照组),采用扫描电子显微镜、X线能谱仪、维氏显微硬度仪对两组前磨牙根部牙本质进行结构观察、矿物质含量以及显微硬度测试比较。结果实验组根管峡部位置牙本质小管不明显,结构排列紊乱,对照组无根管峡部前磨牙牙根相对应位置根管壁牙本质小管排列规则,管腔开口清晰;实验组牙本质Ca、P含量及Ca/P比值低于对照组(P<0.05);实验组牙本质显微硬度低于对照组(P<0.05)。结论根管峡部牙本质结构发生改变,Ca、P含量及显微硬度偏低。根管峡部是牙根的薄弱环节,可削弱根部牙体硬组织抗力,可能是导致牙根纵裂发生的因素之一。

Objective To investigate the differences in dentin structure,mineral content and microhardness of sin-gle premolar roots with or without an isthmus.Methods Thirty single-root premolars with a canal isthmus(experimen-tal group)and thirty single-root premolars without a canal isthmus(control group)were collected and analyzed by scan-ning electron microscopy,X-ray energy spectrometry and a Vickers microhardness tester.Structure,mineral content andmicrohardness were compared.Results In the experimental group,the dentinal tubules were not obvious,and thestructure was disordered.In the control group,the dentin tubules of the root canal wall were arranged regularly,and thelumen opening was clear.The Ca and P contents and Ca/P ratio of the experimental group were lower than those of thecontrol group(P<0.05).The microhardness of the experimental group was less than that of the control group(P<0.05).Conclusion The dentin structure of the root canal isthmus was changed,and the Ca,P contents and microhard-ness were low.The root canal isthmus was a weak link in the root,which could weaken the resistance of the hard tissueof the root tooth,which may be one of the important factors that could cause vertical root fracture.