【作者】 李雅卿；

【导师】 陈吉华； 王辉；

【作者基本信息】 第四军医大学 ， 口腔临床医学， 2008， 硕士

【摘要】 随着口腔修复技术的不断发展,患者和牙医对修复体的要求也逐渐提高。有文献报道,以瓷熔附金属修复体为代表的口腔固定修复体在临床上的应用已占修复体总数的65%以上。然而,固定修复失败的现象却时有发生,边缘不密合和固位不良导致的失败占失败修复体总数的33.3%～41.8%。可以说,适合性不佳和固位不良已成为导致固定修复失败的两个主要原因。提高固定修复体的固位力和边缘适合性的方法很多,通过改变牙预备体表面粗糙度,从而调整全冠修复体的固位效果并改善其适合性也是一种行之有效的手段。目前关于牙预备体表面粗糙程度对冠修复体固位及内部适合性影响的研究还较少,有限的研究结果中亦存在较大分歧。本研究旨在比较不同粒度车针预备后的牙体与三种牙科水门汀的粘固效果;分析不同粒度车针预备牙体对基底冠适合性的影响;探讨不同粒度车针预备牙体对基底冠粘固性能的影响,以期为临床操作提供一定参考依据。本课题分为四个实验,分别是不同粒度车针预备后的牙体表面粗糙度测试、不同粒度车针预备牙体对其与三种牙科水门汀粘固性能的影响、不同粒度车针预备牙体对基底冠适合性的影响和不同粒度车针预备牙体对基底冠粘固性能的影响。实验一,采用临床常用的4种不同粒度的MANI金刚砂车针,在冷水喷雾下分别打磨牙本质表面。粗糙度测量仪测定牙本质表面粗糙度并在扫描电镜下观察车针及牙本质试件的表面形貌。实验发现:预备完成后的基牙表面粗糙度是由金刚砂车针的粒度决定的,车针的粒度越小,牙本质表面粗糙度越低。实验二,将经不同粒度车针打磨后的4组牙本质片分别与聚羧酸锌水门汀、玻璃离子水门汀和树脂改性玻璃离子水门汀粘固,测试其剪切粘固强度并观察试件的断裂模式。实验发现:牙本质表面粗糙度对水门汀材料与牙本质之间的粘固强度具有显著影响;预备用车针的粒度越小,水门汀材料与牙本质之间的剪切强度越低;牙本质表面粗糙度相同时,玻璃离子水门汀和树脂改性玻璃离子水门汀与牙本质的粘固效果间未见显著差异,且均优于聚羧酸锌水门汀。实验三,在自制平行研磨仪上,用4种不同粒度的MANI金刚砂车针依次打磨牙预备体的表面,然后用玻璃离子水门汀将个别制作的镍铬合金基底冠粘固在牙预备体上。将试件浸泡在0.5%品红溶液中24h后纵向剖开,体视显微镜下测量指定点位的粘固剂层厚度并记录微渗漏等级。实验发现:随预备用车针粒度的减小,牙预备体与镍铬合金基底冠之间的微渗漏等级逐渐降低;使用车针依次精修牙面至粒度为53～63μm的金刚砂车针(即细型MANI车针)时,牙预备体与镍铬合金基底冠之间的适合性可满足临床要求。实验四,为每个牙预备体试件制作相对应的带环金属冠,牙预备体试件的制备方法同实验三,采用玻璃离子水门汀粘固牙预备体与相应金属冠,测试冠的固位力并借助体视显微镜观察断裂模式。实验发现:采用不同粒度车针预备牙体对冠修复体的固位力无显著影响;当其它条件一定时,基底冠试件与牙预备体脱位后的断裂模式和牙体表面粗糙度之间的相关性较小。综上所述,当牙体预备初步完成后,采用粒度较小的金刚砂车针对牙预备体表面进行精修时,随车针粒度的减小:(1)牙本质表面粗糙度逐渐降低;(2)水门汀材料与牙本质之间的剪切粘固强度降低,玻璃离子水门汀和树脂改性玻璃离子水门汀与牙本质的粘固效果间未见显著差异,且均优于聚羧酸锌水门汀;(3)牙预备体与镍铬合金基底冠之间的适合性逐渐提高;(4)牙预备体与镍铬合金基底冠间的固位力间未见显著差异。根据上述研究结果,临床上基牙预备时,为了兼顾全冠修复体的固位力和内部适合性,建议使用粒度为53～63μm的细型金刚砂车针对牙预备体进行精修。更多还原

【Abstract】 With the development of dental prosthodontics,the requirements from dentists and patients increased gadually.Fixed restorations,especially porcelain fused to metal crown/ bridge(PFM),have been widely applied in clinic restoration,accounting for 65%in all kinds of restorations.However,in cases of restoration failure,33.3%～41.8%of restorations are caused by bad marginal seal and poor retention.Therefore,marginal seal and retention have come to be of the two main factors inducing the failure of fixed restorations.There are numbers of methods have been applied to improve the retention and internal adaptation of fixed restorations.Among these,changing dentin surface roughness by diamond burs with different grit sizes may be an effective and simple way.Most of the relative have been focusing on the effect of etching on restorations,the effect of different luting agents on marginal adaptation between dentin and crown,and surface treatments that may improve crown retention.The effect of trimming with diamond burs of different grit sizes on the bond strength and internal adaptation between full crown and dentin has seldom been reported. The purpose of the present study is to evaluate the effect of trimming with diamond burs of different grit sizes on the shear and tensile bond strength, internal adaptation between dentin and luting agents;retention between dentin and based crowns after cementation.It may be helpful to improve the retention and adaptation of fixed restorations in clinic.The total study was divided into four experiments:Experiment 1:All the dentin plates were divided into four groups which were prepared with diamond burs of different grit sizes.The dentin surface roughness was measured and observed with SEM,respectively.Results showed that:dentin surface roughness was affected by the grit size of diamond burs applied.The smaller the grit size of diamond bur was,the lower the dentin surface roughness would be.Experiment 2:After being prepared with diamond burs of different grit sizes, all the dentine plates were divided into three subgroups and bonded with polycarboxylate cement,glass-ionomer cement,and resin-modified glass ionomer cement respectively.Specimens were then subjected to shear bond strength test. The fracture mode of each specimen was also recorded.Results showed that:the smaller the grit size of diamond bur was,the lower the shear bond strength was; with the same dentin surface roughness,the use of glass-ionomer cement and resin-modified glass ionomer cement could obtain higher shear bond strength than polycarboxylate cement.Experiment 3:According to the type of the final diamond bur used for the finishing of tooth preparation,all the prepared teeth were divided into 4 groups. All the teeth were prepared using a set of diamond burs with decreasing grit size equipped on a self-made parallel muller.A Ni-Cr alloy crown was individually fabricated.Glass ionomer cement was used to cement the crowns.Specimens were soaked into 0.5%fuchsine solution for 24h.The bonded specimens were evaluated for microleakage and internal adaptation.Results showed that:as the grit size of diamond bur for preparation decreases,the adaptation between dentin and Ni-Cr based crown increased;when using the brand of MANI diamond bur to prepare teeth ruth decreasing-sized bur until a red code,the internal adaptation between abutment and Ni-Cr based crown could meet clinical needs.Experiment 4:The specimens were prepared according to the methods mentioned in experiment 3.The impressions were made and Ni-Cr alloy crowns with rings were fabricated.Glass ionomer cement was used to cement the crowns. The tensile bond strength and the fracture mode were observed for each bonded specimen.Results showed that:no significant effect was found on the tensile bond strength between teeth prepared with diamond bur of different grit sizes and Ni-Cr based crown when bonded with glass ionomer cement;regardless of other related factors,the correlation between fracture mode and dentin surface roughness after the separation of the cemented specimens is little.Based on the results above,it could be briefly concluded that:when a final trimming with diamond burs of smaller grit size was applied to dentin surface after the regular tooth preparation,as the grit size of diamond bur for preparation decreases,(1) dentin surface roughness would decrease;(2) the shear bond strength between cements and dentin decreases;with the same dentin surface roughness,glass-ionomer cement and resin-modified glass ionomer cement obtain higher shear bond strength than polycarboxylate cement;(3) the adaptation between dentin and Ni-Cr based crown increased; (4) no significant difference was found on tensile bond strength between prepared teeth by diamond bur with different grit sizes and Ni-Cr based crown when bonded with glass ionomer cement.Based on these conclusions mentioned above,considering the retention and internal adaptation of full crown,it is suggested that when using the MANI diamond bur to prepare teeth following the grit size order to red code (53～63μm),the retention and internal adaptation between abutment and Ni-Cr based crown could meet clinical needs.更多还原