【作者】 冯翠娟；

【导师】 艾红军；

【作者基本信息】 中国医科大学 ， 口腔临床医学， 2003， 硕士

【摘要】 目的 口腔修复临床实践中，全冠是最常见的牙体缺损修复方法，也常常被用作固定义齿的固位体。研究发现，继发龋和冠固位丧失是固定修复失败的主要原因。虽然粘接剂能提供修复体和基牙之间的良好封闭，使修复体与基牙形成一体化结构，但是在受力后全冠可产生不同程度的变形，而粘接层则可能发生微小的龟裂破坏。由于修复体在口腔内长期反复受到咀嚼、吞咽等功能性咬合力的作用，这种龟裂破坏逐渐进展，日久就会产生粘接剂溶解、破坏，导致并促进冠松动脱位、继发龋等一系列问题的发生，从而导致固定修复体的失败。 目前临床常用的粘接剂有多种类型，如何评价粘接剂的临床效果，指导临床医生选择合适的粘接剂非常重要。本研究对TypeⅣ型金合金及铸造冠用钴铬合金全冠试件用三种不同类型的粘接剂：磷酸锌水门汀、玻璃离子水门汀、树脂粘接剂粘接后，冠的变形与粘接剂层破坏的相互影响进行了实验研究，希望为临床选择合适的粘接剂提供一定的指导。 材料和方法 本实验采用失蜡铸造法制作带有悬臂梁的TypeⅣ型金合金和铸造冠用钴铬合金检测用冠试件：咬合面厚1.5mm，悬臂梁长11mm，宽5mm，厚3mm，轴面厚度1.0mm。铸造钴铬合金冠15个，随机分为3组，每组5个试件，分别应用磷酸锌水门汀、玻璃离子水门汀、树脂粘接剂(Super Bond C&B，SB)粘接。TypeⅣ型金合金冠5个，粘接剂用玻璃离子水门汀。 采用电阻应变花测量法检测冠在试合状态下和粘接状态下、分别受咬合面中央负荷和悬臂梁末端负荷时的负荷-应变情况及粘接层的破坏负荷。应用SpSS10．0软件包对不同合金作配对辽检验，对不同粘接剂作单因素方差分析（ANOVA）及组间用SNK检验。 实验结果 试合状态下咬合面中央负荷时，所有冠当由最大负荷去除负荷达无负荷状态时，主应变8；术。的值也达零。所有测定的应变值在冠的不同部位没有明显的差异。试合状态下的悬臂梁末端负荷时，所有冠当由最大负荷去除负荷达无负荷状态时，主应变S；。8。的值也达零。所有测定的应变值在悬臂梁正下方最大。经统计学检验，两种合金冠在两种负荷状态下的应变均无显著性差异。 粘接状态下咬合面中央负荷时，所有冠随负荷的增大，主应变值没有较大的变化，当负荷由最大去除至零时，主应变值也回零。粘接状态下的悬臂梁末端负荷实验中，所有冠随负荷增大其主应变值亦无较大的变化，但是负荷一应变曲线上有急剧的变化。当负荷由最大去除至零时，主应变值不能回零。所有测定的应变值在悬臂梁正下方最大。经统计学检验，不同合金及粘接剂类型对粘接状态下冠的应变的影响及粘接层的破坏负荷均无显著性差异。 结 论 本实验结果证实固定修复体粘接后修复体的刚性增强。单纯从力学角度看，三种粘接剂对全冠粘接效果无明显差异。悬臂梁末端受力更易造成冠的变形和粘接层的破坏。而在保证修复体一定的轴面厚度时，增强材料的刚性并不能使修复体的刚性随之增强。更多还原

【Abstract】 ObjectiveThe full crown is mostly used for the tooths repair and retainer of fixed partial denture (FPD) in the clinical practice of prosthodontics. It is discovered that secondary caries and losing of retention are the main reasons for the failure of fixed prostheses. The luting cement may seal the prosthesis and abutment well and make them an integral structure but the crown will deform and the cement layer may crack while be loaded. The crack will gradually propagate as the prosthesis is loaded day after day, and the cement will dissolve and destroy, thus cause the secondary caries and the losing of retention, and then the failure of fixed prostheses take place. There are many types of luting cements and it is important to select an ideal one for the dentist in dental clinical practice. In this experiment the deformations of crown and the failure of cements are measured and the relationship between them is discussed. Type IV gold alloy and casting Co - Cr alloy, zinc phosphate cement ( ZPC) , glass ionomer cement (GIG) and resin cement (Super Bond C&B, SB) are evaluated in this study.Materials and methodsThe crowns with cantilever are made by Type IV gold alloy and casting Co - Cr alloy: thickness of occlusal surface 1. 5mm, cantilever length 11 nun, width 5mm, thickness 3mm, thickness of axial surfaces1.0 ram. The fifteen crowns made by casting Co - Cr alloy are divided into three groups randomly, each group have five crowns, cemented by ZPC, GIG and SB, respectively. The five Type IV gold alloy crowns are cemented by GIG. Rosette gauge technique is used to measure the load - strain of crowns and the fracture strength of cements at two states and two loading ways, respectively. SpsslO. 0 is used to make statistical process.ResultsThe main strains of all the crowns non - cemented become 0 while the load decreases to 0 when loaded at the center of the occlusal surface, it is the same as when loaded at the end of the cantilever . But the former have no significant difference among the four gauges, while it is come to the latter, the strain is biggest just under the cantilever. There is no significant difference between the two types of alloy.The main strains of cemented crowns have no obvious variation as the load at the center of the occlusal surface increases, and become 0 when the load decreases to 0, too. But when the load is given at the end of the cantilever, the load - stain curves of the cemented crowns have sudden changes, and the strain couldnt decrease to 0 as the load become to 0. Statistical analysis confirm that different types of alloy and luting cements have no significant effect on the strains of cemented crowns and the failure load of cements.ConclusionThe results of this study confirm that fixed prostheses have better rigidity after cemented. The three types of cements used have no significant difference in luting results just by mechanical characteristics.The crowns deformed and the cements fracture more easily when the load is given at the end of the cantilever. The rigidity of the prostheses doesnt increase as the rigidity of materials increases if the thickness of the axial surface is enough.更多还原