【作者】 张凌；

【导师】 陈吉华； Marco Ferrari；

【作者基本信息】 第四军医大学 ， 口腔临床医学， 2008， 博士

【摘要】 龋坏、创伤及修复失败导致大量牙体组织丧失的患牙通常需要借助桩-核为全冠修复体提供固位和抗力支持,使修复后的患牙可以承载各种口腔功能性应力。与传统的铸造桩-核和成品金属桩相比,纤维增强型树脂根管桩(简称纤维桩)具有优良的生物机械性能和美观修复效果,近年来广泛的被用于修复无髓牙。纤维桩的弹性模量与牙本质相近,受力时牙根内的应力分布均匀,可有效降低根折率;纤维桩与树脂粘接材料合用可以加固因根管预备变薄弱的牙根;玻璃、石英等纤维制成的纤维桩与自然牙颜色接近,可以满足全瓷修复和前牙美容修复的要求;纤维桩具有良好的抗腐蚀性,可以避免金属桩的电化学腐蚀导致的修复体周围组织的着色和变色等问题。但是大量的实验室及临床实验表明,纤维桩修复的主要失败类型是各种形式的粘接失败,如粘接界面出现裂隙、桩-核松动或者桩-核脱落等。因此,如何提高根管牙本质与树脂粘接材料之间、以及纤维桩与树脂粘接材料之间的粘接性能是一个具有临床意义的研究方向。关于根管牙本质与树脂粘接材料的粘接,目前认为主要有三方面的因素影响粘结效果:一是经过根管治疗和桩道预备后的根管壁表面覆盖着较厚的玷污层,牙本质粘接剂不能有效渗透形成粘接;二是根管壁是一个狭窄而有限的空间,根据C-因子理论,树脂粘接材料聚合时会形成很大的收缩应力,影响粘接强度;三是不同深度的桩道内壁间牙本质结构上存在着差异,操作的难易程度也不同,以致深部的桩道牙本质粘接强度较低,影响纤维桩在局部的固位强度。关于纤维桩与各类复合树脂材料的粘接,则因为环氧树脂基质的纤维桩与Bis-GMA基质的复合树脂之间缺乏有效的化学粘接,粘接性能亦亟待进一步提高。本课题针对以上这些影响纤维桩固位性能的因素所设计,目的是通过扫描电子显微镜超微结构观察以及薄片推出实验、微拉伸测试等实验力学测试的方法,全面分析纤维桩粘接过程中粘接基质、粘接材料及操作方法等因素对纤维桩固位性能的影响,进一步探讨纤维桩在根管内的固位原理,并在此基础上尝试利用不同的表面处理方法、粘接材料和粘接技术来提高纤维桩的固位能力。课题研究分为两部分,第一部分分为三节,是关于纤维桩在根管内的固位性能的研究。第二部分由两个实验组成,是关于纤维桩与不同复合树脂材料包括树脂水门汀和核树脂的粘接性能的研究。第一部分实验中,第一节观察了不用粘接剂、使用全酸蚀和自酸蚀粘接剂在粘接界面形成的杂化层和树脂突结构以及根充和不根充两种处理对桩道内壁的牙本质表面结构的作用,比较了粘接剂、桩道深度以及桩道预备方法对纤维桩在根管内的微推出强度的影响。实验结果发现:根管充填、粘接剂和桩道深度都对纤维桩的固位性能有影响;根管充填会在深部的桩道表面形成一层富含牙本质碎屑、牙胶和糊剂的玷污层,会显著降低纤维桩在深部桩道的微推出强度;使用粘接剂只能提高纤维桩在上部桩道内的固位强度,在下部桩道,酸性较弱的自酸蚀粘接剂对纤维桩的固位强度无提高作用;全酸蚀粘接剂对纤维桩的粘结作用受桩道深度的影响,自酸蚀粘接剂对纤维桩的粘结作用不受桩道深度的影响。第二节包括两个实验:实验一比较了3%H2O2、5.25%NaOCl+17%EDTA这两种化学冲洗液与四种牙本质粘接剂(一种全酸蚀、三种自酸蚀)对纤维桩固位性能的影响;实验二比较了35%磷酸酸蚀、5.25%NaOCl+17%EDTA化学溶液冲洗以及超声振动结合5.25%NaOCl+17%EDTA化学溶液冲洗去除桩道内壁玷污层的能力,以及它们对两种自酸蚀粘接剂粘接纤维桩的固位效果的影响。实验结果发现:两种化学冲洗液对纤维桩固位强度的作用均因粘接剂的种类和化学成分而异;35%磷酸酸蚀、5.25%NaOCl+17%EDTA化学溶液冲洗以及超声振动结合5.25%NaOCl+17%EDTA化学溶液冲洗这三种根管壁处理方法均可以有效去除桩道内壁表面的玷污层;35%磷酸酸蚀、超声结合EDTA/NaOCl溶液冲洗可以提高自酸蚀粘接剂在深部桩道内粘接纤维桩的微推出强度,但是单纯的5.25%NaOCl+17%EDTA化学溶液冲洗对纤维桩的固位强度没有影响。第三节包括两个实验:实验一借助薄片推出实验比较了桩道深度和粘接材料种类对纤维桩的固位强度的影响;实验二研究了双固化型树脂性粘接材料的固化方式对纤维桩的微推出的影响。实验结果发现:粘接材料的种类和桩道深度都会影响纤维桩在根管内的固位强度;粘接材料的固化方式对纤维桩固位性能的影响因材料的种类和成份而异;使用双固化型的粘接剂和树脂水门汀粘接透明的纤维桩时,无需在水门汀充填前单独光照粘接剂使其固化,但树脂水门汀应被充分光照固化以获得最理想的粘接性能和机械性能。在第二部分的实验中,实验一比较了不同方式固化的表面处理剂对预硅烷化的纤维桩与两类复合树脂(流动性树脂水门汀、混合型核树脂)的微拉伸强度;实验二借助简单水存模型,评价了水存一个月的老化条件对粘接剂表面涂层的纤维桩与树脂水门汀和核树脂粘接的界面密合度及微拉伸强度。实验结果发现:自固化粘接剂表面涂层可以提高预硅烷化的纤维桩与混合型核树脂的粘接强度,但对于桩与流动性树脂水门汀的粘接强度无影响;光固化粘接剂表面涂层对预硅烷化的纤维桩与两种复合树脂的粘接强度均无影响;光固化粘接剂表面涂层后的纤维桩水存1个月后桩-树脂粘接界面出现了明显的裂隙且桩与复合树脂的粘接强度显著降低;自固化粘接剂表面涂层或不用粘接剂表面涂层的纤维桩与复合树脂的粘接性能在1个月内未观察到明显的老化现象。更多还原

【Abstract】 A post-core restoration is usually recommended for endodontically treated teeth in cases when little coronal tooth tissue remains due to caries, traumas or removal of previous restorations. Post and core built-up is necessary to provide support to the full crown and thus enable the final restoration to sustain various oral functional load. Recently, fiber posts have been more popularly used than conventional cast post-core and pre-fabricated metallic post in the restoration of endodontically treated teeth. Due to the similar elastic modulus with dentin, fiber posts could allow more favorable stress distribution and reduce the risk of root fractures. Fiber posts in combination with resin cements could reinforce the root weakened by the root canal preparation. Lots of glass- or quartz- fiber posts have natural tooth color, supporting all-ceramic and esthetic restoration for anterior teeth. Owe to the good biocompatibility and resistance to corrosion of fiber posts, the problems of discoloration, corrosion and secondary infection induced by metallic posts can therefore be delimited when using fiber posts. However, many laboratorial and clinical studies have revealed that the most frequent failure mode of fiber post restoration is adhesive failure. Therefore, it is clinical important to develop procedures that can effectively enhance the adhesion between intraradicular dentin and resinous luting materials and/or between luting materials and fiber posts.As to the adhesion between intraradicular dentin and luting resin materials, it is relatively weak considering three parts of factors. The first is that the post space after sequential endodontic treatment and post-space preparation is covered by a thick smear layer, which may hamper the infiltration of adhesive resin. Secondly, root canal is a narrow and confined space, so that resin polymerization may produce contraction stress and influence the bonding to dentin according to the C-factor theory. The last factor is that the dentinal structure is different within different root regions and the deep region is hard to access by both instrument and luting materials. The bond strength in deep root region is therefore lower than that in upper region. Concerning the adhesion between fiber posts and various composite resins, it is still inferior to the adhesion of dental substrate because of the chemical incompatibility or an absence of chemical bond between the epoxy resin based fiber posts and the Bis-GMA based composite resin.This study is designed to improve the retention of fiber posts when taking into account these factors. The purpose of this study was to evaluate the effect of bonding substrate, luting material, and luting procedure etc. on the retention of fiber posts, to investigate the retentive mechanism of fiber posts, and to attempt to improve the retentive strength of fiber posts using different surface treatments and luting procedures as well.The experimental study could be divided into two parts. Part 1 is composed of three sections and is about the evaluation of retentive strength of fiber posts in root canal. Part 2 is composed of two experiments and is about the adhesion between fiber posts and different composite resin, including resin cements and resin core.In Section 1 of Part 1, the hybrid layer and resin tags formed by different adhesives, as well as the morphological aspects of post-space dentin either with or without root canal obturation, were observed using SEM. Also, the effect of root canal obturation, root region and luting procedure on the push-out strength of fiber posts in roots were evaluated in this section. The following results were achieved:①r oot canal obturation, root region and luting procedure all have an effect on the push-out strength of fiber posts;②root canal obturation could produce a smear layer containing large amount of dentinal debris, gutta-percha/sealer remnants, which decreased the push-out strength of fiber posts by interfering with the infiltration of adhesives;③the use of adhesive could only improve the retention of fiber posts in coronal root region, while the use of mild self-etching adhesive showed no effect on the improvement of post retention in the apical root region;④the push-out strength of fiber posts using a total-etching adhesive was affected by the root region, while the push-out strength of fiber posts using a self-etching adhesive was not affected by the root region.There are two experiments in Secion 2 of Part 1. In experiment 1 the effect of two chemical irrigations -3%H2O2 and 5.25%NaOCl+17%EDTA on the retention of fiber posts using four adhesives (1 total-etching and 3 self-etching) was evaluated. In experiment 2, the efficacy of three post-space treatments, 35% phosphoric acid etching, irrigation using 5.25%NaOCl+17%EDTA and ultrasonic agitation associated with 5.25%NaOCl+17%EDTA, in the removal of smear layer on post spaces were evaluated with SEM. The effect of these post-space treatments on push-out strength of fiber posts were also investigated in this experiment. The following results were achieved:①The effects of 3%H2O2 and 5.25%NaOCl+17%EDTA irrigations on the retention of fiber posts were both dependent on the type and chemical composition of adhesives;②All the treatments tested in Experiment 2 were effective in the removal of the smear layer on the post-spaces;③Treatment with 35% phosphoric acid or ultrasonic agitation associated with EDTA/NaOCl irrigation on the post space improves the retention of fiber posts in the apical region;④A solo irrigation with an EDTA/NaOCl solution had no effect on the retention of fiber-posts.There are two experiments in Secion 3 of Part 1. In experiment 1 the push-out strength of fiber posts luted using four luting materials were compared. In experiment 2 the effects of curing modes of dual-cured luting systems and root regions on the push-out strength of fiber posts were evaluated. The following results were achieved:①Luting materials, luting procedures and root regions all showed a significant effect on the retention of fiber posts;②the retention of fiber posts were affected by the curing modes of dual-cured luting materials, which depended on the type of the materials;③I t is not necessary to separately light cure the dual-cured dentin adhesives before post cementation when translucent fiber posts were used;④T he photoirradiation of dual-cured resin cement after post cementation may give an increase to both bonding and mechanical strength of fiber posts.There are two experiments in Part 2. In experiment 1 the effect of coupling agents on the adhesion of pre-silanized fiber posts to two composite resins (One flowable resin cement and one hybrid core resin) were evaluated. In experiment 2 the durability of bonding interfaces between adhesive-mediated fiber posts and two types of composite resins were investigated using a simplified model of accelerated aging. The following results were achieved:①The use of self-cured coupling agent could increase the bond strength of pre-silanized fiber posts to hybrid core resin, while it showed no effect on adhesion of fiber posts to flowable resin cement;②The use of light-cured coupling agent had no effect on the adhesion of pre-silanized fiber posts to composite resin regardless of the type of composite resin;③The bonding interface between light-cured adhesive mediated fiber posts and composite resin presented degradation after storage in water for one month;④No degradation were detected at the bonding interfaces between self-cured adhesive mediated or no treated fiber posts and composite resin after storage in water for one month.更多还原