光固化流动复合树脂修复老年人根面龋的临床观察

目的探讨老年人根面龋充填治疗的合适材料。方法288颗患牙随机分为3组,分别用玻璃离子水门汀、光固化流动复合树脂和银汞合金充填修复,随访2年。结果3种材料修复成功率分别为81.2%、92.7%、75.0%。经统计学分析,光固化流动复合树脂组优于玻璃离子组,玻璃离子组优于银汞合金组,差异有统计学意义(P<0.05)。结论光固化流动复合树脂是修复根面龋较为合适的材料,其疗效优于银汞合金与玻璃离子。     

楔状缺损充填治疗后牙颈部硬组织应力分析

目的 了解楔状缺损患牙充填治疗后，牙颈部硬组织的应力分布。方法 在下颌前磨牙颊舌向纵剖面上设计楔状缺损模型，选择复合树脂和玻璃离子水门汀两种材料模拟充填缺损区；用二维有限元法对模型受He力作用时牙颈部应力做分析。结果 复合树脂充填和玻璃离子水门汀充填均可使缺损附近的应力集中明显改善；缺损最深处的最大主应力值分别降至36．2MPa和42．5MPa，接近正常牙应力值32．6MPa。结论 楔状缺损充填修复可缓解缺损区牙体硬组织的应力集中。     

三种充填材料修复磨牙大面积缺损221例分析

目的:观察三种充填材料修复磨牙大面积缺损的临床疗效。方法:通过对254个磨牙大面积缺损的患牙进行根管治疗后置根管桩与自攻螺纹钉行支架固位,分别用登士柏TPH复合树脂、银汞合金、玻璃离子水门汀充填,1年后复查。结果:1年后复查,TPH修复成功率97.82%,银汞合金修复成功率74.69%,玻璃离子水门汀修复成功率68.85%。结论:TPH树脂联合根管桩钉修复磨牙大面积缺损临床疗效明显优于银汞合金与玻璃离子水门汀。     

三种修复方法用于楔状缺损修复的疗效评价

目的 比较玻璃离子水门汀、复合树脂及联用两种材料用于楔状缺损修复的远期临床疗效。方法 89例360颗楔状缺损牙分别用玻璃离子水门汀、复合树脂和联用两种材料修复。于修复后1、2及3年,比较成功率等指标情况。结果 玻璃离子水门汀防龋性和黏结性优于复合树脂,复合树脂的色彩稳定性优于玻璃离子水门汀;3年后,联用组临床成功率为88.6％高于玻璃离子水门汀组(74.8％)或复合树脂组(7.6％),差异显著(P<0.05)。结论 玻璃离子水门汀和复合树脂联用优于单独充填。     

比较6种口腔材料对体外生物膜形成的影响

目的比较体外混合菌在不同充填材料表面形成早期生物膜的能力,探讨生物膜状态下不同充填材料细菌形成的差异。方法用6种不同修复材料按临床比例制成试件各3件,将各试件放入国际标准菌株牙龈卟啉单胞菌、具核梭杆菌、伴放线放线杆菌、粘性放线菌、血链球菌、变形链球菌混合培养24h,使之在试件表面形成生物膜。在激光共聚焦扫描显微镜(LCSM)下观察生物膜厚度和平均荧光强度,比较不同充填材料表面生物膜细菌形成的差异。结果形成的生物膜平均厚度依次为聚羧酸锌水门汀>磷酸锌水门汀>玻璃离子体水门汀>复合树脂>银汞合金>富士Ⅱ型玻璃离子水门汀。组间比较发现:四种充填材料生物膜厚度无统计学的差异,富士Ⅱ型玻璃离子水门汀、银汞合金的生物膜厚度与两种垫底材料之间都有显著性差异,复合树脂、玻璃离子体水门汀、磷酸锌水门汀的生物膜厚度与聚羧酸锌水门汀有显著性差异。结论材料表面形成的不同生物膜厚度提示:富士Ⅱ型玻璃离子水门汀、银汞合金具有较强的抑制生物膜形成的能力。     

下颌第一磨牙任意两壁缺损不同充填材料全瓷冠修复的三维有限元应力分析

目的:应用三维有限元法对不同充填材料全瓷冠修复两壁缺损下颌第一磨牙应力分析。方法:通过CBCT扫描离体牙,Mincis三维重建,Geomagic优化处理,Ansys布尔运算建立下颌第一磨牙两壁缺损6种模型,分别使用银汞合金充填及复合树脂充填全瓷冠修复,在最大、垂直、斜向及水平4种载荷下,分别比较牙本质Mohr应力分布及牙本质最大Mohr值。结果:下颌第一磨牙牙冠缺损1/2时,不同充填材料全瓷冠修复,同一载荷下6种缺损模型的牙根应力分布无明显区别,银汞合金充填全瓷冠修复的应力集中区较复合树脂充填全瓷冠修复更偏向根方。结论:下颌第一磨牙牙冠缺损1/2时,复合树脂充填全瓷冠修复优于银汞合金充填全瓷冠修复,且缺损位置对修复效果无明显影响。     

各种充填材料修复牙齿颈根部龋的微漏研究

选择临床上常用的银汞合金、进口或国产玻璃离子水门汀、银合金粉玻璃离子水门汀和光固化复合树脂作充填材料,采用染料逆扩散法,测出牙齿浸出液中曙红的含量,观察充填材料与牙齿颈根部微漏的情况。观察结果表明,GC玻璃离子水门汀与牙齿颈根部组织粘接最好,其次为国产玻璃离子水门汀、复合树脂、银粉玻璃离子水门汀、银汞合金。     

几种常用及新型充填材料密合度的实验研究

目的 :为前牙及后牙充填选择合适的材料提供依据。方法 :将 75颗离体牙分为五组 ,分别充填银汞合金 ,银汞合金 +粘接剂 ,复合树脂 ,玻璃离子 ,DyractAP。所有离体牙均进行染料渗透试验 ,观察染料渗漏深度。结果 :单纯银汞合金充填渗漏率最大 ,与银汞合金 +粘接剂组渗漏率具有显著性差异 (p <0 0 1) ;复合树脂、GC及DyractAP相比 ,DyractAP密合度最好 ,三者渗漏率具有显著性差异 (p<0 0 5 )。结论 :对于后牙面充填 ,银汞合金粘接修复是首选方法。对于楔状缺损及根颈部缺损 ,以Dyract较好。     

自攻钉临床应用的体会

在临床上 ,常见到有的患牙缺损很大 ,缺乏力学固位形 ,致充填体容易脱落的情形 ;过去对该类患牙通常予以拔除或充填后假以牙冠修复。现根据该类患牙的缺损大小及牙体的情况 ,攻入 1～ 4枚自攻自断螺纹钉 ,以增加充填体的固位力 ,使一些残冠得以修复保存 ,或免除了充填后的牙冠修复。1　临床资料 :　笔者集中复查了 1997年 5月～ 1999年4月治疗的患者 10 2人 ,115牙。患者年龄 2 3～ 80岁。前牙46颗 ,其中 42颗牙的补牙材料为光固化复合树脂 ,3颗牙为玻璃离子 ,1颗牙为银汞合金。后牙 6 9颗 ,其中 2 2颗牙的补牙材料为后牙用光固化复合树脂 ,…     

几种玻璃离子水门汀磨耗性能的比较

在选择牙体修复材料时，耐磨性是一个需要考虑的重要问题。目前，广泛用于口腔各类洞的修复材料主要是银汞合金、复合树脂及玻璃离子水门汀。这些材料在口腔内的磨耗主要是由牙刷磨耗和咀嚼造成的［１］。本研究采用自制的往复式牙刷磨耗机，对比研究了４种玻璃离子水门汀...     

桩核材料对牙本质应力分布的影响

目的 研究6种不同材料行桩核修复前后牙本质的应力分布情况,为临床桩材料的选择提供理论依据。方法 采用螺旋CT扫描数据建立上颌中切牙烤瓷桩核冠的三维有限元模型,在此模型上对用铸造Ni-Cr合金、铸造钛合金、铸造金合金、玻璃纤维树脂、聚乙烯纤维树脂及普通复合树脂6种材料行桩核修复前后的牙本质应力分布情况进行数值分析。结果 在6种材料中,与桩修复前的烤瓷熔附金属冠修复牙相比较,临床最常用的铸造Ni-Cr合金桩修复使桩尖周围牙本质的最大主应力和Von Mises应力分别升高了152％和162％;聚乙烯纤维树脂桩修复后,牙本质中的应力分布情况无明显改变。其他材料行桩修复后牙本质中应力分布的差异较大。桩植入后对牙本质应力分布模式的影响与桩的弹性模量密切相关。结论 与牙本质弹性模量接近的聚乙烯纤维树脂更适合用于桩修复。     

不同垫底材料对全瓷嵌体修复应力分布影响的三维有限元研究

目的应用三维有限元应力分析法对采用不同垫底材料的上颌前磨牙Ⅱ类洞全瓷嵌体进行应力计算分析,为临床全瓷嵌体修复垫底材料的选择提供理论参考。方法建立垫底厚度为1.0mm的上颌前磨牙Ⅱ类洞嵌体修复三维有限元模型。采用ANSYS10.0有限元分析软件,计算分析应用3种不同弹性模量的垫底材料时,全瓷嵌体修复各个部分的应力分布状况。结果随着垫底材料弹性模量的增高,且越接近牙本质弹性模量时,嵌体、牙釉质和粘结剂层的最大主应力逐渐减小;而牙本质的最大主应力逐渐增高。结论当牙体缺损较小,洞型较浅时,可采用弹性模量较高,并与牙本质弹性模量接近的垫底材料;而当牙体缺损洞型较深,洞底部牙本质较薄弱时,应采用弹性模量较低的垫底材料。     

Conservative restoration of severely damaged endodontically treated premolar teeth: a FEM study

The aim of this finite element method (FEM) study was to test two different restorative techniques used for construction of severely damaged endodontically treated premolar teeth using Finite Element Stress Analysis Method. In this study, four types of three-dimensional (3-D) FEM mathematical models simulating (1) a sound lower single rooted premolar tooth with supporting structures; (2) a root-filled lower premolar tooth without lingual cusp, restored with resin composite; (3) a root-filled lower premolar tooth without lingual cusp restored with resin composite in combination with a polyethylene fiber which is placed circumferentially to help to create a composite lingual wall; (4) a root-filled lower premolar tooth without lingual cusp restored with resin composite in combination with a glass fiber post, were modeled. A 300-N static vertical occlusal load was applied on the node at the center of occlusal surface of the tooth to calculate stress distributions. Solidworks/Cosmosworks structural analysis programs were used for FEM analysis. The analysis of the von Mises stress values revealed that maximum stress concentrations were located at loading areas for all models. Root dentine tissue, lingual cortical bone, and apical bone structures were other stress concentration regions. There were stress concentration differences among the models at root dentine tissue. Although the distribution pattern was similar with composite resin restored tooth model, highest stress values were observed at root dentine in the model restored with post-and-core. Post structure accumulated more stress on its own body. Stress distribution patterns of sound tooth and fiber-reinforced restoration models were found as similar. The present study showed that the use of post material increased the stress values at root dentine structure while reinforcing the restoration with a fiber decreases stress transmission. Fiber-reinforced restoration provided stress distributions similar to sound tooth.     

Additional studies on the distribution of stresses during vertical compaction of gutta-percha in the root canal.

OBJECTIVE: This study was designed to investigate the effect of certain pathological alterations of the dental structures (diminishing bone support, internal resorption, root perforation, periapical lesion) on stress distribution during root canal filling procedures by the warm vertical compaction technique. DESIGN: The computer stress analyses were done for a maxillary canine tooth model which was based on dimensions recovered from a human cadaveric maxilla scanned by CT. METHODS: The finite element method was used to calculate the stresses generated during root canal filling procedures by warm vertical compaction technique. Patterns of stress distribution associated with various alterations in dental structures were investigated. For this purpose 60 cases were simulated. The hypothetical force of 10 N is taken as a unit representation. For other magnitudes of applied force, the corresponding stresses would be scaled directly because the calculations were made for linear materials. RESULTS AND CONCLUSION: It is found that, when diminishing bone support and internal resorption are concurrently simulated, a marked increase in stress magnitudes occur (maximum von Mises stress 5.37 N/mm2). However, these values still remain much below the most frequently reported tensile strength of dentine (50-100 N/mm2). If dentist's handwork is transformed into equivalent edge tractions on gutta-percha, then stresses in dentine, even when they are corrected for 3-kg applied force, appear to remain below fracture strengths of this material. This result leads us to conclude that when warm vertical compaction technique is skillfully performed and inadvertent undue force is not applied, a premature root fracture in a large rooted maxillary anterior tooth with straight root canal anatomy is not likely to occur, even for the unfavourable conditions simulated in our model. This result, like all results derived from modelling applications, is of course contingent upon agreement between the way in which the clinical operations are performed and the way in which they are mirrored for computer representation. We believe that the approach described here avoids the spurious stresses that have been reported in similar investigations.     

An evaluation of localized debonding between fibre post and root canal wall by finite element simulation

AIM: To investigate the effect of localized bonding defects between fibre post and root canal wall on the stress distribution in the radicular dentine. METHODOLOGY: A tooth restored with a fibre post together with the alveolar bone were axisymmetrically modelled. A total of four models with localized debonding at the post to canal wall interface in different locations were analysed: Model A: perfect bonding layer over the entire interface; Model B: debonding at the cervical 1/3 of the interface; Model C: debonding at the mid 1/3; and Model D: debonding at the apical 1/3. A tooth restored without using a post was also included as the control (Model E). A load of 50 N was applied to the top of the full veneer cast crown at angles of 0, 15, 30, and 45 degrees with the tooth's longitudinal axis. The stress distribution across the fibre post and root dentine was compared. RESULTS: Higher stresses were generated in the radicular dentine as a function of the load angle. The differences in the stress distribution were negligible between the four models and virtually the same as that for model E (control). CONCLUSIONS: In this simulation, localized debonding at the fibre post to root canal wall interface, regardless of its location along the post, had little effect on the stress distribution in the root dentine.     

不同形态的氧化锆陶瓷桩对牙本质应力的三维有限元分析

目的:通过三维有限元分析的方法模拟牙体组织的力学组成,分析不同形态的氧化锆陶瓷桩修复上颌中切牙后对周围剩余牙本质的应力分布规律。方法:根据成年男性上颌中切牙的标准数据,通过ANSYS 12.0软件直接建立平行桩、锥形桩、末端锥形桩3种不同形态的氧化锆陶瓷桩修复上颌中切牙的三维有限元模型;对建立的模型进行网格划分;通过加载边界条件,设定模型主参数以及加载静态载荷;分析牙本质内的Von Mises应力的分布规律,观察不同形态的桩核对其周围剩余牙本质的影响。结果:成功建立了不同形态的氧化锆陶瓷桩核和牙根的三维有限元模型;柱形桩和锥形桩的牙本质应力分布沿牙本质界面向牙颈部逐渐增大达高峰,末端锥形桩应力最高峰在根末1/3;锥形桩所受的牙本质应力大于柱形桩,且锥度越大,受到的应力也相应越大。结论:柱形桩组所受应力值均小于锥形桩组,末端锥形桩组在牙根部应力值最大;选择氧化锆材料时,柱形桩为最佳设计。     

下颌第二前磨牙3种修复方式的应力分析

目的采用3种不同的设计方式修复根管治疗后牙冠完整的下颌第二前磨牙,观察其牙本质的应力大小及分布情况。方法采用螺旋式CT扫描获取数据,建立下颌第二前磨牙4种情况下的三维有限元模型：1）直接全冠修复;2）用树脂材料充填开髓洞形后全冠修复;3）铸造镍铬合金桩核与全冠修复;4）纤维桩树脂核与全冠修复。在颊尖顶偏颊侧加载,比较牙本质中最大主应力和von Mises应力的大小及分布情况。结果应力计算分析的结果显示：铸造镍铬合金桩修复时,桩尖周围有明显的应力集中区;纤维桩修复时桩尖周的应力集中不明显;无桩设计而直接用树脂材料充填开髓洞形时,其应力大小和分布与对照组基本一致。结论在本实验条件下,与铸造镍铬合金桩相比,纤维桩更适合于下颌前磨牙的桩核冠修复;在下颌前磨牙牙冠部有足够牙体组织的情况下,在根管中放置桩不一定是必须的,直接用树脂材料充填开髓洞形后行全冠修复也是一种可能的选择。     

Demineralisation and remineralisation of dentine caries, and the role of glass-ionomer cements

In accordance with the principles of modern operative dentistry, to conserve tooth structure and to use therapeutic restorative materials, an understanding of the carious process in dentine and the biological properties of glass-ionomer cements (GICs) are necessary. Delineation of the outer necrotic from the inner vital and remineralisable carious dentine allows for the preservation of tooth structure. This delineation is not possible when relying on visual and tactile perceptions, but requires the use of a caries detecting dye. GICs are ideal dentine substitutes because of their anticariogenic properties, stable long-term ionic bonding, and ability to assist the process of remineralization. The range of usage of these restorative materials continues to expand with the development of improved products.     

Investigation of the operative response of a group of general dental practitioners to varying extents of proximal caries.

The aim of this investigation was to assess the operative response of a representative sample of Irish General Dental Practitioners of various times since qualification to carious lesions of varying extent in both approximal surfaces of a lower left first molar tooth. 82 General Dental practitioners participated. The dentists were asked to treat 2 manikin teeth for minimal caries on both approximal surfaces extending to the enamel dentine junction, 2 teeth for caries extending approximately to half the thickness of the dentine and 2 teeth for caries extending more than 3/4 of the dentine thickness. Weight measurements were made of the tooth substance cut away. Mean volumes of tooth material removed ranged from 21 mm3 for minimal caries to 76 mm3 for the largest amount of caries. A two-factor analysis of variance revealed that the type of cavity preparation the dentist used had a significant effect on the volume of tooth material removed for all three extents of caries. Time since graduation had a significant effect on the volume of tooth material removed for the least extent of caries, but not for the other categories of carious involvement.     

On the repair of the dentine barrier

The overall aim of this thesis was to study some aspects of the repair of the dentine barrier, especially in conjunction with dental pulp capping. Understanding the events leading to the healing of the dentine and pulp, and hence successfully preserving the vitality and functions of the tooth, would lead to a scientific basis for a less invasive treatment of pulp exposures than performing root canal treatments. The surfaces of the body have physiological barrier functions aimed at protecting the body from external noxious agents. In the tooth, the odontoblasts, which line the outermost part of the pulp and are responsible for the formation of dentine, play a central role in the barrier function and thus in the defence mechanisms of the tooth. The micro-organisms in the caries lesion can reach the pulp via the dentinal tubules. However, the barrier function helps to prevent microbial invasion and thereby avoid deleterious inflammation and subsequent necrosis of the pulp. Dentine repair is an important part of the barrier function. There are however doubts as to whether the repair also leads to restitution of the function and the ability to withstand bacterial influx over the longer term. Pulp capping is a treatment method used when the pulp has been exposed in order to stimulate healing of the pulp and dentine. The evidence for repair of the dentine after pulp capping in humans has been studied by means of a systematic review. The focus of the literature search was studies performed in humans where hard tissue formation had been studied with the aid of a microscope. We concluded, based on the limited evidence available, that calcium hydroxide based materials but not bonding agents promote formation of a hard tissue bridge. Scientific evidence was lacking as to whether MTA was better than calcium hydroxide based materials in this regard. A gel (Emdogain Gel) containing amelogenin, known to be involved in dentinogenesis, was evaluated with regard to formation of hard tissue in a clinical study. A greater amount of hard tissue was formed after application of the gel compared to the control. Characterization of the tissue concluded it to be dentine, based on its content of type 1 collagen and dentine sialoprotein, although it was not formed as a continuous bridge covering the pulp wound. Beneath a deep caries lesion an important part of the barrier function is the odontoblasts' response to bacteria with the formation of new dentine. A cell model with odontoblasts was used to study the effects of clinical isolates from a deep carious lesion on their viability and production of type 1 collagen, the major component of the dentine in the early stages of its formation. There were bacteria that negatively affected the viability of the odontoblast-like cells and different bacteria varied in their effects on type 1 collagen production, suggesting that some bacteria may have a direct influence on the odontoblasts' ability to form dentine. In summary; Emdogain Gel initiated dentine formation, though not in a form that could constitute a barrier and there are indications that bacteria may differentially affect the odontoblasts' ability to repair the dentine barrier.