Microleakage of core materials for complete cast gold crowns

This study evaluated the microleakage patterns of complete cast-gold crowns cemented onto teeth rebuilt with pin-retained cores made from cast gold, amalgam, composite resin, and silver-reinforced glass ionomer by using three different cements (zinc phosphate, glass ionomer, and resin cement). Crowns cemented onto unrebuilt tooth preparations with zinc phosphate cement served as controls. The cemented specimens were thermocycled between 4 degrees and 50 degrees C in waterbaths. They were then embedded in epoxy resin and sectioned. The extent of marginal microleakage was evaluated with a stereomicroscope and scored. The findings indicated that the type of luting agent used appeared to affect microleakage more than the core material. No significant differences in the degree of microleakage were found under crowns cemented onto teeth rebuilt with the four core materials when cemented with the same luting cement.     

不同粘接剂对金属烤瓷冠边缘微渗漏影响的研究

目的 评价4种不同粘接剂在金属烤瓷冠修复中的微渗漏情况.方法 制作16个金属烤瓷冠,随机分成4组,分别采用玻璃离子黏固剂、树脂加强玻璃离子黏固剂、PanaviaF粘接剂和super-Bond C&B粘接剂黏固于前磨牙,经温度循环试验后,将样本浸入2%品红溶液中24 h,用体视显微镜观察牙-黏固剂界面边缘微渗漏状况,并进...     

Microleakage and marginal gap of adhesive cements for noble alloy full cast crowns

Very limited comparative information about the microleakage in noble alloy full cast crowns luted with different types of adhesive resin cements is available. The purpose of this study was to evaluate the microleakage and marginal gap of two self-adhesive resin cements with that of other types of adhesive luting cements for noble alloy full cast crowns. Fifty noncarious human premolars and molars were prepared in a standardized manner for full cast crown restorations. Crowns were made from a noble alloy using a standardized technique and randomly cemented with five cementing agents as follows: 1) GC Fuji Plus resin-modified glass ionomer cement, 2) Panavia F 2.0 resin cement, 3) Multilink Sprint self-adhesive resin cement, 4), Rely X Unicem self-adhesive resin cement with pretreatment, and 5) Rely X Unicem with no pretreatment. The specimens were stored in distilled water at 37°C for two weeks and then subjected to thermocycling. They were then placed in a silver nitrate solution, vertically cut in a mesiodistal direction and evaluated for microleakage and marginal gap using a stereomicroscope. Data were analyzed using a nonparametric Kruskal-Wallis test followed by Dunn multiple range test at a p<0.05 level of significance. The Rely X Unicem (with or with no pretreatment) exhibited the smallest degree of microleakage at both tooth-cement and cement-crown interfaces. The greatest amount of microleakage was found for Panavia F 2.0 resin cement followed by GC Fuji Plus at both interfaces. No statistically significant difference in the marginal gap values was found between the cementing agents evaluated (p>0.05). The self-adhesive resin cements provided a much better marginal seal for the noble alloy full cast crowns compared with the resin-modified glass ionomer or dual-cured resin-based cements.     

应用扫描电镜对金属烤瓷冠不同粘接剂边缘微渗漏的比较研究

目的:评价不同粘接剂粘固金属烤瓷冠的边缘微渗漏情况,为临床选择粘接剂提供实验依据.方法:选取传统的玻璃离子粘接剂、树脂加强型玻璃离子粘接剂、Panavia F粘接剂和Super-Bond C&B粘接剂4种材料,应用于离体牙金属烤瓷冠的粘接,用扫描电镜测量粘接剂与牙组织面间微缝隙的缝隙宽度.数据处理用SPSS 11.5软...     

Marginal seal of injection-molded ceramic crowns cemented with three adhesive systems

This in vitro investigation evaluated the marginal seal of an injection-molded ceramic crown system used in combination with three adhesive luting systems. One of these systems was a glass-ionomer cement and the other two were based on composite resin materials. One of the latter materials is claimed by the manufacturer to bond to tooth structure and also to porcelain. The final luting material was used in conjunction with a commercially available porcelain bonding system and specific dentin bonding pretreatments. Following thermocycling, the marginal seal of the crowns was tested by use of a chemical marker intrusion technique. The extent of leakage along the sectioned crown/luting agent/tooth structure interfaces was recorded by using digital imaging microscopy. Minimal microleakage was demonstrated with the composite luting cement used in association with specific porcelain and dentin bonding pretreatments.     

3种黏接剂的微渗漏比较

目的采用冷热循环后染色的方法,比较贵金属、树脂两种不同嵌体材料使用树脂黏接剂、玻璃离子水门汀、磷酸锌水门汀3种不同黏接材料的微渗漏。方法在前磨牙上分别制作贵金属、树脂嵌体各30件;分别用3种不同黏接材料与相应牙体窝洞黏固。将所有试件冷热循环后品红染色,沿嵌体长轴剖开,观测染料渗漏的情况。并测量修复体和牙体边缘的距离。结果各嵌体组都发生了明显的微渗漏。每组的染色都达到了窝洞底并且累及牙本质,龈缘的染色比牙合面深,而树脂黏接剂相对玻璃离子水门汀和磷酸锌水门汀染色浅。结论3种黏接剂经过4000次冷热循环以后边缘都发生了渗漏。染色显示渗漏发生在龈缘的量比牙合面的量大,而其与边缘的宽度未显示明显的关联。     

Leakage of various types of luting agents

Freshly extracted molar teeth were prepared for complete cast gold crowns cemented with either zinc phosphate cement, polycarboxylate cement, glass ionomer cement, a resin luting agent, or a zinc oxide-eugenol temporary cement. The specimens were tested at 1-, 6-, and 12-month intervals with radioactive 45Ca. The specimens were sectioned, autoradiographs were made, and the marginal leakage was evaluated on a scale of 0 to 3. The results showed that zinc phosphate, polycarboxylate, and glass ionomer cements are equally suited for permanent cementation of restorations. The resin luting agent showed high initial leakage, indicating that it is not as desirable for permanent cementation purposes. The zinc oxide-eugenol cement showed increased leakage with time but is well suited for its indicated purpose, temporary cementation.     

两种粘结剂粘结CAD/CAM氧化锆全瓷冠边缘微渗漏的研究

目的评价两种不同粘结剂在CAD/CAM氧化锆全瓷冠修复中的边缘微渗漏情况。方法制作10个CAD/CAM氧化锆全瓷冠,随机分成2组,分别采用磷酸锌水门汀粘结剂和Panavia F树脂粘结剂粘固于前磨牙,经温度循环试验后,将样本浸入2%品红溶液中24h,用体视显微镜观察牙-粘结剂界面边缘微渗漏状况,并进行分级评估。结果采用SPSS 17.0软件对2组的微渗漏程度进行统计分析,得出Panavia F树脂粘结剂微渗漏小于磷酸锌水门汀粘结剂(χ2=81.142,P<0.05)。结论 Panavia F树脂粘结剂具有较优越的抗边缘微渗漏性能。     

Marginal leakage of visible light-cured glass ionomer restorative materials

This study examined the sealing of two visible light-cured glass ionomer restorative materials and a conventional glass ionomer. Class V cavity preparations were completed at the cementoenamel junction on the facial and lingual surfaces of extracted human molars. The cavity preparations were restored with either VariGlass VLC, GC Fuji II LC, or GC Fuji II glass ionomer cements. The restored teeth were thermocycled, immersed in fuchsin dye for 24 hours, sectioned, and evaluated with a measuring microscope. No microleakage occurred at the enamel/glass ionomer or dentin/glass ionomer cement interfaces of any samples, but the enamel adjacent to the VariGlass glass ionomer cement restorations exhibited crazing and staining.     

3种黏固剂与根管牙本质粘接界面的扫描电镜观察

目的通过观察黏固剂与根管牙本质的粘接界面,比较各种黏固剂的粘接性能。方法将15颗牙分成3组,分别用Rely X luting、Panavia F、Paracore 5 mL粘接纤维桩,实验牙纵剖后,置于扫描电镜下观察纤维桩冠1/3、中1/3及根尖1/3处牙本质黏固剂界面,并分别测量混合层厚度。结果1组牙本质黏固剂界面未发现明显混合层,2组与3组可发现明显混合层,且3组可发现树脂突及粘接性侧枝。从根尖方向冠方,1组粘接界面裂隙逐渐缩小,而2组与3组混合层逐渐增厚。结论全酸蚀树脂黏固剂与牙本质结合紧密,粘接性能较树脂改良型玻璃离子黏固剂、自酸蚀树脂黏固剂优越。     

Effects of Tooth Preparation Burs and Luting Cement Types on the Marginal Fit of Extracoronal Restorations

Purpose: Although surface roughness of axial walls could contribute to precision of a cast restoration, it is unclear how the roughness of tooth preparation affects marginal fit of the restoration in clinical practice. The purpose of this study was to describe the morphologic features of dentin surfaces prepared by common rotary instruments of similar shapes and to determine their effects on the marginal fit for complete cast crowns. Materials and Methods: Ninety crowns were cast for standardized complete crown tooth preparations. Diamond, tungsten carbide finishing, and crosscut carbide burs of similar shape were used (N = 30). The crowns in each group were subdivided into three groups (n = 10) for use with different luting cements: zinc phosphate cement (Fleck's), glass ionomer cement (Ketac‐Cem), and adhesive resin cement (Panavia 21). Marginal fit was measured with a light microscope in a plane parallel to the tooth surface before and after cementation between four pairs of index indentations placed at equal distances around the circumference of each specimen. Difference among groups was tested for statistical significance with analysis of variance (ANOVA) followed by Ryan‐Einot‐Gabriel‐Welsch Multiple Range Test (α= 0.05). Results: Analysis of measurements disclosed a statistically significant difference for burs used to finish tooth preparations (p < 0.001); however, luting cement measurements were not significantly different (p= 0.152). Also, the interaction effect was not significantly different (p= 0.685). For zinc phosphate cement, the highest marginal discrepancy value (100 ± 106 μm) was for tooth preparations refined with carbide burs, and the lowest discrepancy value (36 ± 30 μm) was for tooth preparations refined with finishing burs. For glass ionomer cement, the highest marginal discrepancy value (61 ± 47 μm) was for tooth preparations refined with carbide burs, and the lowest discrepancy value (33 ± 40 μm) was for tooth preparations refined with finishing burs. For adhesive resin cement, the highest marginal discrepancy value (88 ± 81 μm) was for tooth preparations refined with carbide burs, and the lowest discrepancy value (19 ± 17 μm) was for tooth preparations refined with finishing burs. Conclusions: Marginal fit of complete cast crowns is influenced by tooth preparation surface characteristics, regardless of the type of luting agent used for cementation. Tooth preparations refined with finishing burs may favor the placement of restorations with the smallest marginal discrepancies, regardless of the type of cement used.     

An in vitro investigation of marginal dentine caries abutting composite resin and glass ionomer cement restorations

BACKGROUND: There are a number of studies citing the primary reason for replacing auto cure glass ionomer cements was due to recurrent caries. The purpose of this study was to use an in vitro model to measure caries at the dentine restoration interface of bonded composite resin and auto cure glass ionomer cement restorations and to measure the amount of surface degradation occurring in the restorative materials. METHODS: Specimens of auto cure glass ionomer cements (Riva Fast, Fuji IX Fast, Ketac Molar Quick and Fuji VII) and bonded composite resin restorations (Ice, SDI) were placed separately at the dentino-enamel junction of 10 recently extracted human third molar teeth, disinfected and placed into the overflow from a continuous culture of S. mutans for two weeks. Restorations were sectioned and prepared for scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). Restoration tooth interfaces were photographed and the distance from the surface of the teeth to the surface of the restorations measured. EPMA of percentage weights of calcium, phosphorous and fluoride were made outwards from the restoration surface 130pm at a depth of 10 microm below the surface of the dentine. RESULTS: There were significant differences between the surface heights of composite resin, auto cure glass ionomer cements compared to teeth surfaces. Percentage weights of calcium and phosphorus levels were similar to non-demineralized dentine in the auto cure glass ionomer cement samples but there were significant reductions in mineral content of dentine adjacent to bonded composite resin restorations. Fluoride levels were mixed. CONCLUSIONS: This study shows that placing a bonded composite resin restoration into dentine affords little protection to the surrounding tooth from caries attack although insignificant degradation of the restorative surface occurs. Placing a glass ionomer cement restoration into dentine protects the surrounding tooth from caries but degradation of the restoration surface occurs.     

Changes in retention strength of luting cements by repeated loading

The retention of crowns cemented on abutment tooth model was examined for three types of luting cements when compressive loads of 2.5 to 10.0 kg were repeatedly applied to the occlusal plane. The chamfer type Ni-Cr alloy crown and abutment tooth model were prepared, and their surfaces to be cemented were sandblasted with glass beads. Loads were applied 7,200 times a day for 1, 3, or 7-day period after cementing. The polycarboxylate and zinc phosphate cements showed higher crown retentions than glass ionomer cements. Although retention strength of glass ionomer cements was significantly increased by storing the cemented specimen in water for 7 days, repeated loading tended to decrease retention. In polycarboxylate cements and one brand of zinc phosphate cement employed, retention strengths were decreased when stored in water over 3 days. However, their highest levels were maintained or even positively impacted by repeated loading for 7 days.     

Acidity of glass ionomer cements during setting and its relation to pulp sensitivity

Recent findings regarding pulp sensitivity to luting glass ionomer cements have aroused controversy as to the cause of the problem. Contributing factors may include chemical irritation from the material and leakage. The pH changes during setting were determined for three glass ionomer cements, a zinc phosphate cement, and a polycarboxylate cement. The data showed that the glass ionomer luting cements may show lower pH values for longer times than the other cements. This initial acidity, involving a prolonged period at pH below 3, coupled with cytotoxicity of other ingredients, may lead to damaging effects on the pulp when manipulation of the material and tooth preparation and cementation procedures are less than ideal.     

Microleakage of indirect inlays placed on different kinds of glass ionomer cement linings

The objective of this study is to compare the marginal seal of Class II cavities restored with indirect inlays constructed on glass ionomer cement linings having different curing properties. Also the effect of acid-etching of these liners on microleakage was investigated. Mesio-occlusal and disto-occlusal cavities in 80 extracted human molars having the cervical floor below the cementoenamel junction were prepared (n:160). Half of the preparations were restored with Ceramco II porcelain and the rest with SR-Isosit resin inlay material. Liners as light curing Ionoseal light+chemically curing LCL 8 and Zionomer and chemically curing Ketac-Bond glass ionomer cements (GICs) were used. On mesial preparations GICs were acid-etched but were not on distal preparations. All inlays were cemented with Ultrabond composite material. After thermocycling the teeth were placed in a basic fuchsin dye solution for 24 h, then each tooth was sectioned. By using a stereomicroscope the extent of marginal leakage was scored and statistically evaluated. Microleakage was observed beneath all GIC linings and was more extensive between light curing GIC/dentine interface. By acid-etching of GICs the microleakage between GIC/dentine interface was increased significantly. Whether acid-etching was applied or not a significantly increased microleakage was recorded between chemically curing GIC/composite interfaces. Although the marginal microleakage was witnessed in both inlays, it appeared that porcelain inlays provided a better marginal seal, in comparison to SR-Isosit inlays.     

Microleakage of crowns cemented with glass ionomer cement: effects of preparation finish and conditioning with polyacrylic acid.

This study compared the marginal leakage of cast gold complete crowns cemented with glass ionomer and with zinc phosphate cement. The effect of polishing the preparations and conditioning with polyacrylic acid was also evaluated for glass ionomer cement. The cast gold crowns cemented with glass ionomer cement demonstrated significantly lower marginal leakage than did those with zinc phosphate cement. The extent of microleakage was not substantially different between crowns when the preparations were polished and conditioned with polyacrylic acid.     

In vitro microleakage of luting cements and crown foundation material

STATEMENT OF PROBLEM: Microleakage is a concern for the long-term prognosis of a cemented crown and foundation. PURPOSE: The aims of this investigation were, first, to evaluate microleakage of zinc phosphate cement and resin-reinforced glass ionomer cement under ideal (dry) versus contaminated (wet) conditions, and second, to compare 3 foundations under both ideal and contaminated conditions. MATERIAL AND METHODS: One hundred forty extracted molar teeth were cleaned and mounted. Tooth preparations for complete veneer cast crowns were completed with a chamfer finish line. A mesial surface class II cavity preparation 4 mm wide buccolingually and 2 mm deep was made in each tooth. Seven restorative groups were formed: amalgam/cavity varnish, amalgam/dentinal bonding agent, and composite/dentinal bonding agent, each with dry and contaminated groups, and a seventh group of class II cavity preparations without foundations. Finish lines for crown margins were refined 1.5 mm gingival to the restoration. Artificial crowns were cast in type III gold. Treatment groups were divided into 4 cement groups: dry and contaminated zinc phosphate cement and dry and contaminated resin-reinforced glass ionomer cement. The specimens were thermocycled and immersed in erythrosine B solution for 24 hours. Subsequently, they were rinsed, and their coronal portions were embedded in clear resin. Teeth were sectioned mesiodistally, and standard photomicrographs were made. The microleakage of each restoration and crown was measured. RESULTS: The least foundation microleakage was recorded for amalgam/dentinal bonding agents (ideal group) and composite/dentinal bonding agents (ideal group). The most microleakage was observed within the group without a foundation. In cement groups, the control and experiment sides were evaluated separately but displayed the same order of finding. The least leakage was recorded with resin-reinforced glass ionomer cement (ideal group); the most microleakage was noted with zinc phosphate cement (ideal group). An interaction was demonstrated on the experimental side between cements and the foundations (P=.0001). CONCLUSION: Within the experimental conditions of this study, less microleakage was recorded with resin-reinforced glass ionomer cement (ideal or contaminated) than with zinc phosphate cement (ideal or contaminated). There also was less microleakage evident with a foundation of silver amalgam or composite when a dentinal bonding agent was used under ideal conditions.     

4种玻璃离子水门汀对ITI基台与金属内冠之间粘接力的比较研究

目的：研究4种玻璃离子类水门汀对ITI种植系统标准颈粘接固位基台和金属内冠之间的粘接力。方法将10只金属内冠与10只I T I标准颈粘接固位基台分别使用以下4种水门汀进行交叉粘固：A组为玻璃离子水门汀（日本）;B组为树脂加强型玻璃离子水门汀（美国）;C组为暂时粘固用玻璃离子水门汀（日本）;D组为玻璃离子水门汀（德国）;粘固后测试并记录样本粘接力（N）,同时观察并记录粘固界面的断裂模式,最后,对粘接力进行统计学处理。所有内冠和基台经清洗后重复使用。结果4种水门汀的粘接力及由大至小的排列顺序为C组（183.6±29.4） N〉D组（153.4±36.2） N〉B组（144.4±41.1） N〉A组（109.9±25.7）N,其中C组的粘接力最高,A组的粘接力最低,A组显著低于其它3种水门汀（P〈0.05）。对样本的断裂面观察显示,A组和D组样本断裂面发生在水门汀和基台表面之间,而B组和C组样本的断裂面则呈现混合断裂的模式。结论2种玻璃离子水门汀和树脂加强型玻璃离子水门汀都具有临床可接受的粘接力,而暂时粘固用玻璃离子水门汀因粘接力太大,不适用对种植牙冠进行暂时粘固。     

不同粘结剂与桩核材料微渗漏发生的实验研究

目的：评价不同核材料修复后的牙齿经铸造金属全冠修复后边缘微渗漏的情况。方法：将90个大小相似的完好前磨牙,随机分为9个实验组。对离体牙进行铸造金属全冠及固定尺寸的Ⅱ类洞牙体预备后,分别用3种不同的核材料（树脂、银汞合金、铸造合金）充填窝洞。常规方法铸造镍铬合金全冠,用3种不同的粘结材料（聚羧酸锌、玻璃离子、树脂C＆B）进行粘固。温度循环、染色、包埋后,标本片切,镜下观察冠边缘及核下微漏情况。结果：银汞核与树脂核下微漏小于铸造核（P〈0.05）,树脂粘结剂抗微漏性能优于聚羧酸锌水门汀和玻璃离子粘结剂（P〈0.05）。结论：树脂粘接剂抗微漏性能优于玻璃离子与聚羧酸锌粘结剂。树脂核在预先对粘结面处理后,其抗微漏性能与银汞核近似,优于铸造合金核。     

Effect of cement types on the tensile strength of metallic crowns submitted to thermocycling

The relationship between metallic cast crowns and tensile strength according to cement types submitted to thermocycling was studied. Seventy-two metallic crowns were cast with Verabond II Ni-Cr alloy and cemented in standardized preparations with 10 masculine tapering. Three types of finishing line (45-degree chamfered, 20-degree bevel shoulder and right shoulder) were made with diamond burs on bovine teeth. Twenty-four metallic crowns in each group were randomly subdivided into three subgroups of 8 samples each according to the cement used: SS White zinc phosphate cement, Vitremer resin-modified glass ionomer cement, and Rely X resin cement and were submitted to thermocycling. Retention was evaluated according to tensile load required to displace the metallic cast crowns from tooth preparations with an Instron testing machine. ANOVA and Tukey's test showed a statistically significant difference among luting materials, with greater results for Rely X resin cement (24.9 kgf) followed by SS White zinc phosphate cement (13.3 kgf) and Vitremer resin-modified glass ionomer cement (10.1 kgf). The finishing line types did not influence the tensile resistance of the crowns fixed with the three cements. Increased tensile resistance of metallic crowns fixed on bovine teeth was obtained with resin cement, independent of the finishing line types.