粘结剂与核材料微漏的体外研究

目的 :讨论常用的粘结材料与核材料对修复体边缘微漏的影响。方法 :选用 4 5颗大小相似的完好前磨牙 ,随机分为 9个实验组。对离体牙进行标准的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、铸造合金 )充填窝洞。常规方法铸冠 ,用 3种不同的粘结材料 (锌汀、聚羧酸、玻璃离子 )进行粘固。温度循环、染色、包埋后 ,片切标本 ,镜下观察冠边缘及核下微漏。结果 :银汞核与树脂核下微漏小于铸造核 (P<0 .0 5 ) ,玻璃离子粘结剂抗微漏性能优于聚羧酸和锌汀 (P <0 .0 5 )。结论 :本实验提示 :玻璃离子抗微漏性能优于锌汀与聚羧酸。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。粘结剂的选择对微漏有影响     

玻璃纤维桩-树脂核与银汞-银粉玻璃离子桩核修复磨牙残冠的临床研究

目的比较玻璃纤维桩-树脂核与银汞-银粉玻璃离子桩用于磨牙冠缺损的修复效果。方法临床选择55例磨牙缺损患者,共75颗患牙,随机分为两组,玻璃纤维桩-树脂核组共24例29颗患牙,银汞-银粉玻璃离子桩核组31例共46颗患牙,分别进行玻璃纤维桩-树脂核和银汞-银粉玻璃离子桩核全冠修复,2年后对修复效果进行评价。结果玻璃纤维桩-树脂核组有1颗患牙出现根折,成功率96.6%;银汞-银粉玻璃离子桩核组有1颗患牙出现桩折,成功率97.8%,两组均无冠桩脱落,两组成功率差异无统计学意义(χ2=0.161,P>0.05)。结论对于重度磨牙缺损病例,选用玻璃纤维桩-树脂核和银汞-银粉玻璃离子桩核全冠修复均可。     

三种粘结剂粘结嵌体的微渗漏对比研究

目的：评价复合树脂嵌体及纯钛嵌体采用3种不同粘结剂的微渗漏情况。方法：选择72颗健康上颌前磨牙,随机分为6个实验组,每组12颗。按嵌体备洞要求制备Ⅱ类洞。前三组制作纯钛嵌体,分别用玻璃离子、树脂改良型玻璃离子和树脂粘结剂粘结固位。后三组制作复合树脂嵌体,分别用玻璃离子、树脂改良型玻璃离子和树脂粘结剂粘结固位。结果：同一种材料嵌体用不同粘结剂处理,其微渗漏程度差异有显著性（P〈0.05）;在相同粘结处理不同种嵌体的组间比较,其微渗漏差异P〉0.05。结论：树脂改良型玻璃离子粘结剂与树脂粘结剂抗微渗漏性能优于玻璃离子粘结剂。     

粘固剂对桩核烤瓷全冠修复后抗折强度的影响

目的探讨树脂粘结系统对前牙桩核烤瓷全冠抗折强度是否具有增强作用。方法40个新鲜拔除大小一致的上颌中切牙,随机分成4组,每组10个,分别用钛合金预成桩和铸造桩核修复,同一种桩及烤瓷全冠分别用树脂粘结系统和玻璃离子粘固剂粘固。经温度循环疲劳试验,用万能力学试验机,测试抗折强度,并观测折裂型。结果钛合金预成桩树脂粘结组抗折强度为499.82±168.90N,玻璃离子粘固剂组为388.98±125.22N;铸造桩核树脂粘结组抗折强度为412.55±99.29N,玻璃离子粘固剂组为337.41±121.18N。可再修复折裂型标本比例分别为40%、20%和20%、30%。统计学分析表明,两种桩核冠修复树脂粘结组的抗折强度及可再修复折裂型标本比例与玻璃离子粘固剂组均无显著性差异(P>0.05)。结论树脂粘结系统对金属桩烤瓷全冠修复的前牙抗折强度无显著的增强作用,有待进一步研究。     

玻璃离子水门汀与银汞粘接的剪切力测试

探讨了玻璃离子水门汀增强银汞充填体与牙体之间的粘结作用。取新鲜离体人磨牙制成3mm厚的牙块,在其中央制备直径3mm的圆柱形洞,分别以玻璃离子、银汞粘结剂涂于洞壁,再充填银汞合金,另设空白对照组。两周后测各组的剪切力并作统计学分析。结果表明:玻璃离子与银汞粘结剂组的剪切力比空白对照组大,并有显著差异;说明玻璃离子与银汞粘结剂均有相似的增强银汞修复体与牙体之间粘结力的作用。     

几种新型牙科充填材料边缘微漏的实验研究

选择临床常用的银汞合金，国产ＣＯ－１玻璃离子粘固剂以及新研制的新型银－稀土汞齐合金、无汞银合金、银玻璃离子粘固剂、Ｌ－型玻璃离子粘固剂作充填材料，采用染料逆扩散法测定牙齿浸出液中伊红含量，观察充填材料边缘微漏情况。结果表明，无汞银合金边缘微漏低于银汞合金，新型银－稀土汞齐合金较银汞合金大，银玻璃离子粘固剂和国产ＣＯ－１玻璃离子粘固剂的微漏无区别，Ｌ－型玻璃离子粘固剂的微漏高于银玻璃离子粘固剂和国产     

不同被粘结材料对5种水门汀粘结性能的影响

目的 分析不同被粘材料对水门汀粘结性能的影响,为临床烤瓷冠粘结时选择合适的水门汀材料提供科学依据.方法 模拟临床使用状况,设计镍铬合金-钴铬合金、镍铬合金-离体牙、镍铬合金-树脂等三种不同组合的被粘结材料,分别选用国产增强型玻璃离子水门汀(RGC)、增强型聚羧酸锌水门汀(RPC)和增强型磷酸锌水门汀(RZPC),以及日产玻璃离子水门汀(CX)和聚羧酸锌水门汀(CE)共5种水门汀进行粘结,测试并比较5种水门汀在不同被粘结材料组合下的剪切粘结强度.结果 5种水门汀在镍铬合金-钴铬合金组合中均表现出最高的粘结强度(7.38～9.14MPa),在镍铬合金-离体牙组合中,粘结强度由高到低排列为:CX>CE>RGC>RPC>RZPC,在镍铬合金-树脂组合中,其顺序为:CX>RGC>CE>RZPC>RPC.结论 水门汀的牯结性能与被粘结材料的性质密切相关.     

正畸树脂加强型玻璃离子光敏粘结剂微渗漏的研究

目的：研究新型正畸树脂加强型玻璃离子光敏粘结剂的微渗漏,为临床正畸粘结材料的选择提供依据。方法：选取新鲜拔除的第一前磨牙24颗,分成A1,A2两组,A1组：正畸复合树脂光敏粘接剂（3M）,A2：正畸树脂加强型玻璃离子光敏粘接剂（GC）。所有样本经过2000次冷热循环（5～55℃）后,浸泡于0.5%的碱性品红24 h,样本切片,低倍体视显微镜下拍照测量微渗漏情况,扫描电镜观察样本的釉质-粘结剂界面。结果：树脂加强型玻璃离子光敏粘接剂（GC）在两个界面的微渗漏均大于复合树脂光敏粘结剂（3M）,差别具有显著统计学意义。结论：树脂加强型玻璃离子光敏粘结剂有较大的微渗漏,在正畸粘结应用中值得关注。     

三种方式修复严重缺损的上颌中切牙抗折性能研究

目的：比较三种方式修复严重缺损的上颌中切牙的抗折性能,探讨保存残根残冠更合理的修复方式。方法：36颗上颌中切牙随机分为3组,根管治疗后平齐唇侧釉牙本质界垂直与牙体长轴截冠。分别行铸造镍铬合金桩核、铸造镍铬合金桩树脂核及玻璃纤维桩树脂核＋金属全冠修复。在万能测试机进行力学测试,记录最大载荷和断裂模式。结果：3组的抗折强度分别为292.06±155.51N、439.89±89.55N和284.98±133.56N,铸造镍铬合金桩树脂核组明显高于另外2组,差异具有统计学意义。铸造镍铬合金桩均导致牙根垂直折裂,玻璃纤维桩10颗桩折,2颗桩折合并唇侧颈1/3折裂。结论：无箍作用时应充分利用树脂与牙体的粘结作用,高强度的铸造镍铬合金桩较玻璃纤维桩能更好地抵抗外力,结合高强度的树脂核强度更大。     

金属全冠固位力影响因素的实验研究

本实验是使用两种金属全冠和三种粘固剂及不同的金属全冠组织面的处理,通过测试粘结抗张强度和扫描电镜表面形态观察,评价这些因素对金属全冠固位力的影响。结果表明,金属全冠组织面经喷砂处理后可增大与粘固剂接触的面积及显著增加其固位力;铸造全冠的固位力显著大于锤造全冠;使用聚羧酸锌粘固剂所获得固位力最大,并显示出对牙体及金属全冠有较好的化学粘结性;其次为玻璃离子体粘固剂和磷酸锌粘固剂,两者的粘固力主要来源于机械性锁结作用。     

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.     

Microleakage of four core materials under complete cast crowns

This study evaluated the microleakage patterns of complete cast-metal crowns cemented onto teeth that were rebuilt with pin-retained cores made from cast metal, composite resin, acrylic resin and amalgam by using four different cements. One hundred extracted human teeth were used to compare the microleakage of composite resin core, metal core, acrylic resin core and amalgam core, and regular crown preparations under a complete cast metal crown cemented with different cements as determined by 2% methylene blue dye solution. Specimens were compared with and without aging after cementation in a thermal bath by cycling some of them between 4 degrees C and 50 degrees C in a 2% methylene blue bath and others in a similar bath held at 37 degrees C. The extent of marginal microleakage was evaluated with a stereomicroscope and scored. It was determined through variance analysis that the type of core used in the substructure, the cement used for cementing and the thermocycling process were all important in microleakage. 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.     

Microleakage of temporary endodontic restorations in teeth restored with amalgam

Microleakage of seven temporary restorative materials was evaluated in endodontic access preparations made in teeth restored with amalgam. Ten teeth were used for each of the seven materials: Cavit, Cavit-G, TERM, zinc phosphate cement, polycarboxylate cement, glass ionomer cement, and IRM. A class I amalgam was placed in the occlusal surface of each experimental tooth and an endodontic access preparation was made entirely within the amalgam. Then the access preparation was restored with one of the temporary restorative materials, and microleakage was evaluated using a fluid filtration technique. The amount of microleakage was quantitated by measuring the fluid flow at 15 min, 1 h, 24 h, 1 wk, and 2 wk after insertion of the temporary restoration. Cavit, Cavit-G, TERM, IRM, and glass ionomer cement all provided excellent seals while zinc phosphate cement and polycarboxylate cement provided less effective seals.     

Comparative Evaluation of Bond Strengths of Different Core Materials with Various Luting Agents Used for Cast Crown Restorations

The coronal cast restoration continues to be used commonly to restore mutilated, endodontically treated teeth. The tensile bond strength of luting cements is of critical importance as many of failures are at the core and the crown interface. An invitro study with aim to evaluate and compare bond strengths of luting cements between different core materials and cast crowns. A total of 45 extracted identical mandibular second premolars were endodontically treated and divided into 3 groups of 15 each. Specimens in first group were restored with cast post and core (Group C), and specimens in second group were restored with stainless steel parapost and composite core material (Group B) and specimens in third group were restored with stainless steel parapost and glass ionomer core build (Group G). Standardized crown preparation was done for all the specimens to receive cast crowns. Each group was further divided into 3 subgroups and were cemented using 3 different luting cements namely, resin cement, polycarboxylate cement, glass ionomer cement (Type I). The samples of each subgroup (n = 5) were subjected to tensile testing using Universal Testing Machine at a crosshead speed of 2 mm/min till the dislodgement of crown from the core surface was observed. The bond strengths were significantly different according one way ANOVA (F-150.76 and p < 0.0000). The results of the study showed that the specimens cemented with resin cement in cast core, composite core and glass ionomer core exhibited significantly higher bond strengths as compared to specimens cemented with glass ionomer and polycarboxylate cement. Composite resin core and resin cement combinations were superior to all other cement and core combinations tested.     

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.     

A study in vitro of threaded titanium pins used for retrograde obturation of root canals

The microleakage of four retrograde filling materials was compared in vitro. Fifty-three single rooted teeth were instrumentated and root filled with resin chloroform and gutta-percha. The gutta-percha cones were left extruding from the access opening. All teeth were apicected and retrograde fillings placed. The materials used were a non γ2 amalgam (Amalcap), a glass ionomer cement (ChemFil II), threaded titanium pins cemented with a glass ionomer cement (ChemFil II) and identical titanium pins cemented with a silicone material (Adheseal). After removal of the gutta-percha with tweezers, a radioactive isotope solution was placed in the teeth. Extraradicular samples were taken at 3, 7, 28, 77 and 104 days. All retrograde fillings showed some microleakage. The group with titanium pins cemented with silicone showed the least leakage: significantly less than the teeth with glass ionomer cement (P < 0.01) and with amalgam (P < 0.01). No significant differences were found between other groups.     

3种粘接剂对金属基底冠边缘微渗漏影响的研究

目的 观察使用磷酸锌水门汀(ZPC),玻璃离子水门汀(GIC)和复合树脂粘接剂(CRC)对钴铬烤瓷合金基底冠边缘微渗漏的影响。方法 选择32个离体磨牙,常规制作钴铬烤瓷合金基底冠。随机分为ZPC组,GICⅠ组(不涂凡士林),GICⅡ组(涂凡士林)和CRC组。其中一半标本进行冷热循环。均采用染料渗入法测定冠边缘微渗漏值,并进行统计分析。结果 冷热循环前,GICⅡ组显著小于GICⅠ组和ZPC组。冷热循环后,四组的微渗漏值较循环前均有显著增加,GICⅠ组和GICⅡ组显著小于ZPC组。冷热循环前后,CRC组均显著小于其他三组。结论 CRC对修复体和牙预备体之间微间隙的封闭能力要优于ZPC和GIC。     

Fatigue testing and microscopic evaluation of post and core restorations under artificial crowns.

STATEMENT OF PROBLEM: Coronoradicular reconstruction techniques of pulpless teeth include prefabricated post systems that retain a core material such as silver amalgam, composite, glass ionomer, or modified glass ionomer cement. Mechanical properties of these materials are critical to sustain masticatory forces. PURPOSE: This in vitro study compared the mechanical resistance of 3 core materials (silver amalgam, composite, and silver-reinforced glass ionomer) under masticatory conditions. MATERIAL AND METHODS: Industrially fabricated teeth were used and a total of 75 specimens were divided into 3 groups of 25 specimens. Titanium canal posts were placed, followed by core buildups in amalgam, composite, or glass ionomer. Teeth were prepared for full cast crowns and the crowns were fabricated and cemented with glass ionomer cement. Twenty specimens from each group were placed in a mastication simulator cyclically loading the teeth with a 400 N force for 1.5 million cycles. The 5 remaining specimens were used as controls. Teeth were sectioned and observed macroscopically and microscopically to determine the rate of defects for each material. Observed defects were verified with the Kruskal-Wallis test. The 3 core materials were ranked with the Tukey multiple comparison test. RESULTS: Significant differences of mechanical behavior were found for the 3 materials. At P <.01, silver amalgam was significantly superior to composite and glass ionomer. Composite was significantly superior to glass ionomer. CONCLUSION: Cores fabricated with amalgam had the lowest rate of defects when tested under artificial crowns. Glass ionomer, when used as a core material under artificial crowns, showed the highest rate of defects after an instantaneous load of 400 N for a 1,500,000 repetition cycle.     

五种黏固剂下纤维/树脂复合材料桩钉固位力的研究

目的 比较纤维/树脂复合材料(FRC)桩钉在5种黏固剂下的固位力。方法 将FRC桩钉用5种黏固剂(磷酸锌水门汀、玻璃离子水门汀、聚羧酸水门汀、EB复合树脂、AB组份复合树脂)分别黏固于新鲜离体上前牙牙根内,在电子力学试验机上测试其固位力。结果 FRC桩钉在不同黏固剂下与根管的固位力由大到小的顺序是:AB组份复合树脂>玻璃离子水门汀>EB复合树脂>聚羧酸锌水门汀>磷酸锌水门汀。AB组份复合树脂的固位力最大,为(418.14±23.40)N。结论 新研制的FRC桩钉的固位力可以满足临床需要。     

桩核修复体的微漏研究

本文的桩核修复体微漏研究采用染色法,选28个完整的离体上中切牙分成4组.实验结果表明:铸造Ni-Cr合金桩核报漏值最小,简单桩附自凝甲基丙烯酸甲脂核、螺纹桩附光敏树脂核微漏值较大,临床上应用后两种桩核材料修复时应谨慎.