Full mapping tensile bond strength of luting in search for differences due to centripetal curing shrinkage

Objectivestesting if hypothetical transverse centripetal strains due to polymerization contraction of luting materials produce differential alterations in its bonding to luted structures, depending on distances to the center of the luting mass, and if this effect is C-factor related. Two hypotheses were tested: (1) there is a statistically significant decreasing relationship between the bonding strength and the transverse distances to the center of the luting material, and (2) there is a statistically significant difference between bonding strengths among luting spaces with different configuration factors.Methods10 PMMA (15 mm Ø) pairs of cylinders were cemented (Scotchbond Universal adhesive & Relyx Universal, both chemically cured) in a compliant setup under two (20 and 70 N) luting forces forming 2 groups (5 samples each), resulting in different C-factors. Whole samples were sectioned in x and y directions obtaining non-trimmed beams from all along the luting surfaces. Their relative positions in each sample were assessed before separating and categorized (10 categories) according to their distances to the center of the sample. All beams were tested in tension and, because of their uneven bonding areas and to balance its influence, UTS results were transformed into UTS_res. First hypothesis was tested trough a linear relationship between UTS_res and distances to vertical centers per samples. Second hypothesis was tested using Mann-Whitney U tests to compare UTS_res between groups, along all categories. Further Weibull analysis was applied.ResultsANOVA’s p of the regression UTS_res – categories were statistically significant for all samples in group 70 N and for all except one in group 20 N: first hypothesis is partially maintained. Although Mann-Whitney tests p comparing UTS_res of both groups for all categories but the first were statistically significant this hypothesis was maintained relying in Weibull analysis. Significance: bonded attachment of cemented materials decreases from centers to outbounds in plane, extensive surfaces, and this decrease is C-factor related.     

Influence of light-cured luting agents and associated factors on the color of ceramic laminate veneers: A systematic review of in vitro studies

Objective

The luting agent plays a significant role in the appearance of ceramic laminate veneers (CLV), allowing improved/stable shade matching with adjacent teeth. A systematic review was conducted to investigate the influence of light-cured luting agents and color-associated factors aiming to draw guidelines for stable shade matching of CLV. The paper has also given an overview of the compositional characteristics of all luting agents and ceramic systems whose performance was presented herein.

Effect of alumina particle morphology used for air abrasion on loss of enamel and luting composite resin

ObjectiveTo evaluate the volume loss after air abrasion with alumina particles with different morphology on bovine enamel and luting composite resin.MethodsAir abrasion was performed on 12 unscathed bovine teeth and 72 luting composite resin discs with 85 μm round-shaped and 50 μm sharp-edged alumina particles applied for 20 s, 40 s and 60 s (n = 12). Air abrasion was standardized by uniform areas of 2 mm diameter, a pressure of 0.25 MPa and a distance of 3 mm. The volume loss was determined by using a laboratory scanner.ResultsAir abrasion with round-shaped alumina particles was mostly not measurable with the laboratory scanner, while sharp-edged alumina air abrasion resulted in significant loss of enamel. The median of volume loss by sharp-edged alumina particles ranged from 0.78 mm³ (20 s) to 2.52 mm³ (60 s). In contrast to round-shaped alumina the removal caused by sharp-edged alumina increased significantly with increasing application times (p ≤ 0.05). For air abrasion on luting composite resin the median of the removed volume ranged from 2.25 mm³ (20 s) to 6.18 mm³ (60 s), while round-shaped alumina showed a range from 0.45 mm³ (20 s) to 1.40mm³ (60 s). The round-shaped alumina produced a statistically significant lower volume loss than sharp-edged alumina for all three air abrasion times.SignificanceThe 85 μm round-shaped alumina particles removed less composite resin than 50 μm sharp-edged alumina particles but barely any enamel, making it an option for removing composite resin residues from enamel.     

4种黏结剂与氧化锆陶瓷黏结剪切强度的比较

目的:探讨氧化锆陶瓷与牙本质间合适的黏结材料。方法:将烧结喷砂后的氧化锆陶瓷片分为4组,每组8片,将经过唾液污染→水冲洗→磷酸凝胶(含35%正磷酸)酸蚀→水冲洗处理过的氧化锆陶瓷片分别选用Multilink Automix、3M RelyXTM Unicem AplicapTM、Tokuso Ionomer和Shofu Polycarboxylate Cement等4种黏结材料与牙本质进行黏结,水浴24h后,测试其黏结剪切强度。采用SPSS12.0软件包比较不同黏结剂所得的黏结剪切强度以及黏结的破坏形式。结果:Multilink Automix的黏结抗剪强度最高,3M RelyXTM Unicem AplicapTM次之,但亦显著高于Tokuso Ionomer和Shofu Polycarboxylate Cement,差别有统计学意义(P<0.05)。结论:全酸蚀树脂黏结系统是牙科氧化锆陶瓷黏结的理想选择,可以获得较高的黏结强度。     

Effect of chlorhexidine on initial adhesion of fiber-reinforced post to root canal

Objectives

Chlorhexidine is used as final irrigant before endodontic obturation and fiber-reinforced composite posts are recommended for restoration retention. Our aim was to evaluate the effect of chlorhexidine on adhesion of cements used in post cementation. We hypothesized that chlorhexidine would not negatively affect the immediate bond strength.

Methods

Root canals of eighty human extracted third molars were prepared for post cementation with each post systems’ own burs. Four commercially available FRC posts (Glassix, D.T.Light-Post, Unicore, everStickPOST) with three cements (Duo-link with All-bond 2, PermaFlo DC with PermaFlo DC Primers, RelyX Unicem) were used. After etching, except with self-etching RelyX Unicem, the post spaces were irrigated either with 2% chlorhexidine (Consepsis) or physiological saline for 60 s. With RelyX Unicem, respective treatments were done before cement application. The roots (n = 5 per group) were cut into 2 mm thick dentin discs. The bond strength was measured with push-out method, and the failure mode was evaluated with a stereomicroscope.

Results

Significant differences in bond strength were observed between various post/cement combinations. Unicore/PermaFlo DC and everStickPOST/RelyX Unicem showed significantly higher bond strengths than Glassix or D.T.Light-Post with Duo-link both with saline and chlorhexidine. Chlorhexidine improved the bond strength slightly with all posts/cements except with D.T.Light-Post, but the differences were not statistically significant. With chlorhexidine, significant reduction of adhesive failures towards dentin cohesive or mixed failures was observed with all posts/cements except with everStickPOST.

Conclusion

Chlorhexidine did not negatively affect the push-out bond strength in post bond cementation.     

粘固剂对种植义齿部件稳定性影响的比较研究

目的:通过循环疲劳试验比较不同粘固剂对粘固固位种植义齿种植体颈部周围骨组织的应变大小及上部支架稳定性的影响。方法:在计算机软件控制下,使用Instron材料测试机以15 Kg循环负荷加载于使用磷酸锌、玻璃离子、ARC树脂粘固剂固位的单个种植牙上进行疲劳实验。使用动态应变仪和涡流传感器分别测量不同时间的种植体颈部周围骨的应变变化大小和修复体的振幅位移大小,并转换成电压信号输入计算机进行结果分析。结果:3种粘固剂对种植体颈部周围骨的应变和修复体的位移的影响存在差异(P<0.05)。应变的均数排列为:磷酸锌(2.059)<玻璃离子(2.470)相似文献   

Adhesive bonding of noble metals with a thiohydantoin primer

ObjectiveThe purpose of this study was to assess the effects of an experimental primer containing acetone solution and a sulfur-containing functional monomer, 10-methacryloyloxydecyl-(2-thiohydantoin-4-yl)propionate (MDTHP), on the bonds between noble metals and acrylic resin.MethodsThe experimental primer used as the control for comparison consisted of 6-(4-vinylbenzyl-n-propyl)amino-1,3,5-triazine-2,4-dithione (VBATDT) in acetone. These primers were prepared as equimolar functional monomers (0.1 mol%). A self-polymerizing acrylic resin initiated with tri-n-butylborane (TBB) was used as the luting agent. Four elemental metal disks (silver, copper, palladium, and gold) were used as adherend specimens. All the disks were wet-ground with silicon carbide paper (#1500). Bonding reactions were performed on 12 combinations of the four metals, and the disks were either primed with MDTHP or VBATDT or were unprimed (control). Shear bond strengths were determined pre- and post-thermocycling (5–55 °C, dwell time 60 s, 20,000 cycles). The results were statistically analyzed via a non-parametric test (α = 0.05).ResultsThe post-thermocycling shear bond strengths of the MDTHP primer were as follows (median, n = 11): 13.2 MPa on silver, 25.9 MPa on copper, 4.1 MPa on palladium, and 11.3 MPa on gold. The MDTHP primer showed higher post-thermocycling shear bond strength on all the four metals. Additionally, on silver and copper, the MDTHP bond strengths were higher than on the other metals.SignificanceWithin the limitation of current of experimental setting, the MDTHP compound may be applicable as a functional monomer for bonding noble metal alloys.     

不同表面处理和不同粘结剂对氧化锆粘结强度的影响

目的探讨不同表面处理和不同粘结剂对氧化锆粘结强度的影响。方法将氧化锆分别制成直径为12.0mm和4.0mm的瓷片,各120个,分别随机分成12组。粘结剂选用磷酸锌粘结剂、聚羧酸锌粘结剂、BifixQM和Super-Bond CB。对氧化锆的表面分别进行不处理、喷砂、硅烷化、先喷砂后硅烷化处理。用上述4种粘结剂将4.0mm瓷片粘结在12.0mm瓷片上,置于37℃蒸馏水中保存24h后,进行剪切粘结强度测试。结果粘结剂相同时,不同表面处理时的粘结强度有显著统计学差异(P0.01),由小到大依次为不处理喷砂硅烷化先喷砂后硅烷化处理;表面处理相同时,不同粘结剂之间的粘结强度有显著统计学差异(P0.01),由小到大依次为磷酸锌粘结剂聚羧酸锌粘结剂Bifix QMSuper-Bond CB。结论粘结剂相同时,表面处理提高了粘结强度。Super-Bond CB的粘结强度比较理想。使用Super-Bond CB时,喷砂后硅烷化处理是一种比较理想的表面处理方法。     

A Study on Provisional Cements,Cementation Techniques,and Their Effects on Bonding of Porcelain Laminate Veneers

Minimal tooth preparation is required for porcelain laminate veneers, but interim restorations are a must to protect their teeth against thermal insult, chemical irritation, and to provide aesthetics. Cement remaining after the removal of the provisional restoration can impair the etching quality of the tooth surface and fit and final bonding of the porcelain laminate veneer. This in vitro study examined the tooth surface for remaining debris of cement after removal of a provisional restoration. Determine the presence of cement debris on prepared tooth surface subsequent to the removal of provisional restoration. Determine the cement with the least residue following the cleansing procedures. Determine the effect of smear layer on the amount of residual luting cement. Eighty-four extracted natural anterior teeth were prepared for porcelain laminate veneers. For half of the teeth, the smear layer was removed before luting provisional restorations. Veneer provisional restorations were fabricated and luted to teeth with six bonding methods: varnish combined with glass ionomer cement (GIC), varnish combined with resin modified GIC, varnish, spot etching combined with dual-cure luting cement, adhesive combined with GIC, adhesive combined with resin modified GIC, and adhesive, spot etching combined with dual-cure luting cement. After removal of provisional restorations 1 week later, the tooth surface was examined for residual luting material with SEM. Traces of cement debris were found on all the prepared teeth surfaces for all six groups which were cemented with different methods. Cement debris was seen on teeth subsequent to the removal of provisional’s. Dual-cure cement had the least residue following the cleansing procedures. Presence of smear layer had no statistical significance in comparison with cement residue. With the use of adhesive the cement debris was always found to be more than with the use of varnish. GIC showed maximum residual cement followed by dual-cure.     

4种黏接剂对全瓷颈缘和合金颈缘的金属烤瓷冠微渗漏影响的对比研究

目的对比4种黏接剂黏固全瓷颈缘和合金颈缘的金属烤瓷冠微渗漏。方法选择离体上颌第一前磨牙48颗,制作24颗全瓷颈缘金属烤瓷冠和24颗合金颈缘金属烤瓷冠,随机分4组,每组6颗牙,分别用4种黏接剂黏固,温度循环试验后,浸入2%亚甲基蓝溶液,恒温37℃保持24h后,沿牙体长轴纵行剖开,体视显微镜观察颈缘微渗漏情况。结果聚羧酸锌水门汀、玻璃离子水门汀、树脂加强型玻璃离子、树脂黏接剂黏固全瓷颈缘金属烤瓷冠的微渗漏依次减小,差异有统计学意义。同组黏接剂黏固金属颈缘与镍铬合金颈缘的微渗漏,差异无统计学意义。结论树脂黏接剂抗颈缘微渗漏性能优越,是黏接全瓷颈缘金属烤瓷冠的理想材料。