Microleakage of Seven Dentin Bonding Agents

The purpose of this study was to evaluate the ability of seven dentin bonding agents to reduce dye penetration at the margins of microfill composite restorations in dentinal cavities.
Forty extracted molars were selected and cleaned. Cavity preparations were made in dentin with #55 carbide burs. The preparations were restored with Silux after application of one of the following dentin bonding agents: Gluma, Scotchbond 2, Tenure, Prisma Universal Bond 2, Mirage-Bond, XR Bond, and All-Bond. Samples were thermocycled for 200 cycles between 3°C and 60^CC, then immersed in a 0.05 percent crystal violet solution for 2 hours. The samples were embedded in clear casting resin, sectioned, and examined with a light microscope.
Our results indicated that the dentin bonding systems reduced, but failed to totally eliminate, microleakage around the composite resin restorations.     

Third Generation Dentin Bonding Agents: A Microleakage Study

This article examines and compares the extent of microleakage after 24 hours in freshly extracted teeth using three newer or "third generation" dentin bonding agents. Gluma/Pekalux and Scotchbond 2/Silux were more effective in preventing microleakage in cementum/dentin margins than was Universal Bond/Prisma Micro-fine.     

银汞合金粘结修复后充填体边缘微漏的实验研究

目的 研究银汞合金粘结修复填体边缘的微漏情况,方法 将制备洞型后４０颗离体牙随机分二组,一组采用ＢＡＲ法充填银汞,另一组按常规充填银汞,所有标本均进行染料渗透试验,观测染料渗漏情况,并在ＳＥＭ下测量充填体与牙体间的微逢隙宽度,结果 ＢＡＲ组染料渗漏的例数少,程度轻,其微漏明显小于常规组（Ｐ〈０．０１）,扫描电镜观察发现,ＢＡＲ组充填体边缘缝隙宽度明显小于常规组（Ｐ〈０．０１）,结论 银汞合金粘结修     

体外模型中3种光固化树脂充填体边缘微渗漏实验研究

目的：比较3种光固化充填材料在体外模型中充填体边缘的微渗漏程度。方法：在36颗离体的前磨牙颊侧颈部备洞。随机分为3组,每组12颗牙。分别充填3M前后牙通用树脂Valux Plus、流动性纳米复合树脂Z350、登士柏Esthet.XTM复合树脂。样本经温度循环,采用10g/L碱性品红染色后,颊舌向沿长轴连续切开,在体式显微镜下观察修复体与牙体洞壁间染料渗漏情况。结果：3种材料中流动性纳米复合树脂Z350微渗漏最小。前后牙通用树脂Valux Plus微渗漏最大。流动性纳米复合树脂Z350与其他两组相比有显著性差异（P〈0.01）。结论：流动性纳米复合树脂Z350是临床上充填颊侧颈部窝洞的较好材料。     

Effect of Whitening Agents on Dentin Bonding

Background: Several studies have shown a reduction in enamel bond strengths when the bonding procedure is carried out immediately after vital bleaching with peroxides. This reduction in bond strengths has become a concern in cosmetic dentistry with the introduction of new “in‐office” and “waiting‐room” bleaching techniques. The aim of this in vitro study was to evaluate the effect of three bleaching regimens: 35% hydrogen peroxide (HP), 35% carbamide peroxide (CP), and 10% CP, on dentin bond strengths. Materials and Methods: One hundred and twenty fresh bovine incisors were used in this study. The labial surface of each tooth was ground flat to expose dentin and was subsequently polished with 600‐grit wet silicon carbide paper. The remaining dentin thickness was monitored and kept at an average of 2 mm. The teeth were randomly assigned to four bleaching regimens (n = 30): (A) control, no bleaching treatment; (B) 35% HP for 30 minutes; (C) 35% CP for 30 minutes; and (D) 10% CP for 6 hours. For each group, half of the specimens (n = 15) were bonded with Single Bond/Z100 immediately after the bleaching treatment, whereas the other half was bonded after the specimens were stored for 1 week in artificial saliva at 37°C. The specimens were fractured in shear using an Instron machine. Results: For the groups bonded immediately after bleaching, one‐way analysis of variance (ANOVA) followed by the Duncan's post hoc test revealed a statistically significant reduction in bond strengths in a range from 71% to 76%. For the groups bonded at 1 week, one‐way ANOVA showed that group B (35% HP for 30 min) resulted in the highest bond strengths, whereas 10% CP resulted in the lowest bond strengths. Student's t‐test showed that delayed bonding resulted in a significant increase in bond strengths for groups B (35% HP) and C (35% CP); whereas the group bleached with 10% CP (group D) remained in the same range obtained for immediate bonding. Storage in artificial saliva also affected the control group, reducing its bond strengths to 53% of the original.     

Microleakage of Dentin Adhesive Systems

Five different dentin adhesives were evaluated under various experimental conditions (using different restorative materials, placement techniques, and specimen storage). A silver-staining technique was used to detect microleakage. Pentra Bond II was less effective than Tenure in prevention of marginal leakage, but similar to Scotchbond 2 and Gluma.     

Microleakage Evaluation in Amalgam Restorations Used with Bases

Marginal leakage in amalgam restorations often precedes the development of secondary caries. One potential way to improve the marginal seal of such restorations, and thus minimize the risk of carles development, is to apply a glassionomer base prior to amalgam placement.
This study compared microleakage resistance among amalgam restorations placed with and without light-cured glass-ionomer base materials. Preparations were made in extracted human molar teeth. Four groups were studied, including copal varnish, which was used as a control. All specimens were restored with amalgam. Results indicated significantly greater leakage at the cavity wall/base interface for restorations with a copal varnish cavity liner than for those with a glass-ionomer base. Leakage differences among bases were also found at the amalgam/base interface. Best results were obtained with a dual-cure resin-based system. These samples showed minimal leakage at both the cavity wall/base and the base/amalgam interfaces. These findings suggest that light-cured glass-ionomer bases can be effective in the prevention of microleakage in amalgam restorations.     

Evaluation of Microleakage in Tenure-Based Restorations

This study evaluates the effects of six composite resins, which use three different curing systems, on the ability of Tenure to resist microleakage. The curing systems were a photoinitiated dual-cure system, a dual-cure system, and light-cure systems. A total of 39 human molars were used. Following 2,000 cycles on a thermocycler, specimens were exposed to 0.2 percent basic fuchsin dye for 24 hours and then examined for microleakage. Results indicated that the composite resin plays an important role in the ability of a restorative system to resist microleakage. The photoinitiated dual-cure system produced significantly less microleakage than light-activated systems. No difference in microleakage was found between light-activated systems and the dual-cure system.     

Effects of Dentin Bonding Agents on the Cell Cycle of Fibroblasts

The aim of this study was to evaluate the effects of 3 dentin bonding agents on cell survival and proliferation and on cell cycle progression of cultured cells. The experiments were performed on RPC-C2A and L929 cells. Specimens of the 3 dentin bonding agents (Clearfil Tri-S, AdheSE, and XP BOND) were placed in culture medium, and the extraction media were applied to cells as experimental material. The effect of the bonding materials on cell survival and proliferation was assessed by a modified sulforhodamine B staining assay, and the effect on DNA synthesis was assessed by bromodeoxyuridine uptake. Flow cytometry was used for cell cycle analysis. Cell viability and proliferation decreased in a dose-dependent manner after exposure of cells to the tested materials. XP BOND expressed the highest activity of all tested bonding agents (P < .05). The self-etch bonding agents tested did not produce any significant effects on cell cycle distribution. However, exposure of cells to the total-etch agent XP BOND induced a G₂-phase arrest in both cell lines, and this effect was more evident in L929 cells than in RPC-C2A cells.     

Bonding of Composite Resin to Contaminated Human Enamel and Dentin

Purpose The purpose of this in vitro study was to evaluate the bond strengths of a bonding agent and composite resin system to human enamel and dentin treated with five contaminants (saliva, plasma, zinc oxide–eugenol cement, noneugenol zinc oxide cement, and handpiece lubricant) using air, moisture, and water as controls. Materials and Methods A commercial bonding agent (Gluma 2000; Bayer AG, Dormagen, Germany) and its composite (Pekafill; Bayer AG) were applied to tooth structure under two conditions (contaminated and re-etched). Samples were debonded in tension after 24 hours using an inverted, truncated cone bond test. Results Among the controls, the highest bond strengths were obtained to enamel (20 MPa) and dentin (12 MPa) with air drying. Contaminants lowered the bond strength by 20% to 100%. Re-etching without additional mechanical preparation resulted in bond strengths similar to the air control. Conclusions Bond strength of Gluma 2000/Pekafill to tooth structure is sensitive to common forms of contamination but can be improved by re-etching after contamination occurs.     

酸蚀剂浓度对牙本质粘接界面影响的SEM和TEM研究

目的：研究不同浓度的酸蚀剂对牙本质湿粘接界面的影响。方法：选用10%、32％、和37％ 3种浓度的磷酸酸蚀剂处理牙本质粘结面，然后用四种牙本质湿粘接剂将复合树脂粘结在处理后的牙本质粘结面，在扫描电镜(SEM)和透射电镜(TEM)下观察粘接界面的微观形态。结果：用不同浓度的酸蚀剂处理牙本质粘结表面时，4种粘接系统OptiBond Solo、Single Bond、Gluma One-Bond和One-Step均可以观察到较为理想的渗透图像，同一粘接剂、不同浓度酸蚀剂处理后的界面超微结构之间没有明显区别。结论：10％、32％和37％ 3种浓度的磷酸酸蚀剂处理牙本质后，形成的湿粘接界面超微结构之间没有显著差别。     

The Efficacy of Three Desensitizing Agents Used to Treat Dentin Hypersensitivity

BackgroundIn a single-center, double-masked, split-mouth–designed, clinical short-term trial, the authors assessed the clinical responses of teeth with dentin hypersensitivity (DH) after treating the teeth with one of three desensitizing agents across four weeks.MethodsThe authors selected 131 teeth with DH in 11 participants. The authors assessed DH of the teeth by using tactile stimuli and air stimuli and had the participants record the level of sensitivity by means of a visual analog scale (VAS). The authors then treated the teeth with one of three desensitizing agents (Pain-Free [Parkell, Edgewood, N.Y.], BisBlock [Bisco, Schaumburg, Ill.], Seal & Protect [Dentsply DeTrey, Konstanz, Germany]) that they applied according to the manufacturers' instructions. The authors used a split-mouth–designed study in which the teeth in different quadrants of the participants' mouths received different desensitizing agents. The authors also conducted DH evaluations at 10 minutes after treatment and at one, two, three and four weeks. The authors analyzed data statistically by using Mann-Whitney U and Kruskal-Wallis tests.ResultsThe results of the statistical analysis showed that all VAS scores at the posttreatment evaluation periods were reduced significantly compared with those at baseline (P < .05). More teeth were sensitive to air stimuli than to tactile stimuli. The mean VAS scores for DH in the mandibular teeth were significantly higher than for those in maxillary teeth immediately after treatment (for tactile stimuli) and two weeks after the first application (for air stimuli) (P < .05)ConclusionsAll three desensitizing agents were effective in relieving DH up to four weeks, independent of their application procedures. There was, however, a significant reduction in mean sensitivity scores of teeth that had been treated with Seal & Protect and Pain-Free compared with those of BisBlock at weeks two, three and four.Clinical ImplicationsThe study results should be considered with caution, as it is not clear how many of the pain relief effects were related to the natural desensitization of teeth over time.     

Effect of Two Abrasive Systems on Resin Bonding to Laboratory-Processed Indirect Resin Composite Restorations

Abstract: Purpose: This study compared two methods of surface roughening or preparation, with or without the use of proprietary surface wetting agents, to evaluate their effect on resin cement adhesion to the following laboratory-processed, indirect restorations: Artglass (AG), belleGlass HP (BG), Concept (C), and Targis (T). Methods of surface roughening or preparation included microetching with aluminum oxide (AC): 50 μm at 34 psi and silanized silica coating, CoJet-Sand (CJ): 30 μm at 34 psi. Artglass and Concept were tested with and without the use of their respective surface wetting agents: Artglass Liquid (AGL) and Special Bond II (SB). Materials and Methods: One hundred twenty specimens, each consisting of a pair of cylinders (7.0 × 3 mm and 4.3 × 3 mm) were fabricated. The larger cylinder or base was embedded in self-curing resin in a phenolic ring, and bonding surfaces were finished with 320-grit silicon carbide paper. Specimen pairs for each restorative material were randomly assigned to treatment groups (n = 10) and received the following surface treatments prior to cementation group 1 (AG/AO/+AGL), group 2 (AG/AO/-AGL), POUP 3 (AG/CJ/+AGL), group 4 (AG/CJ/-AGL), group 5 (BG/AO), group 6 (BG/CJ), group 7 (C/AO/+SB), group 8 (C/AO/-SB), group 9 (C/CJ/+SB), group 10 (C/CJ/-SB), group 11 (T/AO), and group 12 (T/CJ). Specimen pairs were cemented with a dual-cure resin cement (Dual) and a standardized force of 1 MPa. Specimens were light-cured 40 seconds per side (80 s total), then thermocycled 300 times at between 5° and 55°C. Shear bond strengths (MPa) were determined using a Zwick Materials Testing Machine at a crosshead speed of 5 mm per minute. Results: One-way analysis of variance (ANOVA) and Duncan's multiple range test (α= 0.05) by restoration type indicated no significant differences in shear bond strength between BG group 5 (29.8 ± 5.8), BG group 6 (28.3 ± 4.3), T group 11 (29.3 ± 4.9), and T group 12 (29.0 ± 4.4). Shear bond strength in AG group 3 (35.9 ± 3.4) was significantly higher than in AG group 4 (32.4 ± 4.0) and equal to that in AG group 2 (31.9 ± 3.9) and AG group 1 (30.0 ± 3.6). Shear bond strength in C group 10 (24.8 ± 5.7) was equal to that in C group 9 (21.5 ± 2.9), but was higher than in C groups 7 (19.4 ± 3.1) and 8 (19.3 ± 3.4).     

乙醇润湿在牙本质疏水性粘接的应用研究

目的：研究乙醇润湿技术应用于牙本质疏水性粘接的效果。方法：20颗无龋第三磨牙去除冠部釉质后,随机分成4组。实验组用无水乙醇润湿牙面30s或用梯度乙醇润湿牙面后进行疏水性粘接;阳性对照组采用AdperScotchbond Multi-Purpose粘接;阴性对照组在水润湿的牙面进行疏水性粘接。固化24h后进行微拉伸粘接强度检测和扫描电镜观察。结果：梯度乙醇润湿组的粘接强度和阳性对照组相比无显著性差异,所形成的混合层均匀致密,树脂突较多;而乙醇润湿30s组的粘接强度低于对照组（P〈0.05）,其混合层不均匀,树脂突短而少。结论：在牙本质疏水性粘接中使用梯度乙醇润湿的方法可获得良好的粘接效果。