Bonding to sound vs caries-affected dentin using photo- and dual-cure adhesives

This study aimed to evaluate the microtensile bond strength (microTBS) of photo- and dual-cure adhesives to sound and caries-affected dentin using total- and self-etch techniques. Human third molars with occlusal caries were prepared as previously described by Nakajima and others (1995). Dentin surfaces were bonded with Optibond Solo Plus (Kerr; photo-cure adhesive) or Optibond Solo Plus + Dual-cure activator (Kerr; dual-cure adhesive) with total- and self-etch technique. Clearfil AP-X (Kuraray) was used for composite buildups. Following storage in distilled water at 37 degrees C for 24 hours, the teeth were sectioned into 0.7-mm thick slices to obtain sound and caries-affected dentin slabs, then trimmed to form hour glass shapes with a 1 mm2 cross-sectional area. The specimens were subjected to microtensile testing using EZ-test (Shimadzu) at 1 mm/minute. Data were analyzed using three-way ANOVA and Student's t-Test (p<0.05). Bond strengths to sound dentin with photo- and dual-cure adhesives using total- and self-etch techniques were significantly higher than those to caries-affected dentin. Dual-cure adhesive significantly decreased bond strengths both to sound and caries-affected dentin. The total-etch technique showed no beneficial effect on caries-affected dentin compared with the self-etch technique. Scanning electron microscopic observation of the resin-dentin interfaces revealed that hybrid layers in caries-affected dentin were thicker than those observed in sound dentin with photo- and dual-cure adhesives. Resin infiltration into dentinal tubules of caries-affected dentin was hampered by the presence of mineral deposits.     

Aggressiveness of self-etch adhesives on unground enamel

Manufacturers of mild self-etch adhesives advocate the adjunctive use of phosphoric acid etching when bonding to unground enamel. This study tested the null hypothesis that there is no difference between the recently introduced, more aggressive self-etch adhesives and a total-etch adhesive in bonding to unground enamel. The ultrastructure and microtensile bond strengths (microTBS) of Xeno III (Dentsply) and Simplicity (Apex Dental Materials), bonded to unground enamel, were examined after thermocycling. Clearfil SE Bond (Kuraray), a mild self-etch adhesive, was used as the negative control, and One-Step (BISCO), a total-etch adhesive bonded to phosphoric acid-etched unground enamel, was used as the positive control. Differences in the thickness of enamel hybrid layers were observed and the aggressiveness of apatite dissolution in the four adhesives.     

Incompatibility of oxalate desensitizers with acidic, fluoride-containing total-etch adhesives

The use of oxalate desensitizers on acid-etched dentin prior to adhesive application can result in subsurface tubular occlusion by calcium oxalate crystals. However, the solubility of calcium oxalate increases in acidic solution. We hypothesized that total-etch adhesives can, depending upon their pH, interact with oxalate-desensitizer-treated dentin in an adverse manner. Acid-etched human dentin treated with 2 oxalate desensitizers (BisBlock and Super Seal) was bonded with 4 simplified total-etch adhesives: One-Step (OS), Single Bond (SB), OptiBond Solo Plus (OB), and Prime&Bond NT (PB). Composite-dentin beams were examined by SEM and TEM, both of which revealed numerous spherical globules on OB- and PB-bonded, desensitizer-treated dentin, but not in OS or SB samples. Bond strengths produced by OB and PB were significantly lower in oxalate-treated specimens than those produced by OS or SB. These surface globules may have interfered with hybridization of demineralized dentin with OB and PB resins and caused compromised bond strengths.     

修复方式及粘接剂类型对牙本质粘接微拉伸强度的影响

目的 :研究不同修复方式及粘接剂类型对牙本质粘接微拉伸强度的影响。方法 :18个离体牙按牙体预备方法分为窝沟预备及冠部平切两组 ,每组分别使用One StepPlus、Primer&BondNT和SingleBond三种粘接剂进行牙本质粘接 ,最后均用AELITETMLS复合树脂修复牙体外形。样本包埋切割成块后 ,测试牙本质微拉伸强度。结果 :使用One StepPlus和SingleBond粘接剂时 ,冠部平切组微拉伸强度高于窝洞预备组 ,差异具有统计学意义 ;无论何种修复方式 ,One StepPlus和SingleBond的微拉伸强度均高于Primer&BondNT。 结论 :不同修复方式和粘接剂类型对牙本质粘接微拉伸强度存在影响     

Influence of conditioning time on enamel adhesion.

OBJECTIVE: The aim of this study was to calculate enamel bond strengths of 4 self-etch adhesives in function of conditioning time. METHODS AND MATERIALS: Sixty proximal surfaces of 30 extracted human molars were roughened and assigned to 4 self-etch adhesives: AdheSE (Ivoclar Vivadent), Adper Prompt L-Pop (3M Espe), Clearfil SE Bond (Kuraray America), and Tyrian SPE/One-Step Plus (Bisco). Prime & Bond NT (Dentsply) was used as the total-etch control. For 30 surfaces, the adhesives were applied per the manufacturers' directions. For the remaining 30, enamel was conditioned for twice the time recommended by the manufacturer. Buildups were constructed with Filtek Z250 (3M ESPE). Bonded specimens were sectioned in sticks and tested to tensile failure. Data were analyzed with 2-way ANOVA and Duncan's test at P < .05. The pH of the self-etch solutions and the phosphoric acid gel was measured with a pH meter. A correlation coefficient was computed to measure the linear association between pH and bond strengths. RESULTS: Tyrian SPE and Prime & Bond NT, the adhesives whose acidic conditioners yielded the lowest pH, ranked in the highest subset regardless of application time. AdheSE and Clearfil SE Bond, which had the highest pH, were the only adhesives for which double application time resulted in statistically higher bond strengths than the recommended time. When means were pooled for application time, Tyrian SPE and Prime & Bond NT resulted in bond strengths that were significantly higher than those of the remaining adhesives. AdheSE resulted in statistically lower bond strengths than any other adhesive. A significant correlation was found between pH and mean bond strengths. CONCLUSION: Doubling the enamel conditioning time might increase bond strengths for specific self-etch adhesives.     

丁香油酚对全酸蚀/自酸蚀牙本质粘接系统微拉伸强度的影响

目的:评价含丁香油酚的暂封剂氧化锌丁香油糊剂(zincoxide- eugenol ,ZOE)对全酸蚀/自酸蚀牙本质粘接系统微拉伸强度的影响。方法:选择因正畸拔除的完整、无龋前磨牙;两种全酸蚀牙本质粘接系统:AllBond 2和SingleBond ,两种自酸蚀牙本质粘接系统:ClearfilSEBond和iBond。实验组使用氧化锌丁香油糊剂;对照组牙本质表面不做任何处理;分别存储于3 7℃的蒸馏水中,一周后两组分别使用4种牙本质粘接系统,用微拉伸法测试粘接强度。在体视显微镜下观察断裂界面。结果:双因素方差分析使用ZOE对粘接强度有显著影响(P <0 .0 5 ) ,粘接剂的类型对粘接强度无显著性影响(P >0 .0 5 ) ,交互作用有统计学意义(P <0 .0 5 )。多重比较提示,AllBond 2和SingleBond的实验组和对照组无显著性差异,而ClearfilSEBond和iBond实验组的微拉伸强度明显低于对照组,有显著性差异。体视显微镜下观察断裂多发生在粘接剂内。结论:含丁香油酚的暂封剂氧化锌丁香油糊剂对全酸蚀系统的AllBond 2和SingleBond的粘接强度无影响,对自酸蚀系统的ClearfilSEBond和iBond有显著不利影响。     

Enamel bond strengths of pairs of adhesives from the same manufacturer

Most manufacturers of dental adhesives have both a total-etch adhesive and a simplified self-etching adhesive available on the market. This study measured the enamel microtensile bond strengths of five pairs of enamel adhesives as a function of enamel roughness. The proximal surfaces of 25 extracted mandibular molars were sectioned with a diamond saw to obtain 50 enamel rectangles with an area of 8x4 mm2. The enamel rectangles were divided in two equal parts via a groove to obtain 4x4 mm2 squared bonding surfaces. One half was roughened with a coarse diamond bur under water for five seconds, while the other half was kept intact. The enamel surfaces were randomly assigned to 10 enamel adhesives grouped into five pairs. Each pair included one self-etch adhesive and one total-etch adhesive from the same manufacturer: Adper Prompt and Adper Single Bond (PLP and SB, 3M ESPE); AdheSE and Excite (ADH and EXC, Ivoclar Vivadent); OptiBond Solo Plus SE and OptiBond Solo Plus (OPTSE and OPT, Kerr); Tyrian SPE/One-Step Plus and One-Step (TYR and OST, BISCO, Inc); Xeno III and Prime&Bond NT (XEN and PBNT, Dentsply). The adhesives were applied according to the manufacturers' instructions. Buildups were constructed with Filtek Z250 (3M ESPE). The specimens were sectioned in sticks with a cross section of 0.8+/-0.2 mm2 and tested to failure in tension at a crosshead speed of 1 mm/minute. Two-way ANOVA followed by Duncan's post-hoc test at p<0.05 was computed. The highest mean bond strengths were obtained with total-etch adhesives. For "roughened enamel," three pairs of materials had statistically different means in which the total-etch adhesive resulted in statistically higher bond strengths (MPa) than the corresponding self-etch adhesive: EXC (36.6) > ADH (23.0) at p<0.026; OPT (34.5) > OPTSE (25.3) at p<0.028; PBNT (36.6) > XEN (19.5) at p<0.0001. For "intact enamel," four pairs of materials resulted in statistically different means: SB (31.7) > PLP (20.9) at p<0.049; EXC (37.9) > ADH (16.3) at p<0.0001; OST (30.1) > TYR (18.0); PBNT (43.8) > XEN (16.0) at p<0.0001. When the same adhesive was compared on intact vs roughened enamel, all the self-etch materials resulted in lower bond strengths on intact enamel, but this difference was only significant for TYR (p<0.042) and ADH (p<0.050). For total-etch materials, only OPT resulted in statistically lower bond strengths when applied on intact enamel p<0.011).     

Dentin and enamel bond strengths of dual-cure composite luting agents used with dual-cure dental adhesives

OBJECTIVE: The purpose of this in vitro study was to evaluate and compare dentin and enamel bond strengths obtained with dual-cure composite luting agents when used with dual-cure dental adhesives. METHODS: Human molars were ground flat to expose enamel (n=80) or dentin (n=80). Specimens in each substrate group were randomly assigned to eight treatment sub-groups, according to four adhesive-luting agent combinations and two test conditions (with or without thermocycling). Pre-polymerized composite resin posts (TPH Spectrum) were luted to either the enamel or dentin surfaces with one of the following adhesive-luting agent combinations: (1) Xeno IV Dual Cure (dual-cure self-etch adhesive) and Calibra (dual-cure luting agent); (2) Prime & Bond NT Dual Cure (dual-cure total-etch adhesive) and Calibra; (3) OptiBond All-in-One Dual Cure (dual-cure self-etch adhesive) and Nexus 2 Dual Syringe (dual-cure luting agent); (4) OptiBond Solo Plus Dual Cure (dual-cure total-etch adhesive) and Nexus 2 Dual Syringe. For each treatment sub-group, half the specimens (n=10) were tested after 24h storage in water at 37 degrees C, and the other half (n=10) were tested after thermocycling for 1800 cycles between water baths held at 5 and 55 degrees C, with a dwell time in each bath of 30s, and a transfer time of 10s. Bond strengths were measured in shear mode, and expressed in MPa. The fracture mode (adhesive, cohesive, mixed) was examined. Data were analyzed for statistical significance with a factorial ANOVA and post hoc tests. RESULTS: Mean enamel bond strengths ranged from 8.4MPa for non-thermocycled OptiBond All-in-One|Nexus 2 to 35.5MPa for non-thermocycled Prime & Bond NT|Calibra. Mean dentin bond strengths ranged from 14.5MPa for non-thermocycled OptiBond Solo Plus|Nexus 2 to 30.9MPa for thermocycled Xeno IV|Calibra. The fracture mode was predominantly adhesive for all groups. CONCLUSIONS: On enamel, the total-etch adhesives performed better than their self-etch counterparts, while in dentin, the opposite was found, i.e., the self-etch adhesives performed better than their total-etch counterparts. Thermocycling for 1800 cycles did not affect the SBS of the materials tested to dentin and enamel.     

Micro-shear bond strength of five resin-based composites to dentin with five different dentin adhesives

PURPOSE: To test whether the combination of dentin adhesive and resin-based composite from the same manufacturer had higher micro-shear bond strength than the other combinations of different manufacturers. METHODS: 25 experimental micro-shear bond test groups were made from the combination of five resin-based composites and five dentin adhesives (three total-etch adhesives and two self-etch adhesives) with extracted human molars stored in saline for 24 hours. The test was performed with the wire-loop method using a universal testing machine, and the micro-shear bond strengths were calculated. SEM photomicrographs of fractured sites were taken to check the failure mode. RESULTS: The combinations from same manufacturers failed to show higher bond strengths than the other combinations. Self-etch adhesives showed significantly higher micro-shear bond strengths than total-etch adhesives (P < 0.05). In total-etch adhesives, the kind of resin composite was important and in self-etch adhesives, the kind of adhesive had significant effect on micro-shear bond strength (P < 0.05). All sites showed mixed fractures.     

脱矿牙本质与四种粘接剂的粘接强度测试及粘接界面观察

目的比较脱矿牙本质与4种全酸蚀或自酸蚀粘接剂的粘接强度及粘接界面超微结构的差异,以期对临床治疗有所指导。方法选择20颗面龋坏的离体磨牙,在龋显示剂的指示下去除牙本质龋的感染层,保留脱矿牙本质。平齐龋洞洞底平面,去除冠向牙体组织,作为粘接面。选择临床常用的2种全酸蚀粘接剂:材料A(All Bond2)、材料B(Prime&BondNT)和2种自酸蚀粘接剂:材料C(ClearfilSEBond)、材料D(XenoⅢ),分别按说明书要求粘接。用慢速锯将样本牙切为粘接面积约0.9mm×0.9mm的长方体试件。体视显微镜下将试件分为正常牙本质组和脱矿牙本质组,用微拉伸测试仪检测粘接强度。扫描电镜观察各组试件粘接界面的超微形态。结果方差分析提示牙本质类型和粘接剂对微拉伸粘接强度的影响均有统计学意义(P<0.05)。对正常牙本质,不同粘接剂的微拉伸粘接强度差异无统计学意义(P>0.05);对于脱矿牙本质,材料D的微拉伸粘接强度较其他粘接剂明显降低(P<0.05)。扫描电镜下观察脱矿牙本质的混合层多孔稀疏,树脂突短少,无侧枝形成。结论对脱矿牙本质,本项实验中全酸蚀粘接剂的粘接强度优于自酸蚀粘接剂。     

Shear bond strengths of self-etching adhesives to caries-affected dentin on the gingival wall

The purpose of this study was to evaluate the bonding ability of five current self-etching adhesives to caries-affected dentin on the gingival wall. Seventy extracted human molars with approximal dentin caries were employed in this study. In order to obtain caries-affected dentin on the gingival wall, grinding was performed under running water. Following which, specimens mounted in acrylic blocks and composite resins of the bonding systems were bonded to dentin with plastic rings and then debonded by shear bond strength. With Clearfil SE Bond, bonding to caries-affected dentin showed the highest bond strength. With Optibond Solo Plus Self-Etch, bonding to caries-affected dentin showed higher shear bond strength than AQ Bond, Tyrian SPE & One-Step Plus, and Prompt-L-Pop (p<0.05). Further, the bond strengths of Clearfil SE Bond and Optibond Solo Plus Self-Etch to sound dentin were higher than those of Prompt-L-Pop, AQ Bond, and Tyrian SPE & One-Step Plus (p<0.05). In conclusion, besides micromechanical interlocking through hybrid layer formation, bond strength of self-etch adhesives to dentin may be increased from additional chemical interaction between the functional monomer and residual hydroxyapatite. The results of this study confirmed that differences in bond strength among self-etching adhesives to both caries-affected and sound dentin were due to chemical composition rather than acidity.     

Application of a dental adhesive using the self-etch and etch-and-rinse approaches: an 18-month clinical evaluation

BACKGROUND: Laboratory investigations have demonstrated that the application of multiple adhesive coats can increase adhesive infiltration, thereby increasing bond strength values. The authors conducted an 18-month, randomized, controlled prospective study to evaluate the clinical performance of a self-etch and an etch-and-rinse adhesive in noncarious cervical lesions. METHODS: Twenty-nine patients with at least two pairs of similarly sized lesions participated in this study. The authors placed 116 restorations in one of four groups: OS2 (phosphoric acid and dental adhesive [One-Step Plus, Bisco, Schaumburg, Ill.], following the manufacturer's recommendation [two coats]); OS4 (phosphoric acid and One-Step Plus, with four coats); TY2 (Tyrian SPE [Bisco] and One-Step Plus, following the manufacturer's recommendation [two coats]); and TY4 (Tyrian SPE and One-Step Plus, with four coats). The authors evaluated the restorations at baseline and at six, 12 and 18 months, according to modified U.S. Public Health Service criteria. (Eight of the 116 restorations were unavailable for follow-up.) RESULTS: The retention rate for the TY2 group (55.5 percent) was statistically lower than that for the TY4 (77.8 percent) and OS4 (88.9 percent) groups. Only teeth in OS4 exhibited a retention rate at 18 months that was similar to that observed at baseline. Marginal discoloration occurred in all groups, and it was statistically significantly worse in TY2. CONCLUSIONS: Multiple adhesive coats significantly improved retention rates. CLINICAL IMPLICATIONS: Applying multiple coats of adhesive with the etch-and-rinse or self-etch approach can improve retention rates of Class V resin-based composite restorations, although not to the level of the American Dental Association's guidelines for dentin and adhesive materials.     

Micro-tensile and micro-shear bond strengths of current self-etch adhesives to enamel and dentin

PURPOSE: To evaluate the micro-tensile and micro-shear bond strengths of self-etch adhesives to enamel and dentin. METHODS: Extracted human molars were ground to expose flat enamel or dentin surfaces using wet #600 grit SiC paper. The enamel and dentin surfaces were assigned to four groups of four adhesives: three one-step self-etch adhesives (Clearfil S3 Bond; AQ Bond Plus, G-Bond) and a two-step self-etch adhesive (Clearfil SE Bond). Each of the adhesives were applied to the enamel or dentin surfaces in accordance with the manufacturers' instructions and restored with resin composite (Clearfil AP-X). The bonded teeth were then prepared for either micro-tensile or micro-shear bond strength tests. After storage in saline at 37 degrees C for 24 hours, specimens were stressed at a crosshead speed of 1 mm/minute. Mean bond strengths and modes of failure were analyzed using one-way ANOVA followed by Scheffe's F test and the Chi-square test, respectively, at a 95% level of confidence. RESULTS: SE Bond produced significantly higher values than the one-step adhesives in the micro-shear bond test to enamel (P< 0.05), while no significant differences were found among the adhesives in the micro-tensile bond test (P> 0.05). For dentin, SE Bond showed the highest bond strengths in both micro-tensile and micro-shear bond tests; values were significantly higher than both AQ Bond Plus and G-Bond (P< 0.05).     

Effects of filling techniques on the regional bond strength to lateral walls in Class I cavities

OBJECTIVES: Using the push-out technique, this study compared the influence of different composite insertion techniques in Class I cavities on the regional shear bond strength to lateral walls. MATERIALS AND METHOD: Standardized Class I cavities were prepared on the occlusal surface of 60 freshly extracted third molars, which were randomly assigned to one of five groups (n = 10). The cavities were bonded with the self-etch adhesive AdheSE and restored with Tetric Ceram resin composite by one of five techniques: G1, incremental technique (four oblique layers); G2, flowable composite as liner and bulk technique; G3, bulk technique and G4, light cone technique. The total-etch adhesive (Single Bond) and incremental technique were used as the control procedure. Each specimen was sectioned perpendicular to the long axis of the tooth in 1 mm-thick dentin slices. A push-out test was performed to measure regional bond strengths and identify the type of failure. Two additional teeth per group were prepared for the morphological interface study using scanning electron microscopy. RESULTS: Differences between the groups were tested by one-way ANOVA and Scheffé post hoc test (F = 29.635, p < 0.001). The highest shear bond strength values were obtained with the incremental technique, regardless of the adhesive used. Significant differences in bond strength to superficial and deep dentin were only found when a total-etch adhesive was used (Single Bond). CONCLUSIONS: Use of the incremental technique with total-etch or self-etch adhesives is the most effective method of inserting resin-based composites in large Class I cavities.     

Effect of endodontic irrigation on bonding of resin cement to radicular dentin

The influence of endodontic irrigation on shear bond strengths of resin cement to radicular dentin was investigated. Human radicular dentin blocks were divided into four groups and subjected to one of four endodontic irrigations: ethylenediaminetetraacetic acid (EDTA) group, 17% EDTA for 60 s; EDTA/sodium hypochlorite (NaOCl) group, 17% EDTA for 60 s followed by 10 ml of 5% NaOCl for 15 s; NaOCl group, 10 ml of 5% NaOCl for 15 s; and control group, no treatment. Morphological changes of dentin surface after endodontic irrigation were observed by scanning electron microscopy (SEM). A resin block was bonded to the radicular dentin after irrigation using resin cement with either wet-bonding (Uni-Etch/One-Step; Bisco) or self-etching (Tyrian SPE/One-Step Plus; Bisco) adhesives. Shear bond strengths were measured and the penetration of resin tags into dentinal tubules at resin-dentin interface was observed by SEM. With the wet-bonding system, the shear bond strengths for the EDTA/NaOCl group, in which dentinal tubules openings and uniform resin tag penetration into dentinal tubules were observed, were significantly higher than the EDTA and control groups. With the self-etching system, the shear bond strengths were significantly lower in the EDTA group compared with the NaOCl and control groups. The effects of endodontic irrigation on the bonding of resin cement to radicular dentin depended on the dentin bonding system used.     

五种牙本质粘结系统微拉伸强度的比较

目的比较不同类型自酸蚀牙本质粘结系统的粘结强度,为临床应用提供参考。方法选择4种自酸蚀粘结系统Clearfil S3Bond,i Bond,Clearfil SE Bond,XenoⅢ,1种全酸蚀粘结系统Single Bond2,用微拉伸法测试这些粘结系统的粘结强度并进行比较。结果全酸蚀粘结剂Single Bond2的微拉伸强度最高,与自酸蚀粘结剂粘结强度有显著差异（P〈0.05）。自酸蚀粘结剂i Bond,S3Bond,XenoⅢ两两之间粘结强度无显著差异（P〉0.05）。SE Bond的粘结强度显著高于i Bond,S3Bond和XenoⅢ（P〈0.05）。结论第五代牙本质粘结剂具有较强的粘结强度,但第七代牙本质粘结剂临床操作更为方便。     

冷热循环对牙本质粘结耐久性的影响

目的:研究冷热循环对牙本质粘结强度和粘结界面纳米渗漏的影响.方法:选取30个无龋损人磨牙,用600目碳化硅砂纸在流水冲洗下预备牙本质粘结面,分别用3种(Prime&Bond NT,Adper Prompt和Contax)粘结剂进行粘结处理,复合树脂充填.纵向片切牙齿,制备粘结面积为1 mm2的条形树脂牙本质试样.冷热循...     

Incompatibility of self-etch adhesives with chemical/dual-cured composites: two-step vs one-step systems

This study tested the null hypothesis that there no difference between two-step and one-step self-etch adhesives in their compatibility with these composites. The microtensile bond strengths (microTBS) of two two-step systems (Clearfil SE Bond, Kuraray and Tyrian SPE/One-Step Plus, BISCO) were compared with two one-step systems (Xeno III, Dentsply DeTrey and Brush&Bond, Parkell) for their coupling to a dual-cured composite. Silver tracer penetration of the four adhesives bonded to a light-cured or a chemical-cured composite was examined using TEM. Significant differences in microTBSs between composite curing modes were seen only in the one-step adhesives. For one-step self-etch adhesives bonded to the chemical-cured composite, TEM revealed signs of frank composite uncoupling along the adhesive-composite interface, which may be attributed to the adverse chemical interaction between the acidic adhesive and the composite. In addition, "water trees" that represent channels of increased permeability with the polymerized adhesive layer were also observed in the one-step adhesives. Both features were absent along the resin-dentin interfaces when chemical-cured composites were coupled to the two-step self-etch adhesives.     

Bond strength of different adhesive systems to dental hard tissues

This study compared the shear bond strengths of different adhesive systems to enamel and dentin of different depths. The adhesive systems used were: Single Bond one-bottle total-etch; AQ Bond one-step self-etching, Clearfil SE Bond two-step self-etching and Tyrian SPE/One-step Plus two-step self-etching. Eighty extracted non-carious human mandibular molars were mounted in self-curing resin and the occlusal surfaces were ground with a mechanical grinder to obtain flat occlusal enamel surfaces. After applying the adhesive systems, a plastic tube was attached to the enamel surfaces. The tube was filled with a universal hybrid resin composite, which was then polymerized. The specimens were stored in water at 37 degrees C for 24 hours. Shear bond testing was carried out using an Instron Universal testing machine with a crosshead speed of 1 mm/minute. The occlusal enamel of the 80 teeth was removed to determine the bond strengths of the adhesives to superficial dentin. To obtain deep dentin, the same teeth were ground deep towards the pulp, with the remaining dentin thickness approximately 0.7 mm. The adhesives and restorative material were then applied to the prepared dentin surfaces following the methodology described above. For occlusal enamel surfaces, the bond strength of Single Bond was significantly higher than the other adhesives. Single Bond, Clearfil SE Bond and Tyrian SPE/One-step Plus performed equally when bonded to superficial dentin; the lowest bond strength was obtained with AQ Bond. On deep dentin, the highest bond strengths were obtained with Clearfil SE Bond. For each adhesive system, shear bond strength to enamel was statistically higher than it was to either superficial or deep dentin. There were no significant differences between shear bond strengths to superficial versus deep dentin, regardless of adhesive.     

Bond strengths of three different dentin adhesive systems to sclerotic dentin

The two-fold aims of this study were: (1) to evaluate the microtensile bond strengths of different adhesive systems to sclerotic and sound palatal dentin; and (2) to observe the respective resin-dentin interfaces. Thirty extracted human incisor teeth were divided into two groups. Group I comprised sclerotic defects in the palatal zone. Group II comprised sound palatal dentin surfaces as control. Each group (n=15) was divided into three subgroups according to dentin adhesive systems: self-etch (Clearfil SE Bond), total-etch (Scotchbond Multi-Purpose Plus), and glass ionomer (Reactmer Bond) adhesive systems. The specimens were subjected to tensile forces. Obtained data were analyzed by two-way ANOVA and post hoc Duncan's test. Fracture sites and resin-dentin interfaces were observed using a light microscope and SEM. With sound dentin, Clearfil SE Bond showed a significantly higher bond strength than the other adhesives (p < 0.05). With sclerotic dentin, although there were no significant differences in bond strength among the adhesives groups (p > 0.05), the bond strength values of Clearfil SE Bond and Scotchbond Multi-Purpose Plus were significantly decreased. On resin-dentin interface observation, different images were presented by different bonding systems.