The effect of direct and indirect water storage on the microtensile dentin bond strength of a total-etch and two self-etching adhesives

PURPOSE: To evaluate the effect of direct and indirect water storage on the microtensile dentin bond strength of one total-etch and two self-etching adhesives. METHODS: The adhesive materials were: one total-etch adhesive; Admira Bond and two self-etch adhesives; Clearfil SE Bond and Hybrid Bond. Freshly extracted human third molar teeth were used. In each tooth, a Class I cavity (4 x 4 mm) was prepared in the occlusal surface with the pulpal floor extending approximately 1 mm into dentin. The teeth were divided into three groups (n = 12). Each group was restored with the resin composite Clearfil APX using one of the tested adhesives. For each experimental group three test procedures (n = 10) were carried out: Procedure A: the teeth were stored in water for 24 hours, then sectioned longitudinally, buccolingually and mesiodistally to get rectangular slabs of 1.0 - 1.2 mm thickness on which a microtensile test was carried out; Procedure B: the teeth were also sectioned, however the slabs were stored in water at 37 degrees C for 1 year before microtensile testing; Procedure C: the teeth were kept in water at 37 degrees C for 1 year before sectioning and microtensile testing. During microtensile testing the slabs were placed in a universal testing machine and load was applied at a cross-head speed of 0.5 mm/minute. RESULTS: For the 24-hour water storage groups there was no significant difference in bond strength between the three adhesives. After 1 year of indirect water storage, the bond strength decreased but the reduction was not significantly different from those of 24 hours. After 1 year of direct water storage, the mean bond strengths of Admira Bond and Hybrid Bond were significantly reduced compared to their 24-hour results. In contrast the average value of Clearfil SE Bond was not significantly affected.     

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。     

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。     

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。     

Effect of hydrostatic pulpal water pressure on microtensile bond strength of self-etch adhesives to dentin

PURPOSE: To evaluate the effect of pulpal pressure on the microtensile bond strength of four self-etch adhesives to dentin. A total-etch adhesive was added for comparison. METHODS: 60 freshly extracted human third molars were selected. For each tooth, the root was removed below the cemento-enamel junction. A second parallel section was made to remove the coronal enamel to form a crown segment. The root portion of the resulting crown segment was cemented to a Plexiglas platform using cyanoacrylate cement. The crown segment was then connected with a plastic tube to a water column to produce a pressure of 20 cm H2O at the prepared dentin surface of the crown segment. The adhesive materials were: a total-etch adhesive (Scotchbond 1) and four self-etch adhesives (Clearfil SE Bond, Hybrid Bond, Futurabond NR, and AdheSE Bond). The tested adhesives were applied to the dentin surface in three test procedures: applied to dentin without pulpal pressure, applied to dentin with pulpal pressure for 24 hours, and applied to dentin with pulpal pressure and the pressure was maintained for 6 months during storage. Grandio resin composite was placed in 3-4 layers to a height of 5-6 mm to form a crown segment. For bond strength measurement, the composite-dentin segment was removed from the Plexiglas. This segment was then sectioned to prepare the specimens for microtensile bond measurement. RESULTS: None of the tested adhesives showed bond strength reduction when applied to dentin supplied with water pressure. After 6 months of pulpal pressure, Scotchbond 1, Clearfil SE Bond and AdheSE Bond showed significant reduction in bond strength (P < 0.05). In contrast, Futurabond NR and Hybrid Bond were not significantly affected.     

Effect of cyclic loading on the microtensile bond strengths of total-etch and self-etch adhesives

OBJECTIVE: To evaluate the effect of mechanical loading on the microtensile bond strength (MTBS) of five adhesive systems to dentin. METHODS: Flat dentin surfaces from human molars were divided into five groups and bonded with total-etch self-priming adhesives (Single Bond, Prime&Bond NT and Prime&Bond XP), two-step self-etching primer (Clearfil SE Bond) and an all-in-one adhesive (Etch&Prime 3.0), according to the manufacturers' instructions. Composite build-ups were constructed incrementally with Tetric Ceram. After 24 hours of water storage, half the specimens were load cycled (5000 cycles, 90 N). The teeth were then sectioned into beams of 1.0 mm2 cross-sectional area. Each beam was tested in tension in an Instron machine at 0.5 mm/minute. Data were analyzed by two-way ANOVA and Student Newman Keuls multiple comparisons tests (p<0.05). Results: Clearfil SE Bond and Single Bond attained higher MTBS than the other three adhesives. Prime&Bond NT and Prime&Bond XP performed equally, and Etch&Prime 3.0 resulted in the lowest MTBS. After mechanical loading, MTBS decreased in all groups except Prime&Bond XP. Clearfil SE Bond, Single Bond and Prime&Bond XP obtained higher MTBS than Prime&Bond NT. Specimens bonded with Etch&Prime 3.0 resulted in premature failures and MTBS could not be measured. Clinical RELEVANCE: When using Etch&Prime 3.0, bond structures did not withstand mechanical loading, which may have an influence on the long-term success of restorations. If dentin is acid-etched, alcohol-based adhesive systems showed higher bond strength after mechanical loading.     

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).     

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.     

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.     

Microtensile bond strength of one- and two-step self-etching adhesives on sclerotic dentin: the effects of thermocycling

This study evaluated the effects of thermocycling on the microtensile bond strength (microTBS) of one- and two-step self-etch adhesives (SEAs) to sclerotic dentin. Two adhesives, Clearfil S3 Bond (S3), a one-step self-etch adhesive (1-SEA), and Clearfil SE Bond (SE), a two-step self-etch adhesive (2-SEA), were applied on cervical lesions in human premolars with sclerotic or normal dentin. After adhesive application, the lesions were restored and built up using a resin composite (Clearfil AP-X). After 24 hours in water storage, the restored teeth were sectioned into 0.7 x 0.7 mm composite-dentin beams. The beams were then aged with 0, 5,000 or 10,000 thermocycles. The use of two adhesives, two substrate types and three thermocycling regimens yielded 12 experimental groups of 14-19 beams each. The beams were subsequently subjected to microTBS testing at a crosshead speed of 1 mm/minute and statistical analyses were computed with three-way ANOVA and Tukey's post hoc test at p < 0.05. Three-way ANOVA showed statistically significant effects on bonding effectiveness by lesion type, adhesive system, thermocycling or combinations of the adhesive system and thermocycling (p < 0.05). With sclerotic dentin, although S3 and SE provided comparable microTBS after 24 hours of water storage, S3 showed significantly lower microTBS than SE after thermocycling (p < 0.05). Regardless of lesion type, the microTBS for S3 decreased significantly after 5,000 or 10,000 thermocycles, while the microTBS for SE showed a significant decrease only after 10,000 thermocycles. Regardless of the extent of thermocycling, the microTBS values for either SE or S3 bonded to sclerotic dentin were significantly lower than to normal dentin (p < 0.05). The results suggested that thermocycling had a significant negative effect on the bond strength of the two SEAs tested. In contrast to 2-SEA, 1-SEA might not be a good choice for sclerotic dentin when seeking durability of the resin-dentin bond.     

Effect of dentin conditioners on the microtensile bond strength of a conventional and a self-etching primer adhesive system.

OBJECTIVE: To investigate the effect of different dentin treatments on the microtensile bond strength of a self-etching primer and a simplified, total-etch adhesive system. METHODS: Flat dentin surfaces were created on extracted human third molars. The surfaces were treated with one of the following conditioners: self-etching primer for 20 s (Clearfil SE Primer), 37% phosphoric acid for 15 s or 0.5 M EDTA for 30 s. Conditioned surfaces were then bonded with either Clearfil SE Bond or Single Bond followed by resin composite (Z250) build-ups constructed incrementally. Application of SE Primer was included when Clearfil SE Bond was used, after phosphoric acid and EDTA conditioning. After 24 h storage in water at 37 degrees C, the teeth were longitudinally sectioned across the bonded interface to produce beams with 1.0 mm2 of adhesive area, tested with the microtensile method at a rate of 0.5 mm/min. Data were analyzed using two-way ANOVA and Tukey's test. RESULTS: The highest bond strength mean was found for the combination SE Primer/Single Bond (58.5+/-20.8 MPa), followed by the EDTA/Clearfil SE Bond (47.8+/-15.1 MPa) and phosphoric acid/Single Bond (40.9+/-14.3 MPa). The remaining combinations showed statistically similar (p>0.05) tensile bond strength. SIGNIFICANCE: The bond performance of the adhesives tested was dependent on the dentin conditioner. Pre-treatment with a mild etchant such as 0.5 M EDTA improved the bond strength of Clearfil SE Bond. Single Bond performed better when a self-etching primer was used as the dentin conditioner, probably by preventing the formation of a defective zone at the base of the hybrid layer. Overall results indicate that higher bond strengths can be achieved by conditioning dentin with milder etchants, suggesting that deeper demineralization may prevent proper resin infiltration, hence compromising the bond.     

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.     

Morphological characterization of the interface between self-etching adhesives and vital dentin

PURPOSE: To evaluate the in vivo interface between one total-etch and two self-etching adhesives to dentin. METHODS: Two self-etching primers, SE Bond and Hybrid Bond and one total-etch adhesive, Admira Bond, were applied in vivo to flat dentin surfaces on human teeth scheduled for extraction. After adhesive application and curing, a thin layer of resin composite was applied and cured. The teeth were extracted immediately after adhesive application. All samples were split fractured along their long axes. Half of the samples were decalcified and deproteinized to permit visualization of the hybrid layer. The other halves were completely dissolved to observe the morphology of resin tags. RESULTS: The total-etch system Admira Bond showed a thick hybrid layer and long resin tags, while SE Bond showed very thin hybrid layer with short resin tags. The findings of Hybrid Bond were similar to that of Admira Bond.     

Microtensile bond strength of contemporary adhesives to primary enamel and dentin

The purpose of this study was to assess bond strength of three self-etching and two total-etch adhesive systems bonded to primary tooth enamel and dentin. MATERIALS AND METHODS: Forty extracted primary human molars were selected and abraded in order to create flat buccal enamel and occlusal dentin surfaces. Teeth were assigned to one of the adhesive systems: Adper Scotch Bond Multi Purpose, Adper Single Bond 2, Adper Prompt L-Pop, Clearfil SE Bond and AdheSE. Immediately to adhesive application, a composite resin (Filtek Z250) block was built up. After 3 months of water storage, each sample was sequentially sectioned in order to obtain sticks with a square cross-sectional area of about 0.72 mm2. The specimens were fixed lengthways to a microtensile device and tested using a universal testing machine with a 50-N load cell at a crosshead speed of 0.5 mm/min. Microtensile bond strength values were recorded in MPa and compared by Analysis of Variance and the post hoc Tukey test (a = 0.05). RESULTS: In enamel, Clearfil SE Bond presented the highest values, followed by Adper Single Bond 2, AdheSE and Adper Scotch Bond Multi Purpose, without significant difference. The highest values in dentin were obtained with Adper Scotch Bond Multi Purpose and all other adhesives did not present significant different values from that, except Adper Prompt L-Pop that achieved the lowest bond strength in both substrates. Adper Scotch Bond Multi Purpose and Adper Single Bond 2 presented significantly lower values in enamel than in dentin although all other adhesives presented similar results in both substrates. CONCLUSIONS: contemporary adhesive systems present similar behaviors when bonded to primary teeth, with the exception of the one-step self-etching system; and self-etching systems can achieve bond strength values as good in enamel as in dentin of primary teeth.     

Bond strength of adhesives to dentin involving total and self-etch adhesives.

OBJECTIVE: Currently, the trend in dentin adhesion seems to be shifting from moist bonding systems to self-etching systems and from several application steps to single steps. However, recent studies have indicated that the performance of single-step adhesives was lower than the 2-step self-etch or total etch systems. In the present study, microtensile bond strength of a total etch, 2-step self-etch and single-step self-etch adhesives was comparatively evaluated. METHOD AND MATERIALS: The superficial occlusal dentin of 12 noncarious extracted human molars was exposed, finished with wet 600-grit silicon carbide paper, and a block of resin composite bonded with adhesives according to the manufacturers' instructions. The teeth were kept in tap water for 24 hours at 37 degrees C and sectioned to produce beams, with adhesive areas of +/- 0.9 mm2 (4 beams per tooth were obtained). The specimens were stressed at a crosshead speed of 1 mm per minute until the bonds ruptured. RESULTS: The mean bond strengths were calculated as MPa and compared by performing analysis of variance and Tukey tests to identify significant differences between the materials (P = 0.05). The mean bond strength of Clearfil SE Bond was significantly higher than that of OptiBond Solo Plus and iBond (P <.05). OptiBond Solo Plus gave significantly higher bond strengths than iBond (P <.05). CONCLUSIONS: The self-etching adhesive system Clearfil SE Bond (2 step) had higher bond strength than the 1-bottle self-etching adhesive iBond (single application) and the 2-step single-bottle system OptiBond Solo Plus (total etch). However, the 1-bottle adhesive system OptiBond Solo Plus (total etch system) had higher bond strength than the 1-bottle self-etching adhesive system iBond.     

Microtensile bond strength of a filled vs unfilled adhesive to dentin using self-etch and total-etch technique

OBJECTIVE: The purpose of this study was to evaluate the effect of a filled adhesive (One-Step Plus; Bisco) versus an unfilled adhesive (One-Step; Bisco) on the microtensile bond strength (muTBS) to dentin using total-etch (Uni-etch; Bisco) and self-etch (Tyrian SPE; Bisco) techniques. METHODS: Twenty extracted human third molars were ground flat to expose occlusal dentin. After the dentin surfaces were polished with 600-grit SiC paper, the teeth were randomly assigned to four groups according to the bonding agent and technique being used. Dentin surfaces were bonded with One-Step Plus+total-etch; One-Step Plus+self-etch; One-Step+total-etch and One-Step+self-etch. Composite buildups were performed with Clearfil AP-X (Kuraray Medical). Following storage in distilled water at 37 degrees C for 24 h, the bonded specimens were serially sectioned into 0.7 mm-thick slabs and then trimmed to hour-glass shapes with a 1 mm2 cross-sectional area (n=20). Microtensile bond strengths were determined using the EZ-test (Shimadzu) at a cross-head speed of 1 mm/min. Data were analyzed using two-way ANOVA and Tukey's post hoc test. RESULTS: There were no significant differences in the muTBS between One-Step Plus and One-Step adhesives when they were used with the total-etch and self-etch techniques (p>0.05). However with the total-etch technique both adhesives yielded significantly higher bond strength values than the self-etch technique (p<0.001). CONCLUSION: The filled adhesive One-Step Plus did not show any beneficial effect than the unfilled adhesive One-Step on the muTBS to dentin with total-etch and self-etch techniques. Irrespective from the adhesive type, self-etch technique revealed lower bond strengths than the total-etch technique.     

Bond strength of a self-etching adhesive system to caries-affected dentin

This in vitro study evaluated the microtensile bond strengths of sound versus caries-affected dentin using a self-etching adhesive system, Clearfil SE Bond, with or without additional acid pre-conditioning. Extracted human mandibular molars with occlusal caries extending halfway through the dentin were used. In the first group, the teeth were bonded with the self-etching adhesive Clearfil SE Bond according to the manufacturer's instructions. In the second group, prepared dentin surfaces were etched with 37% phosphoric acid prior to applying the same self-etching adhesive. After the bonding procedure, all specimens were built up with composite resin and stored in water for 24 hours. The teeth were serially sectioned vertically into 0.7-mm slabs and trimmed into an hourglass shape for measuring microtensile bond strength. Each specimen was attached to a Bencor device and stressed in tension at a crosshead speed of 1 mm/minute. Statistical analysis was performed using two-way ANOVA and the Tukey HSD test (p<0.05). The microtensile bond strengths of Clearfil SE Bond to sound dentin (32.9) were significantly higher than to caries-affected dentin (15.9). In the second group where acid etching was performed prior to applying Clearfil SE Bond, there were no statistically significant differences between the microtensile bond strengths of sound (19.2) and caries-affected dentin (16.3). While bond strengths to sound dentin were decreased by using additional acid etching prior to applying Clearfil SE Bond, this procedure revealed no statistically significant differences in bond strengths for the caries-affected dentin.     

Effect of thermal aging on the tensile bond strength at reduced areas of seven current adhesives

The purpose of this study was to determine the micro-tensile bond strength (MTBS) to dentin of seven adhesive systems (total and self-etch adhesives) after 24 h and 5,000 thermocycles. Dentin surfaces of human third molars were exposed and bonded with two total-etch adhesives (Adper Scotchbond 1 XT and XP Bond), two two-step self-etch adhesives (Adper Scotchbond SE and Filtek Silorane Adhesive System) and three one-step self-etch adhesives (G-Bond, Xeno V and Bond Force). All adhesive systems were applied following manufacturers’ instructions. Composite buildups were constructed and the bonded teeth were then stored in water (24 h, 37 °C) or thermocycled (5,000 cycles) before being sectioned and submitted to MTBS test. Two-way ANOVA and subsequent comparison tests were applied at α = 0.05. Characteristic de-bonded specimens were analyzed using scanning electron microscopy (SEM). After 24 h water storage, MTBS values were highest with XP Bond, Adper Scotchbond 1 XT, Filtek Silorane Adhesive System and Adper Scotchbond SE and lowest with the one-step self-etch adhesives Bond Force, Xeno V and G-Bond. After thermocycling, MTBS values were highest with XP Bond, followed by Filtek Silorane Adhesive System, Adper Scotchbond SE and Adper Scotchbond 1 XT and lowest with the one-step self-etch adhesives Bond Force, Xeno V and G-Bond. Thermal aging induced a significant decrease in MTBS values with all adhesives tested. The resistance of resin–dentin bonds to thermal-aging degradation was material dependent. One-step self-etch adhesives obtained the lowest MTBS results after both aging treatments, and their adhesive capacity was significantly reduced after thermocycling.     

Hybridization quality in cervical cementum and superficial dentin using current adhesives.

OBJECTIVES: The aim of this research was to determine the hybridization quality of adhesives to gingival cementum and close superficial dentin using both total-etch and self-etch, one-step and two-step adhesives in vitro. METHODS: Five adhesive systems were used and evaluated in this study; three kinds of two-step adhesives (total-etch--Single Bond and self-etch--Clearfil SE Bond and Clearfil Protect Bond) and two one-step adhesives (Clearfil S3 Bond, G Bond). Fifteen extracted intact human third molars were used in this study. A diagonal cut which was approximately 45 degrees to the long axis of the roots, with the initiating point located 2 mm below the buccal enamel-cementum junction and ascending towards the pulp chamber was prepared on each tooth. Flat cervical cementum and dentin surfaces were ground with wet 600-grit silicon carbide paper, and bonded with one of the adhesives and finished by applying a flowable resin composite. After 24 h storage at 37 degrees C in water, the bonded assemblies were sectioned into approximately 1mm thick slabs. Two central slabs from each tooth were chosen. One slab was totally demineralized in 0.5 M EDTA and the other was not demineralized and immersed into 50% (w/v) solution of ammoniacal silver nitrate for 24 h, and successively exposed to photodeveloping solution for 8 h. The specimens were then processed for TEM observation. Both the stained demineralized silver unchallenged and unstained non-demineralized silver challenged resin-cervical cementum/proximal superficial dentin interface were observed and evaluated under a transmission electron microscope. RESULTS: The nanoleakage pathway and extent vary among the different adhesives used and also between the resin-cementum interface and resin-dentin interface. Two-step self-etch adhesives showed better hybridization quality both in cementum and proximal superficial dentin as compared to those of two-step total-etch adhesive and one-step self-etch adhesives. SIGNIFICANCE: Two-step self-etch adhesives may provide a better sealing in cervical cementum and the proximal superficial dentin region.     

Four-year water degradation of a total-etch and two self-etching adhesives bonded to dentin

OBJECTIVES: To evaluate effect of direct and indirect water storage on the microtensile dentin bond strength of one total-etch and two self-etching adhesives. METHODS: The adhesive materials were: one total-etch adhesive; 'Admira Bond' and two self-etch adhesives; 'Clearfil SE Bond' and 'Hybrid Bond'. Freshly extracted human third molar teeth were used. In each tooth, a Class I cavity (4mmx4mm) was prepared in the occlusal surface with the pulpal floor extending approximately 1mm into dentin. The teeth were divided into three groups (n=18). Each group was restored with the resin composite 'Clearfil APX' using one of the tested adhesives. For each experimental group 3 test procedures (n=6) were carried out: Procedure A: the teeth were stored in water for 24h (control), then sectioned longitudinally, buccolingually and mesiodistally to get rectangular slabs of 1.0-1.2mm thickness on which a microtensile test was carried out. Procedure B: the teeth were also sectioned; however, the slabs were stored in water at 37 degrees C for 4 years before microtensile testing (direct water storage). Procedure C: the teeth were kept in water at 37 degrees C 4 years before sectioning and microtensile testing (Indirect water storage). During microtensile testing the slabs were placed in a universal testing machine and load was applied at cross-head speed of 0.5mm/min. RESULTS: For the 24h control, there was no significant difference in bond strength between the three tested adhesives. After 4 years of indirect water storage, the bond strength decreased but the reduction was not significantly different from those of 24h. After 4 years of direct water storage, the bond strengths of all tested adhesives were significantly reduced compared to their 24h results. CONCLUSION: All the tested adhesives showed no reduction in bond strength after indirect water exposure for 4 years. After 4-year direct water exposure, the bond produced by all tested adhesives was unable to resist deterioration.