The Efficacy of Different Sealer Removal Protocols on Bonding of Self-etching Adhesives to AH Plus–contaminated Dentin

IntroductionSmearing of unset root canal sealers over the pulp chamber dentin may adversely affect bonding of self-etching adhesives and jeopardize their coronal sealing potential. This study examined the influence of different sealer removal protocols on the microtensile bond strengths of two self-etching adhesives to AH Plus-contaminated dentin.MethodsCoronal dentin surfaces were prepared from extracted human third molars. In the positive control groups, these surfaces were not contaminated with sealer and were bonded with Clearfil SE Bond or Clearfil Tri-S Bond. For the experimental groups, dentin surfaces were contaminated with AH Plus and wiped with either dry cotton pellets, cotton pellets saturated with ethanol, or cotton pellets saturated with Endosolv R followed by rinsing the dissolved sealer with water prior to bonding with the two adhesives. Bonded specimens were sectioned into resin-dentin beams for microtensile bond strength evaluation. Additional specimens were prepared for transmission electron microscopy to examine the ultrastructure and nanoleakage within the hybrid layers.ResultsFor both adhesives, microtensile bond strengths significantly declined when the sealer was removed with dry cotton pellets or cotton pellets saturated with ethanol. Only the Endosolv R/water sealer removal protocol restored tensile bond strengths to those of the uncontaminated positive controls without adversely affecting hybrid layer formation in intact dentin or increasing nanoleakage within the resin-dentin interfaces.ConclusionThe Endosolv R sealer removal protocol appears to be effective in preventing the deterioration of bond strengths of the two self-etching adhesives to AH Plus–contaminated dentin and warrants further clinical investigation.     

The effects of common errors on sealing ability of total-etch adhesives.

OBJECTIVES: This study evaluated the effect of errors commonly made in using total-etch adhesives, on the resulting bond strength, fluid movement and nanoleakage of resin dentin bonds. METHODS: Two total-etch adhesives were used for bonding to dentin according to the manufacturers' recommendations, with meticulous solvent evaporation (control), or with the introduction of common bonding errors-wet bonding without solvent evaporation (no evaporation), and dry bonding. RESULTS: The 24-hour bond strength of the control was significantly higher than the other groups (p <0.05). For all groups, the higher initial permeability declined significantly after 24 h. The fluid movement across bonded dentin was similar in the control and dry bonding for both adhesives, whereas significantly higher permeability (p<0.05) was recorded for the no evaporation groups even after 24 h. Extensive silver impregnation within hybrid layers was seen by TEM in the no evaporation and dry bonding specimens after 24 h. Dry bonding caused collapse of the collagen matrix and interfered with resin infiltration. In contrast, inadequate solvent evaporation and/or residual water during dentin bonding results in dilution or incomplete polymerization of the resin, leading to severe nanoleakage formation. SIGNIFICANCE: Increased permeability associated with incomplete solvent evaporation in total-etch adhesives may lead to poor bond strength.     

In vitro degradation of resin–dentin bonds with one-bottle self-etching adhesives

The purpose of this study was to evaluate the durability of one-bottle self-etching adhesive during long-term water-storage testing. Resin–dentin bonded specimens were prepared using four commercially available one-bottle self-etching adhesives. The specimens were sectioned perpendicular to the adhesive interface to produce beam-shaped specimens that were stored in water for 24 h (control group) and 100, 200, and 300 d (experimental groups). After each storage period, the beams were subjected to a microtensile bond test. After the bond test, fractured surfaces were examined using a scanning electron microscope. In addition, interfacial observations of the silver tracer were performed using the secondary and back-scatter modes of the scanning electron microscope. The bond strength of all tested adhesives decreased significantly after 100 or more days in water. The interfacial observations showed an oxygen-inhibition zone as electron lucent in the adhesive–composite border in control specimens, displaying silver impregnation with breakage after aging. The deterioration of the oxygen-inhibition zone in the adhesive–resin composite junction resulted in a decrease in bond strength after 100 d in water for one-bottle self-etching adhesives.     

Effect of a whitening agent application on enamel bond strength of self-etching primer systems

PURPOSE: Though reduction in bond strength after tooth whitening has been reported, little is known about it's effect on enamel bond strength of two-step bonding systems that exclude phosphoric acid etching prior to bonding agent application. The purpose of this study was to determine the effect of whitening procedure using an in-office whitening agent on enamel bond strength of self-etching primer systems. METHODS: Three self-etching primer systems, Imperva Fluoro Bond, Mac Bond II, Clearfil SE Bond, and a one-bottle adhesive system Single Bond as a control material, were used. Bovine mandibular incisors were mounted in self-curing resin and the facial enamel or dentin surfaces were ground wet on 600-grit SiC paper. An in-office whitening agent, Hi-Lite was applied on the tooth surface according to the manufacturer's instruction. Bonding procedures were done soon after rinsing off the whitening agent or after 24 hours storage in distilled water. Specimens without whitening procedure were prepared as controls. Fifteen specimens per test group were stored in 37 degrees C distilled water for 24 hours, then shear tested at a crosshead speed of 1.0 mm/minute. One-way ANOVA followed by Duncan multiple range test were used for statistical analysis of the results. RESULTS: For the specimens made soon after rinsing off the whitening agent, a significant decrease in enamel bond strength was observed for all the bonding systems used. For the specimens made after 24 hours storage in water, a small decrease in enamel bond strength was observed and no significant differences were found compared to those of controls (without whitening). From the results of this study, enamel bond strengths of the self-etching primer systems might be affected to a lesser degree after rinsing with water followed by 24 hours storage in water.     

Electric-current-assisted application of self-etch adhesives to dentin

The use of electric current during the application of etch-and-rinse adhesive systems has been recently claimed to increase bonding of etch-and-rinse adhesives by enhancing substrate impregnation. The null hypothesis tested in this study was that electrically assisted application has no effect on bond strength of self-etching bonding systems. Three self-etch adhesives (Protect-Bond, Xeno III, and Prompt L-Pop) were applied with the aid of an electric signal-generating device (ElectroBond) and tested vs. controls prepared with the same disposable sponges but without electric current. Specimens bonded under the influence of electric current exhibited increased microtensile bond strength compared with the controls (p<0.05). High-resolution SEM analysis showed that bonding under the influence of electricity reduced interfacial nanoleakage. It is speculated that resin infiltration may be improved by the attraction of polar monomers by an electric current or by modification of the dentin surface charges, resulting in better water substitution or evaporation.     

自酸蚀黏结剂的牙本质黏结界面纳米渗漏观察

目的观察并评价3种自酸蚀黏结剂(ClearfilTMSEBond、AdperTMPromptTM、PANAVIATMF)黏结处理后的牙本质纳米渗漏。方法选取9颗无龋坏人磨牙,用600目碳化硅砂纸在流水冲洗下预备出统一的牙本质黏结面玷污层。分别用3种自酸蚀黏结剂按使用说明进行黏结处理。每颗牙齿垂直于黏结面切割出5个0.9mm厚黏结试件,避光贮存于氨化硝酸银溶液中24h,在透射电镜(TEM)下观察牙本质黏结界面纳米渗漏。结果3种自酸蚀黏结剂试件牙本质黏结界面混合层的底部在TEM下均观察到排列规则的银粒子渗漏。结论自酸蚀牙本质黏结界面下可能存在未完全封闭的牙本质脱矿层,存在纳米渗漏。     

单瓶型通用粘接剂在牙本质粘接中的应用评价

［摘要］ 目的 评价2种单瓶型通用粘接剂在自酸蚀模式下应用与牙本质的粘接强度以及纳米渗漏情况。方法 制作40枚牙本质样本,分别使用Singlebond Universal和All-Bond Universal 2种单瓶型通用粘接剂在自酸蚀模式下处理牙本质表面,与复合树脂粘接制作粘接试件。各组粘接试件一半于24 h水储后（未老化）切割成细条,测试微拉伸粘接强度,另一半经受10 000次冷热循环后（老化）测试微拉伸粘接强度。数据以单因素方差分析和Tukey多重比较进行检验分析。各组代表性试件处理后以扫描电镜观察粘接界面,检测纳米渗漏情况。结果 不论是否经过老化,2种粘接剂组均获得了较高的粘接强度值,但扫描电镜均能发现纳米渗漏存在。结论 两种单瓶型通用粘接剂在自酸蚀模式下应用均能提供较好的粘接性能,但无法避免纳米渗漏的发生。     

TEM下自酸蚀粘结剂的两种模式牙本质纳米渗漏观察

目的：观察并评价3种自酸蚀粘结剂(Clearfil^TM SE Bond、Adper^TM Prompt^TM、PANAVIA^TM F)牙本质粘结界面的纳米渗漏。方法：选取12颗无龋坏人磨牙,用600目碳化硅砂纸在流水冲洗下预备出统一的牙本质粘结面玷污层。分别用3种自酸蚀粘结剂按使用说明进行粘结处理。每颗牙齿垂直于粘结面切割出5个0．9mm厚粘结试件,分别避光贮存于硝酸银、氨化硝酸银溶液中24h,在TEM下观察牙本质粘结界面纳米渗漏。结果：在TEM下观察到3种自酸蚀粘结剂牙本质粘结界面混合层中呈网状、点状两种模式分布的纳米渗漏。结论：自酸蚀粘结剂由于其自身的组份特性,牙本质粘结界面均存在不同程度的纳米渗漏。     

Effective bond strength of current adhesive systems on deciduous and permanent dentin

PURPOSE: To evaluate the bond strength of a total-etching, self-priming system (Single Bond) and a self-etching system (Clearfil SE Bond) to deciduous and permanent human dentin. METHODS AND MATERIALS: Buccal dentin discs were prepared with a diamond disc from permanent first premolars, permanent third molars and deciduous second molars. The flat dentin surfaces were obtained by polishing with wet 600 grit silicon carbide papers. The specimens of each group were further divided into two groups for bonding to either Single Bond or Clearfil SE Bond. After 24 hours, the microshear bond strength testing was executed on a universal testing machine. Statistical analysis was performed at alpha = 0.05. RESULTS: No significant differences in bond strength were found between materials. However, deciduous dentin demonstrated significantly lower bond strengths than permanent premolar dentin when Single Bond was applied (p < 0.05). CONCLUSION: The difference in bonding substrate (permanent or deciduous dentin) had a significant effect on bond strength when the total-etching, self-priming system was applied.     

Bond strength of newer dentin bonding agents in different clinical situations

This study compared the tensile bond strengths of different adhesive systems to different dentinal substrate conditions. The adhesive systems used were Adper Single Bond 2 total etch, XP Bond total etch, and two all-in-one adhesives, Adper Easy One and Xeno V. Ninety-six intact human premolars extracted on periodontal or orthodontic grounds were collected and stored in 0.9% physiologic saline for less than four weeks. Teeth were carefully cleaned to remove the soft tissue remnants. The occlusal surfaces were ground until the level of the dentinoenamel junction, exposing superficial dentin using a low-speed diamond disc. A standard smear layer was produced by wet sanding the dentin surface with 600-grit silicon carbide sandpaper for 40 seconds. The 96 specimens were embedded in autopolymerizing acrylic resin and divided into four groups of 24 each based on the dentin bonding agents used. Each group consisted of 24 specimens, which were further divided into two subgroups of 12 specimens each, moist dentin and dentin air-dried for 10 seconds. The regions of interest for adhesion were demarcated in each sample using adhesive tape, with a 4-mm–diameter hole isolating the peripheral region, and each adhesive system was employed. Four adhesive systems, two total etch and two self-etching adhesive, were applied to different dentinal substrates as per the manufacturers' instructions. Following the adhesive application, the specimens were restored with composite material using a metallic mold measuring 5 mm in diameter and 5 mm in height to keep the material in cylindrical form and were light cured per manufacturers' instructions. After being stored for 24 hours in distilled water at room temperature, the specimens were thermocycled for 550 cycles at temperatures ranging from 5°C to 60°C with a dwell time of 15 seconds in each bath and a transfer time of five seconds. The tensile bond strengths were determined using a Universal loading machine (Lloyd Universal Testing Machine) at a cross-head speed of 1 mm/min. On moist dentin, total-etch adhesives showed higher bond strength than did the all-in-one adhesives. Under the dry dentin condition, XP Bond exhibited significantly higher bond strength than did the Adper Single Bond 2 and two all-in-one adhesives, Adper Easy One and Xeno V.     

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.     

Histomorphologic characterization and bond strength evaluation of caries-affected dentin/resin interfaces: effects of long-term water exposure.

OBJECTIVES: To evaluate the longevity of sound (SD) and caries-affected dentin (CAD) bonds made with etch-and-rinse and self-etching adhesives after a 6-month water-storage period, using bond strength and morphological evaluations. METHODS: Extracted human molars with coronal carious lesions were selected. Flat surfaces of CAD surrounded by SD were bonded with etch-and-rinse (Adper Scotchbond 1) or with self-etching (Clearfil Protect Bond and AdheSE) adhesives. Trimmed resin-dentin bonded interfaces (1mm2) were stored in distilled water for 24h or 6 months and subjected to microtensile bond strength (microTBS) evaluation. The quality of the dentin beneath fractured specimens was measured by Knoop microhardness (KHN). ANOVA and multiple comparisons tests were used (P<0.05). Fractographic analysis and interfacial nanoleakage evaluation were performed by scanning electron microscopy (SEM). Resin-dentin bonded sections (10microm thick) were stained with Masson's trichrome and examined using light microscopy. Collagen exposure and adhesive penetration were examined qualitatively. RESULTS: microTBS to SD was significantly higher than that to CAD for all bonding agents. Bonds made with AdheSE were weaker than the other adhesives after 6-months storage regardless of the dentin substrate. CAD bonded specimens presented a significant muTBS decrease over time. Lower KHN was recorded in CAD compared to SD. An increase in the exposed collagen zone and a decrease in the quality of the adhesive infiltration were observed in CAD interfaces. SIGNIFICANCE: CAD bonded interfaces are more prone to hydrolytic degradation than SD bonds. Additionally, as compared to SD, there were remarkable differences in depth of demineralization, adhesive infiltration and interfacial bond strength with CAD.     

三种自酸蚀粘接剂使用方法对牙本质粘接的影响

目的 观察不同的酸蚀处理时间和使用方式对3种自酸蚀粘接剂牙本质粘接强度的影响. 方法 将3种自酸蚀粘接剂[粘接剂1(Adper Prompt,3M-Espe,U S A)、粘接剂2(XenoⅢ,Dentsply,Konstanz,Germany)、粘接剂3(Clearfil SE Bond,Kuraray,Japan)]按照酸蚀处理时间和使用方式分组,每种粘接剂均分为标准组(厂家推荐操作组)、缩短处理时间组(缩短组)、延长处理时间组(延长组)及改变使用方式组,每组均选择15个粘接样本,分别测定牙本质微拉伸粘接强度,扫描电镜下观察粘接界面. 结果 缩短、标准及延长酸蚀时间时,粘接强度分别为粘接剂1:(16.30±2.59)、(23.13±2.56)、(22.28±2.83)MPa;粘接剂2:(15.17±6.07)、(34.50±3.64)、(24.87±7.01)MPa;粘接剂3:(29.92±3.32)、(42.21±6.28)、(41.07±3.93)MPa(P<0.01).粘接剂1、2、3改变使用方式组的粘接强度分别为(12.53±3.73)、(23.98±3.86)、(48.37±4.95)MPa,分别与同种粘接剂的标准组相比差异有统计学意义(P<0.01). 结论 缩短酸蚀处理时间可显著降低自酸蚀粘接剂的粘接效果;延长酸蚀处理时间并未提高自酸蚀粘接剂的粘接效果;涂擦使用时,不同粘接剂的牙本质粘接效果不同;使用粘接剂应严格参照厂家推荐的操作步骤.     

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.     

The effect of thermocycling on the adhesion of self-etching adhesives on dental enamel and dentin

AIM: The aim of the present study was to investigate the effectiveness of one total-etch self-priming adhesive and two one-step self-etching adhesive systems on the adhesion of a resin composite to both dentin and enamel. The effect of thermocycling on the adhesion was also investigated. The null hypothesis tested was thermocycling would not affect bond strengths to enamel and dentin treated with self-etching adhesives or a total-etch adhesive. METHODS AND MATERIALS: Two single-step self-etching adhesives [Xeno III (XE3) and Prompt L-Pop (PP)] and one two-step total-etch adhesive system (Prime & Bond NT) (P&B NT) were used in this study. Thirty caries-free unrestored human third molars were used to make specimens of enamel and dentin. Different adhesives were applied on enamel and dentin surfaces according to the manufacturer's instructions then hybrid composite restorative material was condensed on the surface using a mold. The bonded specimens were stored in distilled water at 37 masculineC for 24 hours before being tested. Half of the bonded specimens were tested for shear bond strength without thermocycling. The other half of the test specimens were thermocycled using a thermocycling apparatus in water baths held at 5 masculineC and 55 masculineC with a dwell time of one minute each for 10,000 cycles prior to shear testing. The mean shear bond strength before and after thermocycling was calculated, and the results were subjected to two-way analysis of variance (ANOVA) and repeated measure design to show the interaction between different materials and different times. RESULTS: The results showed shear bond strength on both enamel and dentin of the total-etch adhesive and the self-etching adhesives decreased after the specimens were subjected to thermocycling. CONCLUSIONS: The null hypothesis tested "thermocycling would not affect bond strengths treated with self-etching adhesives" was rejected. Furthermore, the study revealed the following: 1. The shear bond strength to both enamel and dentin of the total-etch adhesive and the self-etching adhesives decreased after the specimens were subjected to thermocycling. 2. XE3 achieved the highest bond strength to both enamel and dentin (26.994+/-1.17 and 25.22+/-1.26, respectively). 3. XE3 showed even better bonding after thermocycling to enamel and dentin than the total-etching system or PP. 4. Although PP bonded to enamel showed lower shear bond strength value than XE3, it has durable bond strength even after thermocycling.     

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??Objective    To evaluate the bonding performance of six self-etching adhesives on dentin by using micro-tensile bond strength test and scanning electronic microscopy ??SEM?? observation.  Methods    Thirty-six human third molars were used in this study. Six self-etching adhesives were employed?? Clearfil Mega Bond ??MB???? Clearfil Protect Bond??PB????BeautiBond??BB????BondForce??BF????EasyBond??EB??and G-Bond plus??GBp??. After exposing the dentin surface by gypsum model trimmer?? 600-grit Sic paper was used to remove the smear layer under water cooling. Each adhesive was strictly applied under the instruction and followed by build-up with resin composite to 6mm. After storage in 37°C distilled water for 24 hours?? the dentin-resin bonded teeth were sectioned into approximately 1.0mm2 specimen for the Micro-Tensile Bond Strength ??μTBS?? test. The fractured surfaces on dentin side and failure modes were observed and determined by SEM respectively. Results    The bond strength of MB was statistically higher than the other adhesives ??P < 0.05??. Bubbles could be observed in the adhesive layer of BB??BF and GBp. Failure modes analysis indicated that over 50% failure modes was dentin or resin failure in MB group.  Conclusion    In this study?? MB shows significantly higher bond strength in comparison with the other self-etching adhesives.     

In vitro durability of one-bottle resin adhesives bonded to dentin

Recently, one-bottle resins adhesives have been developed to reduce the number of clinical steps of resin application. They are now widely used in clinical dental practice. However, little is known regarding the detailed mechanism of bond degradation. Therefore, this study evaluated the durability of one-bottle resin adhesives using long-term water storage testing. Resin-dentin bonded specimens were prepared using five commercially available one-bottle resin adhesives. The specimens were sectioned perpendicular to the adhesive interface to produce beams and stored in distilled water for 24 hours (control), 100, 200, and 300 days. After the water storage, each beam was subjected to a microtensile bond test and then SEM fractography was performed on the fractured surface. Compared to the bond strength at 24 hours after bonding (control), the bond strength of all tested adhesives were significantly decreased after 100 or more days in water. SEM fractography revealed a typical type of deterioration in the adhesive-composite interface that might cause a decline in bond strength after aging.     

Shear bond strength of two resin cements to human root dentin using three dentin bonding agents

This study compared the bond strength of two resin cements to human root dentin when used with three bonding agents. The materials used were Rely X ARC and Perma Cem, two one-bottle bonding agents (Single Bond, Bond-1) and one self-etching bonding agent (Clearfil SE Bond). The dentin was obtained from single rooted human teeth, and the specimens were treated with either 15% EDTA or 37% phosphoric acid to remove the smear layer, except in groups where the self-etching bonding agent was used. The resin cements were placed on dentin surfaces with the use of bonding agents. Shear bond strength (SBS) was tested using a single plane shear test assembly. The dentin specimens were divided into 10 groups. Eight groups were pre-treated with EDTA or phosphoric acid to remove the smear layer, followed by a bonding agent (Bond-1 or Single Bond) and resin cement (Rely X or Perma Cem). In the two remaining groups, the smear layer was left intact, and the two resins cements were used in combination with the self-etching bonding agent (Clearfil SE Bond). No statistically significant differences were observed among the eight groups treated with one-bottle bonding agents. The mean bond strengths of the two groups treated with the self-etching bonding agent did not differ significantly from each other but were both significantly greater than the bond strengths of all the other groups. The results of this study also showed that EDTA can be used as an alternative to phosphoric acid in bonding procedures for resin cements. However, the bond strengths of resin cements, in combination with a self-etching bonding agent, were significantly greater than those of the same cements when used with one-bottle bonding agents.     

Effects of pre- and post-bonding hydration on bond strength to dentin

PURPOSE: This study tested the hypothesis that the hydration condition of the tooth during bonding or storage may affect the bond strength of a single-step, self-etching adhesive to dentin. MATERIALS AND METHODS: Twelve extracted human third molars were transversally sectioned to expose flat, mid-dentin surfaces. Six teeth were dehydrated in ascending ethanol concentrations for several days while 6 teeth were kept hydrated in distilled water. The teeth were bonded with the single-step, self-etching adhesive One-Up Bond F (Tokuyama, Japan) according to directions. Resin composite buildups were constructed incrementally with Z 250 (3M ESPE). The bonded hydrated and dehydrated teeth were then divided into 2 subgroups and stored either in distilled water or in a dry condition for 24 h before being prepared for the microtensile bond strength test. Bonded beams of approximately 0.8 mm2 were tested in tension at 0.5 mm/min in a testing machine. Separate dentin disks were bonded with the adhesive and prepared for transmission electron microscopy (TEM). RESULTS: Bond strengths of specimens stored in water were: 25.0 +/- 10.6 and 18.9 +/- 9.1 MPa for hydrated and dehydrated teeth, respectively. Bond strengths of specimens stored dry were significantly higher (p < 0.001): 46.1 +/- 21.4 and 40.9 +/- 19.1, for hydrated and dehydrated teeth, respectively. Two-way ANOVA showed that previous hydration condition of the teeth had no effect on the bond strength, regardless of the storage condition (p > 0.05). However, storage of the bonded teeth in water caused significant reductions in the bond strength, regardless of the previous hydration condition of the teeth. TEM showed massive silver nitrate impregnation in the adhesive layer of water-stored specimens. CONCLUSIONS: Postbonding water exposure had a highlysignificant effect on bond strength of the single-step, self-etching adhesive.     

Evaluation of the modern self-etching adhesives efficacy

The durability of bonding efficacy of composites with hard tissues of a tooth was investigated at application of one-bottle adhesive with total etching and five self-etching adhesives. The efficiency of etching by 36% orthophosphoric acid and acid components of self-etching adhesives was estimated. The adhesion between substrate and composite was measured by method of microtensile bond strength (mTBS). The control of efficiency of etching and depth of the penetration was carried out with the confocal laser scanning microscopy. It was established, that self-etching adhesives are capable to guarantee bonding of composites with enamel and dentine at a level compared with adhesives of the 5th generation. Deep adhesives penetration in dentine tubules is not the key factor for creation of reliable bonding.