Reinforcement of dentin in self-etch adhesive technology: A new concept

Objective

Characterize the ultramorphology and secondary caries inhibition potential of different dentin adhesive systems in order to find a satisfactory explanation resist to recurrent caries.

Methods

Human premolar dentin was treated with one of the two self-etching adhesive systems, Clearfil SE Bond, Clearfil Protect Bond or an acid-etching adhesive system, Single Bond. The bonded interface was exposed to an artificial demineralizing solution (pH 4.5) for 90 min and then 5% sodium hypochlorite for 20 min. Transmission electron microscopic observation was performed at the adhesive–dentin interface. The width of the reinforced zone was measured and data were analyzed with univariate analysis of variance under general linear model. In order to identify type of crystallites in the reinforced zone selected area electron diffraction was performed.

Results

An acid–base resistant zone (ABRZ) was found adjacent to the hybrid layer in the outer lesion front with only Clearfil SE Bond and Clearfil Protect Bond, while Single Bond was devoid of this protective zone. Crystallite arrangement and the ultramorphology were almost similar in the corresponding regions of Clearfil SE Bond and Clearfil Protect Bond. However, thickness of the ABRZ at the mid portion was 1159(±41.91) nm in Clearfil protect Bond, which was significantly thicker than that of Clearfil SE Bond (F = 514.84, p < 0.001). Selected area electron diffraction confirmed the crystallites in the zone as apatite.

Conclusions

The self-etching adhesive systems created a new reinforced acid resistant dentin under the hybrid layer. Difference in the thickness of the zone expressed a different potential for demineralization inhibition.     

The role of functional monomers in bonding to enamel: Acid–base resistant zone and bonding performance

Objectives

To investigate the effects of two functional monomers on caries-inhibition potential and bond strength of two-step self-etching adhesive systems to enamel.

Methods

Clearfil SE Bond and similar experimental formulations different in the functional monomer were used. Four combinations of primer and bonding agents were evaluated: (1) Clearfil SE Bond which contains MDP in both primer and bonding (M–M); (2) Clearfil SE Bond primer and Phenyl-P in bonding (M–P); (3) Phenyl-P in primer and Clearfil SE Bond bonding (P–M); (4) Phenyl-P in primer and bonding (P–P). Ground buccal enamel surfaces of human sound premolars were treated with one of the systems and the bonded interface was exposed to an artificial demineralising solution (pH 4.5) for 4.5 h, and then 5% NaOCl with ultrasonication for 30 min. After argon-ion etching, the interfacial ultrastructure was observed using SEM. Micro-shear bond strength to enamel was measured for all groups and results were analysed using one-way ANOVA and Turkey's HSD, while failure modes were analysed by chi-square test.

Results

An acid–base resistant zone (ABRZ) was found with all adhesive systems containing MDP either in primer or bond; however, ultramorphology and crystallite arrangement in the ABRZ were different among groups. P–P was the only group devoid of this protective zone. Micro-shear bond strength in M–M was significantly higher than those in M–P, P–M and P–P, while the latter three were not different from each other. Failure modes were significantly different (p < 0.05).

Conclusions

Functional monomers in two-step self-etching systems influence both the bonding performance and the formation of ABRZ on enamel.     

Ultrastructural observation of the acid-base resistant zone of all-in-one adhesives using three different acid-base challenges

The aim of this study was to analyze the ultrastructure of the dentin-adhesive interface using two all-in-one adhesive systems (Clearfil Tri-S Bond, TB; Tokuyama Bond Force, BF) after different acid-base challenges. Three solutions were used as acidic solutions for the acid-base challenges: a demineralizing solution (DS), a phosphoric acid solution (PA), and a hydrochloric acid solution (HCl). After the acid-base challenges, the bonded interfaces were examined by scanning electron microscopy. Thickness of the acid-base resistant zone (ABRZ) created in PA and HCl was thinner than in DS for both adhesive systems. For BF adhesive, an eroded area was observed beneath the ABRZ after immersion in PA and HCl, but not in DS. Conversely for TB adhesive, the eroded area was observed only after immersion in PA. In conclusion, although the ABRZ was observed for both all-in-one adhesive systems, its morphological features were influenced by the ingredients of both the adhesive material and acidic solution.     

Bonding to enamel and dentin using self-etching adhesive systems.

OBJECTIVES: This study investigated the effectiveness of three different dentin adhesive systems on the adhesion of resin composite to both dentin and enamel. METHOD AND MATERIALS: The flat dentin and enamel surfaces of 60 extracted human molar teeth were exposed by wet grinding with 600-grit silicon carbide paper. One total-etch self-priming adhesive system (Prime & Bond NT), one two-step self-etching primer adhesive system (Clearfil SE Bond), and one "all-in-one" self-etching adhesive system (Prompt L-Pop) were evaluated. Each bonding system was applied according to the manufacturer's instructions and followed by composite (TPH Spectrum) application. Twenty-four hours after bonding, the teeth were subjected to shear testing. There were 10 replicates for each group. RESULTS: Prompt L-Pop exhibited significantly higher bond strength values to enamel (27 +/- 4.2 MPa) than all other groups. There were no statistically significant differences for shear bond strength to dentin among adhesives. Prompt L-Pop showed the statistically significantly higher bond strength to enamel than dentin. There were no statistically significant differences between the enamel and dentin bond strengths of Clearfil SE Bond and Prime & Bond NT. CONCLUSIONS: The self-etching adhesive systems produced high bond strengths to human coronal dentin and ground enamel surfaces. These materials seem to be very promising for further clinical applications, and the results are very encouraging for the clinical success of these simplified adhesive systems. The self-etching adhesive systems produced even better bond strengths to both enamel and dentin than conventional total-etch systems, especially the "all-in-one" system, which produced the highest bond strength to enamel.     

Regional bond strength of four self-etching primer/adhesive systems to root canal dentin

The purpose of this study was to evaluate the regional bond strength of a dual-cure resin core material to root canal dentin using four self-etching primer/adhesive systems. Post spaces were prepared in extracted premolars, and their root canal dentin was treated with one of the following self-etching primer/adhesive systems: ED Primer II and Clearfil Photobond, photo-cure/dual-cure systems of Clearfil Liner Bond 2V, or Clearfil SE Bond. Post spaces were filled with the dual-cure resin core material, and microtensile bond strength (microTBS) at the coronal and apical regions was measured after 24-hour storage. There were no regional differences in microTBS of the photo-cure and dual-cure systems of Clearfil Liner Bond 2V, while microTBS at the coronal region of Photobond and SE Bond groups were higher than those at the apical region. At the apical region, photo-cured Clearfil Liner Bond 2V exhibited significantly higher bond strength than those of the other systems.     

Micro-shear bond strength of adhesive systems to cementum

PURPOSE: To investigate the micro-shear bond strength of current adhesive systems to human cementum and compare the results with those to dentin. METHODS: Two commercially available two-step adhesive systems were investigated; a self-etching primer system (Clearfil SE Bond) and a total-etch wet bonding adhesive system (Single Bond). The cementum and dentin surfaces were chosen from the mesial surfaces of extracted human molars and then bonded with each adhesive system. A micro-shear bond test was employed to evaluate the bond strength in this study. In addition, the etched cementum or dentin surfaces without any adhesive and the bonded interfaces between the adhesive and the cementum or the dentin were studied morphologically using scanning electron microscopy (SEM). RESULTS: No significant differences were found between the adhesive systems used (P> 0.05). However, both adhesive systems showed significantly lower bonding to cementum than to dentin (P< 0.05). The relatively lower bond strengths to cementum probably resulted from the existence of coarse collagen fibers, which may cause less or inhomogeneous penetration of resin monomers into the etched zone.     

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.     

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.     

硬化牙本质粘接界面的激光扫描共聚焦显微镜观察

目的使用激光扫描共聚焦显微镜（CLSM）观察牙颈部硬化牙本质在全酸蚀和自酸蚀粘接系统形成粘接界面的超微结构。方法选用12颗因牙周病拔除的具有典型楔状缺损的上颌前磨牙为实验组;12颗新鲜拔除的无龋人上颌前磨牙为对照组,制备人造楔状缺损。使用Single Bond （SB,全酸蚀单瓶系统）、Clearfil SE Bond（CB,自酸蚀底胶系统）、Xeno Ⅲ（XB,自酸蚀一步粘接系统）粘接系统处理牙面,以罗丹明B异硫氰酸盐为荧光素,使用CLSM观察粘接界面的混合层与树脂突的微观结构。结果双因素方差分析表明粘接剂种类、牙本质类型对粘接界面树脂突长度、混合层厚度有显著影响（P<0.05）。无论是正常牙本质还是硬化牙本质,全酸蚀粘接剂（SB）产生的树脂突长度、混合层厚度均大于自酸蚀粘接剂（CB、XB）,并且其差异具有统计学意义（P<0.05）;而CB和XB间树脂突长度、混合层厚度相差不多,二者间无统计学意义。结论硬化牙本质相对于正常牙本质形成的混合层较薄或者没有,树脂突短、少。全酸蚀粘接系统与自酸蚀粘接系统作用同类型的牙本质上,自酸蚀比全酸蚀形成的混合层薄,树脂突短。     

Influence of water-storage time on the sorption and solubility behavior of current adhesives and primer/adhesive mixtures

This study evaluated the effects of water-storage on the water sorption and solubility behavior of five commercially available dental adhesive systems and two primer/adhesive mixtures. The adhesives comprised three different approaches to bonding to hard tooth tissues: a one-step self-etching adhesive (One-up Bond F), two two-step self-etching primers (Clearfil SE Bond and Clearfil Protect Bond) and two etch-and-rinse systems: a water/ethanol-based (Single Bond) and an acetone-based filled adhesive (Prime&Bond NT). The bonding agents and primers of the two-step self-etching systems were mixed in a 1:1 volume ratio. Water sorption and solubility values were determined after 1, 7, 30, 90 and 180 days. The results showed that, except for SB, all adhesives presented increased water sorption with increased storage time. The one-step self-etching adhesive and self-etching primer/adhesive mixtures presented the highest water sorption and solubility values. Equilibrium in the water sorption values was observed for all adhesives after 90 days of water-storage. However, solubility values continued to increase for some materials until 180 days. The sorption and solubility behavior of the materials tested seem to be related to hydrophilicity of the adhesive resin solution and might influence the long-term performance of resin-based composite restorations.     

Micro-tensile bond strength of self-etching primer adhesive systems to human coronal carious dentin

The aim of this study was to evaluate the micro-tensile bond strengths of three self-etching primer adhesive systems to normal dentin (ND), caries-affected dentin (CAD) and caries-infected dentin (CID). Human extracted molars with caries were used, and flat dentin surfaces ground by 600-grit SiC paper were prepared. The surfaces were dyed using Caries-Detector solution, treated with Clearfil SE Bond, Mac-Bond II and UniFil Bond, and then covered with resin composites according to manufacturer's instructions. After immersion in 37 degrees C water for 24 h, the teeth were serially sectioned into multiple slices. Each slice was distinguished into ND, CAD and CID groups by the degree of staining, and the bond strength was measured in a universal testing machine. Scanning electron microscopic (SEM) observation was also performed. For statistical analysis, anova and Scheffe's test were used (P < 0.05). The bond strengths of the three adhesive systems to CAD and CID were significantly lower than those to ND. There was significant difference in the bond strength to ND between Clearfil SE Bond and UniFil Bond, but no significant differences to CAD and CID among the three adhesive systems. On SEM, the hybrid layers in CAD and CID showed more porous structures compared with ND. The results indicated that the bond strengths to CAD and CID were not affected by a variety of self-etching primer adhesive systems because of the porous hybrid layer formation in carious dentin.     

Effects of different burs on dentin bond strengths of self-etching primer bonding systems

This study evaluated the effects of cutting dentin with different types of burs on tensile bond strength using three self-etching primer bonding systems (Clearfil Liner Bond 2 [LB2], Clearfil Liner Bond 2V [2V] and Clearfil SE BOND [SE], Kuraray, Co, Ltd, Osaka, Japan). Thirty-six intact extracted human third molars were ground flat to expose occlusal dentin, followed by polishing the dentin surfaces with #600 SiC paper. The teeth were divided into four groups according to bur type and grit: fine cut fissure steel bur (SB600), cross cut fissure steel bur (SB703), regular grit diamond bur (DB). Controls were abraded with #600 grit SiC paper (AP#600). The dentin surfaces of the SB600, SB703 and DB groups were cut under copious air-water spray with the respective burs mounted in a dental handpiece. The teeth were treated with one of three adhesive systems, then composite buildups were created with Clearfil AP-X (Kuraray Co, Ltd, Osaka, Japan). After soaking in water at 37 degrees C for 24 hours, serial vertical sections (0.7 mm thick, 7-8 slices per one tooth) were made, trimmed to form an hour-glass shape with a 1.0 mm2 cross-section and tensile bond strengths were determined at a cross-head speed of 1 mm/min. Statistical analysis was made using one and two-way ANOVA and Fisher's PLSD test (p<0.05). Eight additional molars were prepared. Burs or abrasive paper were used for SEM observations of the dentin surfaces of each group before and after treatment with the self-etching primers. All adhesive systems yielded the same ranking of bond strengths to the surfaces prepared with different abrasives: from highest to lowest, AP#600 > SB600 > SB703 > DB. This ranking reached statistical significance using Clearfil Liner Bond 2V (p<0.05). Therefore, when cutting dentin, selecting the adequate bur type is important for improved bonding of adhesive systems using self-etching primer to dentin.     

Effect of two-step adhesive systems on inhibition of secondary caries around fluoride-releasing resin composite restorations in root dentine

OBJECTIVE: The purpose of this study was to investigate the effect of two-step adhesive systems on secondary caries inhibition around fluoride-releasing materials in vitro. METHODS: Two self-etching primer systems, Clearfil SE Bond (SE) and UniFil Bond (UB), and two one-bottle systems with a total-etch wet-bonding technique, Single Bond (SB) and One-Step (OS), were used prior to placement of resin composites either with (Reactmer) or without (Z100) fluoride release. Class V cavities prepared in extracted human premolars were restored with various combinations of materials: Reactmer/SE, Reactmer/UB, Reactmer/SB, Reactmer/OS, Z100/SE, Z100/UB, Z100/SB and Z100/OS. After storage for 14 days, the restored teeth were incubated in bacterial medium containing sucrose with Streptoccus mutans for 2 weeks. Water sorption and desorption of the adhesives and fluoride release from the resins either coated with adhesive or uncoated were also determined. RESULTS: The one-bottle groups showed higher water sorption and desorption than the self-etching primer groups. Although fluoride release from the Reactmer specimens was suppressed by the adhesive coating, the one-bottle groups allowed significantly higher fluoride release than the self-etching primer groups. On microradiographs, the radio-opaque layers adjacent to the Reactmer restorations were thick and clear, while the layers adjacent to the Z100 restorations were thin and unclear. For the Reactmer restorations, the radio-opaque layers associated with the one-bottle groups were significantly thicker than for the self-etching primer groups. CONCLUSIONS: These results indicated that the use of one-bottle wet-bonding systems for bonding of fluoride-releasing resin composites to dentine may contribute to inhibit secondary caries compared to self-etching primer systems.     

Comparison of enamel and dentin microshear bond strengths of a two-step self-etching priming system with five all-in-one systems

Data on the adhesive strength of new all-in-one adhesives are still relatively limited. This study compared the microshear bond strengths of five recent all-in-one self-etching priming systems (G-Bond, One-Up Bond-F Plus, Clearfil S3 Bond, Adper Prompt L-Pop and Go!) with a widely used two-step self-etching priming system (Clearfil SE Bond). Human molars were sectioned and finished with 600-grit SiC paper. Both enamel and dentin were bonded using adhesives with a 0.7 mm bonding diameter. Bond strengths were tested using a microshear bond test method at a crosshead speed of 1 mm/minute. The mean bond strengths and standard deviations were calculated and analyzed using ANOVA and the Tukey's HSD test. Results showed the two-step self-etching system had significantly higher bond strengths to dentin. However, for enamel bond strength, Clearfil SE Bond showed no statistical difference to G-Bond and Go!; however, all of the other materials were statistically lower. It is necessary to examine these new materials clinically to determine their efficacy.     

Influence of hydrostatic pulpal pressure on the microtensile bond strength of all-in-one self-etching adhesives

PURPOSE: To evaluate the microtensile bond strength (microTBS) of two all-in-one self-etching adhesive systems and two self-etching adhesives with and without simulated hydrostatic pulpal pressure (PP). MATERIALS AND METHODS: Flat coronal dentin surfaces of extracted human molars were prepared. Two all-in-one self-etching adhesive systems, One-Up Bond F (OBF; Tokuyama) and Clearfil S3 Bond (Tri-S, Kuraray Medical) and two self-etching primer adhesives, Clearfil Protect Bond (PB; Kuraray) and Clearfil SE Bond (SE; Kuraray) were applied to the dentin surfaces according to manufacturers' instructions under either a pulpal pressure (PP) of zero or 15 cm H2O. A hybrid resin composite (Clearfil AP-X, Kuraray) was used for the coronal buildup. Specimens bonded under PP were stored in water at 37 degrees C under 15 cm H2O for 24 h. Specimens not bonded under PP were stored under a PP of zero. After storage, the bonded specimens were sectioned into slabs that were trimmed to hourglass-shaped specimens, and were subjected to microtensile bond testing (microTBS). The bond strength data were statistically analyzed using two-way ANOVA and the Holm-Sidak method for multiple comparison tests (alpha = 0.05). The surface area percentage of different failure modes for each material was also statistically analyzed with three one-way ANOVAs and Tukey's multiple comparison tests. RESULTS: The microTBS of OBF and Tri-S fell significantly under PP. However, in the, PB and SE bonded specimens under PP, there were no significant differences compared with the control groups without PP. CONCLUSIONS: The microTBS of the two all-in-one adhesive systems decreased when PP was applied. However, the microTBS of both self-etching primer adhesives did not decrease under PP.     

Primary dentin etching time,bond strength and ultra-structure characterization of dentin surfaces

Objectives

To evaluate the effect of shortening the etching time on roughness, microhardness and bond strength of three adhesive systems to primary tooth dentin.

Methods

Flat dentin surfaces from primary molars were randomly assigned to six experimental groups. Three different adhesive systems were used: an etch-and-rinse adhesive (Single Bond), a two-step self-etching (Clearfil SE Bond), and a one-step self-etching (One-Up Bond F) adhesive. In half of the specimens, the recommended etching time was used, in the other half the etching time was 50% reduced. After applying the adhesive, resin composite build-ups were constructed and stored in a humid environment for 24 h at 37 °C. Specimens were sectioned into 1 mm² beams and tested for microtensile bond strength (MTBS). Debonded surfaces were analyzed by scanning electron microscopy (SEM). Additional surfaces were conditioned for microhardness measurements (KHN) and for atomic force microscopy (AFM) analysis. Intertubular and total surface roughness (Ra) were recorded. Results were analyzed with ANOVA and Student–Newman–Keuls tests (P < 0.05).

Results

Single Bond and Clearfil SE Bond showed higher MTBS than One-Up Bond F. Bond strength and intertubular roughness increased when Single Bond and One-Up Bond F were used with a reduced etching time. For Clearfil SE Bond no differences in MTBS were detected when reducing the etching time. The application of phosphoric acid, Clearfil SE Bond primer and One-Up Bond F decreases dentin microhardness.

Conclusions

Shortening One-Up Bond F application time and reducing the etching time of phosphoric acid to one-half of the manufacturer's recommended etching time when using Single Bond are recommended when bonding to primary dentin.     

Resin-enamel bonds made with self-etching primers on ground enamel

Self-etching primer adhesives have recently been introduced to simplify bonding. However, the fundamental bonding mechanism of self-etching primers to enamel is not yet fully understood. This study aimed to investigate resin-enamel bonds of self-etching primer adhesives on ground enamel. Two self-etching primer adhesives (Clearfil Liner Bond 2 V and Clearfil SE Bond) were used in this study. A total-etch adhesive (One-Step) was used as a control. Resin-enamel beams were subjected to the microtensile bond test. Subsequently, the failure modes of all specimens were quantified using image analysis. Undemineralized and demineralized ultrathin sections of the resin-enamel bonded specimens were examined using transmission electron microscopy. The bond strengths of Clearfil SE Bond (39.8 +/- 11.9 MPa) and One-Step (46.2 +/- 12.7 MPa) were significantly greater than that of Clearfil Liner Bond 2V (30.4 +/- 6.2 MPa). Scanning electron microscopy of the fractured surfaces revealed the failure direction and weakest portion within each bond. Transmission electron microscopy showed a thin hybridized complex of resin in enamel produced by the self-etching primers without the usual micrometer-sized resin tags seen in resin-enamel bonds produced using the total-etch adhesive. The morphological features of the resin-enamel bonds produced by two self-etching primers tested were different from that created with the total-etch adhesive.     

Effect of functional monomers in all-in-one adhesive systems on formation of enamel/dentin acid-base resistant zone

This study aimed at evaluating the effect of functional monomers in all-in-one adhesive systems on formation of acid-base resistant zone (ABRZ) in enamel and dentin. Experimental adhesive systems containing one of three functional monomers; MDP, 3D-SR and 4-META were applied to enamel or dentin surface and light-cured. A universal resin composite was then placed. The specimens were subjected to a demineralizing solution (pH 4.5) and 5% NaClO for acid-base challenge and then observed by SEM. The ABRZ was clearly observed in both enamel and dentin interfaces. However, enamel ABRZ was thinner than dentin ABRZ in all adhesives. Morphology of the ABRZ was different between enamel and dentin, and also among the adhesives. Funnel-shaped erosion was observed only in the enamel specimen with the 4-META adhesive. The formation of enamel/dentin ABRZ was confirmed in all adhesives, but the morphology was influenced by the functional monomers.     

Quantitative evaluation of microleakage in Class V cavities using one-bottle and self-etching adhesive systems

The aim of this in vitro study was to evaluate quantitatively the microleakage in Class V cavities restored with one-bottle and self-etching adhesive systems with and without previous acid etching. Two one-bottle adhesive systems (Single Bond and Prime & Bond 2.1) and one self-etching adhesive system (Clearfil Mega Bond) were used in this study. One hundred and twenty sound human premolar teeth were randomly divided into 6 groups, and 20 Class V restorations were prepared in the root dentin to test each bonding system. Each bonding system was used with and without acid etching. Specimens were prepared, dyed with 2% methylene blue, sectioned, triturated, and evaluated with an absorbance spectrophotometer test in order to quantify the infiltrated dye. Results were statistically evaluated by ANOVA and Tukey-Kramer test. No statistically significant differences were found among the adhesive systems when no etching agent was used. However, the Single Bond adhesive system showed statistically significant lower microleakage means than Clearfil Mega Bond and Prime & Bond 2.1 when 37% phosphoric acid was used. Single Bond and Clearfil Mega Bond adhesive systems presented similar behavior when the manufacturers' instructions were followed.     

一步法自酸蚀粘接剂微拉伸粘接强度的研究

目的评价一步法白酸蚀粘接剂的牙本质微拉伸粘接强度，观察并分析样本断裂类型。方法选择新拔除的人无龋下颌第三磨牙12颗，分别用3种一步法、1种两步法的白酸蚀粘接剂进行牙本质粘接。用微拉伸测力仪测试粘接强度，并用体视显微镜和扫描电镜观察样本断裂类型。结果3种一步法白酸蚀粘接剂的微拉伸强度分别为：材料A（Adper Prompt）（23．36±2．55）MPa；材料B（Clearfil S^3 Bond）（30．46±3．82）MPa；材料C（Xenon Ⅲ）（34．59±3．46）MPa；1种两步法自酸蚀粘接剂材料D（Clearfil SE Bond）的微拉伸粘接强度为（45．06±5．29）MPa。材料D微拉伸粘接强度最高，与其他3组相比，差异具有统计学意义（P〈0．01）。样本断裂均发生于粘接界面，未观察到复合树脂或牙本质内聚破坏。结论一步法白酸蚀粘接剂的牙本质粘接强度低于两步法白酸蚀粘接剂，但多数仍可满足临床对树脂粘接强度的要求。