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Purpose: The present study evaluated the influence of air entrapment within demineralized dentin on bond strength, nanoleakage, and degree of conversion. Materials and Methods: A vacuum pump with adjustable pressure was used to control the gaseous pressure of a sealed container during the application of a two-step etch-and-rinse adhesive to demineralized dentin. Atmospheric pressure was used as control, and reduced pressures (0.08, 0.06, 0.04 MPa) as experimental variables. Simulated pulpal pressure was adopted during the bonding procedures. After making composite buildups and 24-h water storage, 48 specimens were occlusogingivally sectioned into beams for microtensile bond strength testing, inter- facial morphology observation, and nanoleakage evaluation immediately (6 for each group) or after artificial aging (6 for each group); 20 specimens (5 for each group) were occlusogingivally sectioned into slices for degree of con- version testing. Failure modes were compared using the chi-squared test. The other data were analyzed using ANOVA. Results: When air within composite-dentin interface was thinned with reduced pressures, more thorough adhesive infiltration was achieved, and less distinct nanoleakage as well as higher bond strength were observed compared with control groups, regardless of artificial aging. Mixed failure was predominantly identified, and its percentage was higher in the reduced pressure groups than in the controls. Adhesive application at reduced pressure improved the degree of conversion. Conclusion: Air entrapment in the demineralized dentin adversely affects composite-dentin bonds. Adhesive application at reduced pressure is helpful for reducing entrapped air, thereby improving the durability of composite-dentin bonds. [ABSTRACT FROM AUTHOR]

Nisin is a peptide that possesses potent antibacterial properties. This study evaluated the antibacterial activity of a nisin-doped adhesive against Streptococcus mutans, as well as its degree of conversion and microtensile bond strength (μTBS) to dentin. Nisin was added to the adhesive Adper Single Bond 2 (3M ESPE), resulting in four groups: Control Group (Single Bond 2); Group 1% (1 wt% nisin-incorporated), Group 3% (3 wt% nisin-incorporated) and Group 5% (5 wt% nisin-incorporated). Antibacterial activity against S. mutans was evaluated using colony-forming unit counts (CFU). The degree of conversion was tested using FTIR. Forty human teeth were restored for μTBS evaluation. Data were statistically analyzed with ANOVA and Tukey tests at α = 0.05. The nisin-doped adhesives, for all concentrations, exhibited a significant inhibition of the growth of S. mutans (p < 0.05); Incorporation of 5% and 3% nisin decreased the degree of conversion of the adhesive (p < 0.05). The μTBS (in MPa): Control Group—38.3 ± 2.3A, Group 1%—35.6 ± 2.1A, Group 3%—27.1 ± 1.6B and Group 5%—22.3 ± 1.0C. Nisin-doped adhesives exerted a bactericidal effect on S. mutans. The μTBS and degree of conversion of adhesive were not affected after incorporation of 1% nisin. [ABSTRACT FROM AUTHOR]

Purpose: To examine the effect of CHX pre-treatment on long-term bond strength of fiber posts luted with self-adhesive resin cements. Materials and Methods: Seventy-two single-rooted teeth were selected for root canal treatment and post space preparation. The tested self-adhesive cement/post combinations were (N = 36): 1. RelyX Fiber-Posts luted with RelyX Unicem; 2. Rebilda Posts luted with Bifix SE Cement. For both self-adhesive cements, half of the specimens (experimental groups) were luted after the application of a solution of 2% CHX, while no CHX application was performed for the remaining specimens (control groups). Luted specimens were cut and used for push-out bond strength evaluation immediately, and after storage in artificial saliva for 6 months or 1 year. Additional specimens were processed for quantitative interfacial nanoleakage analysis. Results: ANOVA showed that the variable times of storage had a significant influence on the results (p < 0.05), while no influence of the luting procedure (cements with or without CHX) on the final outcome (p > 0.05) was found. Tukey’s pairwise post-hoc test showed that the radicular bond strength decreased with time of storage. In particular, a significant difference was found between T0 and T1y, but not between T0 and T6m. In contrast, in terms of pre-treatment, no significant reduction in push-out bond strength was observed, irrespective of the aging time. Conclusion: CHX pretreatment did not prevent bond strength degradation of fiber posts luted with self-adhesive cements. [ABSTRACT FROM AUTHOR]

Purpose: To determine whether high-pressure air blowing during adhesive application affects the infiltration of resin comonomers and nanoleakage manifestation in the resin/dentin interface under simulated pulpal pressure. Materials and Methods: Thirty mid-coronal dentin surfaces were bonded with an etch-and-rinse adhesive (Adper Single Bond 2) under simulated pulpal pressure. In the control group, the adhesive was thinned by ordinary air blowing with a pressure of 0.2 MPa, while in the experimental group, a high-pressure air blowing technique (pressure: 0.4 MPa) was used. All other procedures followed the manufacturer's instructions. Resin tag formation and nanoleakage in the bonding interface were evaluated with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results: When adhesive was thinned with high pressure air blowing, longer and more homogeneous resin tags were formed. The bonding interface demonstrated good overall morphology and integrity. Almost perfect infiltration of resin and no obvious nanoleakage were observed. Conclusion: Thinning of adhesive with high-pressure air blowing provides a clinically feasible adjunctive procedure for better resin infiltration. [ABSTRACT FROM AUTHOR]

Purpose: This study evaluated the effect of chlorhexidine (CHX) incorporation into experimental dentin adhesives with different hydrophilicities on the microtensile bond strength (µTBS) to dentin. Materials and Methods: Flat, deep dentin surfaces were prepared from 60 extracted human third molars. Three ethanol-solvated (50 wt% ethanol/50 wt% comonomers) experimental adhesives with varying degrees of hydrophilicity were prepared for the CHX-free groups. For the CHX-containing groups, chlorhexidine diacetate was further added to the ethanol-solvated adhesives to form a concentration of 2.0 wt% CHX. Dentin surfaces were etched with 37% phosphoric acid for 15 s, rinsed and blot dried before bonding. The adhesives were generously applied to dentin with a microbrush for 15 s. A second application of fresh adhesive was made and light cured for 20 s (600 mW/cm²) after solvent evaporation. Composite buildups were made using Filtek Z250 (3M ESPE). The bonded teeth were sectioned into 0.9 mm x 0.9 mm beams and stressed to failure at a crosshead speed of 1 mm/min. Testing was performed 24 h after specimen preparation and 12 months after storage in artificial saliva. The µTBS data were analyzed using three-way ANOVA and Tukey's multiple comparison tests. Fractographic analysis was performed by SEM. Results: Significant differences were observed for the three factors "adhesive hydrophilicity" (p < 0.001), "CHX incorporation" (p = 0.001), and "storage time" (p < 0.001). Interaction among these three factors was also significant (p < 0.001). Incorporation of CHX had no effect on the immediate bond strength of the three experimental adhesives (p > 0.05). After storage in artificial saliva, significant reduction in bond strength was observed in all adhesive groups, except for CHX-containing adhesive I (p < 0.001). The µTBS of the CHX-containing experimental adhesive III was significantly higher than the corresponding CHX-free adhesive (p < 0.001) after aging. Conclusion: When incorporated into hydrophilic dental adhesives, chlorhexidine can partially reduce the degradation of the resin-dentin bonds. [ABSTRACT FROM AUTHOR]

Purpose: This in vitro study evaluated the amount and distribution of outward fluid flow that occurred when an experimental etch-and-rinse hydrophobic adhesive was applied to ethanol-saturated dentin before and after oxalate pretreatment. Materials and Methods: Measurements of dentin permeability were performed under a constant pulpal pressure of 20 cm H2O in deep and middle dentin. A lucifer yellow solution was placed in the pulp chamber to determine the distribution of the water contamination of the hybrid layers. Results: The distribution of fluorescence in dentin specimens that were not pretreated with oxalate revealed that the dye permeated around the resin tags and filled the hybrid layer. Dentin specimens pretreated with oxalate prior to resin bonding, showed 80% to 83% less (p < 0.05) water contamination compared to controls. The dentin permeability results obtained before and after oxalate pretreatment showed that oxalate decreased dentin permeability by 98% (p < 0.05) compared to acid-etched controls. This prevented outward fluid movement during bonding, resulting in better resin sealing of dentin due to the formation of a double seal of resin tags over calcium oxalate crystals in the tubules. Conclusion: Outward dentinal fluid flow may contaminate hybrid layers during adhesive bonding procedures. Pretreatment of acid-etched dentin with 3% oxalic acid prior to bonding procedures can prevent outward fluid flow during bonding and water contamination of the hydrophobic hybrid layers. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the effect of 0.2% and 2% chlorhexidine (CHX) used as a therapeutic primer on the long-term bond strengths of two etch-and-rinse adhesive systems. Materials and Methods: Adper Scotchbond 1XT (SB1) and XP-Bond (XPB) were evaluated. Etched dentin substrates were assigned to 6 treatment groups: (1) 0.2% CHX + SB1; (2) 2% CHX + SB1; (3) SB1 (control); (4) 0.2% CHX + XPB; (5) 2% CHX + XPB; (6) XPB (control). Composite buildups were made and beams prepared for microtensile bond strength testing. Beams were divided into 3 subgroups and either immediately pulled to failure or stored in artificial saliva for 6 or 12 months prior to testing. Data were evaluated with three-way ANOVA. Additional adhesive interfaces were prepared to investigate nanoleakage expression by TEM. Results: SB1 and XPB showed similar immediate bond strength values with or without CHX pretreatment (p > 0.05). After 12 months, bonds fell from 43.9 ± 9.5 MPa to 20.1 ± 5.4 MPa and from 39.6 ± 9.4 MPa to 14.2 ± 5.0 MPa in control specimens for SB1 and XPB respectively, while bond fell only from 41.9 ± 9.6MPa to 33.2 ± 8.3 MPa and 38.3 ± 8.9 MPa to 26.5 ± 10.9 (for SB1 and XPB, respectively) when 0.2% CHX was previously used. CHX concentration did not affect bond strength values (0.2% vs 2%, p > 0.05). Nanoleakage increased during aging in controls, but reduced silver deposits were found in CHX-treated specimens. Conclusion: Chlorhexidine significantly reduced the loss of bond strength seen in control bonds. Since no bacterial growth was present in the aging conditions, the results of this study suggest that endogenous factors thought to degrade the adhesive interface can be inhibited by CHX. Further in vivo trials should confirm the role of CHX in bond durability. [ABSTRACT FROM AUTHOR]

Purpose: This study examined the effects of cutting dentin with different burs at various speeds on the microtensile bond strength (μTBS) of two self-etching adhesive systems. Materials and Methods: Flat deep dentin surfaces from 50 extracted human third molars were divided into 5 groups (n ≤ 10) according to bur type and speed of rotation: (I) high-speed diamond bur, (II) low-speed diamond bur, (III) highspeed tungsten carbide bur, (IV) low-speed tungsten carbide bur. Controls were abraded with 600-grit SiC paper. A two-step self-etching adhesive, Clearfil SE Bond (SE, Kuraray) and a one-step self-etching adhesive, Clearfil S3 Bond (S3, Kuraray) were applied to dentin surfaces and light cured. Composite buildups were performed using Filtek Z250 (3M ESPE). For μTBS evaluation, composite-dentin beams of 0.8 mm2 were stressed to failure at a crosshead speed of 1 mm/min. The μTBS data were analyzed using two-way ANOVA and Tukey's multiple comparison tests. Representative fractured beams from each group were prepared for fractographic analysis under SEM. Results: Two-way ANOVA showed that the effects of dentin surface preparations, adhesive systems, and their interaction were statistically significant (p < 0.001). The μTBS was the highest when bonding SE to dentin surface prepared with 600-grit SiC abrasive paper (47.3 ± 7.4 MPa), followed by high-speed tungsten carbide burs (40.8 ± 6.1 MPa), and the lowest when bonding S3 to dentin surfaces prepared with a high-speed diamond bur (15.2 ± 6.2 MPa). SEM observation of the fractured surfaces revealed mixed and adhesive failures for SE groups, while in the S3 groups, adhesive failures predominated with numerous inclusion droplets. Conclusion: Higher bond strengths are achieved with SE bond when applied on dentin surfaces prepared with tungsten carbide burs. Proper bur and adhesive selection are essential to optimize dentin adhesion of self-etching adhesives. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the microtensile bond strength (µTBS) 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°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 (µTBS). The bond strength data were statistically analyzed using two-way ANOVA and the Holm-Sidak method for multiple comparison tests (α = 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 µTBS 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 µTBS of the two all-in-one adhesive systems decreased when PP was applied. However, the µTBS of both self-etching primer adhesives did not decrease under PP. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate strength and morphology of the interface created on enamel and dentin by Panavia F 2.0 (P, Kuraray), RelyX Unicem (RU, 3M ESPE), and Maxcem (M, Sybron-Kerr), applied under two standardized clinically realistic seating pressures. Materials and Methods: Composite overlays (Paradigm MZ100, 3M ESPE) were luted on flat enamel or dentin surfaces of 48 extracted molars. During the initial 5-min self-curing period, a pressure of either 20 or 40 g/mm² was maintained on the overlay. Curing was completed by light irradiation from the top of the overlay for 20 s. Microtensile sticks and specimens for SEM observations were obtained from the luted teeth. Bond strength data from enamel and dentin (MPa) were analyzed with separate two-way ANOVAs in order to assess the effect of cement type, luting pressure, and their interactions. Tukey's test was used for post-hoc comparisons (α= 0.05). Results: The bond strengths (MPa) to dentin were: P 20 g/mm² 7.5 ± 3.7, 40 g/mm² 10.9 ± 4.5; RU 20 g/mm² 6.8 ± 2.6, 40 g/mm² 14.5 ± 5.3; M 20 g/mm² 4.1 ± 1.8, 40 g/mm² 5.2 ± 1.6. The bond strengths (MPa) to enamel were: P 20 g/mm² 25.2 ± 9.0, 40 g/mm² 30.7 ± 8.6; RU 20 g/mm² 10.7 ± 4.9, 40 g/mm² 11.1 ± 5; M 20 g/mm² 7.3 ± 3.1, 40 g/mm² 7.9 ± 3.2. Cement type, luting pressure, and the interaction of these two factors had significant influences on dentin bond strength, with RU and P outperforming M. RU and P significantly benefited from the increase in luting pressure. In enamel, the type of cement was a significant factor for adhesion, with P yielding the highest and M the lowest strength. The measured bond strengths corresponded with the morphological results. Conclusion: Interfacial strength and adaptation of self-etching and self-adhesive dual-curing cements are enhanced if a seating force greater than finger pressure is maintained throughout the initial self-curing period. [ABSTRACT FROM AUTHOR]

Purpose: To assess the microtensile bond strengths of a core composite with two different viscosities, MultiCore Flow (F) and Heavy Body (HB) (Ivoclar-Vivadent), on dentin and glass-fiber posts with methacrylate resin matrices, in combination with three dentin adhesives: Syntac Classic (S), Excite DSC (E), and AdheSE (A) (Ivoclar-Vivadent). The omission of an intermediate adhesive coating on silanized posts was also examined to see if this resulted in post-core bond strength reduction. Materials and Methods: Six experimental dentin and 6 experimental post groups were formed with different core material viscosity/adhesive combinations. In two control post groups, no adhesive was applied on the silanized posts. The core material was stratified on deep dentin or on the posts. From the built-up teeth and the post-core units, microtensile sticks were obtained. Results: The bond strengths measured on dentin were (MPa): S-F 12.7 ± 6.4; S-HB 18.3 ± 7.6; E-F 33.1 ± 13.7; E-HB 34.1 ± 10.2; A-F 33.5 ± 14.8; A-HB 35.5 ± 14.4. The post-core strengths were: S-F 9.4 ± 2.5; S-HB 7.1 ± 3.8; E-F 8.6 ± 3.8; E-HB 8.1 ± 4.4; A-F 8.1 ± 2.7; A-HB 8.3 ± 2.4; no adhesive-F 10.4 ± 3.6; no adhesive-HB 6.3 ± 2.7. Significantly higher interfacial strengths were achieved on dentin than on posts (p < 0.05). Adhesive type significantly affected core-dentin adhesion, with Excite DSC and AdheSE outperforming Syntac Classic (p < 0.05). Neither core material viscosity nor adhesive type significantly influenced post-core adhesion (p > 0.05). Omission of an intermediate adhesive layer had no effect on post-core adhesion (p > 0.05). Conclusions: Even after post surface silanization, the bond established by the composite core material with the post remains weaker than that created with coronal dentin. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this investigation was to characterize acidic monomers used in self-etching primers/adhesives by determination of their pKa values and by calculation of their calcium dissolving capacity in comparison with phosphoric and hydrochloric acid. Materials and Methods: The following acidic monomers were included in this study: 4-methacryloyloxyethyl trimellitate anhydride (4-META), 10-methacryloyloxydecyl dihydrogen phosphate (MDP), dimethacryloyloxyethyl hydrogen phosphate (di-HEMA-phosphate), ethyl 2-[4-(dihydroxyphosphoryl)-2-oxabutyl]acrylate (EAEPA), 2-[4-(dihydroxyphosphoryl)-2-oxabutyl] acrylic acid (HAEPA), and 2,4,6 trimethylphenyl 2-[4-(dihydroxyphosphoryl)-2-oxabutyl]acrylate (MAEPA). The pKa values were obtained by titration with 0.1 mol/l NaOH in aqueous solution. The inflection points of the resulting potentiometric titration curve were determined as pKa values. In the case of the sparingly water-soluble acidic monomers MAEPA and 4-META, the co-solvent method using different water/ethanol ratios for MAEPA or water/acetone ratios for 4-META was used. The dissolving capacity of each acidic monomer is defined as the amount of hydroxyapatite (HA) dissolved by 1 g of acid. For each monomer, the HA dissolving capacity was calculated by the corresponding pKa value and the molecular weight. To confirm the calculated dissolving capacities, increasing amounts of HA powder (100 mg portions) were slowly added to 15 mmol/l aqueous solutions of the monomers to determine how much HA could be dissolved in the acidic solutions. Results: For all the investigated acidic monomers, pKa1 values between 1.7 to 2.5 were observed. The pKa2 values for the phosphate/phosphonate derivatives are between 7.0 and 7.3, and are comparable to phosphoric acid. For dicarboxylic acid derivatives, the pKa2 values are in the range of 4.2 to 4.5. Due to their comparable molecular weights and pKa1 values, the three tested acids di-HEMA phosphate, MDP and 4-META all possess comparable dissolving capacities for HA (ie, 0.26 to 0.28 g/g monomer). The same amount by weight of acidic monomer EAEPA dissolved more HA (ie, 0.35 g/g monomer). Due to their different molecular weights, phosphoric acid and hydrochloric acid dissolved three and ten times as much HA, respectively, as the first three acidic monomers. As a result, the ability of these acids to dissolve HA increases as their molecular weight decreases. Conclusion: There are no significant differences among the investigated acidic monomers in terms of their pKa values and HA dissolving capacities. Monomer selection criteria for new self-etching adhesives must include properties such as calcium salt stability, wetting of the substrate, and copolymerization behavior. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the immediate microtensile bond strengths achieved with representative adhesive systems from each of the four current bonding approaches. Materials and Methods: Resin composite was bonded incrementally to flat, midcoronal dentin from 33 human molars, using the adhesives (Adper Scotchbond MP; Adper Scotchbond 1; Optibond Solo Plus; Clearfil SE Bond; AdheSE; Tyrian SPE + One Step Plus; Optibond Solo Plus self-etching; One-Up Bond F; iBond; Adper Prompt L-Pop; Xeno III) according to the respective manufacturer's instructions. The bonded specimens were immediately sectioned into sticks and underwent microtensile bond testing either immediately or after 24 h. Data were analyzed with two-way ANOVA and LSD tests. Results: No significant differences were found between immediate and 24-h bond strengths (p > 0.05). However, significant differences were observed among adhesives (p = 0.001). The all-in-one adhesive iBond showed statistically lower values when compared to all the other adhesives. Adper Prompt L-Pop, Xeno III, Tyrian SPE + One Step Plus and One-Up Bond F, all self-etching adhesives, were significantly weaker than AdheSE, Optibond Solo Plus, Adper Scotchbond 1, Optibond Solo Plus self-etching, Clearfil SE Bond, and Adper Scotchbond MP, which did not differ statistically from each other. Conclusion: Microtensile bond strengths of representative adhesive systems from the four categories of bonding agents were not equivalent, with the lowest values recorded for the one-step self-etching adhesives. There were no differences in the bond strengths when measured immediately and after 24 h. [ABSTRACT FROM AUTHOR]

Purpose: Simple changes to bonding technique can improve resin-dentin bond strengths. The objective of this study was to evaluate the effects of multiple coatings of two all-in-one adhesive resins on both microtensile bond strength (µTBS) and nanoleakage. Materials and Methods: The mid-coronal occlusal dentin of extracted human molars was used. Two all-in-one adhesives - iBond (Heraeus Kulzer) and Xeno III (Caulk Dentsply) - were applied to 320-grit abraded dentin surfaces. In groups 1 and 3 during bonding, monomer application and solvent evaporation were done 1, 2, 3, 4 or 5 times on the dentin surface before light curing. In groups 2 and 4 after light curing the first layer, the adhesive was re-applied, the solvent evaporated, and the layer light cured. This was repeated from 2 to 5 times, followed by creation of composite buildups. After 24 h storage in 37°C water, the teeth were sectioned perpendicular to the adhesive interface to produce multiple beams of composite-bonded dentin, approximately 0.9 mm² in area. These were tested to failure in tension. Data were evaluated by three-way ANOVA (material vs coatings vs light curing) followed by multiple comparisons at α = 0.05. Additionally, nanoleakage of silver uptake and adhesive layer thickness were evaluated using transmission electron microscopy (TEM). Results: The results indicated that bond strengths increased with the number of coatings (p < 0.0001) with both adhesives, up to 3 layers, especially if each layer was light cured. Nanoleakage of silver tended to decrease with each coat in both adhesive systems. Conclusion: By simply applying more coats of adhesive, the strength and quality of dentin adhesion can be improved. [ABSTRACT FROM AUTHOR]

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 highly significant effect on bond strength of the single-step, self-etching adhesive. [ABSTRACT FROM AUTHOR]

Purpose: This study examined the polymerization kinetics of acid-contaminated light- and chemically-cured resins with the use of differential scanning calorimetry. Materials and Methods: Light-cured and chemically-cured versions of an experimental bis-GMA/TEGDMA resin at the ratio (w:w) of 62:38 were prepared. Four acidic resin monomers with either carboxylic (DSDM and MAA) or phosphoric functional groups (MP and 2MP) were added at a 10 wt% concentration to these resins to simulate the intermixing of resin composites and unpolymerized acidic monomers along the adhesive-composite interface of simplified-step dentin adhesives. Different concentrations of the most acidic monomer 2MP (10 to 50 wt% for the light-cured resin, and 2 to 4 wt% for the chemically- cured resin) were also added to examine their contribution to reducing the extent and rate of polymerization of these resin mixtures. The effect of sodium benzene sulphinate on the polymerization of the chemically-cured resin that was contaminated with 10 wt% 2MP was also investigated. Results: At 10 wt% concentration, all acidic monomers had a limited effect on the polymerization of the light-cured resin. The rate and extent of polymerization in the chemically-cured resin was substantially reduced by the carboxylic acid monomers DSDM and MAA, while polymerization was completely inhibited in the presence of the organophosphate monomers MP and 2MP. Substantial reductions in the rate and extent of polymerization of the light-cured resin occurred only in the presence of high concentrations (30 to 50 wt%) of 2MP. More acute polymerization inhibition was observed when the chemically-cured resin was contaminated with 2 to 3 wt% 2MP, with polymerization completely inhibited at 4 wt%. Addition of sodium benzene sulphinate to 2MP-contaminated chemically-cured resin revived the previously uncured resins, but their rate and extent of polymerization were still inferior to that of uncontaminated chemically- cured resin. Conclusion: When the influence of adhesive permeability was excluded with the use of neat, water-free resins, deactivation of the tertiary amine utilized in the chemically-cured resin by even very low concentrations of acidic resin monomers accounts for the reported incompatibility between simplified-step dentin adhesives and chemically-cured composites. The polymerization of light-cured resin is only affected by much higher concentrations of acidic resin monomers. [ABSTRACT FROM AUTHOR]

Purpose: As adhesives containing hydrophilic/acidic resin components are vulnerable to water movement after polymerization, this study tested the hypothesis that coupling of a single-bottle adhesive (OptiBond Solo Plus) to self/dual-cured composites is compromised by adhesive permeability, even with the adjunctive use of chemical co-initiators. Materials and Methods: Two versions of chemical co-initiators (activators) were investigated: the proprietary resin-containing OptiBond Solo Plus Activator (A), and a resin-free solution of 2% benzene sulphinic acid sodium salt in ethanol (B). For microtensile bond testing, hydrated (H) or dehydrated (D) bonded human dentin were coupled to a dual-cured composite (Bis-Core) under light- (L) or self-activation (C) mode. A delayed light-activation mode (DL) was also employed to simulate the slower rate of polymerization of self-cured composites but without the influence from adverse chemical interaction. Nine groups were tested: 1) L-H (control); 2) DL-H; 3) DL-D; 4) C-H; 5) C-D; 6) CA-H; 7) CA-D; 8) CB-H; and 9) CB-D. For transmission electron microscopy, a light-cured and an experimental self-cured composite of the same composition were used for the nine groups. Results: Only the bond strength results of the experimental groups DL-D (Group 3) and CB-D (Group 9) were not significantly different from the control group L-H (p > 0.05). TEM revealed the presence of discrete silver-filled water blisters along the adhesive-composite interface in groups 2, 6, and 8, and within the composite in group 4. Adverse chemical interaction in groups 4 and 5 resulted in the observation of a line of silver deposits along the adhesive composite interface. Conclusion: The coupling of composites after prolonged contact with hydrated dentin bonded with Opti- Bond Solo Plus is affected by the intrinsic permeability of the adhesive. The adjunctive use of the Activator is only slightly effective in improving the coupling of this adhesive with self/dual-cured composites. Although the use of resin-free benzene sulphinic acid sodium salt solution completely eliminates the adverse chemical interaction, the inherent permeability of the polymerized adhesive precludes optimal coupling of self/dual-cured composites to bonded hydrated dentin. [ABSTRACT FROM AUTHOR]

Purpose: To determine if adverse chemical interaction and adhesive permeability are both responsible for the incompatibility between a single-step, self-etching adhesive and chemically-cured or dual-cured composites. Materials and Methods: Bonding was performed with Xeno CF Bond (Dentsply-Sankin), on either hydrated (H) or dehydrated (DH) human dentin. For microtensile bond strength evaluation, a dual-cured hybrid composite (Bis-Core) was activated using: (1) the light-cured (L) mode (base syringe only), (2) delayed light activation (DL) (base syringe left on top of cured adhesive in the dark for 20 min before activation), and 3) the chemically-cured (C) mode (base and catalyst syringes in the dark). A chemical co-initiator (B; BondLink) was also applied to the cured adhesive before coupling with the composite in chemically-cured mode. This resulted in seven experimental groups: (1) L-H (control); (2) DL-H; (3) DL-DH; (4) C-H; (5) C-DH; (6) C-B-H; and (7) C-B-DH. For transmission electron microscopy, the dual-cured composite in the seven groups was replaced with a light-cured microfilled composite (Metafil CX) and an experimental chemically- cured microfilled composite of the same composition. Specimens were immersed in ammoniacal silver nitrate for 24 h. After reduction of the diamine silver ions to silver, undemineralized and unstained sections were examined for nanoleakage within the resin-dentin interfaces of the seven groups. Results: For the light-cured modes, bond strengths fell substantially in DL-H but not in DL-DH. For the chemically-cured modes, bond strengths were lowest in C-H and only increased slightly in C-DH. The use of a chemical co-initiator with the adhesive further improved the bond strength in C-B-H. Only C-B-DH was not significantly different from the control light-cured mode L-H. Two abnormal modes of silver deposition were observed in resin-dentin interfaces. A continuous layer of silver was observed when the chemically- cured composite was applied to the cured adhesive in the absence of the chemical co-initiator (C-H; C-DH). Silver-impregnated water blisters were identified when the chemically-cured composite was coupled to bonded hydrated dentin (C-H; C-B-H). Similar water blisters were seen in DL-H in which adverse chemical interaction should not occur. Conclusion: Adverse chemical interaction between catalytic components of chemically-cured composite and the tested single-step, self-etching adhesive was the major cause of reductions in bond strength, while adhesive permeability was a minor cause of bond strength reduction. The combination of these two factors accounts for the substantial reduction in bond strength when chemically-cured or dual-cured composites were coupled to bonded hydrated dentin. [ABSTRACT FROM AUTHOR]

The current trend in the development of dentin adhesives attempts to simplify bonding steps and make them more user-friendly. However, optimizing speed and efficiency should be accomplished without major tradeoffs in the quality or durability of resin bonds. Although dentin adhesives have improved tremendously over the past decade, postoperative sensitivity, incomplete marginal seal, premature bond degradation, biocompatibility, and compromised bonding to abnormal substrates are still considered potential problems associated with their use. Advances in different scientific disciplines will enrich the pool from which ideas may be drawn in designing future dentin adhesives. It is probably on the molecular level that we will see the greatest expansion of horizons. With the advances in biomimetics, future dentin adhesive monomers may contain domains derived from protein-based, underwater bioadhesives secreted by aquatic animals such as mussels and barnacles, making them less dependent on the surface energy of the bonding substrates as well as less susceptible to hydrolytic degradation. As adhesive joints produced by contemporary adhesives are brittle in nature, future adhesive design may incorporate biomimetic intermediate-strength domains that can undergo stepwise reversible unfolding in response to varying functional stress levels before ultimate catastrophic failure of the adhesive joint occurs. These domains may also re-establish folded configurations on stress relaxation, making the adhesive both strong and tough. Using the concept of controlled release, future adhesives may contain fluorescent biosensors that can detect pH changes around leaking restorations. They may even have the capacity to heal autonomously, in response to microcracks formed by functional stresses within the adhesive joint. The ability to self-diagnose and self-repair will increase the life expectancy of adhesive restorations. Future dentin adhesives may also assume a more instrumental role in therapeutics apart from caries prevention. These features may include the controlled release of noncollagenous proteins to promote remineralization of collagen matrices in sound and caries affected dentin, and growth factors to induce controlled formation of reparative dentin. [ABSTRACT FROM AUTHOR]

Purpose: This study compared the effect of water sorption on the extent of marginal gap reduction in two resin-modified glass-ionomer cements (RMGICs), two giomers, two compomers, and two resin composites over a twelve-week storage period. Materials and Methods: Artificial gaps were created in 160 borosilicate glass cylinders. One-half of the internal surface of each cylinder was blocked out with wax and the other half was sandblasted. The bonding surface was further treated with 4% hydrofluoric acid, rinsed, and then coated with silane. After removal of the wax, one coat of dentin adhesive was applied to the silane-treated surface of the cylinder, briefly air dried and light cured. Eight light-cured restorative materials were placed incrementally: Vitremer (V), Fuji II LC (FJ), Beautifil (B), Reactmer Paste (R), Compoglass F (C), F2000 (F), Filtek Z250 (Z), and Tetric-Ceram (T). For each material, ten specimens were stored in deionized water (W), and ten (control) in nonaqueous silicone fluid (O) at 37°C. The dimension of the same maximum gap created in each specimen was repeatedly measured at 0, 1, 2, 4, 6, 8, 10, and 12 weeks. Results: R-W exhibited extensive hygroscopic expansion that resulted in cracking of 40% of glass cylinders after the 2nd week and 70% after the 4th week. One-way ANOVA of the other seven water groups showed significant differences (p < 0.001) among gap widths measured at different time intervals in V-W, FJ-W, C-W, F-W. Both RMGICs had the most significant gap reduction during the first week (p < 0.001). Both compomers exhibited delayed water-sorption characteristics, with more significant gap reduction observed in C-W. B-W was similar to the two resin composites Z-W and T-W and exhibited the least gap reduction. After the first week, there were no significant differences in the percentage reduction in marginal gaps for any of the groups (p > 0.05). Conclusion: Marginal gap reduction that results from water sorption is more extensive and rapid in RMGICs, followed by compomers, whereas composites are relatively stable. Reactmer Paste exhibits rapid and extensive expansion and should probably be avoided in tooth preparations that involve thin unsupported enamel. [ABSTRACT FROM AUTHOR]

Purpose: This study examined the effect of delayed activation of light-cured resin composites on the microtensile bond strengths of two all-in-one adhesives to sound dentin. Materials and Methods: Flat dentin surfaces prepared from caries-free third molars were bonded with either Prompt L-Pop (ESPE) or One-Up Bond F (Tokuyama). Each adhesive was divided into 6 subgroups containing three teeth each. A hybrid composite was left to contact the cured adhesive surfaces for 0, 2.5, 5, 10 or 20 min before light activation. In the 6th subgroup, the cured adhesive was covered with a layer of nonacidic bonding resin before contacting the composite for 20 mm. Composite-dentin beams, with average cross-sectional areas of 0.85 mm² were prepared for microtensile bond testing. Representative fractured beams from the 0, 10- and 20-min delay subgroups were prepared for SEM examination. Additional specimens were prepared in the 0- and 20-min delay subgroups by replacing the hybrid composite with either a flowable composite or a composite liner to facilitate TEM preparation and examination. Results: Kruskal-Wallis ANOVA and Dunn's multiple comparison tests showed that significant differences existed among the subgroups of each adhesive. Regression analyses showed that for each adhesive, there was an exponential decline in mean bond strength with increasing delay In light activation, and the correlation was highly significant (r = -0.99, p < 0.005 for Prompt L-Pop; r = -0.96, p < 0.01 for One-Up Bond F). SEM examination of fractured interfaces in the immediately light-cured subgroups revealed the absence of voids within the fractured composite. However, voids were consistently observed in the 10 min- and 20 min-delay subgroups. They corresponded to soapsuds-like blisters that were observed with TEM in the 20 min-delay subgroups. Conclusion: Adverse interactions between acidic adhesive resin monomers and tertiary amines in light- cured composites normally do not occur because of the fast rate of free-radical generation in photochemical redox reactions. However, such interactions can occur in all-in-one adhesives on prolonged contact of light-cured composites with the cured adhesive layer. [ABSTRACT FROM AUTHOR]

Purpose: To determine if collagen fibrils on the dentin side of failed resin-dentin interfaces undergo mechanical disruption during microtensile bond testing. Materials and Methods: Extracted, caries-free human third molars were divided into four groups. The occlusal enamel was removed, leaving a flat dentin surface for bonding. Resin composite buildups were made after the acid-conditioned dentin was bonded with either Single Bond {Si or One-Step (0}, and using either moist bonding (M) or air drying for 5 s (DJ. After storage in water for 24 h. the teeth were vertically sectioned into an array of 0.9 >■ 0.9 mm resin ccmposite-dentin beams They were stressed to failure using the nontrimming version of the microtensile bond test. Fractured dentin and resln composite sides of representative beams from each group that exhibited adhesive failures under tight microscopy examination were prepared for descanning (SEM) and transmission electron microscopy (TEM). Results: A two-way ANOVA showed that moist bond strengths were significantly higher than those made to dry dentin {M > 0; p < 0.001), but that there was no difference between the adhesive (S vs 0; p = 0.547). SEM analysis showed the presence of loose collagen fibrils within fractured hybrid layers ¡n the dry groups but not in the moist groups. TEM examination of the dry-bonded groups revealed collagen fibrils that wore thinner and exhibited abnormally wide interfibrillar spaces when hybrid layers were intact. Within dry-bonded fractured hybrid layers, broad mechanical disruption zones could be seen, consisting of fibrils that were devoid of cross banding, defibrillation of the subfibrillar architecture, and gross disaggregation into microfibrils. In the moist-bonded groups, only short mechanical disruption zones were found along the torn edges of the collagen fibrils. The rest of the fibrils beyond the fracture site were intact and retained their periodicity. Mechanical testing of demineralized matrices.. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this review is to describe all of the various modifications of the microtensile bond test in one paper, so that investigators can select the modification that best suits their needs. Methods: The essence of the microtensile test is the division of resin-bonded teeth into slabs between 0.5 and 1.0 mm thick that are then trimmed in such a manner that tensile force will be concentrated on the bonded interface during testing. Among the many advantages of the technique are that each tooth produces multiple specimens. Further, there is no need for a matrix to limit the bonded surface area, since the area is determined by the dimensions of the trimmed specimens. Results: The various modifications of the microtensile test have been used to measure differences in regional bond strength across occlusal dentin, down the external surface of teeth from crown through roots, down the internal surface of root canals from cervical to apical thirds, as well as to compare normal vs caries-affected occlusal dentin and normal vs sclerotic cervical dentin. The technique is ideal for evaluating the long-term durability of resin-hard-tissue bonds. Conclusion: The microtensile test methods offer versatility that cannot he achieved by conventional methods. It is more labor-intensive than conventional testing, but holds great potential for providing insight into the strength of adhesion of restorative materials to clinically relevant sites and substrates. [ABSTRACT FROM AUTHOR]

Purpose: This in vitro study examined the interfacial ultrastructure of a nanofilled, simplified-step adhesive (Prime & Bond NT, Dentsply), to determine the distribution of nanofillers within the collagen network of the hybrid layer. Materials and Methods: Twentv-four dentin discs were divided into two groups and bonded using two recommended conditioning techniques: Group I, NRC (Non-Rinse Conditioner}, and Group II, Conditioner 36 (colloidal silica thickened 36% phosphoric acid). Following conditioning, a single coat of adhesive was applied and light-cured. Dentin discs were then bonded to form disc-pairs and processed for TEM examination. Demineralized, ultrathin sections were examined stained or unstained. Non-demineralized sections were used for STEM/EDX analysis of elemental distribution across the resin-dentin interface. In addition, four dentin discs were bonded with a generic adhesive (HEMA/TBBO) for TEM examination of stained collagen and proteoglycans. Results: In unstained sections of both groups, nanofillers from the adhesive layer were congested around patent tubular orifices, but were not found within the mterfibrillar spaces of the hybrid layer. EDX analysis of silicon (Si) showed predominant distribution within the adhesive layer and tubular orifices. Phosphorus (P) was present within the hybrid layer and adhesive layer in Group II. Conclusion: It is hypothesized that a) aggregation of the nanofillers within the adhesive resulted in filler clusters that are too large to infiltrate the interfibrillar spaces of the hybrid layer; and b) retention of ground substance within the demineralized intertubular collagen matrix may also have prevented the infiltration of the nanofillers. [ABSTRACT FROM AUTHOR]

Resin-dentin bonds are not as durable as was previously thought. Microtensile bond strengths often fall 30% to 40% in 6 to 12 months. The cause of this poor durability is a combination of the activation of matrix metalloproteinases (MMPs) by weak acids such as lactic acid released by caries-producing bacteria, and acid-etchants used in adhesive bonding systems. These acids uncover and activate matrix-bound MMPs. The other contributing factor is incomplete resin infiltration. If all exposed collagen fibrils were enveloped by resin, the MMPs would not have free access to water, an obligatory requirement of these enzymes. Recently, several inhibitors of MMPs have been added to adhesive primers. Examples include chlorhexidine (CHX), benzalkonium chloride (BAC), and MDPB, an antibacterial monomer used in a two-step self-etching primer adhesive. The advantage of MDPB over CHX and BAC is that it polymerizes with adhesive resins and cannot leach from the hybrid layer. This is an example of what can be termed a "therapeutic adhesive system" that provides anti-MMP activity along with antibacterial qualities. [ABSTRACT FROM AUTHOR]

Purpose: To adapt a simple gravimetric method to measuring the permeability of adhesive resin films to liquid water, and to compare this to the water vapor permeability of the same resñ's. Methods: Using commercially- available permeability cups designed for industrial permeability testing, the loss of mass of water vapor or liquid water from a stainless steel cup sealed with a resin film was measured over 1-2 days. The permeabilities of Paraflim (control), Clearfil SE Bond adhesive, Xeno IV and One-Up Bond F were compared. Results: The lowest resm film permeability was obtained with Clearfil SE Bond adhesive films. The permeabilities of Xeno IV and One-Up Bond F to liquid water were 2.76 and 3.27-fold higher (P< 0.00 1) than that of Clearfil SE Bond adhesive. Liquid water permeability was always 2.8- 3.8-fold higher (P< 0.05) than water vapor transmission rate. It was concluded that quantitative comparisons of the permeability properties of resin films can be made gravimetrically. The large permeability cups that are available commercially may be reduced in size in the future for measuring dentin adhesive films with smaller surface areas that are less liable to contain imperfections. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: The aim of this study was to explore the therapeutic opportunities of each step of 3-step etch-and-rinse adhesives. Methods: Etch-and-rinse adhesive systems are the oldest of the multi-generation evolution of resin bonding systems. In the 3-step version, they involve acid-etching, priming and application of a separate adhesive. Each step can accomplish multiple goals. Acid-etching, using 32–37% phosphoric acid (pH 0.1–0.4) not only simultaneously etches enamel and dentin, but the low pH kills many residual bacteria. Results: Some etchants include anti-microbial compounds such as benzalkonium chloride that also inhibits matrix metalloproteinases (MMPs) in dentin. Primers are usually water and HEMA-rich solutions that ensure complete expansion of the collagen fibril meshwork and wet the collagen with hydrophilic monomers. However, water alone can re-expand dried dentin and can also serve as a vehicle for protease inhibitors or protein cross-linking agents that may increase the durability of resin–dentin bonds. In the future, ethanol or other water-free solvents may serve as dehydrating primers that may also contain antibacterial quaternary ammonium methacrylates to inhibit dentin MMPs and increase the durability of resin–dentin bonds. The complete evaporation of solvents is nearly impossible. Significance: Manufacturers may need to optimize solvent concentrations. Solvent-free adhesives can seal resin–dentin interfaces with hydrophobic resins that may also contain fluoride and antimicrobial compounds. Etch-and-rinse adhesives produce higher resin–dentin bonds that are more durable than most 1 and 2-step adhesives. Incorporation of protease inhibitors in etchants and/or cross-linking agents in primers may increase the durability of resin–dentin bonds. The therapeutic potential of etch-and-rinse adhesives has yet to be fully exploited. [ABSTRACT FROM AUTHOR]

Abstract: Biomineralization is a dehydration process in which water from the intrafibrillar compartments of collagen fibrils are progressively replaced by apatites. As water is an important element that induces a lack of durability of resin–dentin bonds, this study has examined the use of a biomimetic remineralization strategy as a progressive dehydration mechanism to preserve joint integrity and maintain adhesive strength after ageing. Human dentin surfaces were bonded with dentin adhesives, restored with resin composites and sectioned into sticks containing the adhesive joint. Experimental specimens were aged in a biomimetic analog-containing remineralizing medium and control specimens in simulated body fluid for up to 12 months. Specimens retrieved after the designated periods were examined by transmission electron microscopy for the presence of water-rich regions using a silver tracer and for collagen degradation within the adhesive joints. Tensile testing was performed to determine the potential loss of bond integrity after ageing. Control specimens exhibited severe collagen degradation within the adhesive joint after ageing. Remineralized specimens exhibited progressive dehydration, as manifested by silver tracer reduction and partial remineralization of water-filled microchannels within the adhesive joint, as well as intrafibrillar remineralization of collagen fibrils that were demineralized initially as part of the bonding procedure. Biomimetic remineralization as a progressive dehydration mechanism of water-rich, resin-sparse collagen matrices enables these adhesive joints to resist degradation over a 12-month ageing period, as verified by the conservation of their tensile bond strength. The ability of the proof of concept biomimetic remineralization strategy to prevent bond degradation warrants further development of clinically relevant delivery systems. [Copyright &y& Elsevier]

Our aim was to evaluate the influence of different application parameters on microtensile bond strength (μTBS) of an “all in one” water-based self-etching primer/adhesive to dentin. Extracted human third molars had their crowns transversally sectioned next to the dentinoenamel junction. Prompt-L-Pop adhesive was applied using five modes: (1) following the manufacturer’s instructions (MI); (2) after 36% H3PO4 etching (15 s) (AG); (3) after H3PO4 etching and 5% NaOCl (2 min) with constant agitation (HG); (4) as a double layer (DL); and (5) for double the application time (DT). Resin build-ups were constructed with Tetric Ceram. After storage for 24 h, 6 months, or 12 months in water at 37°C, the specimens were vertically sectioned into beams (cross-sectional areas, 1 mm2). Each beam was tested in an Instron Machine at 0.5 mm/min. Analysis of variance and Student-Newman-Keuls were used ( P < 0.05). Bonded interfaces were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The highest μTBS values were obtained when AG was used, and the lowest when MI was employed. The HG, DL, and DT modes resulted in similar μTBS values. Water storage reduced μTBS in all groups except the MI group. SEM and TEM revealed hybrid layer and resin tag formation in all groups. Applied after AG, HG, DL, and DT, Prompt L-Pop adhesive provided adequate bond strength to dentin after 24 h of water storage. Bond strength decreased when specimens were stored in distilled water for 6 or 12 months. [ABSTRACT FROM AUTHOR]

Abstract: The latest generation of methacrylate resin–based sealers has eliminated the use of separate self-etching primers by incorporating acidic resin monomers in the sealers to render them self-adhesive to dentin. This study examined the adhesive strengths, interfacial ultrastructure, and tracer penetration of a nonetching (EndoREZ; Ultradent, South Jordan, UT) and two self-adhesive methacrylate resin–based sealers (MetaSEAL; Parkell, Farmington, NY, and RealSeal SE; SybronEndo, Orange, CA) when they were applied to radicular dentin following the manufacturers'' recommended use of EDTA as the active final rinse. A modified push-out testing design was used to evaluate the dislodgement of core-free sealers. The mixed sealers were placed in dimensionally identical, artificially created canal spaces prepared in the coronal, middle, and apical thirds of radicular dentin. After setting, each sealer-filled cavity was subjected to compressive loading until failure. Additional specimens were prepared for transmission electron microscopy to examine the ultrastructure and nanoleakage within the sealer-radicular dentin interface. The two self-adhesive sealers MetaSEAL and RealSeal SE exhibited higher push-out strengths than the nonetching sealer EndoREZ when EDTA was used as the active final rinse. All three sealers showed a 1- to 1.5-μm thick zone of partially demineralized dentin, with the EDTA dentin demineralization effect masking the true self-etching potential of MetaSEAL and RealSeal SE. The true self-etching potential of self-adhesive sealers is a clinically important attribute that should be further investigated. Incomplete smear layer removal from the apical third of instrumented canal walls may jeopardize the performance of self-adhesive sealers should they fail to self-etch without the adjunctive use of calcium chelating irrigants. [Copyright &y& Elsevier]

Abstract: Introduction: Smearing 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. Methods: Coronal 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. Results: For 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. Conclusion: The 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. [Copyright &y& Elsevier]

This study evaluated the permeability properties of five experimental resin membranes that ranged from relatively hydrophobic to relatively hydrophilic to seal acid‐etched dentin saturated with water or ethanol. The experimental resins (R1, R2, R3, R4, and R5) were evaluated as neat bonding agents or as solutions solvated with ethanol (70% resin/30% ethanol). The quality of dentin sealing by these experimental resins was expressed in terms of reflection coefficients calculated as the ratio of the effective osmotic pressure to the theoretical osmotic pressure of test solutions. The effective osmotic pressure produced across resin‐bonded dentin was induced in hypertonic solutions (CaCl2 or albumin) at zero hydrostatic pressure. The outward fluid flow induced by these solutions was brought to zero by applying an opposing negative hydrostatic pressure. The least hydrophilic resins blends, R1 and R2, exhibited significantly (p < 0.05) higher reflection coefficients than the most hydrophilic resins (R4 and R5) in both conditions of dentin saturation (water and ethanol). The reflection coefficients of neat resins were, in general, significantly higher when compared with their corresponding solvated versions in both conditions of dentin saturation. In dentin saturated with ethanol, bonding with neat or solvated resins, resulted in reflection coefficients that were significantly higher when compared with the results obtained in dentin saturated with water. Reflection coefficients of CaCl2 (ca. 1 × 10−4) were significantly lower (p < 0.05) than for albumin (ca. 3 × 10−2). Application of hydrophobic resins may provide better sealing of acid‐etched dentin if the substrate is saturated with ethanol, instead of water. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009 [ABSTRACT FROM AUTHOR]

Purpose: To examine the ultrastructure and silver nanoleakage of the resin-dentin interfaces in sound and caries-affected primary tooth dentin bonded with a 4-META one-step self-etch adhesive, Methods: Each of five sound and carious primary molars was bonded with Hybrid Bond. Resin-dentin interfaces were observed with TEM micrographs obtained from silver-impregnated, unstained and undemineralized sections of bonded sound and caries-affected primary dentin, and stained and demineralized sections of bonded sound and caries affected primary dentin without silver impregnation. Results: For sound dentin, silver nanoleakage was observed extensively in the patent dentin tubules, within the dentin beneath the hybrid layer, within the hybrid layer in some specimens, and as water trees that partially protruded into the overlying adhesive layer. The hybrid layer was about 1 µm thick. Smear plugs in the dentin tubules and smear on the ground dentin protruded in the hybrid layer. Remnants of demineralized smear were observed overlying the adhesive layer. For caries-affected dentin, the hybrid layer was obscure. Dentin tubules were occluded with mineral deposits. There were no water trees or nanoleakage in the adhesive layer or hybrid layer. However, smear remnants were observed in the adhesive layer and large silver deposits were observed in the highly porous underlying caries-affected dentin. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the quality of the interface of sound and carious primary tooth dentin bonded with two 4-META one-step self-etch adhesives. Methods: 12 sound and 12 carious primary molars were bonded with AQ Bond Plus (AQBP; Sun Medical) or Hybrid Bond (HB: Sun Medical) and restored with Clearfil Protect Liner F (Kuraray Medical Inc.). After 24 hours of water immersion, the teeth were sectioned and polished. Resin-dentin interfaces were measured with a nano-indentation tester and hardness and Young's modulus were calculated. Data were analyzed using one-way or two-way ANOVA and Fisher's PLSD test with α=0.05. Resin-dentin interfaces were also observed with SEM and TEM. Ammoniacal silver nitrate was used as a tracer for TEM observation. Results: Hardness and Young's modulus of the interracial dentin were significantly lower than the underlying intact dentin except for the carious-AQBP group. However, there was no significant difference of hardness and Young's moduli of the interfacial dentin among all groups. TEM revealed extensive interfacial nanoleakage in sound dentin bonded with either AQBP or HB. For the carious teeth, nanoleakage was absent in the hybrid layers bonded with the two adhesives. However, extensive silver deposits were identified from the subsurface, porous caries affected dentin. [ABSTRACT FROM AUTHOR]

This paper reviews our recent studies on fluoride-releasing adhesives and the related studies in this field based on information from original research papers, reviews, and patent literatures. A revolutionary PRG (pre-reacted glass ionomer) filler technology-where fillers were prepared by the acid-base reaction of a fluoroaluminosilicate glass with polyalkenoic acid in water, was newly developed, and a new category as "Giomer" was introduced into the market. On fluoride release capability, SIMS examination revealed in vitro fluoride ion uptake by dentin substrate from the PRG fillers in dental adhesive. On bonding durability, it was found that the improved durability of resin-dentin bonds might be achieved not only via the strengthened dentin due to fluoride ion uptake from the PRG-Ca fillers, but also due to retention of relatively insoluble 4-AETCa formed around remnant apatite crystallites within the hybrid layer in 4-AET-containing self-etching adhesives. On ultramorphological study of the resin-dentin interface, TEM images of the PRG-Ca fillers revealed that the dehydrated hydrogel was barely distinguishable from normal glass fillers, if not for the concurrent presence of remnant, incompletely reacted glass cores. In conclusion, it was expected that uptake of fluoride ions with cariostatic effect from PRG-Ca fillers would endow dentin substrates with the benefit of secondary caries prevention, together with an effective and durable adhesion to dentin. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate early and 24-hour microtensile bond strength (μTBS) and the degree of conversion (DC) of one representative adhesive system from each of the four current bonding approaches. Methods: 40 human molars were sectioned occluso-gingivally into two halves. Resin composite was bonded incrementally to flat, mid-coronal dentin, using the adhesives Adper Scotchbond MP (MP); Adper Scotchbond 2 (SB); Clearfil SE Bond (SE); and Adper Prompt L-Pop (LP) according to the respective manufacturer's instructions (n= 10). One half was immediately sectioned into sticks and subjected to μTBS test. As the sectioning process took approximately 1 hour, the results were designated as 1-hour bond strengths. The other half was stored in distilled water at 37°C for 24 hours before being sectioned and tested. The DC of these systems was measured using Fourier Transform-Raman spectroscopy in three periods: immediately, 1 and 24 hours after polymerization. Data were analyzed with ANOVA and Tukey's tests. Results: There were no significant differences between the 1-hour and 24-hour bond strengths (P> 0.05), or among the DC measured immediately, 1 hour and 24 hours after polymerization (P> 0.05). However, significant differences were observed among adhesives (P< 0.05). μTBS values obtained, in MPa (1 hour/24 hour), were: SB (48.6 + 1.3/48.4 + 3.5) = SE (51.9 + 4.7/53.3 ± 2.9) > MP (35.3 ± 10.9/38.6 + 6.7) > LP (25.5 + 1.1/26.0 + 1.5). The DC, in percentage (immediately/lhour/24 hour), were: SE (81/82/87) > MP (79/77/81) > SB (60/63/65) > LP (39/37/42). [ABSTRACT FROM AUTHOR]

Electrochemical impedance spectroscopy (EIS) offers a potentially nondestructive quantitative method for measuring the stability of resin films and or resin‐bonded dentin over time. The purpose of this study was to measure the electrical impedance of five experimental dental adhesives of increasing hydrophicities as 30‐μm films and as resin‐bonded coatings on acid‐etched dentin. Resin films or resin‐coated dentin disks were placed in U‐shaped chambers containing pairs of Ag–AgCl electrodes in 0.1M KCl. Electrical impedance spectra were run at day 0, 1, 7, 14, and 21 days. All resin films and resin‐bonded dentin showed increases in capacitance during the first day of storage in electrolyte. This was usually associated with an increase in the pore resistance of the resins. Generally, resin‐bonded dentin gave lower impedance values than their respective resins (resins 1–4) but solvated resin 5 bonded to water‐saturated dentin gave higher capacitance and impedance values than resin 5 films. However, solvated resin 5 films gave higher impedance values than resin 5‐bonded dentin. This behavior was confirmed by TEM examinations of silver uptake into films of neat resin 5 vs. ethanol‐solvated resin 5, where water tree‐like structures seen in the former were not seen in the latter. EIS is useful in examining changes in the capacitance and electrical impedance of very hydrophilic, ionic methacrylate resins. Its utility in detecting degradation in resin‐bonded dentin interfaces remains to be determined in longer term studies. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [ABSTRACT FROM AUTHOR]

Purpose: To retrospectively evaluate the long-term clinical performance of three types of fiber posts aider a service period of 7-11 years. Methods: 985 posts were included in the study: 615 Composiposts, 160 Æstethic Posts and 210 Æsthetic Plus Posts were placed into endodontically treated teeth. Four combinations of dentin adhesives/luting materials were used. Endodontic and prosthodontic results were recorded. Results: A 7-11% failure rate was recorded for the three types of posts. A total of 79 failures were recorded: 39 due to endodontic reasons, one root fracture, one fiber post fracture, 17 crown dislodgements and 21 due to post debondnig. The mechanical failures were always related to the lack of coronal tooth structure. The results indicated that fiber posts in combination with bonding/luting materials may be used routinely for restoring endodontically treated teeth. Mechanical failure of restored teeth with fiber posts can be related to the amount of residual coronal structure. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of different fiber post surface treatments on bond strength, Methods: Extracted endodontically-treated premolars were prepared for the cementation of a methacrylate resin-based fiber post (FRC Postec). The posts received one of the three surface pre-treatments: silane application; hydrofluoric acid-etching and silane application or no treatment. A light-cured composite was used with one of the three dentin adhesives for luting: Single Bond; Clearfil Photo Bond and Clearfil New Bond, followed by a light-cured composite core build-up. Specimens were serially sliced into 0.8 x 0.8 mm-thick beams and loaded in tension until failure. Results: Significant differences in bond strengths were recorded among the dentin adhesives (P< 0.05). However, post pre-treatment did not affect the bonding efficacy of the adhesives except for Clearfil New Bond. [ABSTRACT FROM AUTHOR]

Biomechanical properties of bonded dentin are important for resin restorations. We hypothesized that there are no differences in the hardness and elasticity of sound and caries-affected primary dentin bonded with a one-step self-etch adhesive. Resin-dentin interfaces in sound and caries-affected primary dentin were measured with a nano-indentation tester and observed with SEM and TEM. Interfacial dentin hardness was similar for sound and caries-affected dentin, but significantly lower than the underlying intact dentin. As for the Young's modulus of interfacial dentin, both substrates exhibited significantly lower values than the subsurface dentin. Further, the Young's modulus of interfacial dentin was significantly lower in caries-affected dentin. TEM revealed extensive interfacial nanoleakage in bonded sound dentin, while it was minimal in bonded caries-affected dentin. However, in the latter, silver deposits were identified within the porous substrate. Shorter application time and/or improvement of the adhesive components may be required to obtain stable adhesion in primary dentin. [ABSTRACT FROM AUTHOR]

The study was aimed at examining whether an oxygen inhibition layer is required for bonding a repairing to a pre‐existing composite, and to determine the time required for free radicals within a composite substrate to decay to the extent that the composite repair strength drops significantly. Ten slabs of Gradia Direct Anterior (GC Corp.) were divided into (1) control group: an interfacial oxygen inhibition layer was created by applying and light‐curing two layers of bonding resin (D/E Resin, Bisco) to the slabs surface in atmospheric air; (2) experimental group: the absence of an interfacial oxygen inhibition layer was obtained by light‐curing the second bonding resin layer in a nitrogen atmosphere. After 1 and 2 h, 1, 14, and 30 days of air storage, a composite repair was layered over the bonding resin. Microtensile bond strengths were measured and statistically analyzed. The curing atmosphere was not a significant factor for bond strength (p = 0.82), and time and curing atmosphere‐time interaction were significant (p < 0.001). The 30 day‐strengths were the lowest (p < 0.05). An oxygen‐inhibited layer is not initially required for bonding to resin composite, and it takes more than 14 days before the bond strength between a pre‐existing and a fresh composite drops. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [ABSTRACT FROM AUTHOR]

Purpose: To assess in vitro the hydrolytic stability of adhesive systems in Class V composite restorations bonded to enamel and dentin. Methods: 16 groups of Class V cavities restored with different adhesive systems and challenged with thermal and mechanical loading under the simulation of dentin fluid were evaluated after an 18-month period of water storage at 37°C. The marginal adaptation of these restorations was quantified by evaluation of gold-coated epoxy replicas with scanning election microscopy at x200 magnification. Results: The percentages of "continuous margin" after 18 months of water storage with respect to the total marginal length ranged from 62.9 (5.4)% to 18.5 (3.2)% with significant differences observed among the groups (Bonferroni test P< 0.05). The range in enamel was from 71.8 (14.2)% to 8.9 (6,4)% and in dentin from 94.3 (5.1)% to 0.0 (0.0)%. Marginal adaptation of all the materials tested was affected by water storage, either in enamel, in dentin, or both. None of the restorative systems tested exhibited hydrolytically stable marginal adaptation. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: This study examined the in vivo bonding ability to sound dentin of antibacterial adhesive systems incorporating an antibacterial monomer MDPB based on morphological evaluation of the resin–dentin interface. Methods: Class V cavities were prepared on the buccal surfaces of the teeth of a beagle dog and a composite filling performed using (1) commercial self-etching system Liner Bond 2 (LB primer+LB bond), (2) experimental primer containing 5% MDPB and LB bond, (3) LB primer and experimental bonding-resin containing 2.5% MDPB, or (4) combination of experimental primer and bonding-resin. After 7 days, the tooth crown was cut and fixed in half-Karnovsky''s solution, and the sectioned surface observed under scanning electron microscopy (SEM) after treatment with phosphoric acid and NaOCl. The ultrastructure of the bonding interface was also examined by transmission electron microscopy (TEM). Microtensile bond strengths (μTBS) of each group were measured using extracted teeth. Results: SEM demonstrated that all groups produced a 1–2μm thick hybrid layer with funnel shaped resin tags, although the length of tags was shorter for the group in which MDPB-containing bonding-resin was used. TEM examination supported good adhesion of the comprehensive adhesive system employing MDPB-containing primer/bonding-resin, showing integrity between resin and dentin. There were no significant differences in μTBS among the four groups tested (p >0.05, ANOVA). Significance: This study confirmed that the experimental antibacterial adhesive systems employing MDPB-containing primer or/and bonding-resin could produce an effective bond under in vivo conditions. [Copyright &y& Elsevier]

Multi-purpose bonding performance of three kinds of newly synthesized phosphonic acid monomers was investigated. Methacryloxyalkyl or acryloxyalkyl phosphonoacetates of 6-MHPA, 6-AHPA, 10-MDPA were synthesized in 42.8-51.9% yields with a light yellow viscous liquid, and identified as new compounds by '1'H NMR, IR, and elemental analysis. Conventional adhesive monomers, namely VBPA, 4-META, and 4-AETA, and CEBA-p-TSMo-t-BPMA initiator were also used. Seven experimental composite-type adhesive resins comprising these six kinds of adhesive monomers and None (control) with the initiator were prepared. Tensile bond strengths of adhesive resins to unetched ground enamel and dentin, ground porcelain, and sandblasted Ni-Cr alloy were measured at a crosshead speed of 1.0 mm/min. Results showed that except with VBPA, there were no significant differences among 6-MHPA, 6-AHPA, 10-MDPA, 4-AETA, and 4-META in bonding performance to the adherends (p<0.01). It was found that the new phosphonic acid monomers provided good multipurpose adhesion to all adherends tested. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of two different techniques of seating pressure application on the adhesive-dentin bond of indirect restorations. Methods: Eight non-carious human third molars were randomly divided in two treatment groups (four teeth each). Cylindrical composite blocks were luted with a resin cement (Panavia F). In Group 1, the seating pressure was applied for 5 seconds. In Group 2, the resin cylinder was maintained under constam pressure during the entire 3-minute polymerization period of the resin cement. After storing in distilled water for 24 hours, 0.9 x 0.9 mm sticks were produced from these luted specimens for microtensile bond testing and SEM examination. Results: The Student t-test showed a significant difference (P< 0.05) in bond strength between Groups 1 and 2. SEM revealed the presence of structural defects and resin globules on the seating surface of the composites. These features were exclusively identified from Group 1 specimens and were probably caused by fluid transudation from the underlying dentin through the simplified self-etch adhesive (ED primer). [ABSTRACT FROM AUTHOR]

The aims of this study were to synthesize new phosphonic acid monomers, and to examine their bonding performance. Four kinds of newly designed phosphonic acid monomers were synthesized, and seven experimental composite type adhesive resins comprising the synthesized monomers (3 wt%), with BPO/DEPT/BPBA initiator were prepared. Tensile bond strengths of the adhesive resins to enamel and metal were measured with a universal testing machine at a crosshead speed of 1.0 mm/ min The synthesized adhesive monomers were light yellow viscous liquids with 32.5%-49.3% yields, and identified by ¹H NMR, IR and elemental analysis to be (meth)acryloxyalkyl 3-phosphonopropionates [R-P(=O)(OH)2] (5-MPPP, 6-MHPP, 6-AHPP, 10-MDPP). It was found that the newly developed phosphonic acid monomers with BPO/DEPT/BPBA initiator attained strong adhesion to both unetched, ground enamel and sandblasted Ni-Br alloy with good durability. They exhibited significantly higher bond strengths than conventional phosphorous-containing monomers such as MEPP and VBPA (p <0.01). These findings indicate that the experimental phosphonic acid monomer containing adhesive resins have potential prosthodontic and orthodontic applications, especially as self-etching, non-rinsing orthodontic adhesive resins. [ABSTRACT FROM AUTHOR]

Abstract: The influence of different silane/dentin adhesives on the microtensile bond strengths of a hybrid composite to sodium ethoxide-etched quartz fiber posts was investigated. A prehydrolyzed silane was applied without an adhesive and compared to two-component systems in which hydrolysis of the silane occurred after mixing with the acidic monomer present in the dentin adhesives. Nanoleakage along post/core interfaces was examined after silver nitrate tracer penetration using scanning electron microscopy. Higher interfacial strengths and more uniform adaptation between the etched fiber post surface and the composite core were recorded after post treatment with silane/adhesive couplings. The combination of silane with two-step self-etch adhesives improves the chemical retention of composites around etched fiber posts with minimal nanoleakage. Although the one-step self-etching adhesive/silane combination enhances post adhesion, the extensive nanoleakage provides channels for rapid water sorption that may expedite hydrolytic degradation of the post/core interface. [Copyright &y& Elsevier]

Purpose: To evaluate the effects of dentin adhesives employed as resin sealers and provisional cementation on the bond strengths of a resin cement to dentin. Methods: A two-step etch-and-rinse adhesive (Excite DSC - Group 1) and two-step self-etch adhesive (AdheSE - Group 2) were applied to exposed dentin surfaces prepared from human molars (N=4). Water was used instead of a resin sealer in control Groups 3 and 4. A eugenol-free provisional cement (except for Group 4) was applied to the treated surfaces. After storing in distilled water for 1 week, the provisional cement was removed and cylindrical composite blocks were luted with a resin cement (Variolink II). 0.9 x 0.9 mm sticks were produced from these luted specimens for microtensile bond testing and SEM examination. Results: One-way ANOVA revealed that neither the resin sealer nor the temporary eugenol-free cement had a negative effect on the final bond strength (P> 0.05). Mixed failures were predominantly identified from SEM. [ABSTRACT FROM AUTHOR]

Mild acids are known to activate dentin matrix metalloproteinase (MMPs). All self-etching dental adhesives are acidic (pH 1.5–2.7) and may activate dentin MMPs. The purpose of this study was to compare the ability of several all-in-one adhesives to activate gelatinolytic and collagenolytic activities in powdered mineralized dentin. Powdered dentin made from human teeth was mixed with all-in-one adhesives (Clearfil Tri-S Bond, G-Bond, Adper Prompt L-Pop) or a self-etching primer (Clearfil SE Bond primer) for varying times and then the reaction was stopped by extracting the adhesives using acetone. Fresh untreated mineralized dentin powder had a gelatinolytic activity of 3.31 ± 0.39 relative fluorescent units (RFU) per mg dry weight (24 h) that increased, over storage time, to 87.5 RFU mg−1 (24 h) after 6–8 wk. When fresh powder was treated with acidic Tri-S Bond, the gelatinolytic activity increased from 3.24 ± 0.70 RFU mg−1 to > 112.5 RFU mg−1 (24 h) after 20 min and then remained unchanged. Monomers with lower pH values produced less activity. There was a significant, direct correlation between gelatinolytic activity and pH, with Tri-S giving the highest activity. Coating dentin powder with Tri-S resin prevented fluorescent substrates from gaining access to the enzyme, even though it activated the enzyme. In conclusion, self-etch adhesives may activate latent MMP and increase the activity to near-maximum levels and contribute to the degradation of resin–dentin bonds over time. [ABSTRACT FROM AUTHOR]