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Objective. To use ultrasonic measurements to monitor the effects of adhesive application and power density on the polymerization behavior of dual-cured core build-up resins. Methods. Ultrasonic measurements were carried out using a pulser-receiver, transducers and an oscilloscope. The core build-up resins were mixed, inserted into a transparent mold and then placed onto a sample stage with or without self-etch adhesive. Power densities of 0 (no light irradiation), 200 and 600 mW/cm2 were used for curing. The transit time through the core build-up resin disk was divided by the specimen thickness to obtain the longitudinal sound velocity (V). Results. Light irradiation of the core build-up resins at a power density of 600 mW/cm2 caused V values to rise to an initial plateau of 1550-1650 m/s, then to rise rapidly to a second plateau of 2800-3200 m/s. The rate of V increase was slower when the resin cements were light-irradiated and became faster when irradiated at a higher power density. There were no significant differences between the groups with or without adhesive. Conclusions. The polymerization behavior of the core build-up resins was affected by the power density of the curing unit. The influence of adhesive application differed among the core build-up resins tested. [ABSTRACT FROM AUTHOR]

This study examined the relationship between the adhesive application time and enamel bond strength of several single-step self-etch adhesive systems. The adhesives used were: Bond Force (BF, Tokuyama Dental Corporation, Tokyo, Japan), Clearfil tri-S Bond (CT, Kuraray Medical Inc, Tokyo, Japan), iBond Self-Etch (IB, Heraeus Kulzer, Armonk, NY) and OptiBond All-in-One (OB, sds Kerr). Bovine mandibular incisors were mounted in self-curing resin and wet ground with #600-grit silicon carbide paper to expose labial enamel. Adhesives were applied for 10, 20 or 40 seconds and the resin composites were condensed into a mold (∅4 x 2 mm) on the enamel and light irradiated. Ten samples per test group were stored in 37°C water for 24 hours, then shear tested at a crosshead speed of 1.0 mm/minute. One-way ANOVA and the Tukey HSD test (α=0.05) were performed within each adhesive system. The enamel surfaces after adhesive application were also observed in a Field Emission Electron Probe Surface Roughness Analyzer and the Ra value was calculated. The enamel bond strength ranged from 13.6 to 17.8 MPa for BF, 13.6 to 15.9 MPa for CT, 14.3 to 16.2 MPa for IB and 13.4 to 19.8 MPa for OB. Significant increases in bond strength were found for the 40-second application groups, except for IB. No changes in Ra value were found for BF and IB, while significant decreases in Ra value were recorded with 40-second application for CT and OB. The data suggested that the duration of the single-step self-etch adhesive application was a crucial factor for determining the enamel bond strengths of some of the single-step self-etch adhesives employed in the current study. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the influence of irradiation time on volumetric change and flexural properties of flowable resins. Four commercially available flowable resins were employed. For volumetric shrinkage measurement, resin pastes were inserted into a mold (2 mm in height, 4 mm in diameter) and put into a water-filled dilatometer. This was followed by light irradiation for 10, 20, or 30 seconds at 600 mW/cm². Volumetric shrinkage of the specimens was then determined from the change in the height of water meniscus, and the percentage volumetric change thereof was calculated. For flexural strength measurement, resin pastes were filled into a stainless steel mold (25×2×2 mm, and the middle one-third of the specimen was first irradiated. The remaining two-thirds were irradiated under the same irradiation conditions as volumetric shrinkage measurement. After 24-hour storage in 37°C water, three-point flexural tests were performed with a span length of 20 mm at a crosshead speed of 1.0 mm/min. One-way ANOVA followed by Tukey's HSD test were used for statistical analysis. For all materials tested except Estelite Flow Quick, both volumetric shrinkage and flexural strength increased with longer light irradiation time. Results of this study indicated that both volumetric shrinkage and flexural properties were influenced by light irradiation time and resin composite type. [ABSTRACT FROM AUTHOR]

Purpose: Single-step self-etching adhesives have been developed as a bonding material that adheres to the tooth surface. The adhesives contain acidic resin monomers that penetrate the dentin but can be neutralized to stop the reaction. This study aimed to improve understanding of the pH changes that occur when self-etching adhesives are mixed with dentin powder., Materials and Methods: Dentin disks obtained from extracted bovine incisors were milled and pulverized into a fine powder. The powder was mixed with diluted self-etching adhesives, and pH changes were measured by a solid-state pH sensor connected to a pH meter at various time points after the start of mixing. Data were analyzed by Tukey's Honestly Significant Difference (HSD) test and Dunnett's test at a significance level of 0.05. Precipitates from the adhesive/ dentin powder mixture were observed by scanning electron microscopy (SEM)., Results: The baseline pH values of the self-etching adhesives ranged from 0.97 to 2.83. After mixing with the dentin powder, the pH values significantly increased, ranging from 6.30 to 7.11 at 180 s after mixing. SEM observation revealed products of the reaction between dentin powder and self-etching adhesive which indicate a chemical reaction between the functional monomer and dentin., Conclusion: Dentin has a strong modulation effect against the acidity of self-etching adhesives.

This study was carried out to examine the effect of storage conditions of adhesive vials on the dentin bond strength of single-step self-etch adhesive systems. The adhesive/resin composite combinations used were: Absolute 2/Ceram.X(AB), Adper Prompt L-Pop/Filtek Supreme(AP), Bond Force/Estelite sigma Quick(BF), Clearfil tri-S Bond/Clearfil AP-X(CT) and G-Bond/Gradia Direct(GB). Vials of adhesives were stored at 5 degrees C, 23 degrees C or 40 degrees C. Specimens for the dentin bond strength tests were made after 0, 1, 2, 3, 4, 5 and 6 months. Labial bovine mandibular incisor dentin was wet ground with #600 SiC. The adhesives were applied according to the manufacturer's instructions. After adhesive light irradiation, resin composite cylinders were created (4 mm x 2 mm) and polymerized (n = 10). Samples were stored in 37 degrees C distilled water for 24 hours, then shear tested at a crosshead speed of 1.0 mm/minute. ANOVA and Dunnet tests were performed at a significance level of 0.05. Scanning electron microscopic (SEM) observations of the dentin surfaces were made. Bond strengths varied, with storage conditions ranging from 2.2 +/- 1.4 to 9.3 +/- 2.4 MPa for AB, 4.5 +/- 1.5 to 13.3 +/- 2.7 MPa for AP, 5.1 +/- 1.9 to 5.1 +/- 1.9 MPa for BF, 7.7 +/- 1.9 to 19.7 +/- 2.0 MPa for CT and 7.4 +/- 1.3 to 15.7 +/- 2.8 MPa for GB. With longer storage periods and higher temperatures, significant decreases in bond strength were found for all the adhesives. From SEM observation, the etching effect of the adhesives was weakened and the remaining smear layer was observed. The data suggests that the storage conditions of adhesive vials significantly affects the bond strengths of single-application self-etch adhesive systems.

This study examined the influence of power density on dentin bond strength and polymerization behavior of dual-cured direct core foundation resin systems. Two commercially available dual-cured direct core foundation resin systems, Clearfil DC Core Automix with Clearfil DC Bond and UniFil Core with Self-Etching Bond, were studied. Bovine mandibular incisors were mounted in autopolymerizing resin and the facial dentin surfaces were ground wet on 600-grit SiC paper. Dentin surfaces were treated according to manufacturer's recommendations. The resin pastes were condensed into the mold and cured with the power densities of 0 (no irradiation), 100, 200, 400 and 600 mW/cm2. Ten specimens per group were stored in 37 degrees C water for 24 hours, then shear tested at a crosshead speed of 1.0 mm/minute in a universal testing machine. An ultrasonic measurement device was used to measure the ultrasonic velocities through the core foundation resins. The power densities selected were 0 (no irradiation), 200, and 600 mW/cm2, and ultrasonic velocity was calculated. ANOVA and Tukey HSD tests were performed at a level of 0.05. The highest bond strengths were obtained when the resin pastes were cured with the highest power density for both core foundation systems (16.8 +/- 1.9 MPa for Clearfil DC Core Automix, 15.6 +/- 2.9 MPa for UniFil Core). When polymerized with the power densities under 200 mW/cm2, significantly lower bond strengths were observed compared to those obtained with the power density of 600 mW/cm2. As the core foundation resins hardened, the sonic velocities increased and this tendency differed among the power density of the curing unit. When the sonic velocities at three minutes after the start of measurements were compared, there were no significant differences among different irradiation modes for UniFil Core, while a significant decrease in sonic velocity was obtained when the resin paste was chemically polymerized compared with dual-polymerization for Clearfil DC Core Automix. The data suggests that the dentin bond strengths and polymerization behavior of the dual-cured, direct core foundation systems are still affected by the power density of the curing unit. With a careful choice of the core foundation systems and power density of the curing unit, the benefit of using resin composites to endodontically-treated teeth might be acceptable.

This study investigated the effect of phosphoric acid etching on the dentin bond strength of five single-step self-etch adhesive systems; Absolute, Clearfil tri-S Bond, Fluoro Bond Shake One, G-Bond and One-Up Bond F Plus. Bovine mandibular incisors were mounted in self-curing resin and the facial surfaces were wet ground with #600 SiC paper. Adhesives were applied on the prepared dentin surfaces with and without prior phosphoric acid etching and light irradiated. Resin composite was condensed into a mold (ø4x2 mm), light irradiated and stored in water at 37 degrees C. Four groups (n=10) were made per adhesive system: with and without prior acid etching and with and without thermal cycling between 5 degrees C and 55 degrees C for 10,000 cycles. The specimens were tested in a shear mode at a crosshead speed of 1.0 mm/minute. Two-way ANOVA, Student t-test and Tukey HSD test at a level of 0.05 were done. For specimens without prior acid etching, the mean bond strengths to bovine dentin ranged from 12.8 to 17.1 MPa and ranged from 6.7 to 13.3 MPa for specimens with prior acid etching after 24 hours storage in water. When the specimens were subjected to thermal cycling, the mean bond strengths ranged from 10.7 to 24.8 MPa for the specimens without prior acid etching and 4.6 to 13.9 MPa for the specimens with prior acid etching. The changes in dentin bond strength were different among the adhesive systems tested. Failure modes were commonly adhesive failure associated with mixed failure for specimens with prior acid etching. For specimens without prior acid etching, failures in composite and dentin were increased. From the results of this in vitro study, prior acid etching might be not acceptable for increasing the dentin bond strengths of single-step self-etch adhesive systems.

This study investigated the effect of prior phosphoric acid etching on the enamel bond strength of five single-step self-etch adhesive systems: Absolute, Clearfil tri-S Bond, Fluoro Bond Shake One, G-Bond and One-Up Bond F Plus. Bovine mandibular incisors were mounted in self-curing resin, and the facial surfaces were wet ground with #600 silicon carbide paper. Adhesives were applied to the enamel surfaces with or without prior phosphoric-acid etching and light irradiated. The resin composites were condensed into a mold and light irradiated. In total, 40 specimens were tested per adhesive system with and without prior acid etching and were further divided into two groups: those stored in water at 37 degrees C for 24 hours without cycling and those stored in water at 37 degrees C for 24 hours followed by thermal cycling between 5 degrees C and 55 degrees C with 10,000 repeats. After storage under each set of conditions, the specimens were tested in shear mode at a crosshead speed of 1.0 mm/minute. Two-way analysis of variance, the Student's t-test and the Tukey HSD test were used to analyze the data at a significance level of 0.05. For the specimens without prior acid etching, the mean bond strengths to enamel ranged from 11.0 to 14.6 MPa after 24-hour storage in water, while the corresponding values for specimens with prior acid etching ranged from 15.2 to 19.3 MPa. When these specimens were subjected to thermal cycling, the mean bond strengths ranged from 11.3 to 17.0 MPa without prior acid etching and from 12.3 to 23.2 MPa with prior acid etching. The changes in enamel bond strengths differed among the adhesive systems tested. After 24-hour storage in water, the most common failure modes were adhesive failure and mixed failure for specimens with and without prior acid etching, respectively. Thus, through a careful choice of adhesive system, prior acid etching can increase the bond strengths of single-step self-etch adhesive systems.

This study investigated the influence of thermal cycling on the enamel bond strength of single-step self-etch adhesive systems. The systems used were Absolute, Clearfil tri-S Bond, G-Bond and One-Up Bond F Plus. Bovine mandibular incisors were mounted in self-curing resin, and the facial surfaces were wet ground with #600 SiC paper. Adhesives were applied on the prepared enamel surfaces and light irradiated according to each manufacturer's instructions. Resin composites were condensed into a mold (ø4x2 mm) and light irradiated for 30 seconds. Thirty specimens per adhesive systems were divided into 1 of 3 test groups (n=10) following storage in water at 37 degrees C for 24 hours. The specimens were then stored in 37 degrees C water for 24 hours, followed by thermal cycling 10,000 and 20,000 times between 5 degrees C and 60 degrees C. After each storage condition, the specimens were tested in shear mode at a crosshead speed of 1.0-mm/minute. One-way ANOVAs and Tukey HSD test at a level of 0.05 were conducted. After 24 hours of water storage, the mean enamel bond strengths ranged from 11.3 to 16.9 MPa, and Clearfil tri-S Bond showed significantly higher bond strength. After thermal cycling, the mean bond strengths ranged from 8.3 to 20.7 MPa. The changes in enamel bond strengths were different among the adhesive systems tested. Failure modes after the test were commonly adhesive failure associated with partial cohesive failure adhesive in resin. With a careful choice of adhesive systems, the benefit to using single-step self-etch systems in terms of simplifying the clinical procedure might be acceptable, even after thermal stresses.

Currently, there is little information regarding the bonding efficacy of single-step self-etch systems to primary tooth dentin. This study examined the microtensile bond strength of single-step self-etch systems (Clearfil tri-S Bond and One-Up Bond F Plus) to sound primary and permanent tooth dentin. Adhesives were applied to flat samples of primary and permanent tooth dentin, and resin composites were bonded according to the manufacturers' instructions. After 24 hours of storage in distilled water at 37 degrees C, hour glass-shaped specimens were produced. They were subjected to microtensile testing at a crosshead speed of 1.0 mm/minute. The results were analyzed using 2-way analysis of variance (ANOVA) followed by the Tukey HSD post-hoc test (alpha=0.05). Field-emission scanning electron microscopy (FE-SEM) observations of the adhesive-treated dentin surfaces and the resin/dentin interface were also conducted. The bond strengths of primary tooth dentin were significantly lower than that of permanent tooth dentin for both self-etch systems: 44.7 +/- 10.4 versus 54.3 +/- 9.0 MPa for Clearfil tri-S Bond and 40.6 +/- 9.9 versus 50.0 +/- 8.7 MPa for One-Up Bond F Plus (p<0.001). There was no statistically significant interaction between the type of adhesive system and the dentin substrate (p=0.957). Although there was no statistically significant difference in the mean values among the different adhesive systems (p=0.094), there was a statistically significant difference in mean values among the different dentin substrates (p<0.001), which were lower for primary tooth dentin than for permanent tooth dentin. The failure modes were also independent of the type of dentin but dependent on the adhesive systems, an equal distribution among the 3 types of failure for Clearfil tri-S Bond and cohesive failures in adhesives for One-Up Bond F Plus. FE-SEM observations of dentin to which adhesive had been applied revealed that the smear layer had been removed and the collagen fibers exposed. Though the bond strengths to primary tooth dentin were lower than to permanent tooth dentin, excellent adaptation of the single-step self-etch systems to both dentin substrates was observed by FE-SEM. Further studies are required to determine the long-term clinical performance of these adhesive systems when applied to primary tooth dentin.

This study examined the effect of air-drying time of adhesives on the dentin bond strength of several single-application self-etch adhesive systems. The adhesive/resin composite combinations used were: Adper Prompt L-Pop/Filtek Z250 (AP), Clearfil Tri-S Bond/Clearfil AP-X (CT), Fluoro Bond Shake One/Beautifil (FB), G-Bond/Gradia Direct (GB) and One-Up Bond F Plus/Palfique Estelite (OF). Bovine mandibular incisors were mounted in self-curing resin and wet ground with #600 SiC to expose labial dentin. Adhesives were applied according to each manufacturer's instructions followed by air-drying time for 0 (without air-drying), 5 and 10 seconds. After light irradiation of the adhesives, the resin composites were condensed into a mold (phi4x2 mm) and polymerized. Ten samples per test group were stored in 37 degrees C distilled water for 24 hours; they were then shear tested at a crosshead speed of 1.0 mm/minute. One-way ANOVA followed by Tukey's HSD tests (alpha = 0.05) were done. FE-SEM observations of the resin/dentin interface were also conducted. Dentin bond strength varied with the different air drying times and ranged from 5.8 +/- 2.4 to 13.9 +/- 2.8 MPa for AP, 4.9 +/- 1.5 to 17.1 +/- 2.3 MPa for CT, 7.9 +/- 2.8 to 13.8 +/- 2.4 MPa for FB, 3.7 +/- 1.4 to 13.4 +/- 1.2 MPa for GB and 4.6 +/- 2.1 to 13.7 +/- 2.6 MPa for OF. With longer air drying of adhesives, no significant changes in bond strengths were found for the systems used except for OF. Significantly lower bond strengths were obtained for the 10-second air-drying group for OF. From FE-SEM observations, gaps between the cured adhesive and resin composites were observed for the specimens without the air drying of adhesives except for OF. The data suggests that, with four of the single-application self-etch adhesive systems, air drying is essential to obtain adequate dentin bond strengths, but increased drying time does not significantly influence bond strength. For the other system studied, the bond strength of the non-air dried group was not significantly different from the five second drying time, but prolonged drying was very detrimental to bond strength. For all five of the systems studied, a five-second air-drying time appeared to be appropriate.

This study examined the relationship between delay in composite placement over cured adhesives and the dentin bond strength of several single-application self-etch adhesive systems. The adhesive system/resin composite combinations used were: Adper Prompt L-Pop/Filtek Z250 (AP), AQ Bond Plus/Metafil C (AQ), Fluoro Bond Shake One/Beautifil (FB), G-Bond/Solare (GB), One-Up Bond F Plus/Palfique Estelite (OF), Xeno IICF Bond/Xeno CF (XE). Bovine mandibular incisors were mounted in self-curing resin and wet ground with #600 SiC to expose labial dentin. The adhesives were applied according to each manufacturer's instructions, and resin pastes were condensed into a mold (ø4x2 mm) immediately, and 1, 2, 5 and 10 minutes after light irradiation of the adhesives. Ten samples per test group were stored in 37 degrees C water for 24 hours, then shear tested at a crosshead speed of 1.0 mm/minute. One-way ANOVA followed by Tukey's HSD test (alpha = 0.05) was done. SEM observations of the dentin surface after the tests were also conducted. Dentin bond strength ranged from 9.5 +/- 2.2 to 14.0 +/- 2.4 MPa for AP, 7.3 +/- 2.2 to 12.2 +/- 3.1 MPa for AQ, 10.0 +/- 3.5 to 16.3 +/- 2.4 MPa for FB, 11.4 +/- 1.5 to 16.3 +/- 1.2 MPa for GB, 14.2 +/- 3.4 to 15.1 +/- 3.0 MPa for OF and 11.5 +/- 2.4 to 15.9 +/- 2.2 MPa for XE. Except for OF, no significant differences were found among the 2 to 10 minute delayed placement groups for the systems used. Significant lower bond strengths were obtained for the immediate placement groups except for OF. From SEM observations, cohesive failure of the dentin surface was more pronounced with the longer delay in placement. The data suggest that delayed composite placement over the cured adhesives are suggested for optimum dentin bond strength of single-application self-etch adhesive systems.

This study examined the relationship between the bond agent application duration and the dentin bond strength of several single-application bonding systems. The restorative material/ bonding systems used were Reactmer, with its single-application bonding system Reactmer Bond (RB, Shofu Inc, Kyoto, Japan); Palfique Estelite, with its single-application bonding system One-Up Bond F (OU, Tokuyama Co, Tokyo, Japan) and F2000 Compomer, with its bonding system Primer/Adhesive in Clicker (F2,3M Dental Products, St Paul, MN 55144, USA). Bovine mandibular incisors were mounted in self-curing resin and wet ground with #600 SiC to expose labial dentin. Adhesives were applied for 5, 10, 20, 30 and 60 seconds, and restorative materials were condensed into a Teflon mold (04 x 2 mm) on the dentin and light activated. Fifteen samples per test group were stored in 37 degrees C water for 24 hours, then shear tested at a crosshead speed of 1.0 mm/min. One-way ANOVA followed by Duncan test (p = 0.05) was done. SEM observations of the treated dentin surface were also conducted. The dentin bond strength ranged from 6.9 +/- 2.4 to 11.2 +/- 2.8 MPa for RB, 8.9 +/- 2.2 to 12.2 +/- 1.9 MPa for OU, and 7.8 +/- 3.1 to 11.4 +/- 2.6 MPa for F2. No significant differences were found among the 10-60 second application duration groups for the systems used. From the SEM observations, demineralization of the dentin surface was more pronounced with longer application duration. The data suggest that the duration of single-application bonding systems was not a crucial factor for determining dentin bond strength, even though morphological changes were observed on the dentin surface.