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Objectives:: The objective of this in vitro study was to quantify the amount of mineral change in demineralized dentin at pH 5.5 after the application of dental varnishes containing fluoride with casein phosphopeptide-amorphous calcium phosphate, fluoride and bioglass, or fluoride alone., Methods and Materials:: A total of 12 extracted human sound mandibular premolar root samples were coated with an acid-resistant varnish, leaving a 2 × 3 mm window at the outer root surface. These root specimens were then randomly divided into four groups and separately subjected to the demineralizing cycle at a pH of 4.8 for five days to create artificial caries-like lesions in dentin. Subsequently, each sample was imaged using quantitative x-ray microtomography (XMT) at a 15-μm voxel size. Each test group then received one of the following treatments: dental varnish containing casein phosphopeptide-amorphous calcium phosphate and fluoride (CPP-ACP, MI varnish, GC Europe), bioglass and fluoride (BGA, Experimental, Dentsply Sirona), or fluoride alone (NUPRO, Dentsply Sirona), as well as a control group, which received no treatment. These samples were kept in deionized water for 12 hours. The thin layer of varnish was then removed. All samples including the nonvarnish group were subjected to the second demineralizing cycle at pH 5.5 for five days. The final XMT imaging was then carried out following the second demineralizing cycle. XMT scan was also carried out to varnish samples at 25 μm voxel size. The change in mineral concentration in the demineralized teeth was assessed using both qualitative and quantitative image analysis., Results:: There was an increase in radiopacity in the subtracted images of all varnish groups; a significant increase in mineral content, 12% for the CPP-ACP and fluoride ( p≤0.05 and p≤0.001), 25% BGA ( p≤0.001), and 104% fluoride alone varnish ( p≤0.001). There was an increase in the size of radiolucency in the lesion area with a significant decrease in mineral content in the nonvarnish group, 10% ( p≤0.05 and p≤0.001)., Conclusions:: There was encouraging evidence of a remineralization effect following the application of dental varnish on dentin and also an observed resistance to demineralization during the acidic challenge in all cases. However, a dental varnish containing fluoride alone appeared to have a much greater effect on dentin remineralization when compared with CPP-ACP with fluoride and bioglass with fluoride.

Aim: This in vitro study analyzed the antierosive potential of a high-fluoride dentifrice on enamel adjacent to restorations., Methods and Materials: Enamel blocks (6 × 6 × 3 mm) from bovine incisor teeth were restored with three different restorative materials (resin, conventional glass ionomer cement, and resin-modified glass ionomer cement) and treated with dentifrices containing 0, 1100, or 5000 ppm F. After restorative procedures, initial surface Vickers hardness of the blocks were obtained. The specimens were submitted to pH cycles (4 × 90 seconds in soft drink) and treatments for five days. Between the challenges and overnight, the blocks remained in artificial saliva. At the end of the experiment, the final hardness was assessed and the percentage of surface mineral loss (%SML) was calculated. A 3 × 3 factorial design was used to conduct statistical analysis. Data were analyzed by analysis of variance and t-test, with significance level fixed at 5%., Results: High-fluoride dentifrice decreased demineralization caused by erosive challenge regardless of the restorative material used (p<0.001). Likewise, the blocks restored with conventional glass ionomer cement showed lower values of SML irrespective of dentifrice used (p<0.001)., Conclusion: Use of a high-fluoride dentifrice on teeth restored with conventional glass ionomer cement offers additional protection against enamel erosion.

This study evaluated the bond strength of resin composite to dentin, mediated by a self-etching adhesive, following the application of various dentin desensitizing treatments and artificial saliva storage. The buccal cervical areas of 24 extracted human third molars were ground flat to expose cervical dentin. The dentin surfaces were polished with 1200-grit SiC paper, then the teeth were randomly assigned to six groups, five desensitizing treatments and one control: Group I-VivaSens; Group II-Fluor Protector; Group III-Isodan; Group IV-Futura Bond NR; Group V-Nd:YAG laser and Group VI-Control (without application of a desensitizing agent). After applying the desensitizing treatments and storing the molars in artificial saliva for 14 days at 37 degrees C, Futura Bond NR was used to bond resin composite to dentin. TPH composite build-ups were constructed incrementally to a height of 5 mm. The teeth were sectioned to obtain bonded slices of 0.7 mm thick specimens containing the resin-composite joint. The specimens were then trimmed into an hourglass shape and subsequently subjected to microtensile testing at a crosshead speed of 1 mm/minute. The data were analyzed using the Kruskal-Wallis analysis and multiple comparisons test. The control (Group VI) and Futura Bond NR self-etching treatment (Group IV) group yielded statistically significant higher bond strength values than the other desensitizing treatment groups tested (p < 0.005). While pretreatment of dentin surfaces with desensitizing agents (Fluor Protector, VivaSens and Isodan) and laser (Nd:YAG) reduced the bond strength values of the resin composite, higher bond strengths were achieved using a self-etching adhesive (Futura Bond NR) as a desensitizing agent.

This study measured the degree of remaining C=C bonds (RDB), linear polymerization shrinkage (LPS) and polymerization stresses (PS) of dual-cured resin composite build-up materials using a variety of light exposure scenarios. Four commercially available materials were used: Bis-Core, FluoroCore, Build-it! and Permalute. The RDB was measured using FTIR spectroscopy, and custom-made devices were used to measure LPS and PS values. Data were obtained using three different modes of photoactivation: NLC (No Light-Curing); ILC (Immediate Light-Curing, where 60 second light-curing was applied at the start of the observation period); and DLC (Delayed Light-Curing, where 60-second light-curing was applied 10 minutes from the start of the observation period). Statistical evaluation of the data at the end of the 13-minute observation period was performed with two-way analysis of variance (ANOVA), Tukey's Studentized Range (HSD) Test (p=0.05) and simple linear regression. Differences in the development of LPS and PS during the 13 minutes were studied using mathematical calculus. Bis-Core presented the highest RDB and Permalute the lowest when ILC was applied, while no differences were found between Build-it! and FluoroCore and NLC and DLC increased RDB for FluoroCore and Permalute compared to ILC; whereas, no differences were noted for Build-it! and Bis-Core. Using DLC, a decrease in RDB was found only for Build-it! FluoroCore and Permalute exhibited a reduction in LPS and PS using NLC relative to ILC. No differences in LPS and PS values were detected for the materials Bis-Core and Build-it! when subjected to NLC or DLC, compared to ILC. Simple linear regression showed that only the two polymerization shrinkage properties studied were highly correlated (LPS-PS r2=0.85). The RDB rate was not correlated with either polymerization shrinkage properties (RDB-LPS r2=0.40; RDB-PS r2=0.57). A study of the evolution of the real-time curves of percentage values of LPS and PS showed that these properties evolved in a similar exponential mode and that, most often, there was a delay in the development of PS.

Fluoride varnish applications were applied to two hybrid resin composite materials, Z-100 (3M Dental Products, St Paul, MN, USA) and Esthet-X (Dentsply Caulk, Milford, DE, USA), shades A1 and A2 and a glass ionomer, GC Fuji IX GP Fast (GC Corporation, Tokyo, Japan), shade A2, to evaluate color stability. Specimens (12.6-mm dia x 2.3 mm) were prepared using a polyethylene frame, light-cured and polished through a 1-microm alumina finish. After the initial baseline color measurements, the discs were suspended in Fusayama artificial saliva (FAS) solution at 37 degrees C for 48 hours. Post immersion, the specimens were divided into five groups (n=15 each). The following fluoride varnishes were applied to four groups of test specimens: Duraphat (Colgate Oral Pharmaceutical, Inc, Canton MA, USA), Cavity Shield (OMNII Oral Pharmaceuticals, West Palm Beach, FL, USA), Duraflor (Pharmascience Inc, Montreal, Canada) and Fluor Protector (Vivadent, Ivoclar North America, Amherst, NY, USA). The varnish was allowed to dry for five minutes before immersion. The control group was not coated with varnish, although the specimens were immersed in FAS. All specimens were incubated in newly prepared FAS at 37 degrees C for 24 hours, cleaned with an electric toothbrush and the process repeated using newly prepared FAS. CIE L*a*b* color measurements were recorded five times: at baseline, after 48 hours FAS immersion, after cleaning the first and second fluoride varnish applications and after the final brushing using a commercial toothpaste (Crest). A Minolta CR-300 tristimulus colorimeter with an 8-mm aperture (Ramsey, NJ, USA) was used to record color measurements with the daylight (D65) setting. Calculations were performed for using CIE parameters deltaE*, deltaL*, delta a*, delta b*. Analysis of variance (ANOVA) and post-hoc test (Fisher's PLSD) were used for statistical analysis. After immersion in saliva, the tested glass ionomer (Fuji IX) produced the most significant color changes (deltaE*=1.19 and deltaL*=-1.03), indicating the effect of the color change was due to absorption. After fluoride varnish applications, Duraphat varnish produced significant changes in all tested materials and shades, resulting in color changes with deltaE greater than (>) 1 but less than (<) 3. These color changes are considered visually perceptible, yet have been reported in dental literature as clinically acceptable. Fluoride varnishes can be used without adversely affecting the color of restorative materials.

This study investigated the effects of professionally applied topical fluorides on the surface hardness of a composite (Spectrum TPH), a compomer (DyractAP) and a giomer (Reactmer). Thirty specimens of each material were fabricated and stored in distilled water at 37 degrees C for one week. These specimens were then randomly divided into five groups of six and treated for 36 hours at 37 degrees C with one of the following: distilled water (control), 1.23% acidulated phosphate fluoride (APF) foam, 0.9% neutral foam, 1.23% APF gel and 0.4% stannous fluoride gel. The treated specimens were subsequently subjected to microhardness testing (load = 500 gf; dwell time = 15 seconds). Results were analyzed using ANOVA/Scheffe's test (p<0.05). The effects of topical fluoride application on surface hardness was material dependent. For all materials, treatment with APF gel and foam significantly reduced surface hardness when compared to the control. KHN values after exposure to APF gel were consistently the lowest and ranged from 4.53 to 15.97. Control KHN values were higher, ranging from 32.88 to 47.47. The surface hardness of the compomer was also significantly reduced after exposure to neutral foam. Therefore, the use of professionally applied topical fluorides, especially APF gel and foam, may be detrimental to the long-term durability of composite-based restoratives.

This study tested the hypothesis that long-term durability of resin bonds to dentin is directly related to the nanoleakage of dentin bonding systems. Extracted human third molars were ground flat with 600-grit SiC paper under running water to expose middle dentin. Clearfil Liner Bond 2V (LB2V) or Fluoro Bond (FB) was applied to dentin surfaces according to the manufacturer's instructions. A crown was built-up with Clearfil AP-X resin composite, and the specimens were stored in water for 24 hours at 37 degrees C. The bonded assemblies were vertically sectioned into approximately 0.7 mm thick slabs and trimmed for microtensile bond test. All slabs were immersed in individual bottles of water at 37 degrees C, which was changed every day. Specimens were incubated for one day, and three, six, and nine months, and at the specified time period, they were randomly divided to two subgroups: 50% AgNO3 and the control. In the 50% AgNO3 subgroup, the slabs were immersed for one hour in 50% AgNO3, followed by exposure in a photo-developing solution for 12 hours just prior to debonding. The specimens in the control subgroup were soaked in water until debonding. Then, all specimens were subjected to microtensile bond testing. The debonded specimens of the AgNO3 subgroup had micrographs subjected to image analysis by NIH Image PC (Scion, Fredrick, MD, USA), and the area of silver penetration was quantitated. The bond strength data and silver penetration areas were subjected to two- and three-way ANOVA and Fisher's PLSD test at the 95% level of confidence. Regression analysis was used to test the relationship between bond strengths and the silver penetration area at each time period. For both adhesive systems, the bond strengths gradually decreased over time, although there were no statistically significant differences in the FB bond strength among the four time periods tested (p>0.05). Silver penetration in specimens bonded with LB2V and FB gradually increased over time. Regression analysis showed a higher correlation between bond strength and silver penetration at 9 months for specimens bonded with LB2V (R2=0.844) than at shorter time periods. The authors speculate that hydrolytic degradation within the hybrid layer gradually increased due to water penetration through nanoleakage channels, resulting in lower bond strengths and interfacial failure after as little as nine months.

The mechanism of resin adhesion to caries-affected dentin is still unclear. This study evaluated the interfacial morphology of two bonding systems to caries-affected dentin, coupled with the measurement of microtensile bond strengths (mu TBS). Carious human molars were prepared as previously described in Nakajima and others (1995) and were bonded with Single Bond (SB) or FluoroBond (FB) according to the manufacturer's instructions, followed by creation of AP-X composite buildups. After one day of storage in 37 degrees C water, the teeth were serially sectioned vertically into 0.8 mm slabs, trimmed to yield a 1 mm2 test area, and tested to failure in a Bencor device used in an Instron machine operated at 1 mm/min. Resin-dentin interfaces were observed with SEM before or after acid/base challenge. Bonding to normal dentin with the two bonding systems (SB and FB) showed tensile bond strengths significantly higher than those to caries-affected dentin. The moist bonding technique significantly increased bond strength of SB to normal and caries-affected dentin. SEM examination revealed that typical hybrid layer and resin tags could not be formed to caries-affected dentin. The results suggested that resin penetration may be prevented by occlusion of dentinal tubules by mineral deposits that may also impart acid-resistance to the intertubular matrix of caries-affected dentin.

The purpose of this study was to investigate the influence of thermal cycling on enamel bond strength of 2-step bonding systems. The systems used were self-etching primer systems; Imperva Fluoro Bond, Clearfil Liner Bond II, and Mac Bond II; and self-priming adhesive systems; One Step, OptiBond Solo, Prime & Bond 2.0, and Single Bond. Bovine mandibular incisors were mounted in self-curing resin and the facial surfaces were wet ground with #600 SiC paper. Enamel surfaces were treated following each manufacturer's instructions. Adhesives were applied and composites were condensed into a Teflon mold (phi 4 x 2 mm) and light cured. Bonded specimens were divided into four groups; stored in 37 degrees C water for 24 hours, followed by thermal cycling between 5 degrees C and 60 degrees C for 3,000, 10,000, and 30,000 cycles. Ten samples per test group were tested in shear mode at a crosshead speed of 1.0 mm/min. One-way ANOVAs followed by Duncan's multiple range test (p < 0.05) were done. For self-etching primer systems, a significant decrease in bond strength was observed for the thermal cycling groups. For the self-priming adhesive systems, a small decrease in bond strength was observed but no significant differences were found for thermal cycling groups. The changes in bond strength after thermal cycling were different between the bonding systems.