SUMMARY Objective: To evaluate, in vitro , the effect of mouth rinse exposure on bleached enamel. Methods: Enamel/dentin bovine blocks (4×4×2 mm) were bleached with 35% hydrogen peroxide (HP) and were submitted to immersion twice daily for 14 days with different rinses (n=10), including those involving: distilled water (C [control]), 225-ppm NaF (FM, Colgate Plax Classic), essential oil (EM, Listerine Tartar Control), 1.5% hydrogen peroxide (HPM, Colgate Plax Whitening), and 2% hydrogen peroxide, pyrophosphates, and 225-ppm NaF (HPM+P, Colgate® Luminous White). The specimens were stored in a remineralizing solution during all experiments. Analyses of color (ΔE, L*, a*, b*) and roughness (Ra) were performed at the baseline, after HP, and after exposure to the rinse. The cross-sectional microhardness (CSMH) and images by scanning electron microscopy (SEM) were assessed at the end. The data were subjected to analysis of variance (ANOVA) (ΔE), repeated measures ANOVA (Ra), and split-plot ANOVA (CSMH), followed by the Tukey test. The L*, a*, and b* values were analyzed by generalized linear models (α=0.05). Results: Color changes were not statistically different in the groups. Ra increased in all groups after bleaching; however, it was reestablished in C, FM, and HPM+F and increased in EM after 14 days of the rinse. EM and HPM reduced the CSMH values differing from C and promoted alterations on the enamel surface visualized by SEM. Conclusion: The mouth rinses did not affect the whitening efficacy or promote benefits on bleached enamel properties. Moreover, the 1.5% hydrogen peroxide– or essential oil–based mouth rinses affected the bleached enamel properties, promoting an alteration in morphologic surface and mineral loss in depth.

SUMMARY Aim: To investigate the effect of different toothpaste formulations used prior to dental bleaching with 35% hydrogen peroxide (HP) on the mineral content and surface morphology of enamel. Methods: Seventy bovine enamel blocks (4×4×2 mm) were submitted to in vitro treatment protocols using a toothbrushing machine prior to dental bleaching or a placebo procedure (n=10) as proposed in the following groups: unbleached control (PLA), bleached control (HP), and brushing with differing toothpastes prior to HP bleaching, including: potassium nitrate toothpaste containing sodium fluoride (PN), sodium monofluorophosphate/MFP toothpaste (FT), arginine-carbonate (8% arginine) (PA) or arginine-carbonate (1.5% arginine) toothpaste (SAN), and toothpaste containing bioactive glass (NM). Phosphorus concentration in gel ([P]) was evaluated (μg of P/mg of gel), and the elemental levels (wt%) of Ca, P, and Na as well as the proportion between Ca and P and spectra graphics were determined using an energy-dispersive X-ray spectrometer (EDS). The surface morphology was assessed using scanning electron microscopy (SEM). The data were subjected to analysis of variance and the Tukey test (α=0.05). Results: HP demonstrated the greatest [P] values in gel, being statistically different from PLA. The [P] of NM was statistically similar to PLA. HP showed a significant decrease in the Ca% and Ca/P values when compared to PLA in EDS analysis. PA showed Ca/P values statistically different from HP. In accordance with SEM analysis, the PA, SAN, and NM groups presented a smooth and uniform enamel surface, while HP and FT demonstrated some alterations in morphology. Conclusion: The toothpastes containing bioactive glass or arginine carbonate used prior to dental bleaching were effective in protecting enamel against mineral loss promoted by the whitening procedure.

SUMMARY Objective: To evaluate the microshear bond strength of composite resin restorations in dental blocks with or without exposure to cigarette smoke. Method: Eighty bovine dental blocks were divided into eight groups (n=10) according to the type of adhesive (Scotchbond Multi-Purpose, 3M ESPE, St Paul, MN, USA [SBMP]; Single Bond 2, 3M ESPE [SB]; Clearfil SE Bond, Kuraray Medical Inc, Okayama, Japan [CSEB]; Single Bond Universal, 3M ESPE [SBU]) and exposure to smoke (no exposure; exposure for five days/20 cigarettes per day). The adhesive systems were applied to the tooth structure, and the blocks received a composite restoration made using a matrix of perforated pasta. Data were statistically analyzed using analysis of variance and Tukey test (α<0.05). Results: For enamel, there was no difference between the presence or absence of cigarette smoke ( p =0.1397); however, there were differences among the adhesive systems ( p <0.001). CSEB showed higher values and did not differ from SBU, but both were statistically different from SB. The SBMP showed intermediate values, while SB demonstrated lower values. For dentin, specimens subjected to cigarette smoke presented bond strength values that were lower when compared with those not exposed to smoke ( p <0.001). For the groups without exposure to cigarette smoke, CSEB showed higher values, differing from SBMP. SB and SBU showed intermediary values. For the groups with exposure to cigarette smoke, SBU showed values that were higher and statistically different from SB and CSEB, which presented lower values of bond strength. SBMP demonstrated an intermediate value of bond strength. Conclusion: The exposure of dentin to cigarette smoke influenced the bonding strength of adhesives, but no differences were noted in enamel.

SUMMARY Objective The purpose of this study was to investigate the effects on the enamel properties and effectiveness of bleaching using 35% hydrogen peroxide (HP) when applying toothpastes with different active agents prior to dental bleaching. Methods Seventy enamel blocks (4 × 4 × 2 mm) were submitted to in vitro treatment protocols in a tooth-brushing machine (n=10): with distilled water and exposure to placebo gel (negative control [NC]) or HP bleaching (positive control [PC]); and brushing with differing toothpastes prior to HP bleaching, including potassium nitrate toothpaste (PN) containing NaF, conventional sodium monofluorophosphate toothpaste (FT), arginine-based toothpastes (PA and SAN), or a toothpaste containing bioactive glass (NM). Color changes were determined using the CIE L*a*b* system (ΔE, ΔL, Δa, and Δb), and a roughness (Ra) analysis was performed before and after treatments. Surface microhardness (SMH) and cross-sectional microhardness (CSMH) were analyzed after treatment. Data were analyzed with repeated measures ANOVA for Ra, one-way ANOVA (SMH, ΔE, ΔL, Δa, and Δb), split-plot ANOVA (CSMH), and Tukey post hoc test (α<0.05). The relationship between the physical surface properties and color properties was evaluated using a multivariate Canonical correlation analysis. Results Color changes were statistically similar in the bleached groups. After treatments, SMH and CSMH decreased in PC. SMH increased significantly in the toothpaste groups vs the negative and positive control (NM > PA = SAN > all other groups) or decreased HP effects (CSMH). Ra increased in all bleached groups, with the exception of NM, which did not differ from the NC. The variation in the color variables (ΔL, Δa, and Δb) explained 21% of the variation in the physical surface variables (Ra and SMH). Conclusion The application of toothpaste prior to dental bleaching did not interfere with the effectiveness of treatment. The bioactive glass based toothpaste protected the enamel against the deleterious effects of dental bleaching.

SUMMARY A seven-year-old boy with enamel-dentin fractures on both maxillary central incisors presented to the Piracicaba Dental School–UNICAMP seven days after the trauma. At the clinical evaluation, there were no clinical signs of pulp exposure, neither tooth was mobile, and both affected teeth presented a positive response to sensitivity tests and a negative response for percussion and palpation. The radiographic examination showed an undeveloped root and opened apex for both teeth. Indirect pulp capping was performed on the left maxillary central incisor, followed by a direct restoration. After one month, the patient complained of pain in the left central incisor, which responded negatively to sensitivity testing. Pulp revascularization was performed only on this tooth and was followed for 18 months. During this period, the left maxillary central incisor did not recover sensitivity, although radiographic examination showed apical closure, a slight increase in root length, and the formation of a mineralized barrier between the root canal and sealing material. The technique achieved its goal of restoring biological aspects, function, and esthetics of traumatized teeth when using this multidisciplinary approach.

SUMMARY The aim of this study was to assess the influence of light-curing time on the nanohardness (H) and reduced elastic modulus ( E r ) of components (underlying dentin, hybrid layer, adhesive, and composite) of methacrylate- and silorane-based restorations after 24 hours and six months of storage. Class II slot preparations were carried out in human molars (n=3) and restored with methacrylate (Clearfil SE Bond [Kuraray] + Filtek Z250 [3M ESPE]) or silorane (LS restorative system [3M ESPE]) restorative systems and light-cured using light-emitting diode at 1390 mW/cm 2 for the recommended manufacturers' time or double time. Restorations were sectioned, and bonded dentin-resin interfaces were embedded in epoxy resin and polished for evaluation with a Berkovich fluid cell tip (TI 700 Ubi-1 nanoindenter, Hysitron). Data were statistically analyzed by analysis of variance and Tukey's test (alpha=0.05). Overall, the H and E r values were higher for methacrylate-based restorations than for silorane materials ( p ≤0.05), an increase in curing time did not improve the H and E r of the bonded interface components of either material ( p >0.05), and aging significantly decreased the mechanical properties of interface components of both resin-based restorative systems ( p ≤0.05). In general, nanomechanical properties decreased after six months of storage, the methacrylate restorative system exhibited higher H and E r than silorane, and light-curing time did not influence the properties tested.

SUMMARY The aim of this in vitro study was to qualitatively and quantitatively evaluate the microleakage of Class II cavities restored with a methacrylate-based composite (Filtek Z250, 3M ESPE) or silorane-based composite (Filtek LS, 3M ESPE), varying the application of an intermediary base, using a low-viscosity composite resin (Filtek Z350 Flow, 3M ESPE) or resin-modified glass ionomer cement (RMGIC) (Vitrebond, 3M ESPE) and no intermediary base (control groups). Sixty cavities were prepared on the proximal surfaces of bovine teeth and were randomly divided according to the experimental groups (n=10). Following the restorative procedures and thermocycling, the samples were immersed in methylene blue for two hours. The qualitative evaluation was made using a stereomicroscope, whereby two observers analyzed the infiltration level of the dye within the tooth/filling. Microleakage scores among the groups were compared using the Kruskal-Wallis test followed by the Mann-Whitney test ( p ≤0.05). The samples were then ground and the powder was prepared for quantitative analysis in an absorbance spectrophotometer. The results were statistically analyzed by analysis of variance and the Tukey test ( p ≤0.05). Results from the quantitative analysis showed that LS presented higher values of microleakage than did Z250. There was a significant difference between both composites concerning the intermediary materials, with the lowest values obtained using RMGIC as an intermediary base. Results from the qualitative analysis showed that there were no statistically significant differences between composites; however, there were significant differences for both composites concerning the intermediary materials, with the lowest values obtained using RMGIC as an intermediary. It is possible to conclude that using RMGIC as an intermediary base provided lower microleakage, indicating better sealing of the tooth-restoration interface.

SUMMARY This case report describes the restoration of the anterior dentition with porcelain laminate veneers. The advances in bonding of porcelain to tooth structure make this treatment a feasible alternative to restore teeth with alteration in shape and position in cases in which the esthetic demand is high. The rationale for various choices in this treatment protocol is detailed with reference to the pertinent literature. Thus, the clinical success of the technique depends on the correct identification of a case for which this treatment is appropriate and the successful execution of the clinical steps involved.

SUMMARY This study evaluated the effect of dentin pretreatment with 2% chlorhexidine (CHX) or 24% ethylenediamine tetra-acetic acid gel (EDTA) on the dentin microtensile bond strength (μTBS) of resin cements. Composite blocks were luted to superficial noncarious human dentin (n=10) using two resin cements (RelyX ARC [ARC] and RelyX U100 [U100]) and three dentin pretreatments (without pretreatment–control, CHX, and EDTA). CHX was applied for 60 seconds on the acid-etched dentin in the ARC/CHX group, and for the same time on smear layer-covered dentin in the U100/CHX group. EDTA was applied for 45 seconds on smear-covered dentin in the U100/EDTA group, and it replaced phosphoric acid conditioning in the ARC/EDTA group for 60 seconds. After storage in water for 24 hours, specimens were prepared for microtensile bond strength testing. The results were submitted to two-way analysis of variance (ANOVA) followed by Tukey test. ARC produced significantly higher μTBS ( p <0.05) compared to the U100, except when EDTA was used. For ARC, no pretreatment and CHX produced higher μTBS than EDTA. For U100, EDTA produced higher μTBS; no statistical difference occurred between CHX pretreatment and when no pretreatment was performed. While CHX did not affect immediate dentin bond strength of both cements, EDTA improved bond strength of U100, but it reduced dentin bond strength of ARC.

Clinical Relevance Prior bleaching treatment, with both low and high concentrations of bleaching agents, does not affect the push-out bond strength of dimethacrylate- and silorane-based materials to enamel-dentin cavities. SUMMARY The aim of this study was to evaluate the influence of tooth bleaching on the push-out bond strength of a composite resin based on dimethacrylates and silorane to cavities that involve both enamel and dentin. A total of 80 bovine incisors were sectioned on the buccal surface to obtain specimens (10 × 10 mm) presenting enamel and dentin (1-mm thick each substrate). The specimens were randomly distributed into eight groups (n=10), according to the bleaching protocol (1—none; 2—10% carbamide peroxide [CP] for 21 days, six hours each day; 3—three applications of 35% hydrogen peroxide [HP] in 15-minute sessions, one session every seven days for three weeks; 4—10% CP for 18 days, six hours each day + three applications of 35% HP in 15-minute sessions, one session every seven days for three weeks) and the restorative system applied (Adper Single Bond 2 + Filtek Supreme; Filtek Silorane adhesive and composite resin). After treatment, cavities were made (1.2-mm diameter on dentin; 1.5-mm diameter on enamel) with a diamond bur. At 24 hours after restoration, a push-out bond strength test was performed at a crosshead speed of 0.5 mm/min. The bleaching treatments did not significantly affect the bond strengths of either restorative system to enamel-dentin. Regardless of the bleaching treatment, the dimethacrylate-based resin system exhibited significantly higher bond strengths to enamel-dentin than did the silorane-based system.