The aim of this study was to compare the effectiveness of and tooth sensitivity to 10% and 20% carbamide peroxide (CP) home-use bleaching agents and 35% and 38% hydrogen peroxide (HP) in-office bleaching agents, all of which contain desensitizing agents, in a clinical trial. Four agents were evaluated: 10% CP and 20% CP (Opalescence PF 10% and Opalescence PF 20%, Ultradent, both with 0.5% potassium nitrate and 0.11% fluoride ions), 38% HP (Opalescence Boost PF, Ultradent, with 3% potassium nitrate and 1.1% fluoride ions), and 35% HP (Pola Office, SDI, with potassium nitrate). The initial screening procedure included 100 volunteers, aged 18 to 42, with no previous sensitivity or bleaching treatment and with any tooth shade. Volunteers were randomly assigned among the technique/bleaching agent groups. A run-in period was performed 1 week before the beginning of the bleaching treatment. For the home-use bleaching technique, each volunteer was instructed to dispense gel (10% CP or 20% CP) into the trays and then insert them into his or her mouth for at least two hours per night for three weeks. For the in-office bleaching technique, the bleaching agents (38% HP or 35% HP) were prepared and used following the manufacturer's instructions, with three applications performed in each session. Three sessions were carried out with an interval of seven days between each session. The participants were evaluated before, at one week, two weeks, and three weeks after the beginning of the bleaching treatment, and again one and two weeks after the bleaching treatment ended. A shade guide (Vita Classical, Vita) was used by a blinded examiner to perform shade evaluations before bleaching and two weeks after the end of bleaching. At the time of the shade evaluations, tooth sensitivity was also recorded by asking the volunteers to classify the sensitivity during bleaching treatment as absent, mild, moderate, or severe. The present study found that 13.8% of the volunteers withdrew from the study due to tooth sensitivity, and 43.2% of the participants experienced some type of sensitivity during bleaching treatment. The χ(2) test showed that there was a significant prevalence of tooth sensitivity during bleaching treatment using the home-use 20% CP agent, with 71.4% of volunteers reporting any level of tooth sensitivity (p=0.0032). A low prevalence of tooth sensitivity was observed for volunteers who used the in-office 38% HP agent (15.0%). The Wilcoxon test (p<0.05) showed that all of the bleaching treatments were effective in bleaching teeth and that there were no differences between the final color shade results among the treatments (Kruskal-Wallis, p<0.05). This study showed that 43.2% of all the volunteers experienced mild or moderate tooth sensitivity during the treatment with bleaching agents. A higher prevalence of tooth sensitivity was observed for 71.4% of the volunteers who used the 20% CP home-use bleaching agent, which may be ascribed to the peroxide concentration and/or the time/length the agent was in contact with the denta...

SUMMARY The purpose of this in situ study was to evaluate the influence of staining solutions (coffee and cola) on the color change, microhardness, roughness, and micromorphology of the enamel surface during at-home and in-office dental bleaching. One hundred and thirty-five enamel bovine blocks were prepared to perform the evaluations. Fifteen volunteers used an intraoral appliance with nine enamel blocks for 15 days. The enamel blocks were randomly assigned among the different groups according to the three treatments: in-office bleaching with high hydrogen peroxide concentration (Opalescence Boost PF 40%, Ultradent) for 40 minutes in three sessions (first, eighth, and 15th days of treatment), at-home bleaching with low carbamide peroxide concentration (Opalescence PF 10%, Ultradent) for 60 minutes daily for 15 days, and a control group (no bleaching agent applied). The enamel blocks were immersed daily in different staining solutions (coffee or cola) for 30 minutes for 15 days or were not submitted to staining (control) to obtain a factorial scheme (3×3) of the dental bleaching treatment and staining solution (n=15). The microhardness analyses (Knoop), roughness evaluations (Ra), surface micromorphological observations, and color measurements (using the CIELAB system and the VITA Classical scale) were made before and after the bleaching treatments to assess immersion in staining solutions. Mixed model tests showed that there was a decrease in enamel microhardness after exposure to cola compared with coffee and the control group (p&lt;0.0001) for both bleaching techniques. Roughness was higher for the cola groups (p&lt;0.0001), and there was no significant difference between the coffee and the control groups. Generalized linear models showed that when no staining solution was applied, lighter color scores were found for the VITA Classical scale (p&lt;0.0001). Without the staining solutions, there was an increase in luminosity (ΔL) (p=0.0444) for in-office bleaching. Lower values of Δa (p=0.0010) were observed when the staining solutions were not used. The Δb (p=0.3929) did not vary significantly between the bleaching agents, but when cola was applied, the values were significantly higher than for the control (p=0.0293). Higher values of ΔE (p=0.0089) were observed for in-office bleaching without staining solutions, while lower values of ΔE were observed for the in-office associated with coffee immersion. Regardless of whether being submitted to bleaching, the enamel stained with cola showed a decrease in microhardness, an increase in roughness, and changes in the micromorphology. The efficacy of the bleaching agents was greater when no staining solution (cola or coffee) was used, and in-office bleaching showed greater color change than the at-home bleaching technique.

The purpose of this study was to evaluate bleaching methods containing hydrogen peroxide (HP) or carbamide peroxide (CP), dispensed in customized or prefilled trays, in terms of color change, tooth sensitivity, gingival irritation, acceptance, and comfort. Seventy-five volunteers were randomly selected and distributed according to the whitening agent (n=25): 10% HP dispensed in prefilled trays (Opalescence Go 10%) and 9.5% HP (Pola Day) and 10% CP both delivered in customized trays (Opalescence PF 10%). HP was applied for 30 min/d for 14 days (d), and CP for 8 h/d for 14 days. Evaluations were performed at baseline and at 7 days and 14 days of treatment. Color change was measured with Commission internationale de l'éclairage color coordinates (L*, a*, b*), Vita Classical, and 3D Master scales. A visual analog scale was used to assess tooth sensitivity, acceptance of the method and degree of comfort of the tray. Gingival irritation was evaluated as present or absent and localized or generalized. Regarding gingival irritation, tray acceptance, and tooth sensitivity, no differences were observed among the groups at any time (p>0.05). As for degree of comfort, 10% HP showed lower scores (comfortable) than 10% CP, with significant differences (p<0.05) from the other groups (comfortable to very comfortable). In terms of ΔL, Δa, and ΔE, no difference was observed among the groups or between the time periods (p>0.05). The Δb average was higher at 14 days (p<0.05), and there was no difference among the groups (p>0.05). Localized gingival irritation was observed in both tray methods. Mild tooth sensitivity was observed with time, regardless of the bleaching agent concentration or the application time. Color change was similar for all the groups at 7 days and 14 days, but there was a greater reduction in the yellow hue at 14 days. All the bleaching methods were highly accepted and effective in promoting whitening. Although prefilled trays are generally comfortable, they proved less comfortable than customized trays.

The aim of this in vitro study was to evaluate the effect of bleaching protocols on the surface roughness (Ra), color change and surface micromorphology of a low-viscosity bulk-fill composite (Filtek Bulk Fill Flow, 3M ESPE), a highviscosity bulk-fill composite (Filtek Bulk Fill, 3M ESPE) and a conventional nanoparticulate composite resin (control) (Filtek Z350 XT, 3M ESPE). Forty samples of each composite (disks 5 mm in diameter and 2 mm thick) were randomly divided into four groups (n=10), according to bleaching protocol: a) 10% carbamide peroxide gel (Opalescence, Ultradent Products) (2 h/ day, for 14 days); b) 40% hydrogen peroxide gel (Opalescence Boost, Ultradent Products) (three bleaching sessions, once a week, 45 min/session); c) whitening rinse (Listerine Whitening Extreme, Johnson & Johnson) (2 min/day, for 14 days); and d) distilled water (control). The samples were submitted to triplicate readings (Ra and color [CIELAB parameters]) before and after contact with bleaching protocols. Micromorphology was analyzed in a scanning electron microscope (SEM). Ra and color parameters (ΔL, Δa, Δb and ΔE) were analyzed by generalized linear models (α=0.05). The Ra of the high-viscosity bulk-fill was significantly higher than that of the other composites (p<0.05). Ra increased significantly (p<0.05) and surface became more irregular (SEM analysis) in all the composite resins, regardless of the bleaching protocol (p<0.05). The high-viscosity bulk-fill composite resin group had significantly lower ΔE (p<0.05) than the nanoparticulate composite resin group immersed in distilled water. It was concluded that the characteristics of each resin significantly influenced the Ra more than the bleaching protocol. The high-viscosity bulk-fill resin presented minor color change.

The aim of this study was to compare low- and high-viscosity bulk-fill composites for Knoop microhardness (KHN), microtensile bond strength (MTBS) to dentin in occlusal cavities, and fracture strength (FS) in molars with mesialocclusal-distal restoration. Disk-shaped samples with different thicknesses (2 or 4 mm) of low-viscosity (SDR Flow, Dentsply) and high-viscosity bulk-fill composites (Filtek BulkFill, 3M ESPE; and Tetric-N Ceram Bulk Fill, Ivoclar Vivadent) were prepared for top and bottom KHN analysis (n=10). MTBS to dentin and fracture pattern was evaluated in human molars with occlusal cavities restored with (n=10): conventional nanocomposite (Z350XT, 3M ESPE), low-viscosity (Filtek Bulk-fill Flow, 3M ESPE) or high-viscosity bulk-fill composites (Filtek BulkFill). The FS and fracture pattern of human molar with mesial-occlusal-distal restorations submitted or not to thermomechanical cycling were investigated (n=10) using: intact tooth (control), and restoration based on conventional microhybrid composite (Z250, 3M ESPE), low-viscosity (SDR Flow) or high-viscosity bulk-fill composites (Filtek BulkFill). The data were submitted to split-plot ANOVA (KHN), one-way ANOVA (MTBS), two-way ANOVA (FS) followed by Tukey’s test (α=0.05). For KHN, there was no significant difference for the resin composites between the top and bottom. For MTBS, no significant differences among the materials were detected; however, the low-viscosity composite presented lower frequency of adhesive failures. For FS, there was no significant difference between composites and intact tooth regardless of thermomechanical cycling. Low- and high-viscosity bulk-fill composites have comparable microhardness and microtensile bond strength when used in occlusal restorations. Likewise, the bulk-fill composites present similar fracture strength in molars with mesio-occlusal-distal restorations.