Effect of whitening products on sound enamel and on artificial caries lesions during a cariogenic challenge.

OBJECTIVE: To investigate the effect of fluoride-containing whitening products on sound enamel and on artificial caries lesions during a cariogenic challenge. MATERIALS AND METHODS: Bovine enamel specimens (n = 120) with three areas [non-treated sound enamel (NSE), treated sound enamel (TSE), and treated artificial caries lesion (TACL)] were randomly assigned to the four groups: whitening mouthrinse (WM: 2.5% hydrogen peroxide-100 ppm F-), placebo mouthrinse (PM: 0% hydrogen peroxide-100 ppm F-), whitening gel (WG: 10% carbamide peroxide-1130 ppm F-), and deionized water (negative control; NC). The treatments (2 min for WM, PM, and NC, and 2 h for WG) were carried out during a 28-day pH-cycling model (6 × 60 min demineralization/day). Relative surface reflection intensity (rSRI) and transversal microradiography (TMR) analyses were performed. Fluoride uptake (surface and subsurface) was measured in additional enamel specimens. RESULTS: For TSE, a higher value of rSRI was observed in WM (89.99% ± 6.94), and a greater decrease in rSRI was observed for WG and NC, and no sign of mineral loss was verified for all groups (p > 0.05). For TACL, rSRI significantly decreased after pH-cycling for all experimental groups with no difference between them (p < 0.05). Higher amounts of fluoride were found in WG. WG and WM exhibited intermediate values of mineral loss, similar to PM. CONCLUSIONS: The whitening products did not potentialize the enamel demineralization under a severe cariogenic challenge, and they did not exacerbate mineral loss of the artificial caries lesions. CLINICAL RELEVANCE: Low concentrated hydrogen peroxide whitening gel and mouthrinse containing fluoride do not intensify the progression of caries lesions.

Optical Property Stability of Light-Cured versus Precured CAD-CAM Composites.

Objective: The aim of this study was to evaluate the optical property changes after staining of precured (PC) and light-cured (LC) composites. Materials and Methods: Specimens were prepared using different LC composites (GrandioSO-Voco, Filtek Z350-3M/ESPE, Opallis-FGM, and Kalore-GC) and four PC blocks (Grandio Blocs-Voco, Lava Ultimate-3M ESPE, Brava Block-FGM, and Cerasmart-GC) from the same manufacturers (n = 20). Baseline color, gloss, translucency, and fluorescence were evaluated. The staining protocol was performed for 15 days, and the final optical properties were reevaluated. Results: The changes in each property were calculated (ΔGloss, ΔTranslucency, ΔFluorescency, ΔE ∗ 00). Data were analyzed by ANOVA and Tukey's test (α = 5%). Changes in all properties were observed after staining for all materials, with darkening and reduction of gloss, fluorescence, and translucency. Nonsignificant differences were observed between the light-cured and precured materials of the same manufacturer for ΔG and ΔT, but significant differences existed for ΔF and ΔE ∗ 00. For ΔF, the only significant differences were observed between Brava Block and Opallis (smaller). For ΔE ∗ 00, only the light-cured composites GrandioSO and Z350 showed significantly less change than the corresponding blocks. Precured composites were affected the same way as light-cured ones by the staining in relation to the reduction of gloss and translucency. Conclusion: A higher reduction in fluorescence was observed for only one brand of block and was similar for the others. The two brands of light-cured materials showed less staining, while for the others, the staining was similar. The effects of staining vary according to the composite formulation.

Two-year clinical performance of self-etching adhesive systems in composite restorations of anterior teeth.

OBJECTIVE: The aim of this study was to evaluate the two-year clinical performance of Class III, IV, and V composite restorations using a two-step etch-and-rinse adhesive system (2-ERA) and three one-step self-etching adhesive systems (1-SEAs). MATERIAL AND METHODS: Two hundred Class III, IV, and V composite restorations were placed into 50 patients. Each patient received four composite restorations (Amaris, Voco), and these restorations were bonded with one of three 1-SEAs (Futurabond M, Voco; Clearfil S3 Bond, Kuraray; and Optibond All-in-One, Kerr) or one 2-ERA (Adper Single Bond 2/3M ESPE). The four adhesive systems were evaluated at baseline and after 24 months using the following criteria: restoration retention, marginal integrity, marginal discoloration, caries occurrence, postoperative sensitivity and preservation of tooth vitality. After two years, 162 restorations were evaluated in 41 patients. Data were analyzed using the χ(2) test (p<0.05). RESULTS: There were no statistically significant differences between the 2-ERA and the 1-SEAs regarding the evaluated parameters (p>0.05). CONCLUSION: The 1-SEAs showed good clinical performance at the end of 24 months.

Ultrasonic activation of internal bleaching agents.

AIM: To evaluate the effectiveness of ultrasonic activation of bleaching agents during ex vivo internal bleaching. METHODOLOGY: Fifty canine human teeth were artificially stained, root filled and divided into five groups (n = 10) that received SP - sodium perborate plus deionized water (control group), CP - 37% carbamide peroxide gel, CPUS - 37% carbamide peroxide gel plus ultrasonic application, HP - 35% hydrogen peroxide gel or HPUS - 35% hydrogen peroxide gel plus ultrasonic application. In groups CP and HP, the bleaching agent was left inside the pulp chamber for three applications of 10 min. In groups CPUS and HPUS, the same process was performed, but ultrasonic vibration was applied to the bleaching agent by an alloy tip for 30 s, with 30 s intervals. Two sessions were performed. The colour was measured initially and after each session by an intraoral dental spectrophotometer. The variation (Δ) of the colour parameters based on the CIELab system L*, a* and b*, and the colour alteration ΔE* were calculated after first and second section. Data were analysed by one-way anova and Tukey's test. RESULTS: There was no significant difference amongst groups for ΔL*, Δa* and ΔE*, but there was a significant difference for Δb* in the first and second sessions (P = 0.0006 and 0.0016, respectively). After the first session, Δb* was significantly greater for groups HP and HPUS, without a significant difference between them. For the second session, group HPUS had the greatest Δb* values, but they were similar to groups HP and SP; group CP had the lowest values, which were similar to groups CPUS and SP. CONCLUSION: Ultrasonic activation of bleaching agents during ex vivo internal bleaching was no more effective than conventional internal bleaching procedures, without activation.

Efficacy of mouth rinses and toothpaste on tooth whitening.

OBJECTIVES: People increasingly desire tooth whitening. Considering the wide range of whitening products on the market, this study evaluated the efficacy of whitening toothpastes and mouth rinses compared with the 10% carbamide peroxide (CP) whitening gel. METHODS: We obtained 120 cylindrical specimens from bovine teeth, which were darkened for 24 hours in a coffee solution. The color measurement was performed by a spectrophotometer using the CIE L*a*b* system, and specimens were divided into six groups according to the use of the following agents: group 1, conventional fluoridated toothpaste; group 2, Close Up White Now; group 3, Listerine Whitening; group 4, Colgate Plax Whitening; group 5, experimental mouth rinse with Plasdone; and group 6, 10% CP Whiteness Perfect. After the simulation of 12 weeks of treatment for groups 1 to 5 and 14 days of treatment for group 6, the specimens were subjected to a new color reading. RESULTS: Data were subjected to one-way analysis of variance (α=0.05), which showed significant differences among groups after 12 weeks for ΔE (p=0.001). Results of the Tukey test revealed that groups 3, 4, and 6 presented significantly higher color alteration than groups 1, 2, and 5. CONCLUSIONS: The whitening toothpaste Close Up White Now and the experimental mouth rinse with Plasdone showed similar color alteration as conventional toothpaste after a 12-week treatment simulation. These groups presented significantly lower color alteration compared with whitening mouth rinses Listerine and Colgate Plax Whitening, which showed similar results to those observed after 14 days of bleaching with 10% CP treatment.

Influence of Nd:YAG or Er:YAG laser surface treatment on microtensile bond strength of indirect resin composites to resin cement. Lasers surface treatment of indirect resin composites.

This study evaluated the influence of the surface pretreatment of indirect resin composite (Signum, Admira Lab and Sinfony) on the microtensile bond strength of a resin cement. Sixty samples made of each brand were divided into 6 groups, according to surface treatment: (1) control; (2) controlled-air abrasion with Al2O3; (3) Er:YAG Laser 200 mJ, 10 Hz, for 10s; (4) Er: YAG Laser 300 mJ, 10 Hz, for 10 s; (5) Nd:YAG 80 mJ, S15Hz for 1 min; (6) Nd:YAG 120mJ, 15 Hz for 1 min. After treatments, all the groups received an application of 37% phosphoric acid and adhesive. The pair of blocks of the same brand were cemented to each other with dual resin cement. The blocks were sectioned to obtain resin-resin sticks (1 x1 mm) and analyzed by microtensile bond testing. The bond strength values were statistically different, irrespective of the surface treatment performed, with highest values for Sinfony (43.81 MPa) and lowest values for Signum (32.33 MPA). The groups treated with the Nd:YAG laser showed the lowest bond strength values and power did not interfere in the results, both for Nd:YAG laser and Er:YAG. Controlled-air abrasion with Al203 is an efficient surface treatment method and the use of the Nd:YAG and Er:YAG lasers reduced bond strength, irrespective of the intensity of energy used.

Influence of hydrogen peroxide bleaching gels on color, opacity, and fluorescence of composite resins.

The aim of the present study was to evaluate the effect of 20% and 35% hydrogen peroxide bleaching gels on the color, opacity, and fluorescence of composite resins. Seven composite resin brands were tested and 30 specimens, 3-mm in diameter and 2-mm thick, of each material were fabricated, for a total of 210 specimens. The specimens of each tested material were divided into three subgroups (n=10) according to the bleaching therapy tested: 20% hydrogen peroxide gel, 35% hydroxide peroxide gel, and the control group. The baseline color, opacity, and fluorescence were assessed by spectrophotometry. Four 30-minute bleaching gel applications, two hours in total, were performed. The control group did not receive bleaching treatment and was stored in deionized water. Final assessments were performed, and data were analyzed by two-way analysis of variance and Tukey tests (p<0.05). Color changes were significant for different tested bleaching therapies (p<0.0001), with the greatest color change observed for 35% hydrogen peroxide gel. No difference in opacity was detected for all analyzed parameters. Fluorescence changes were influenced by composite resin brand (p<0.0001) and bleaching therapy (p=0.0016) used. No significant differences in fluorescence between different bleaching gel concentrations were detected by Tukey test. The greatest fluorescence alteration was detected on the brand Z350. It was concluded that 35% hydrogen peroxide bleaching gel generated the greatest color change among all evaluated materials. No statistical opacity changes were detected for all tested variables, and significant fluorescence changes were dependent on the material and bleaching therapy, regardless of the gel concentration.

Effect of caries infiltration technique and fluoride therapy on microhardness of enamel carious lesions.

Enamel white spot subsurface lesions compromise esthetics and precede cavitation; therefore, they must be halted. The aim of this study was to evaluate the effect of a caries infiltration technique and fluoride therapy on the microhardness of enamel carious lesions. Subsurface carious lesions were produced in 60 bovine specimens with polished enamel surfaces. The specimens were divided into four groups (n=15), according to the treatment used: CON, control-immersion in artificial saliva; DF, daily 0.05% fluoride solution; WF, weekly 2% fluoride gel; and IC, resin infiltration (Icon). The specimens were kept in artificial saliva and evaluated for microhardness at five points: baseline, after caries production, after four and eight weeks of treatment, and a final evaluation after being submitted to a new acid challenge. The repeated-measures analysis of variance showed significant differences according to the type of treatment (TREAT; p=0.001) and time of evaluation (EV; p=0.001). The results of the Tukey test were TREAT: CON = 45.18 (±29.17)a, DF = 107.75 (±67.38)b, WF = 83.25 (±51.17)c, and IC = 160.83 (±91.11)d. Analysis of correlation between the TREAT and EV factors showed no significant differences for DF (138.63 ± 38.94) and IC (160.99 ± 46.13) after the new acid challenge. The microhardness results in decreasing order after eight weeks were IC > DF > WF > CON. It was concluded that the microhardness of carious lesions increased with the infiltration of resin, while the final microhardness after a new acid challenge was similar for DF and IC.