Over-the-counter bleaching agents can help with tooth whitening maintenance.

OBJECTIVE: This study evaluated the influence of over-the-counter agents on the maintenance of color and microhardness of the enamel after home bleaching protocol. MATERIALS AND METHODS: Specimens of bovine teeth (6 × 6 × 2 mm) were prepared, and color (Easyshade, VITA) and microhardness (HMV-2, Shimadzu) readings were performed. All the specimens were bleached using 22% carbamide peroxide (22%CP), except for the control group, and then separated into seven groups (n = 10) according to the interaction of toothpaste (whitening, conventional, and whitening with peroxide) and mouth rinse (whitening and conventional). The study simulated 1 year of toothbrushing (Pepsodent, MAVTEC) and mouth rinse by immersion. After that, final color and microhardness measurements were performed. Data were analyzed by one-way ANOVA, Tukey's test (P < .05). RESULTS: The group submitted to 22%CP + whitening toothpaste + whitening mouth rinse showed higher color maintenance (P < .05) than the control group. The perception of whitening of teeth (ΔWID ) was higher than the color change (ΔE00 ). There was a decrease in microhardness after treatment with 22%CP + conventional toothpaste + whitening mouth rinse. CONCLUSIONS: Over-the-counter products can help with the maintenance of tooth whitening after bleaching with carbamide peroxide; however, special attention should be given since the association of products can also reduce the microhardness of the dental enamel. CLINICAL SIGNIFICANCE: The association between whitening toothpastes and mouth rinses might be beneficial for maintaining color during 1 year after bleaching treatment.

Comparative effects on acrylic resin properties of short- and long-term immersion in alkaline peroxide solution.

PURPOSE: To evaluate the color stability (ΔE), surface roughness (ΔRa), and flexural strength of denture base acrylic resin after short (20 minutes) and long-term (8 hours) immersions simulating a period of 5 years of use. METHODS: 120 disk-shaped (16 mm x 4 mm) and 120 rectangular (65 mm x 10 mm x 3.3 mm) specimens were prepared (Lucitone 550) and distributed into three groups (n=20): distilled water (Control); Corega Tabs (CT) and Polident (Po), for immersions of 20 minutes and 8 hours. ΔE were determined by a colorimeter, ΔRa by a profilometer and the flexural strength by a universal testing machine. Data were evaluated by two-way ANOVA followed by Tukey's test and Bonferroni correction (α= 0.05). RESULTS: Short-term immersions for 20 minutes resulted in significant differences in ΔE, as CT values (1.46 ± 1.41) were higher than Po (0.55 ± 0.25) and Control (0.47 ± 0.21). Specimens immersed for 8 hours showed more extensive alterations overall than the control (ΔE [Po: 7.27 ± 0.53; CT: 5.58 ± 0.49; Control: 1.26 ± 0.23]; 916;Ra [Po: 0.16 ± 0.08; CT: 0.12 ± 0.11; Control: 0.07 ± 0.06]; flexural strength [Po: 42.99 ± 9.34; CT: 63.96 ± 12.98; Control: 64.59 ± 12.87]). The tested alkaline peroxide-based solutions promoted significant alteration on acrylic resin properties after overnight immersion. Therefore, short-term immersions seem to be more suitable for daily denture hygiene. CLINICAL SIGNIFICANCE: Alkaline peroxides were able to alter color stability, surface roughness and flexural strength of acrylic resin after overnight immersions, in a 5-year-simulated period of use.

Color stability and surface roughness of composite resins submitted to brushing with bleaching toothpastes: An in situ study.

OBJECTIVE: To evaluate, in situ, the color stability (CS) and surface roughness (SR) of composite resins after toothbrushing with whitening toothpaste. MATERIALS AND METHODS: Specimens (6 × 2 mm/) of composite resin (Tetric N-Ceram, Z250 and Z350) were randomly fixed on thirty participants' upper molars (buccal surface). For an initial standardization (7 days), participants used a soft toothbrush and nonwhitening toothpaste (SDB - Sorrisos Dentes Brancos). Initial CS (Easyshade) and SR (Surfcorder RS) measurements were performed. For SR, impressions of specimens were taken (Express, 3 M ESPE) to produce replicas in polyurethane resin (Axon F16, Abcol). Participants were randomly separated into three groups (n = 10) regarding used toothpaste (SDB; Close up White Now - CWN; Colgate Luminous White - CLW). After 90 days, CS and SR measurements were obtained, and data were analyzed (2-way ANOVA, repeated measures, Bonferroni, P < .05). RESULTS: Z250 showed higher (P < .05) color change than Z350. Tetric N-Ceram presented an intermediary value for ΔE, however, it also demonstrated higher SR (P < .05) after brushing with CLW, compared with SDB and CWN. CONCLUSIONS: The SR change of composite resin after toothbrushing with a whitening toothpaste is material dependent, but the toothpaste abrasiveness does not change the CS. CLINICAL SIGNIFICANCE: Whitening toothpaste do not change the color stability of composites; however, it can alter the restorative composite surface roughness.