To compare the effect of two bleaching systems (bleaching gel and whitening strips) on the color change, roughness, and microhardness of enamel and two resin composites. Two cavities were prepared on bovine enamel specimens (n = 16) and restored with two composites: a nano-hybrid [Herculite Ultra (HU)] and a micro-hybrid composite [TPH Spectra (TS)]. Baseline color (CIE L*a*b*), roughness (μm), and microhardness (kgf/mm2) were measured using a spectrophotometer, optical profilometer, and Vickers microhardness (VHN) tester, respectively. The specimens were stained with coffee for 14 days, and randomized into two bleaching groups: gel and strips (n = 8), then submitted to a 10-day bleaching/staining test. Color, roughness, and microhardness were re-measured. The outcomes were analyzed using two-way ANOVA and Fisher’s-PLSD test (α = 0.05). Gel significantly improved the color (ΔE 4.9–8.3) and increased the roughness (Ra 0.04–0.08 μm) of all substrates (p < 0.0001) compared to strips. Enamel color was significantly improved (ΔE 5.4–8.3) compared to that of HU (ΔE 2.6–4.9) and TS (ΔE 2.0–4.9) with either gels or strips. TS roughness (0.03–0.08 μm) was significantly higher than that of enamel (0.01–0.05 μm) and HU (0.02–0.04 μm). Enamel had significantly reduced microhardness compared to HU (p = 0.0144). Gels produced the greatest color improvement and roughness compared to strips. Enamel had significant color improvement but had the greatest decrease in microhardness. There was unacceptable color change between enamel and the composites after the combined cyclic effects of staining and bleaching.

To investigate the effects of a coffee beverage and two whitening systems on the surface roughness and gloss of glazed Lithium Disilicate Glass-Ceramics (LDGC) for computer-aided design/computer-aided manufacturing (CAD/CAM) systems. Sixty-eight LDGC disks (12 × 10 × 2 mm) were prepared from blocks of CAD/CAM systems (IPS e.max CAD ceramic). Baseline measurements for surface roughness (Ra) and gloss (GU) were taken using a 3-D optical profilometer and a glossmeter, respectively; then specimens were randomized into four groups (n = 17). All specimens were immersed in a coffee solution (24 h × 12 days) then subjected to two whitening systems. G1-negative control (kept moist × 7 days); G2-positive control (brushed with distilled water, 200 g/load, 2 min twice daily × 7 days); G3-whitening toothpaste (Colgate optic white; relative dentin abrasivity (RDA) = 100, 200 g/load, 2 min twice daily × 7 days); and G4-simulated at-home bleaching protocol (Opalescence,15% carbamide peroxide (CP), 6 h/day × 7 days). The study outcomes were measured at baseline and after the treatments. Data were analyzed using paired T-test and one-way ANOVA (α = 0.05). The mean surface roughness significantly increased (p ⩽ 0.002) for all groups after the designated treatment protocols. Among groups, the mean surface roughness of G2 and G3 were significantly higher (p ⩽ 0.001) (Ra: 0.51 and 0.57 μm, respectively) compared to the control group (Ra: 0.23 μm), and were not significantly different from G4 (Ra: 0.46 μm). Surface gloss decreased with no significant change within or among groups after treatment. All glazed LDGC had a significant increase in surface roughness after being subjected to simulated 1 year of coffee drinking and whitening systems (15% CP and whitening toothpaste), and the greatest change was associated with brushing (simulating 8 months). However, coffee beverages and whitening systems had no significant effect on the surface gloss.

Objective Conservative approaches to esthetically treat stained arrested caries lesions (s-ACLs) have not been explored in clinical studies. This study aims to investigate the efficacy of in-office dental bleaching agent, as a conservative approach, to esthetically treat s-ACLs. Materials and Methods Twelve patients (n = 46) presented with s-ACLs were treated with 40% hydrogen peroxide (in-office bleaching protocol; 20 minutes × 3). Color values were measured using a spectrophotometer (CIE L*a*b*), aided with digital photography to assess visual color change clinically. Measurements were taken for each specimen at baseline and immediately after bleaching. Statistical Analysis The color change calculated before and after bleaching for each dental substrate was analyzed using paired t-test (α = 0.05). Results The bleached s-ACLs had a significant increase in L* values (p < 0.001), and a significant decrease in both a* (p = 0.001) and b* (p = 0.007) values, indicating lighter color improvement (bleaching efficacy). The baseline mean L*, a*, and b* values were 61.5, 2, and 15.4, respectively, and after bleaching were 67.7, 1.4, and 13.3, respectively, with a mean increase in ∆E of >7.9, which resulted in a visible clinical stain improvement as orange/light brown stains were removed completely, while gray/black stains improved to a lesser extent. Conclusion Significant color improvement was observed when the in-office bleaching protocol (40% hydrogen peroxide) was used in orange/brown s-ACLs. However, it showed lesser improvement in gray/black s-ACLs. Publication Date: 08 September 2020 (online) © . Thieme Medical and Scientific Publishers Private Ltd. A-12, Second Floor, Sector -2, NOIDA -201301, India

This study aimed to investigate the effect of potassium iodide (KI), bleaching, and microabrasion on the colour of caries-like lesions treated with silver diamine fluoride (SDF). Enamel specimens were demineralised and then randomised into six groups (n = 15): G1, demineralised; G2, remineralised with 38% SDF to create stained remineralised caries-like lesions (s-RCLs); G3, s-RCLs + KI; G4, s-RCLs + KI + at-home bleaching protocol (15% carbamide peroxide (CP), 4 h/d×7); G5, s-RCLs + KI + microabrasion (6.6% hydrochloric acid); G6, s-RCLs + KI + microabrasion and at-home bleaching protocol. Colour was measured spectrophotometrically at baseline, after demineralisation, and after the treatments. Outcomes were analysed using ANOVA followed by Tukey's test (α = 0.05). The increased colour change after demineralisation (ΔE ≥ 6.7) indicated the creation of white spot lesions. G2 (ΔE = 12.3) and G3 (ΔE = 11.1) were significantly discoloured (P ≤ 0.0039), with no significant difference between them, and significantly darker (P 0.0001) than G1 (ΔE = 0.4) and G5 (ΔE = 4.4). G2 was significantly (P ≤ 0.0325) darker than G1, G4, G5, and G6 (ΔE = 0.4, 8.1, 4.4, 7.9), respectively. While KI did not reduce SDF staining, microabrasion offered limited aesthetic improvement. However, 15% CP demonstrated greater efficacy in partially improving the colour outcome of SDF-stained lesions.

This study investigated the effect of silver diamine fluoride (SDF) on the shear bond strength (SBS) of dual, light, and self-cured cement on enamel and dentin. Specimens were randomized into four groups (n = 32): G1, sound; G2, sound/treated with SDF; G3, demineralized; G4, demineralized/treated with SDF. Buildups were made using the following: dual-cured cement; RelyX Unicem (RXU); light-cured cement; Variolink Esthetic LC (VE); and self-cured cement Ketac Cem Maxicap (KetC). The SBS was performed, and data were analyzed using ANOVA models followed by Tukey’s test (α = 0.05). Enamel (E) had a significantly different SBS value (p < 0.001), (11.6–19.9 MPa) than dentin (D) (7.2–14.8 MPa), except for the KetC group (D: 3.1–5.1 MPa, E: 3.4–3.7 MPa), apart from G3 (E: 3.8 MPa, D: 3.1 MPa). In E/D, RXU had a more significant SBS value (p < 0.001), (11.5–19.9 MPa), followed by VE (7.2–15.4 MPa), then KetC (3.1–5.1 MPa). All groups within VE/E were more significant (p = 0.035) than G2. However, G4 in KetC/D was more significant (p < 0.001) than G1 and G2, which were more significant than G3. Enamel had a more significant SBS value than dentin in RXU and VE cements. RXU had significant strength, followed by VE, then KetC cements. SDF decreased the SBS of VE cement on sound enamel. However, it increased the SBS of demineralized dentin with KetC cement.