Evaluation of Different Protocols with 4% Hydrogen Peroxide in Bleaching Efficacy and Tooth Sensitivity - A Single-blind, Randomized Clinical Trial

OBJECTIVES

To compare the bleaching efficacy and tooth sensitivity (TS) of 4% hydrogen peroxide (HP) in adults using a continuous or fractioned protocol.

METHODS AND MATERIALS

A single-blind randomized controlled trial with a parallel design was conducted. Eighty-six patients with upper canines A2 or darker were submitted to bleaching with 4% HP gel for three weeks after random allocation into the fractioned protocol (two 30-minute daily applications) or continuous protocol (single one-hour application). We evaluated the color change at baseline, weekly, and 30 days after the bleaching using Vita Classical and Vita Bleachedguide using the units of shade guides (SGU) and by spectrophotometer using CIELab 1976 (ΔEab) and CIEDE 2000 formulas (ΔE00), as well as Whiteness Index (ΔWID). We assessed the absolute risk of TS with a visual analog scale (VAS) and numeric rating scale (NRS). Color changes in each recall were compared with the Student t-test. The risk of TS was evaluated by the Chi-square test, and the intensity by Mann-Whitney test (NRS) and Student t-test (VAS).

RESULTS

The mean difference for the ΔSGU Vita Classical (0.5; 95% CI: -0.5 to 1.5), ΔSGU Vita Bleachedguide (-0.4; 95% CI: -1.5 to 0.7), ΔEab (1.4; 95% CI: -0.1 to 2.9), ΔE00 (0.6; 95% CI: -0.4 to 1.6), and ΔWID (-3.2; 95% CI: -7.3 to 0.9) after three weeks of bleaching was not clinically or statistically significant (p>0.10). The absolute risk of TS was 44% (95% CI: 30-58%) and 46% (95% CI: 32-61%) in the fractioned and continuous protocols, respectively (RR=1.0; 95% CI: 0.6 to 1.5; p>0.91).

CONCLUSION

A fractioned bleaching protocol with 4% HP (30 minutes twice daily) did not increase the whitening degree nor affect the risk and intensity of TS when compared with the one-hour continuous protocol.

Five-year Randomized Clinical Trial on the Performance of Two Etch-and-rinse Adhesives in Noncarious Cervical Lesions

OBJECTIVES

To evaluate the 5-year clinical performance of two-step etch-and-rinse adhesives in noncarious cervical lesions (NCCL).

METHODS AND MATERIALS

The sample comprised 35 adults with at least two similar-sized NCCL. Seventy restorations were placed, according to one of the following groups: Adper Single Bond 2 (SB) and Ambar (AM). The restorations were placed incrementally using a resin composite (Opallis). The restorations were evaluated at baseline and after 6 and 18 months and 5 years using some items of the FDI criteria. The differences in the ratings of the two materials after 6 months, 18 months, and 5 years were performed with Friedman repeated measures ANOVA by rank and McNemar test for significance in each pair (α=0.05).

RESULTS

Five patients did not attend the 60-month recall. No significant differences were observed between the materials for any criteria evaluated. Twenty-one restorations failed (12 for SB and 9 for AM) after 60 months. Thus, the retention rate for SB at 60 months were 55.6% for SB and 71% for AM (p=0.32). After 60 months, 12 restorations (6 for SB and 6 AM) showed some loss of marginal adaptation (p=1.0). Slight marginal discoloration was observed in 10 restorations (6 for SB and 4 AM; p=0.91). Five restorations (2 for SB and 3 for AM) showed recurrences of caries (p=1.0).

CONCLUSIONS

Both two-step etch-and-rinse adhesives-Adper Single Bond 2, a polyalkenoic acid-containing adhesive, and Ambar, a 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-containing adhesive-showed acceptable clinical performance after 60 months.

Comparison of the Effect of Agitation on Whitening and Tooth Sensitivity of In-Office Bleaching: A Randomized Clinical Trial

OBJECTIVE

This single-blind, split-mouth, randomized trial was aimed at evaluating the bleaching efficacy (BE) and tooth sensitivity (TS) of a 20% hydrogen peroxide (HP) bleaching agent used under active or passive application.

METHODS AND MATERIALS

Twenty-two patients with canines darker than C2 were selected. Teeth were bleached in two sessions, with a one-week interval between treatments. The bleaching agent was applied using active (HPactive) or passive (HPpassive) application. Each tooth in the HPactive-allocated hemiarch received bleaching gel with sonic activation after 10 and 30 minutes from the start of treatment, with rounded movements all over the buccal surface. The color changes were evaluated by subjective (Vita Classical and Vita Bleachedguide) and objective (VITA Easyshade Spectrophotometer) methods at baseline and 30 days after the second session. TS was recorded up to 48 hours after treatment using a 0-10 visual analog scale. Color change in shade guide units (SGUs) and ΔE was analyzed using a Wilcoxon test (α=0.05). The absolute risk and intensity of TS were evaluated using McNemar test and a Wilcoxon test, respectively (α=0.05).

RESULTS

Significant whitening was observed in both groups after 30 days of clinical evaluation. The activation did not significantly influence BE (ΔSGU HPpassive=5.6 and HPActive=5.8; p=0.98; and ΔE HPpassive=10.6 and HPactive=10.3; p=0.83). Absolute risk of TS (HPactive=36.4% and HPpassive=31.8%; p=0.94) was similar for both groups (Fisher exact test). TS intensity (visual analogue scale) was higher during the bleaching sessions and up to 24 hours thereafter for both groups, with no differences between groups (twoway analysis of variance and Tukey).

CONCLUSION

The active application of a 20% HP gel did not improve BE and TS.