Effectiveness of different carbamide peroxide concentrations used for tooth bleaching: an in vitro study.
OBJECTIVE
This in vitro study evaluated the effectiveness of three carbamide peroxide concentrations used for tooth bleaching treatments.


METHODS
Sixty bovine dental slabs (6x6x3 mm) were obtained, sequentially polished, submitted to artificial staining (baseline) and randomized into four groups (n=15), according to the bleaching agent concentration: distilled water (control), 10% (CP10), 16% (CP16) or 37% (CP37) carbamide peroxide. CP10 and CP16 were covered with 0.2 mL of the respective bleaching gels, which were applied on enamel surface for 4 h/day during two weeks. Samples of CP37 were covered with 0.2 mL of the bleaching gel for 20 min. The gel was light activated by two 40-s applications spaced by 10-min intervals. The gel was renewed and applied 3 times per clinical session. This cycle was repeated at 3 sessions with 5 days of interval between them. Tooth shade evaluations were done with a digital spectrophotometer at T0 (baseline), T1 (after 1-week of treatment) and T2 (1-week post-bleaching). Tooth shade means were statistically analyzed by Kruskal-Wallis and Friedman's tests and color parameters were analyzed by two-way ANOVA and Tukey's test (p<0.05).


RESULTS
At T1 and T2 evaluations, tooth shade was significantly lighter than at baseline for all treatment groups, considering the color parameters ΔL*, Δa*, Δb*, ΔE* (p<0.001) or tooth shade means (p<0.001). CP37 group showed lower shade mean change than CP10 and CP16 at T1 (p<0.01), but this difference was not statistically significant at T2 (p>0.05).


CONCLUSIONS
One week after the end of the treatment, all carbamide peroxide concentrations tested produced similar tooth color improvement.
Department of Operative Dentistry, Federal University of Paraíba, João Pessoa, PB, Brazil. soniasaeger@hotmail.com
Sônia Saeger
SS
Meireles
Silvia Terra
ST
Fontes
Luiz Antônio Afonso
LA
Coimbra
Álvaro
Á
Della Bona
Flávio Fernando
FF
Demarco
D000818:Animals; D000077463:Carbamide Peroxide; D002417:Cattle; D003116:Color; D003743:Dental Enamel / Q000737:chemistry / Q000187:drug effects; D008422:Materials Testing; D010545:Peroxides / Q000737:chemistry*; D017797:Prosthesis Coloring; D013053:Spectrophotometry; D013997:Time Factors; D014073:Tooth Bleaching / Q000379:methods*; D058205:Tooth Bleaching Agents / Q000737:chemistry*; D014508:Urea / Q000031:analogs & derivatives* / Q000737:chemistry
D010545:Peroxides; D058205:Tooth Bleaching Agents; D000077463:Carbamide Peroxide; D014508:Urea