Effects of black tea tooth staining previously to 35% hydrogen peroxide bleaching

Aim: To determine if the artificial staining with black tea (BT) influences the enamel microhardness before in-office bleaching and if BT staining is necessary to evaluate the efficacy of bleaching with 35% hydrogen peroxide Methods: Enamel/dentin blocks were randomized into groups according to the staining protocol (n=5/group): (CO) control ­ maintained in artificial saliva solution (AS); (BT4) immersed in black tea solution for 4 h; (BT24) immersed in black tea solution for 24 h. After the staining protocols, all specimens were kept in AS for one week, followed by bleaching (three sessions of HP application for 40 min). Knoop surface microhardness (kgF/mm2) was determined at baseline (T0), after staining (T1), after 7 days of storage in AS (T2), and after bleaching (T3). The color (∆E00) and coordinate changes (∆L, ∆a, ∆b) were measured using a digital spectrophotometer at T0 and T3. Data were submitted to one-way (∆E00, ∆L, ∆a, ∆b) or two-way ANOVA repeated measures (kgF/mm2) and Tukey's test (a=5%). Results: The staining protocols (BT4 and BT24) promoted significantly lower microhardness (T1 and T2, p<0.05) than CO, whereas CO was the only group to maintain microhardness values over time. Bleaching promoted perceptible ∆E00 without a significant difference among the groups regardless of the staining protocol (p=0.122). CO and BT4 showed no differences in terms of ∆L and ∆a (p>0.05), but BT4 displayed a higher ∆b than CO. Conclusion:The artificial staining with BT negatively affected the enamel surface microhardness and was not essential to evaluate the efficacy of 35% hydrogen peroxide bleaching

ScanWhite: método objetivo para avaliação do nível de clareamento dentário / ScanWhite: Objective method for dental bleaching level evaluation

Introdução: o clareamento dentários pode ser avaliado por meio de técnicas comparativas subjetivas (visual) ou objetivas (instrumental). Essa última tem se mostrado mais adequado para tal tipo de avaliação. Métodos: a avaliação do sistema foi realizado em laboratório, utilizando-se uma câmara digital, escala de cores Vita Classical e tres diferentes tipos de iluminação. No total, foram realizadas 480 imagens. Em seguida, o software foi avaliado quanto à sua eficiência clínica. Para tal, foi selecionado um caso de microabrasão complementado com clareamento dentário fotoacelerado. Resultados: os testes laboratoriais com diferentes iluminantes apresentaram resultados similares. Clinicamente, foram obsaervados diferentes níveis de clareamento em cada uma das sessões clínicas realizadas. Discussão: os vários métodos objetivos disponíveis atualmente apresentam diferentes graus de imitação na análise da cor de corpos semitranslúcidos (por exemplo, dentes e materiais dentários). Essas estão relacionadas ao posicionamento e ao sistema de cor utilizado (por exemplo, RGB, CYM) por cada equipamento. Portanto, o método proposto apresenta algumas vantagens em relação aos sistemas objetivos, como a ausência da necessidade de manutenção do posicionamento da amostra ou do paciente, algoritmo calibrador e a geração de gráficos e laudos. Conclusões: as comprovações geradas pelo sistema proposto geram maior conforto e segurança durante o tratamento

Introduction: The dental bleaching outcome can be evaluated using subjective (visual) and objective (instrumental) comparative techniques. The latter has demonstrated more suitable results to that kind of evaluation. Methods: The assessment of the proposed system was realized in th laboratory using Vita Classical color pallets, digital camera and three different illuminations. In total, 480 images were acquired. Next, the software was evaluated to check its clinical efficiency.For this, a case of micro-abrasion complemented with photoacelerated dental bleaching was chosen. Results: The laboratorial tests with different illuminants showed similar results. Clinically different levels of dental bleaching were observed in each one of the clinical appointments realized. Discussion: The several objective methods available nowadays present different limitation levels when analysing semitranslucid samples (e.g. teeth and dental materials). These limitations are related with the samples's position and with the color space used by each system (e.g. RGB, CYM). Therefore, the proposed method shows some advantages when compared with the traditional objective methods, such as the absence of position maintenance of the sample or of the patient, calibration algorithm and generation of graphs and reports. Conclusions: The outcomes generated by the proposed system can provide more security both to patient and professional during the treatment