Inflammatory response of human dental pulp to at-home and in-office tooth bleaching

ABSTRACT Tooth bleaching is a technique of choice to obtain a harmonious smile, but bleaching agents may damage the dental pulp. Objective: This study evaluated the inflammatory responses of human dental pulp after the use of two bleaching techniques. Material and Methods: Pulp samples were collected from human third molars extracted for orthodontic reasons and divided into three groups: control - no tooth bleaching (CG) (n=7); at-home bleaching with 15% carbamide peroxide (AH) (n = 10), and in-office bleaching with 38% hydrogen peroxide (IO) (n=12). Pulps were removed and stained with hematoxylin-eosin for microscopic analysis of inflammation intensity, collagen degradation, and pulp tissue organization. Immunohistochemistry was used to detect mast cells (tryptase+), blood vessels (CD31+), and macrophages (CD68+). Chi-square, Kruskal-Wallis, and Mann Whitney tests were used for statistical analysis. The level of significance was set at p<.05. Results: The inflammation intensity and the number of macrophages were significantly greater in IO than in AH and CG (p<0.05). The results of CD31+ (blood vessels per mm2) were similar in CG (61.39±20.03), AH (52.29±27.62), and IO (57.43±8.69) groups (p>0.05). No mast cells were found in the pulp samples analyzed. Conclusion: In-office bleaching with 38% hydrogen peroxide resulted in more intense inflammation, higher macrophages migration, and greater pulp damage then at-home bleaching with 15% carbamide peroxide, however, these bleaching techniques did not induce migration of mast cells and increased the number of blood vessels.

Influência da ciclagem térmica na microinfiltração de restaurações com resina composta utilizando fucsina básica 0, 5 por cento / Thermocycling influence for assessing microleakage of restoration with resin composite using basic fuchsine 0, 5 por cento

Introdução : A microinfiltração na interface dente/restauração é considerada fator crítico nas restaurações com resina composta. Muitas são as técnicas para testar a propriedade de selamento marginal de restaurações "in vivo" e "in vitro" . O objetivo deste trabalho foi verificar a influência do número de ciclos no processo de termociclagem para o estudo da microinfiltração marginal de restaurações de resina composta. Materiais e Métodos : Foram confeccionadas, em pré-molares extraídos, 44 cavidades circulares localizadas em cemento e/ou dentina, na face vestibular e/ou lingual, e posteriormente restauradas com o sistema Single Bond / Z-100 (3M). As cavidades foram divididas em 4 grupos: Grupo 1- sem ciclagem térmica (controle), Grupo 2- 100 ciclos, Grupo 3- 200 ciclos, Grupo 4- 1000 ciclos. Após a termociclagem, tais grupos permaneceram armazenados por 24 horas a 37ºC, em fucsina básica a 0,5% . A seguir, cada dente foi incluído em um cilindro de resina poliestirênica e levado à máquina de corte de tecidos duros. Os cortes obtidos foram avaliados qualitativamente por dois examinadores calibrados, seguindo escores preestabelecidos de 0 a 4, de acordo com a penetração do corante. Resultados : Os resultados foram avaliados usando o teste não-paramétrico de Kruskal-Wallis e não mostraram diferença estatisticamente significante. Conclusão : Nas condições empregadas no presente trabalho, a termociclagem não promoveu diferenças estatisticamente significantes na microinfiltração de resinas compostas.

Introduction : Microleakage at interface tooth/restoration is considered critical factor at resin composite restoration. The aim of this study was to verify the influence of the number of cycles on thermocycling process for assessing the marginal microleakage of resin composite restorations. Materials and Methods : Forty four circular cavities were prepared in premolars with margins dentin. Each tooth received one cavity preparation at buccal and/or lingual surfaces and was restored with Single Bond/Z-100 system. The teeth were divided into four groups: Group 1 - no thermocycling (control group), Group 2 - 100 cycles, Group 3 - 200 cycles, Group 4 - 1000 cycles. After thermocycling, the teeth were stored and immersed in 0,5 % basic fuchsine solution at 37ºC for 24 hours. After this period, the specimens were totally embedded in polystyrene resin and sectioned by a hard tissue cut machine. The sections were evaluated by qualitative method following score pre-established from 0 to 4 according to stain penetration. Results : The results were analyzed by non-parametric Kruskal-Wallis' test and they showed no significant difference. Conclusion : Thermocycling, under the conditions of this study, did not influence statistically the microleakage of resin composite restoration when compared to control group.