Experimental gel containing bioactive glass-ceramic to minimize the pulp damage caused by dental bleaching in rats

Abstract Objectives This study evaluated if the use of a bioactive glass-ceramic-based gel, named Biosilicate (BS), before, after or mixed with bleaching gel, could influence the inflammation of the dental pulp tissue of rats' molars undergoing dental bleaching with hydrogen peroxide (H2O2). Methodology The upper molars of Wistar rats (Rattus norvegicus, albinus) were divided into Ble: bleached (35% H2O2, 30-min); Ble-BS: bleached and followed by BS-based gel application (20 min); BS-Ble: BS-based gel application and then bleaching; BS/7d-Ble: BS-based gel applications for 7 days and then bleaching; Ble+BS: blend of H2O2 with BS-based gel (1:1, 30-min); and control: placebo gel. After 2 and 30 days (n=10), the rats were euthanized for histological evaluation. The Kruskal-Wallis and Dunn statistical tests were performed (P<0.05). Results At 2 days, the Ble and Ble-BS groups had significant alterations in the pulp tissue, with an area of necrosis. The groups with the application of BS-based gel before H2O2 had moderate inflammation and partial disorganization in the occlusal third of the coronary pulp and were significantly different from the Ble in the middle and cervical thirds (P<0.05). The most favorable results were observed in the Ble+BS, which was similar to the control in all thirds of the coronary pulp (P>0.05). At 30 days, the pulp tissue was organized and the bleached groups presented tertiary dentin deposition. The Ble group had the highest deposition of tertiary dentin, followed by the Ble-BS, and both were different from control (P<0.05). Conclusion A single BS-based gel application beforehand or BS-based gel blended with a bleaching gel minimize the pulp damage induced by dental bleaching.

In vivo study of the action of a topical anti-inflammatory drug in rat teeth submitted to dental bleaching

Abstract Bleaching gel containing hydrogen peroxide (H2O2) cause damages in pulp tissue. This study investigated the action of a topical anti-inflammatory, the Otosporin®, in rats' bleached teeth with the null hypothesis of which the Otosporin® is no able to minimize the pulp inflammation that bleaching gel generates. The rat's molars were divided into groups: BLE: bleached (35% H2O2 concentration /single application of 30 min); BLE-O: bleached followed by Otosporin® (10 min); and control: placebo gel. In the second day after dental bleaching, the rats were killed, and the jaws were processed for hematoxylin-eosin and immunohistochemistry analysis for tumor necrosis factor alpha (TNF-α), interleukin (IL)-6 and IL-17. The data collected were subjected to Kruskal-Wallis and Dunn statistical tests with at a 5% level of significance (p<0.05). The BLE group had moderate to strong inflammation in the occlusal third of the coronary pulp, with necrotic areas; and BLE-O, mild inflammation (p<0.05). There was a significant difference in the occlusal and middle thirds of the coronary pulp between the BLE with BLE-O and control groups (p<0.05). There was no difference in the cervical third (p>0.05). The BLE group had a high immunoexpression of TNF-α than BLE-O and control groups (p<0.05), with moderate and mild immunoexpression, respectively. Regarding IL-6 and IL-17, the BLE group had higher immunoexpression than control (p<0.05); the BLE-O was similar to the control (p>0.05). The topical anti-inflammatory Otosporin® can reduce pulp inflammation after dental bleaching in the rat teeth.

Resumo O gel clareador à base de peróxido de hidrogênio (H2O2) causa danos ao tecido pulpar. Este estudo investigou a ação de um anti-inflamatório tópico, o Otosporin®, nos dentes de ratos clareados com a hipótese nula de que o Otosporin® não é capaz de minimizar a inflamação da polpa gerada pelo gel clareador. Os molares dos ratos foram divididos em grupos: ClA: clareado (H2O2 a 35% / aplicação única de 30 min); CLA-O: clareado seguido do Otosporin® (10 min); e controle: gel placebo. No segundo dia após a clareação dentária, os ratos foram mortos e suas maxilas foram processadas para análise de hematoxilina-eosina e imunohistoquímica para o fator de necrose tumoral alfa (TNF-a), interleucina (IL)-6 e IL-17. Os dados coletados foram submetidos aos testes estatísticos de Kruskal-Wallis e Dunn com um nível de significância de 5% (p<0,05). O grupo CLA apresentou inflamação moderada à severa no terço oclusal da polpa coronária, com áreas necróticas; e CLA-O, inflamação leve (p<0,05). Houve diferença significativa nos terços oclusal e médio da polpa coronária entre o grupo CLA com os grupos CLA-O e controle (p<0,05). Não houve diferença no terço cervical (p>0,05). O grupo CLA apresentou maior imunoexpressão para TNF-a comparado aos grupos CLA-O e controle (p<0,05), com imunoexpressão moderada e leve, respectivamente. Em relação a IL-6 e IL-17, o grupo CLA apresentou maior imunoexpressão comparado ao controle (p<0,05); o CLA-O foi semelhante ao controle (p>0,05). O anti-inflamatório tópico Otosporin® pode reduzir a inflamação pulpar após clareação em dentes de ratos.

In-office tooth bleaching with 38% hydrogen peroxide promotes moderate/severe pulp inflammation and production of ll-1ß, TNF-ß, GPX, FGF-2 and osteocalcin in rats

Abstract Objectives: To study the intensity of inflammatory infiltrate and production of interleukin-1β (ll-1β), tumor necrosis factor-β (TNF-β), fibroblast growth factor-2 (FGF-2), glutathione peroxidase (GPX), and osteocalcin in response to in-office tooth bleaching in rats. Material and Methods: Twenty male Wistar rats were randomized into four groups (n=5) according to the received treatment (tooth bleaching or no treatment - control) and the period of euthanasia after treatment (24 h or 10 days). We performed tooth bleaching using a 38% hydrogen peroxide gel on maxillary and mandibular incisors. After euthanasia, incisors (20 per group) were processed for histological analysis, immunohistochemistry staining of ll-1β, TNF-β, FGF-2 and GPX and osteocalcin by immunofluorescence. We analyzed data using the Mann-Whitney and Kruskal-Wallis/Dunn tests (p<0.05). Results: The bleached groups presented statistically significant differences regarding the pulp inflammation stage compared with the control groups. Bleached teeth showed moderate/severe inflammatory infiltrate and control groups presented absent inflammatory cells or a negligible number of mononuclear cells (p<0.001) at two times (24 h and 10 days). There was strong staining for ll-1β, TNF-β, and GPX in bleached groups at 24 h and strong staining for ll-1β, TNF-β, GPX and FGF-2 at 10 days. After 10 days of tooth bleaching, the bleached group showed a statistically superior amount of osteocalcin than the other groups (p<0.01). Conclusions: Tooth bleaching with 38% hydrogen peroxide causes severe pulp inflammation, but characteristics of tissue repair after 10 days.

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.

Histologic evaluation of pulpotomy performed with ethyl-cyanoacrylate and calcium hydroxide / Avaliação histológica de pulpotomia realizada com etil-cianoacrilato e com hidróxido de cálcio

The aim of this study was to evaluate histological aspects of the pulp-dentin complex of dogs submitted to pulpotomy and capped with ethyl-cyanoacrylate and calcium hydroxide. Thirty dog teeth were divided into 2 groups of 15 as follows: Group 1 - ethyl-cyanoacrylate; Group 2 - calcium hydroxide. The pulpotomies were carried out following all of the treatment precautions recommended for dogs. After 30 days the specimens were submitted to histological preparation and were then blindly evaluated by a histologist. Data were analyzed statistically by the Fisher exact test, comparing the two groups. After 30 days, the presence of a hard tissue barrier was observed in 83.3 percent of Group 1, and in 100 percent of Group 2 (p = 0.478). A continuous hard tissue barrier was observed in 50 percent of the ethyl-cyanoacrylate group and 75 percent of the calcium hydroxide group (p = 0.652). It can be concluded that both materials induced hard tissue barrier formation, but Group 2 had a higher percentage than Group 1, with no significant statistical differences; the differences observed between the different barriers (continuous/non-continuous) were not significant between groups and there was no pulpal necrosis in either group.

O objetivo do presente estudo foi avaliar o aspecto histológico do complexo dentino-pulpar de cachorros quando capeado após a pulpotomia com etil-cianoacrilato e hidróxido de cálcio. Trinta dentes de cães foram divididos em 2 grupos de 15 da seguinte forma: Grupo 1 - Etil-cianoacrilato; Grupo 2 - Hidróxido de cálcio. A pesquisa foi realizada tomando-se todos os cuidados recomendados para o tratamento com os cães. Após 30 dias do procedimento realizado os espécimes foram submetidos ao preparo histológico e logo após foram avaliados de forma cega por um histologista. Os resultados foram analisados estatisticamente através do Teste Exato de Fisher. No grupo 1, 83,3 por cento e no grupo 2, 100 por cento dos dentes apresentaram a barreira de tecido duro (p = 0,478). A barreira de tecido duro contínua foi observada em 50 por cento dos casos tratados com etil-cianoacrilato e em 75 por cento dos com hidróxido de cálcio (p = 0,652). Pode-se concluir que tanto o grupo 1 como o grupo 2 induziram a formação da barreira de tecido duro, porém o grupo 2 teve um percentual maior do que o grupo 1, não havendo diferença estatisticamente significante; a diferença observada entre as estruturas das barreiras (contínuas e não-contínuas) não foi significante. A necrose pulpar não foi observada em nenhum grupo.

Reacciones pulpares por clorhexidina en cavidades dentinarias profundas en perros: informe preliminar / Pulp reactions due to chlorhexidine in deep dental cavities in dogs: preliminary report

El barniz de clorhexidina se ha usado como un agente bactericida contra el streptococo mutans aplicándose tópicamente sobre esmalte. Con el propósito de determinar el tipo de respuesta pulpar provocada por la aplicación de barniz de clorhexidina se realizaron cavidades dentinarias profundas en 32 piezas dentarias de perros, aplicándose barniz de clorhexidina al grupo experimental. Las piezas una vez extraídas fueron procesadas para su estudio histológico, analizándose según los criterios de Bergenholtz y Warfvinge. Los resultados obtenidos nos indicaron que barniz de clorhexidina provocó una respuesta inflamatoria mayor que la encontrada en los grupos controles. La inflamación siempre estuvo localizada en la zona pulpar bajo la cavidad operatoria y no se observó necrosis en ninguna de ellas. Asimismo la resolución del proceso inflamatorio fue más lento en el grupo tratado con el barniz. Se concluyó que el barniz de clorhexidina es irritante pulpar y que produce una reacción inflamatoria de tipo reversible que es más lenta en su resolución que en la piezas obturadas sin el barniz de clorhexidina