Toxicidade do peróxido de carbamida 16% adicionado de nanopartículas de hidroxiapatita / Carbamide peroxide toxicity added 16% hydroxyapatite nanoparticles

O clareamento dental é um dos tratamentos mais realizados nos consultórios odontológicos a fim de melhorar a aparência do sorriso. O procedimento consiste na aplicação de um gel clareador, a base de peróxido de carbamida ou de hidrogênio, sobre os dentes a serem clareados. A sensibilidade dentária é o efeito adverso mais frequentemente relatado no clareamento dentário e é a principal causa de desmotivação dos pacientes. O mecanismo pelo qual se produz a sensibilidade após clareamento dentário ainda não foi completamente elucidado; no entanto, parece estar associado à rápida difusão dos agentes clareadores através do esmalte e dentina que, devido ao seu grau de citotoxicidade, podem agir agredindo as células pulpares, causando sensibilidade. O objetivo deste estudo foi avaliar a biocompatibilidade de nanopartícula de hidroxiapatita adicionada ao gel clareador peróxido de carbamida 16% com flúor e sem flúor e, para tanto, foram realizados testes de citotoxidade empregando MTT. Como resultados verificou-se que as nanopartículas de hidroxiapatita, quando comparadas aos géis de peróxido de carbamida a 16% com e sem flúor, foram as menos citotóxicas (p< 0.05). As diluições citotóxicas convertidas para 70% das amostras testadas também foram comparadas através do teste de Anova com tukey. Foi possível observar que as partículas de nanoHap quando adicionadas nos géis de clareamento com e sem flúor reduziu significativamento a citotoxidade. Concluímos que o novo material proposto nesta investigação apresenta melhor biocompatibilidade do que o gel sem hidroxiapatita, acompanhado da redução da citotoxidade, tais aspectos sugerem que as nanopartículas de hidroxiapatita podem ter aplicações clínicas futuras em tecidos mineralizados em procedimentos de clareamento dental, contribuindo para a redução da sensibilidade dentária.

The dental bleaching is one of the most procedures performed at dental offices to improve the appearance of the smile. The procedure consists of the application of a bleching gel, based on carbamide peroxide or hydrogen over the teeth to be whitened. Tooth sensibility is the frequently reported adverse effect on tooth whitening and is the leading cause of demotivation by the patients. The mechanism that provides the sensibility after tooth whitening has not already been fully elucidated; however, it appears to be associated with the rapid diffusion of bleaching agents through the enamel and dentin that, because of their degree of cytotoxicity, may act attacking pulp cells, causing the sensibility. The aim of this study was to evaluate the biocompatibility of hydroxyapatite nanoparticles added to whitening gel of 16% carbamide peroxide with and without fluoride and, therefore, cytotoxicity tests were performed using MTT. As a result, it was found that the hydroxyapatite nanoparticles, compared to the gels of 16 % carbamide peroxide with and without fluoride, were less cytotoxic (p <0.05). Cytotoxic dilutions converted to 70 % of the tested samples were compared using ANOVA test with Tukey. We concluded that the new material proposed in this research has a better biocompatibility in comparison with the gel without hydroxyapatite, followed by a reduction of cytotoxicity. These aspects suggest that the hydroxyapatite nanoparticles may have clinical future applications in mineralized tissues when dental bleaching procedures are performed, contributing to the reduction of tooth sensitivity. We conclude that the new material proposed in this research has a better biocompatibility of the gel without hydroxyapatite, accompanied by a reduction of cytotoxicity, these aspects suggest that the hydroxyapatite nanoparticles may have future clinical applications in mineralized tissues in dental bleaching procedures, contributing to a reduction tooth sensitivity.

Evaluation in vitro of cytotoxicity of dentin desensitizers on human gingival fibroblasts / Evaluación in vitro de la citotoxicidad dedesensibilizantes dentinarios en fibroblastos gingivales humanos

The purpose of this study is to compare the cytotoxic effect of threematerials, which have been used for treating dental hypersensitivity. Materialand method: In vitro study. Clinpro (3M Co, St. Paul, MN. USA), Seal & Protect(Dentsply, DeTrey GmbH. Germany) and UltraEZ (Ultradent Products,Inc., S. South Jordan UT. USA) were used at concentrations of 0.1, 0.05, 0.01 and 0.001g/ml on human gingival fibroblasts. Furthermore, Clinpro and Seal & Protect were applied to this cell culture as polymerized disks. Toxicity was assessed at 24 and 48 hours by the use of the cell viability assay (MTT). Statistical analysis for cell viability was performed using two-way ANOVA and Tukey’s post hoc test. Statistical significance was set at 5 percent. Results: Seal & Protect and Clinpro were found to be highly toxic at 24 and 48 hours, reaching 70 percent toxicity at concentrations over 0.01g/ml. Seal & Protect and Clinpro polymerized disks were toxic at 24 and 48 hours. UltraEZ showed an increased between 46 percent and 67 percent in cell viability at 24 hours and between 8 percent and 45 percent at 48 hours. Statistical analysis showed differences between these three desensitizers when comparing concentration and control group (p<0.05). Discussion: UltraEZ did not have a cytotoxic effect and may be considered a compatible and safe material, whereas polymerized and non-polymerized Clinpro and Seal & Protect should be used with caution...

Introduccion: El proposito de este estudio es comparar el efecto citotoxico de tres materiales que se han utilizado para el tratamiento de la hipersensibilidad dental. Material y metodo: Estudio in-vitro. Los desensibilizantes dentinarios Clinpro (3M ESPE), Seal&Protect (Dentsply) yUltraEZ (Ultradent) fueron utilizados a concentraciones de 0,1; 0,05; 0,01 y 0,001 g/ml sobre cultivos celulares de fibroblastos gingivales humanos. Ademas, Clinpro y Seal&Protect se aplicaron a este cultivo celular como discos polimerizados. La toxicidad se evaluo a 24 y 48 horas mediante ensayo de viabilidad (MTT). El analisis estadistico para la viabilidad celular se realizo mediante ANOVA de dos vias seguido de analisis Tukey. La significancia estadistica se fijo al 5 por ciento. Resultados: Clinpro y Seal&Protect resultaron ser altamente toxicos a las 24 y 48 horas, alcanzando un 70 por ciento de toxicidad aconcentraciones superiores de 0,01 g/ml. Los discos polimerizadosde Clinpro y Seal&Protect fueron toxicos a 24 y 48 horas. UltraEZ produjo un aumento de la viabilidad celular entre un 46 por ciento y 67 por ciento a las 24 horas y entre un 8 por ciento y 45 por ciento a las 48 horas. El analisis estadistico mostro diferencias entreestos tres desensibilizantes al comparar la concentracion y su grupo control (p<0,05). Discusion: UltraEZ no tuvo efecto citotoxico y puede ser considerado como un material compatible y seguro para ser utilizado, mientras que Clinpro y Seal&Protect en su estado polimerizado y no polimerizado deberian ser utilizados con precaucion...

Cytotoxicity of 45S5 bioglass paste used for dentine hypersensitivity treatment.

OBJECTIVES: 45S5 bioglass mixed with 50% phosphoric acid has been suggested to treat dentine hypersensitivity and incipient enamel caries. This study is going to evaluate the biocompatibility of using the aforementioned technique with the rat pulpal cells. METHODS: The relative cytotoxicity of 45S5 bioglass on rat dental pulp cells was compared to the cytotoxicity of a temporary filling material (Caviton; GC, Japan), Type 1 glass ionomer cement (Fuji I; GC, Tokyo, Japan) and commercial desensitising agent (SuperSeal; Phoenix Dental, Fenton, MI, USA) using a transwell insert model. Cell viability was measured by means of a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The number of viable cell counts were compared using one way ANOVA (p<0.05). The morphological alterations of the pulp cells were observed directly by phase contrast microscope. RESULTS: The results of this study indicated that cell viability recorded by the 45S5 bioglass paste group did not differ significantly from those of the Caviton, glass ionomer or superseal, moreover pulpal cells microscopic analysis revealed that 45S5 bioglass elicited minimal toxic effect. CONCLUSIONS: 45S5 bioglass paste can serve as a biocompatible material that can potentially be used safely on dentine.

Properties of a new mouthrinse for patients receiving radiation therapy.

INTRODUCTION: Patients receiving radiation therapy due to oral cancer develop complications such as hyposalivation, mucositis, oral infections, dental hypersensitivity and caries. Mouthrinses can alleviate some of these problems. AIMS AND OBJECTIVES: To investigate the in vitro antimicrobial properties and cytotoxicity of an experimental mouthrinse. METHODS: The mouthrinse contained 30% hexylene glycol (glycerine), 7% potassium nitrate and 0.025% sodium fluoride. The minimal inhibitory concentration (MIC) of these ingredients and the mixture was determined for C. albicans, S. aureus and S. mutans over 24 hours at different concentrations. The MICs of two commercial mouthrinses, Corsodyl and Plax, were also determined using the same organisms. All mouthrinses were then tested to determine the percentage kill over 1, 2, and 3 minutes. RESULTS: The MICs for hexylene glycol were 10%, 30% and 10% for C. albicans, S. aureus and S. mutons respectively. Potassium nitrate and sodium fluoride had no antimicrobial effects. The MIC of Corsodyl was 0.016 mg/ml for all the test organisms. The MIC for Plax varied from 0.0002 mg/ml to 0.001 mg/ml. The kill rates for all mouthrinses were acceptable, with no statistical differences between them. The experimental mouthrinse was not toxic to human oesophageal SCC cells after 1 minute exposure. At the time of the experiment, the costs of a similar quantity of the experimental mouthrinse, Corsodyl and Plax were R5.24, R30.00 and R10.00 respectively. CONCLUSIONS: The experimental mouthrinse was cost-effective and proved to have an antimicrobial effect and could be used safely to alleviate oral infections, desensitize teeth, improve oral hygiene and control dental caries in cancer patients after radiation therapy.