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Evaluation of the Biocompatibility of the at-home dental bleaching and therapies for reduction of the deleterious effects caused by the bleaching agents on the pulp tissue: in vitro and in vivo studies

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Author(s):
Adriano Fonseca de Lima
Total Authors: 1
Document type: Doctoral Thesis
Press: Piracicaba, SP.
Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba
Defense date:
Examining board members:
Giselle Maria Marchi; Mônica Campos Serra; Marcelo Tavares de Oliveira; José Augusto Rodrigues; Mário Alexandre Coelho Sinhoreti
Advisor: Carlos Alberto de Souza Costa; Giselle Maria Marchi
Abstract

The objectives of the present study were: a) to evaluate the cytotoxic effects of consecutive applications of a bleaching agent based on 10% cabamide peroxide (CP) on odontoblastic cells; b) to evaluate the "in vivo" toxicity of the bleaching treatment on the pulp tissue of Wistar rats; c) to evaluate if the ascorbic acid (AA) is capable to reduce the toxic effects of the bleaching treatment to the dental pulp of the Wistar rats; d) to analyze the efficacy of the lasertherapy with different patterns on the odontoblastic cell response, in face of the deleterious effects caused by the bleaching agents. At the Chapter 1, the toxicity of consecutive applications of a 10%CP gel and 35% hydrogen peroxide (HP) on odontoblast--like cells was evaluated. The cells were exposed to the bleaching products for 1h during 1 or 5 days, and the cell metabolism, alkaline phosphatase (ALP) activity and cell membrane damage were evaluated. It could be observed that 1 application of 10%CP did not cause deleterious effect to the odontoblastic cells, however, consecutive applications caused severe toxicity to these cells. Both 10%CP and 35%HP promoted reduction on the ALP activity. At the Chapter 2, the aim was to evaluate if AA would be able to reduce the inflammation caused by the bleaching agents on the dental pulp of Wistar rats. Groups were formed with and without AA administration, and the solutions were applied 1h and 30min before the bleaching procedure. Pulp necrosis was observed 6h and 24h after bleaching. The AA was not capable to prevent the tissue necrosis, however, faster tissue repair was observed in the dental pulp of the animals treated with AA. At the Chapters 3 and 4, were evaluated if 3 or 1 lasertherapy sessions would modulate the cell response after exposition to bleaching agents. The cells were exposed to the bleaching agent, and the lasertherapy was performed after this (InGaAsP - 780nm-- doses 4, 10 e 15 J/cm²), with interval of 24h between each session. The bleaching reduced the cell metabolism and ALP activity, and the lasertherapy was not able to influence positively the cell metabolism. Nevertheless, the energy dose of 4 J/cm² increase the ALP activity on cell with or without exposition to bleaching agente when 3 session of laser were performed. The lasertherapy was not capable to modulate the cell metabolism, ALP activity and gene expression of ALP and colagen--I (COL--I). Nevertheless, one session of laser irradiation decreased the gene expression of fibronectin (FN), on the cells without exposition to bleaching agent. It can be concluded that consecutive applications of 10%CP can cause extensive damage to the MDPC--23 cells; HP35% caused pulp necrosis at the teeth of the Wistar rats, and AA was not capable to prevent the damages caused by the bleaching treatment; one application of the laser, in the energy doses evaluated, was not capable to modulate the cell response after bleaching. Three applications of laser with the energy dose of 4 J/cm² increased the ALP activity produced by the odontoblast--like cells (AU)

FAPESP's process: 09/08992-7 - Effect of direct and trans-dentinal application of low level laser on odontoblast cells exposed to bleaching agents
Grantee:Adriano Fonseca de Lima
Support Opportunities: Scholarships in Brazil - Doctorate