Avaliação in vitro e in vivo de um cimento de ionômero de vidro incorporado com diacetato de clorexidina e radiado sob condições de tratamento radioterápico / In vitro and in vivo assessments of a glass ionomer cement embedded with chlorhexidine diacetate and radiated under radiotherapy conditions

RESUMO

Radiotherapy (RXT) is one of the main treatments in cases of head and neck cancer and effects of radiation, such as radiation caries, xerostomia and oral mucositis are among the most observed effects after treatment. Chlorhexidine association to glass ionomer cement (GIC) has shown effective antimicrobial activity against the Streptococcus mutans in vitro conditions. However it has only been tested without the use of radiation. The objective of this work is to study the antibacterial effect against S. mutans, the biocompatibility and the pro-inflammatory process induced by a GIC with or without incorporation of chlorhexidine diacetate (dCHX) before and after being radiated under radiotherapy treatment conditions. Test specimens were made in dimensions of 2.5 mm radius x 2 mm thick with GIC incorporated with dCHX percentages at 0%, 0.5%, 1.0% and 2.0%. Half of the samples of each concentration were irradiated with 60 Gy. Antimicrobial activity was tested after exhaustion, with daily changes of sterile distilled water for 270 days. The cytotoxicity was performed by MTT assay according to ISO 10993-5/2009. The pro-inflammatory response was evaluated histologically from the implantation of the samples in subcutaneous tissue of rats. Statistical analysis was performed by Kruskal-Wallis and Dunn tests (p <0.05). All experimental groups were able to inhibit the growth of S. mutans. Cytotoxicity was higher in irradiated groups, regardless of the percentage of incorporation of dCHX. The group without dCHX and subjected to radiation was the condition with higher pro-inflammatory effects, whereas the group with 0.05% dCHX and also submitted to radiation showed less pro-inflammatory effect was (p <0.05). Considering the limitations of this work the following conclusions can be made 1- radiation or incorporation of dCHX not interfere with the antimicrobial activity against S. mutans for up to 270 days of exhaustion; 2 - the radiation influenced the cytotoxicity, reducing cell viability in all groups, suggesting the use of GIC incorporated with less than 2% dCHX if there is submission to radiation under the conditions of this study; 3 - the proinflammatory analysis also adivse that, in radiation exposure cases, to choose the use of GIV embedded with dCHX and, otherwise, to choose GIC without dCHX.

ABSTRACT

Radiotherapy (RXT) is one of the main treatments in cases of head and neck cancer and effects of radiation, such as radiation caries, xerostomia and oral mucositis are among the most observed effects after treatment. Chlorhexidine association to glass ionomer cement (GIC) has shown effective antimicrobial activity against the Streptococcus mutans in vitro conditions. However it has only been tested without the use of radiation. The objective of this work is to study the antibacterial effect against S. mutans, the biocompatibility and the pro-inflammatory process induced by a GIC with or without incorporation of chlorhexidine diacetate (dCHX) before and after being radiated under radiotherapy treatment conditions. Test specimens were made in dimensions of 2.5 mm radius x 2 mm thick with GIC incorporated with dCHX percentages at 0%, 0.5%, 1.0% and 2.0%. Half of the samples of each concentration were irradiated with 60 Gy. Antimicrobial activity was tested after exhaustion, with daily changes of sterile distilled water for 270 days. The cytotoxicity was performed by MTT assay according to ISO 10993-5/2009. The pro-inflammatory response was evaluated histologically from the implantation of the samples in subcutaneous tissue of rats. Statistical analysis was performed by Kruskal-Wallis and Dunn tests (p <0.05). All experimental groups were able to inhibit the growth of S. mutans. Cytotoxicity was higher in irradiated groups, regardless of the percentage of incorporation of dCHX. The group without dCHX and subjected to radiation was the condition with higher pro-inflammatory effects, whereas the group with 0.05% dCHX and also submitted to radiation showed less pro-inflammatory effect was (p <0.05). Considering the limitations of this work the following conclusions can be made 1- radiation or incorporation of dCHX not interfere with the antimicrobial activity against S. mutans for up to 270 days of exhaustion; 2 - the radiation influenced the cytotoxicity, reducing cell viability in all groups, suggesting the use of GIC incorporated with less than 2% dCHX if there is submission to radiation under the conditions of this study; 3 - the proinflammatory analysis also adivse that, in radiation exposure cases, to choose the use of GIV embedded with dCHX and, otherwise, to choose GIC without dCHX.