Evaluation of the Genotoxicity of Endodontic Materials for Deciduous Teeth Using the Comet Assay

ABSTRACT Objective: To evaluate genotoxicity of zinc oxide, P. A. calcium hydroxide, mineral trioxide aggregate and an iodoform paste using comet assay on human lymphocytes. Material and Methods: Two positive controls were used: methyl-methanesulfonate for the P.A. calcium hydroxide and mineral trioxide aggregate; and doxorubicin for the iodoform paste and zinc oxide. There were also two negative controls: distilled water for the P.A. calcium hydroxide and mineral trioxide aggregate; and DMSO for the iodoform paste and zinc oxide. Comets were identified using fluorescence microscopy and 100 of them were counted on each of the three slides analyzed per drug test. A damage index was established, taking into consideration the score pattern that had previously been determined from the size and intensity of the comet tail. Analysis of variance, followed by Tukey's test, was used to compare the means of the DNA damage indices. Results: The DNA damage index observed for mineral trioxide aggregate (7.08 to 8.58) and P.A. calcium hydroxide (6.50 to 8.33), which were similar to negative control index. On the other hand, damage index for zinc oxide (104.7 to 218.50) and iodoform paste (115.7 to 210.7) were similar to positive control index. Conclusion: Iodoform paste and zinc oxide showed genotoxicity at all concentrations used.

DNA damage in buccal cells in oral PMDs and malignant disorders by comet assay: a comparison with blood leukocytes

Aim: DNA damage associated with Oral Squamous Cell Carcinoma (OSCC) and potentially malignant disorders (PMDs) is produced due to carcinogenic agents or increased oxidative stress. Comet assay can assist in early detection and evaluation of the amount of DNA damage; lymphocytesare the most commonly used cells for performing comet assay. Utilisation of buccal epithelial cells in comet assay can be a minimally invasive and rapid method. The present study compared the efficacy of comet assay in assessing DNA damage in buccal cells over peripheral blood leucocytes (PBLs) in oral potentially malignant and malignant disorders. Methods: The study included fifty five patients each of Leukoplakia, Oral Submucous Fibrosis (OSMF) and OSCC along with fifty five healthy individuals as control. Buccal epithelial cells were collected from all the selected subjects. DNA damage was evaluated bymeasuring the mean tail length (µm). Results: A significantly increased mean tail length (µm) and higher DNA damage were found in OSCC (26.1096 + 1.84355) and there was a progressive stepwise increase in mean tail length from control(8.4982 + 0.93307) to PMD [leukoplakia (14.6105 + 0.71857); OSMF (12.5009 + 1.12694)] to OSCC.The mean tail length in different habit groups was greater than controls, though no significant difference was noted between habit groups. The mean tail length of buccal cells was significantly greater than the mean tail length of PBLs in all study groups and controls. Conclusion: Hence, use of comet assay on buccal epithelial cells can prove to be beneficiary for evaluation of DNA damage

Influência do tempo após manipulação na citotoxicidade e genotoxicidade de diferentes cimentos endodônticos / Influence of time after manipulation on cytotoxicity and genotoxicity of different root canal sealers

Objetivo deste estudo foi avaliar a citotoxicidade e a genotoxidade de quatro cimentos endodônticos: AH Plus (Dentsply De Trey, Alemanha); Endo Rez (Ultradent, USA); RoekoSeal (Coltene Whaledent, Alemanha) e o Cimento experimental à base de óleo-resina de Copaiba (Brasil). A avaliação foi realizada em três diferentes tempos após manipulação: 0h,12h e 24h. Os espécimes foram preparados, deixados por 12 e 24h emestufa (37 °C a 100% umidade a 5% de CO2) e colocados em contato com meio de cultura (82,4 mm2 superfície/ml) por 24 h. Células V79 foram expostas à diferentes diluições dos cimentos por 24 h e a viabilidade celular foi mensurada pelo teste de MTT em espectrofotômetro. Para o teste de genotoxicidade os extratos que apresentaram concentrações de citototoxicidade média foram selecionados para o teste cometa após 24 h de exposição. A viabilidade celular e o dano ao DNA foram comparados aos grupos controles e analisados pelos testes de Kruskal-Wallis e Dunn(p<0,05). No teste de citotoxicidade, todos os cimentos presentaram diferença significativa em relação ao controle, com exceção doRoekoSeal. A viabilidade celular de acordo com cimento utliizado pode ser classificada da maior toxicidade para a menor seguindo: EndoREZ >AH Plus > Copaíba > RoekoSeal. O dano ao DNA verificado no teste cometa pode ser classificado do maior para o menor em: EndoREZ > RoekoSeal > AH Plus > Copaíba. Conclui-se que o cimento EndoREZ é citotóxico e genotóxico nos tempos e diluições estudadas

The aim of this study was to evaluate cytotoxicity and the genotoxicity offour different root canal sealers, AH Plus (Dentsply De Trey, Germany); Endo REZ (Ultradent, USA); RoekoSeal (Coltene Whaledent, Germany) and the experimental root canal sealer based on Copaiba oil-resin sealer (Brazil). The evaluation of the materials was performed after three different times of manipulation: 0h, 12h and 24h. The specimens were prepared, incubated in a humidified incubator (37°C with 5% CO2 in air for 12h and 24h) and them put in contact with the culture medium (82,4 mm 2surface/ml) during 24h. V79 cells were exposed at different dilutions of the sealers during 24h and the cell’s viability was measured by the MTT test in a spectrophotometer. For the genotoxicity tests, the extracts from the concentrations with medium citotoxicity were selected for the cometassay after 24h of exposure. The cellular viability and the DNA damage were compared with the control groups and analyzed by the tests of Kruskal-Wallis and Dunn (p<0,05). The citotoxicity test showed that all root canal sealers showed a statistically significant difference when compared with the control group, with the exception of the RoekoSeal. The ranking of cell’s viability according with sealer utilized from the most to the least toxicic material was: EndoRez > AH Plus > Copaíba > RoekoSeal. Theranking of DNA damage verified at the comet assay, from the most to theleast was: EndoREZ > RoekoSeal > AH Plus > Copaíba. It was conclude that, at the times and dilutions studied, the EndoREZ sealer is genotoxicand citotoxic

DNA damage in viscose factory workers occupationally exposed to carbon di-sulfide using buccal cell comet assay

Aim: The most important industrial use of carbon disulfide (CS2) has been in the fabrication of regeneratedcellulose rayon by the viscose process and cellophane. CS2 leads to increased frequency of chromosomal aberrations in workers with occupational exposure to CS2. Methods: In the present study, the DNA damage was analyzed by using buccal cell comet assay for 30 viscose plant workers who are occupationally exposed to CS2 and 30 healthy individuals. Both groups were classified as smokers and non-smokers and only the experimental subjects were classified based on the exposure period. The data were analyzed statistically bythe Student’s t-test. Results: The results of this study showed increased levels of DNA damage among viscose plant workers. Conclusion: The habit of cigarette smoking among the viscose workers had a synergistic effect on inducing DNA damage.