RESUMO
This study was conducted to measure the activity of the enzyme glutathione S-transferase (GST) in saliva and to compare the activity of this enzyme in children with and without dental fluorosis in communities with different concentrations of naturally fluoridated water. A total of 141 schoolchildren participated in this cross-sectional study. Children were selected from two communities: one with a low (0.4 ppm) and the other with a high (1.8 ppm) water fluoride concentration. Dental fluorosis was evaluated by applying the Thylstrup and Fejerskov Index (TFI) criteria. Stimulated saliva was obtained, and fluoride concentration and GST activity were measured. The GST activity was compared among children with different levels of dental fluorosis using multinomial logistic regression models and odds ratios (OR). The mean age of the children was 10.6 (±1.03) years. Approximately half of the children showed dental fluorosis (52.5 %). The average GST activity was 0.5678 (±0.1959) nmol/min/µg. A higher concentration of fluoride in the saliva was detected in children with a higher GST activity (p = 0.039). A multinomial logistic regression model used to evaluate the GST activity and the dental fluorosis score identified a strong association between TFI = 2-3 (OR = 15.44, p = 0.007) and TFI ≥ 4 (OR = 55.40, p = 0.026) and the GST activity level, compared with children showing TFI = 0-1, adjusted for age and sex. Schoolchildren with higher levels of dental fluorosis and a higher fluoride concentration in the saliva showed greater GST activity. The increased GST activity most likely was the result of the body's need to inactivate free radicals produced by exposure to fluoride.
Assuntos
Água Potável/química , Fluoretação , Fluoretos/metabolismo , Fluorose Dentária/diagnóstico , Glutationa Transferase/metabolismo , Western Blotting , Catalase/metabolismo , Criança , Estudos Transversais , Feminino , Fluorose Dentária/enzimologia , Humanos , Modelos Logísticos , Masculino , México , Análise Multivariada , Razão de Chances , Saliva/química , Saliva/enzimologia , Superóxido Dismutase-1/metabolismoRESUMO
Dental fluorosis is common in individuals exposed to different sources of fluoride during tooth development. The mechanism causing this enamel defect is still unknown. Enamel matrix proteinases play a central role in the maturation of dental enamel, and inhibition of these enzymes by fluoride has been one explanation for dental fluorosis. We have investigated the effect of fluoride on the activity of enamel matrix proteinases using a colorimetric assay, casein zymography, and an enamel protein degradation assay. Fluoride (625 microM to 10 mM) inhibited neither the enzymatic activity of the crude matrix extract nor the activity of individual enamel enzymes separated by SDS-PAGE. The proposition that fluoride could directly inhibit enzymes was not confirmed in this study.