vigilância epidemiológica da fluorose dentária em município de clima tropical com água de abastecimento público fluoretada Epidemiological surveillance of dental fluorosis in a city with a tropical climate with a fluoridated public drinking water supply

Objective: To evaluate the surface hardness of a national glass ionomer cement with increased powder / liquid ratio, suitable for the atraumatic restorative treatment technique. Material and Methods: This is a study of the quantitative experimental type, in which 30 specimens were made and divided equally into 03 experimental groups (glass ionomer cement restorative Vitro Molar -DFL in the proportion specified by the manufacturer; glass ionomer cement restorative Vitro molar ratio -DFL modified with incorporation of 50% powder; and Gold Label 9 -GC Corporation in the proportion specified by the manufacturer). After handling, the materials were placed in a Teflon mold for manufacturing the cylindrical samples (5mm x 2 mm), with the aid of a Centrix syringe (Centrix, Shelton, CT, USA). Specimens were stored in liquid petroleum jelly at a temperature 37 ° ± 1 for up to 7 days. The specimens were evaluated by Vickers hardness test at time intervals of 24 hours and 7 days after manufacture. The data were subjected to the Independent Student's-t tests and analysis of variance (ANOVA), and subsequently by Tukey's test at 95% level of significance. Results: The setting time positively influenced the hardness of the two glass ionomer cements (p<0,001). Cement Gold Label 9 showed higher hardness values than cement Vitro Molar (p<0,001), irrespective of the evaluation time interval. The latter in turn, showed improved values when manipulated with the modified powder / liquid ratio (3: 2) (p<0,001). Conclusion: Vitro Molar glass ionomer cement showed higher hardness values when manipulated with the modified powder/liquid ratio.