Abstract
Objectives:Production of acids such as lactic acid contributes to establish a cariogenic environment that leads to dental substrate demineralization. Fluoride plays an important role in this case and, as fluoride-releasing materials, glass-ionomer cements are expected to contribute to minimize deleterious reactions. This study evaluated interactions of glass-ionomer cements used in atraumatic restorative treatment (ART-GICs) with an aqueous lactic acid solution, testing the null hypotheses that no changes occur in the pH of the solution or on the surface roughness and mass of the ART-GICs when exposed to lactic acid solution over a 6-week period.Material and Methods:Ketac Molar, Fuji IX, Vitro Molar and Magic Glass were tested, and compared to Filtek Z250 and Ketac Fil Plus as control groups. Six specimens of each material were made according to manufacturers' instructions. The pH of the solution and roughness and mass changes of each specimen were determined over 6 weeks. Each specimen was individually stored in 2 mL of 0.02 M lactic acid solution for 1 week, renewing the solution every week. pH of solution and mass of the specimens were monitored weekly, and surface roughness of the specimens was assessed before and at the end of the 6-week acid challenge. pH and mass data were analyzed statistically by repeated measures using one-way ANOVA and Tukey's post-hoc tests for each material. Paired t-tests were used for roughness analysis. Tukey's post-hoc tests were applied to verify differences of final roughness among the materials. Significance level was set at 5%.Results:The null hypotheses were partially rejected. All materials were able to increase the pH of the lactic acid solution and presented rougher surfaces after immersion, while mass change was minimal and generally not statistically significant.Conclusions:These findings can be helpful to predict the performance of these materials under clinical conditions. A protective action against the carious process with significant surface damage due to erosion may be expected.
Highlights
Atraumatic restorative treatment (ART) is a dental approach based on the removal of carious tissue with hand instruments followed by placement of an adhesive restoration[2,7,24,29]
Since conventional Glass-ionomer cement (GIC) are not indicated for restoring stress-bearing contact areas[5,14,22,25,26,30], some types of GICs have been formulated for ART restorations
The anticariogenic capacity is a relevant property of GICs and it is expected that the interaction of these materials with an acidic environment will lead to pH increase[10,17-19] Under the present experimental conditions, all tested GICs were able to increase the initial pH of the acid lactic solution, though a progressive decline of this ability occurred for all materials over time
Summary
Atraumatic restorative treatment (ART) is a dental approach based on the removal of carious tissue with hand instruments followed by placement of an adhesive restoration[2,7,24,29]. It is recommended by the World Health Organization (WHO), mainly in communities with poor financial resources and for people who have physical disabilities or are fearful[2,7,24,29]. When sugar is available in the oral environment, microorganisms produce organic acids such as lactate and acetate[23] Another relevant factor involved in caries progression is related to the low pH generated from carbohydrate metabolism that selects cariogenic species[3,23]. Resistance to biodegradation is a highly desirable property of dental materials to allow for satisfactory clinical performance
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