Method: Twenty sound human molars were selected to obtain forty fragments of 4x4mm. The fragments were randomly assigned to 4 groups (n=10) according to the enamel surface treatment: G1- no treatment – control, G2 – CO2 laser irradiation, G3 – no treatment + brushing and G4 – CO2 laser irradiation + brushing. The laser device emitting at 10.6 mm wavelength was used, the parameter settings used were: power 0.5W, energy per pulse 0.05mJ, frequency of 10KHz. At G3 and G4 specimens were brushed for 80,000 strokes in a reciprocal action brushing simulator using toothpaste. After surface treatment, the samples were submitted to challenge with acid consisting of a 5-day immersion in demineralizing (6 h) and remineralizing solution (18 h). Next, the specimens were longitudinally sectioned and polished and the enamel demineralization was quantitatively evaluated by cross-sectional microhardness tests. Three indentations were made at 10, 30, 50, 90 and 110 μm from the outer enamel surface. Microhardness indentations were made using a Knoop diamond under a 25-gram load for 5 s. The mean values at all 5 measuring points were then averaged. The area under the curve (KHNxμm) was calculated by numerical integration using the trapezoidal rule. ANOVA one-away and Fisher’s test were performed for the statistical analysis (p<0.05).
Result: The group G2 (31,185 ±4,706) was statistically different from the groups G1 (26,723 ± 2,446), G3(28,194 ±1,376) and G4(28,207 ±2,234) which were statistically similar.
Conclusion: From the results of the present in vitro study it may be concluded that the time of brushing used probably promote a wear in the CO2 lased enamel and them the prevention of demineralization was not observed at brushed group.
Keywords: Cariology, Demineralization, Enamel and Lasers
See more of: Cariology Research - Demin/Remineralization