Effects of Laser and Preventive Treatments on Root Caries Prevention

Objectives: The aim of this study is to evaluate the preventive effects of Er,CR:YSGG laser, 5% NaF varnish, a new calcium-phosphate based material Teethmate Desensitizer (TMD) and their combinations on root dentin demineralization in vitro.
Methods: 98 human third molar collected and crowns were seperated from cemento-enamel junction. Cementum was removed by carborundum discs (3M, Espe, USA). Root dentin samples sealed by two layers of acid resistant nail varnish except of a 4x4 mm² window and than divided into 7 groups: Group 1: no treatment/intact dentin (negative control), Group 2: only pH cycling group/artifical caries (positive control), Group 3: 5% NaF varnish, Group 4: TMD, Group 5: Er,Cr:YSGG laser (4.4 J/cm²), Group 6: laser+NaF, Group 7: laser+TMD. After preventive treatments were done, samples submitted to 18 days of pH cycling in an oven at 37 ˚C. And then the samples were sectioned bucco-lingualy through middle of the window and cross-sectional microhardness testing was performed by Knoop Hardness at 20, 50, 80, 110, 140, 170, 200 μm depths from the outer dentin surface. Surface morphology is analyzed by SEM and AFM. Statistical analyses were done by Levene's Test for Homogeneity and Tukey’s Studentized Range test.
Results: Knoop hardness of Group 6 was statistically higher than other groups at 20, 50, 80, 110, 140 μm (p<0.05). No statistically significant differences were found between group 1 and group 6 at 170 μm; group 1, group 6 and group 7 at 200 μm (p>0.05). Partially tubular occlusion and CaF₂ like formations on dentin surface of experimental groups were verified by AFM and SEM images.
Conclusions: Within the limitations of this study, combination of Er,Cr:YSGG laser irradiation at 4.4 J/cm² and 5% NaF varnish can increase the acid resistance of human root dentin.