Evaluation of the effects of newly developed Er,Cr:YSGG laser system on primary tooth dentine

The aim of this study was to evaluate the surface morphology of cavities etched with or without phosphoric acid following preparation with either Er,Cr:YSGG laser or conventional burs and to compare the thickness of hybrid layer as well as the degree of nanoleakage determined by the amount of silver ions within hybrid layerThe primary teeth were randomly allocated to 4 groups consisting of 10 samples: Laser (Group 1), Laser+acid (Group 2), bur (Group 3) and bur+acid (Group 4). Standard class V cavities were prepared. 35% phosphoric acid gel was applied if it was indicated according to group regimen. Following application of Single Bond, restorations of all samples were completed. Then, teeth were sectioned and the sections were immersed to ammoniakal silver nitrate solution. After polishing, surface morphology and hybrid layer thickness were examined under SEM and the ion analysis was carried out with SEM-EDX in terms of nanoleakage. Since, hybrid layer was not observed in Groups 1 and 3, line scan method was used. The hybrid layer thickness and the amount of silver ions within hybrid layer were assessed at the acid etched groups. The collected data were statistically evaluated with one-way ANOVA and Spearman correlation coefficient and intra-and inter-group comparisons of the relationship between the increase of hybrid layer thickness and the amount of silver ions and any difference with respect to hybrid layerIn the laser+acid and bur+acid groups, the mean values of the hybrid layer thickness were 4.25±1.41 µm and 5.24±1.07 µm respectively. In these groups, the silver ion percentages were 10.97±13.81% and 22.79±21.62% respectively. The hybrid layer thickness in bur-etch cavities was statistically greater than laser-etch cavities. The amount of silver ion particles in bur-etch cavities was statistically greater than laser-etch cavities (P<0.05). Although no significant correlation was observed between the increase of hybrid layer thickness and the amount of silver ions, more silver ions were observed in bur+acid group. Line scan analysis revealed that the amount of silver ions at resin-dentine interface increased in groups 1 and 3In the surface morphology evaluations, surfaces prepared with laser (Groups 1 and 2) were observed rough and without smear layer, dentin tubules were exposed and resin tags were increased. In bur cavities the cavity was well performed and in the non-etched group smear layer and gap were observedIn conclusion, resin-dentin bond was found best in laser prepared and acid etched group (Group 2) and worst in bur prepared group (Group 3).