Introduction: The microleakage of restorative material can cause secondary caries. The application of laser for tooth preparation has been recently studied. The present study aimed to determine the ...microleakage of two types of glass ionomers in class V cavities prepared by conventional method and laser Er-YAG.Materials and Methods: A total of 28 extracted caries-free premolar teeth were selected and assigned to four groups, including Group A(preparation method: bur/restorative material: conventional glass ionomer), Group B(preparation method: bur/restorative material: resin-modified glass ionomer), Group C(preparation method: Er-YAG laser/restorative material: conventional glass ionomer), and Group D(preparation method: Er-YAG laser/ restorative material: resin-modified glass ionomer). Class V cavities with the same dimensions (in a way that occlusal margin was in enamel and gingival margin in cementum) were prepared on buccal surface of 14 teeth by bur and other 14 teeth by laser Er-YAG. Glass ionomer self-cure and resin modified glass ionomer was used for the restoration of the cavities. After thermocycling of the teeth, they were immersed for 24 h in Fushin 2%; thereafter, the samples were sectioned buccolingually at the center of each restoration and evaluated by stereomicroscope. To analyze the data, the Fisher-exact test, Kruskal-Wallis and Mann-Whitney tests were used.Results: The groups did not significantly differ in the gingival margin. There was a statistically significant difference between group B (preparation method: bur/restorative material: resin-modified glass ionomer) and other groups. According to the Mann-Whitney test, there was a significant difference between occlusal and gingival margin only in group B.Conclusion: Due to the statistically significant difference between group B and other groups in occlusal microleakage and the lower mean rank microleakage in group B, compared to that in other groups, it can be concluded that the laser method and conventional glass ionomer had higher microleakage than the conventional method and resin-modified glass ionomer.
Background and Aims: Recently, the addition of nanoparticles into the restorative materials and tooth preparation by laser for improving the bond strength have been concidered by researchers. The aim ...of this study was to investigate the shear bond strength of the bioactive glass ionomer containing titanium particles and a conventional glass ionomer with two surface treatments by Er-YAG laser and conventional methods. Materials and Methods: In this in-vitro study, 64 sound extracted premolars were collected. For conventional method, the specimens were prepared in such a way that dentin surfaces with a depth of 0.5 millimeter created at distance of 2 mm from the joint of CEJ at the root or crown. In the laser group, after preparing the teeth, the surface area was prepared by Er-YAG laser. Then, in the middle part of the buccal surface, a cylindrical mold with dimensions of 3.5 mm in diameter and 4 mm in height was placed and for each group was filled with its own glass ionomers. The specimens were divided into 8 groups by simple random sampling (n=8): A (laser, conventional glass ionomer, coronal dentin)/ B (laser, glass ionomer containing titanium nanoparticle, coronal dentin)/C (conventional, conventional glass ionomer, coronal dentin)/ D (conventional, glass ionomer containing titanium nanoparticle, coronal dentin)/ E (laser, conventional glass ionomer, root dentin)/ F (laser, glass ionomer containing titanium nanoparticle, root dentin)/ G (conventional, conventional glass ionomer, root dentin)/ H (conventional, glass ionomer containing titanium nanoparticle, coronal dentin). Finally, the shear bong strength by a universal testing machine was measured at a cross-head speed of 1 mm/min. For data analysis, Two-way ANOVA test was used to evaluate the effect of each variable and their interaction on the shear bond strength and Tukey test was used to compare the two groups. Results: There was significant difference only between groups B with C (P=0.002), E (P=0.007), G (P=0.001) and H (P=0.01). The highest bond strength was found for group B (laser, glass ionomer containing titanium nanoparticle, coronal dentin) and the lowest bond strength for group G (conventional, conventional glass ionomer, root dentin). Conclusion: All three factors of Er-YAG laser, glass ionomer containing titanium nanoparticle and coronal dentin had a positive effect on the improvement of the bond strength.
