No abstract

Objective: To evaluate the surface characteristics of restorations performed after simulated toothbrushing and to compare the results between the composites. Materials and Methods: In total, 80 samples were made (7 mm × 4 mm) from the composites: Bulk Fill One, Bulk Fill Flow, Z350 XT, and Z350 XT flow (3M/ESPE, St. Paul, MN, USA). Half of the specimens was submitted to 60,000 cycles of simulated toothbrushing, while the other half was the control group (n = 10). The surface was evaluated through Scanning electronic microscopy (SEM), surface roughness (Ra), and weight loss, before and after the simulated toothbrushing. To evaluate the statistical analysis, a two-factors variance test and the Tukey's posttest were performed. Results: In the analysis performed by SEM, it was observed the presence of both small and medium protruding particles in all groups after simulated toothbrushing, with the exception of the group which used Z350 flow composite. All materials presented increasing on Ra after simulated toothbrushing. Regarding weight variation, there was not any significant statistical difference in all materials. Conclusions: The abrasive process occasioned by toothbrushing leads to changes on the particles' disposition, which causes changes on the surface and increase on the Ra. On the other hand, there was not any difference regarding to weight variation.

Introduction: The roughness of glass ionomer cement (GIC) is a limitation that interferes with its mechanical and aesthetic performance, and it is necessary to use appropriate finishing and polishing procedures in restorations produced with this material. Objective: To evaluate the effect of different finishing and polishing systems on roughness, hardness and surface of restorations performed with two types of GIC. Material and method: 100 specimens were made and divided into 10 groups, according to the type of GIC (conventional and resin modified GIC) and the finishing and polishing system used (C (Control) -Mylar strip; PD -diamond burs; DA -abrasive disks; PE -Enhance system; BM -carbide burs). After 7 days in distilled water, the specimens were evaluated by Scanning Electron Microscopy (SEM) and submitted to surface roughness and Vickers microhardness tests. Statistical analysis was performed by two-way ANOVA and Tukey post-test. Result: SEM analysis demonstrated a smoother surface in BM group in both types of GIC. Regarding roughness, a statistically significant difference (p <0.05) was observed between some groups of conventional GIC, but there was no difference between GIC types. Regarding hardness, conventional GIC showed better results than resin-modified GIC; Concerning to finishing and polishing materials factor, there was no statistically significant difference, regardless of the type of GIC. Conclusion: BM groups presented better results on SEM; The type of GIC did not influence the roughness values; The type of polishing did not influence the hardness.

Introduction One of the most common treatments of head and neck cancer patients is radiotherapy, a treatment method which uses ionizing radiation beam and destroys tumor cells, minimizing damage to neighbor cells. Purpose To evaluate the bond strength of a conventional adhesive system in irradiated teeth. Method 24 third human molars, 12 of which were randomly exposed to radiation and prepared from the removal of occlusal enamel, then exposed to a flat dentine surface. The adhesive system Stae was applied according to the manufacturer’s instructions. Next, two 2 mm increments of resin were implemented. The samples were hemi sectioned specimens, originating shapped toothpick. To evaluate the bond strength, a micro tensile test was done with 500N load and speed of 0.5 mm/minute. Result There was no statistically significant difference between the bond strength of teeth which were or were not exposed to radiation and which used a conventional adhesive system. Conclusion Although the radiation doses applied may cause some alterations in microscopic range in dental tissues, it can be concluded that these alterations do not influence in the bond strength in dentin of irradiated teeth.