Objective: To evaluate student perception of early simulation in dentistry. Material and Methods: The design of the study was quantitative, observational and cross-sectional. A total of 121 students, from third year to senior year were evaluated. The perception and its dimensions: satisfaction, self-confidence and good educational practices were evaluated by a survey with a high level of reliability (0.89), modified and adapted for the present investigation, checking coefficients for its use: Aiken's V, Cronbach's Alpha, Test-Retest (Spearman), classified in ability, scenario and general simulation practices, based on the Likert scale (from 1 to 5). For the univariate analysis, the descriptive statistics from qualitative and quantitative variables were obtained and for the bivariate analysis, Spearman's rank correlation coefficient and Kruskal Wallis and Mann-Whitney U-tests were employed. Results: The students rated the simulation perception positively with anaverage of 4.42±0.49, 4.14±0.63 y 4.73±0.66 regarding the ability, scenario and general simulation practices, respectively. No statistically significant differences were found between the perception of early preclinical practices with the variables age, gender, year of study and previous experience. Conclusion: The perception of students regarding early preclinical practices got a high score and it is not related with the variables studied, according to the survey modified and adapted.

Objective: To compare the adhesive strength in dentin of three universal adhesive systems in vitro by means of the shear test. Materials and methods: Seventy-five bovine teeth were selected and cut. Dentin was exposed from the buccal surface of the crowns with 220 grit sandpaper, and samples were then inserted in transparent acrylic bases (15x10mm). The samples were randomly divided in 3 groups (n=25): G1-Universal adhesive system Scotchbond™ Universal (3M ESPE-USA); G2-Universal adhesive system Peak Universal Bond (Ultradent); G3-Universal adhesive system Tetric N-Bond (Ivoclar Vivadent). The adhesive procedures were carried out according to the instructions of each manufacturer and the restorative procedures were carried out with micro-cylinders (made of Tygon type tubing 0.79x1.5mm) of the composite resin Filtek™ Z350XT-A2 (3M ESPE-USA). The samples were incubated at 37ºC (+/-5ºC) for 24 hours. Adhesive strength was evaluated in a universal test machine by means of the shear test (0.5mm/ min, 500N) and the resulting fracture type was evaluated with a Dinolite digital microscope (x200). The results were analyzed by descriptive statistics (Mean±SD), and inferential statistics by a one-way ANOVA. Results: No statistically significant differences were found between the universal adhesive systems evaluated G1 (14.91±4.76), G2 (16.90±4.11) and G3 (17.34±4.04)/(p=0.114). Conclusions: The shear test resulted in similar values of immediate adhesive strength of the three universal adhesive systems used.