The aim was to compare the enamel surface roughness (ESR) and absolute depth profile (ADP) (mean peak-to-valley height) by atomic force microscopy (AFM) before and after using four different phosphoric acids. A total of 160 enamel samples from 40 upper premolars were prepared. The inclusion criterion was that the teeth have healthy enamel. Exclusion criteria included any of the following conditions: facial restorations, caries lesions, enamel hypoplasia and dental fluorosis. Evaluations of the ESR and ADP were carried out by AFM. The Mann-Whitney U-test was used to compare continuous variables and the Wilcoxon test was used to analyze the differences between before and after etching. There were statistically significant differences (P

The aim of this study is to evaluate the maximum and minimum distances between the model and the cast crown of three techniques using Scanning Electron Microscopy (SEM). Three technique groups were used for this study: group A (control), traditional manual wax patterns; group B, dipping wax patterns; group C, resin patterns made with CAD/CAM. For each group, 10 samples were made using the same model, and then metal cast. Marginal accuracies of the samples were evaluated by performing gap measurements using SEM with a magnification of 1200× (minimum distance). The data were statistically analyzed using the one-way analysis of variance (ANOVA) at the 0.05 significance level. The average (standard deviation) of the minimum distance [µm] was 22.5 (12.1), 9.9 (4.3), and 14.7 (6.6), in groups A, B, and C, respectively. The average standard deviation of gap area [µm 2 ] was 21667.2 (3476.4), 9906.4 (1512.1), and 16048.8 (8123). In the minimum distance comparison, groups A and B (p = 0.006) showed statistically significant results. In the gap area comparison, there was no statistical significance among groups A, B, and C (p = 0.174). The marginal adaptations of all three techniques were within a reported clinically acceptable range of margin.