Marginal Accuracy of Provisional Restorations Fabricated From Acrylic Resins

Objectives: to evaluate the marginal accuracy of crowns fabricated from acrylic resins and to identify the surfaces with higher values of marginal discrepancy.
Methods: A direct technique was used to fabricate 96 provisional restorations with 8 materials: Dencrilay, Dencôrlay, Dencôr, Vipicor, Duralay, Resinlay Speed, Refine Bright and Alike (n=12). The provisional crowns were made on a prepared molar-shaped metal die with a vinyl polysiloxane impression as a matrix. The acrylic resins were manipulated according to the manufacturer's recommendations and then inserted into the impression. The specimens were adapted into the metal die and evaluated using astereoscopic microscope with 100x magnification. This metal die received three markings in each surface (mesial, distal, buccal and lingual) using a diamond bur. The images were transferred to the Corel Draw X7 software, and the distance between the cervical margin of the provisional crowns to the markings were vertically measured. Twelve readings were recorded for each sample (three for each surface).
Results: Statistical analysis was performed using ANOVA and Tukey (p <0.05) tests. The Alike resin showed the lowest average (0.018 mm) and differed from the Dencôrlay (0.037 mm), Refine Bright (0.034 mm), Duralay (0.033 mm) and Vipicor (0.032) resins. The buccal surface showed higher values of marginal discrepancy (0.040 mm) in comparison with the other tested surfaces.
Conclusions: The marginal adaptation of all materials and surfaces tested in this study were within a clinical acceptable limit. The Alike resin showed the best performance compared to Dencôrlay, Refine Bright, Duralay, and Vipicor resins. The buccal surface showed the most marginal discrepancy.