Adjustment of cast metal post/cores modeled with different acrylic resins

Aim: Evaluate the performance of four commercially available chemically-activated acrylic resins (CAARs) by measuring the level of displacement of the cores following casting. Materials and Methods: Two devices were constructed to model the cores based on a natural tooth. Forty post/cores were modeled, 10 in each of the following CAARs: Duralay (Reliance Dental, Illinois, USA), Pattern Resin (GC, Tokyo, Japan), Dencrilay (Dencril, Sao Paulo, Brazil), and Jet (Clássico, Sao Paulo, Brazil). Two casting rings were included,each of which contained 5 post/cores for each of the four CAARs tested, a total of 20 per ring. Following casting, the specimens were only sandblasted and separated from the feeding channels. The post/cores wereplaced in device 1 and, with the aid of an optical microscope, were attached to a digital camera. Images were then taken of the adjustment between the core and the remaining tooth on the labial surface. The images wereprocessed using the Image Tool for Windows, version 3.0, measuring three fixed points in each specimen. Data were statistically analyzed using the ANOVA and Tukey test. Results: The 40 post/cores were dividedinto eight groups according to resin brand and casting, obtaining the following results for mean and standard deviation (in mm): Dencrilay 0.192 CI (± 0.08), CII 0.058 (± 0.03); Duralay CI 0.097 (± 0.03), CII 0.131 (±0.06); Pattern CI 0.07 (± 0.03), CII 0.10 (± 0.05); and Jet CI 0.06 (± 0.02), CII 0.382 (± 0.17). Statistically significant differences could be identified when comparing the Dencrilay CI and the Jet CII with the remaining groups, which all proved to be unfavorable. Conclusion: The quality of cast metal post/core adjustment is not associated with the use of a specific acrylic resin.Uniterms: Post and core techinique. Acrylic resins.