INTRODUCTION: The dimensional stability of acrylic resins influences the temporary crowns fitting and can affect the final restoration results. OBJECTIVE: To evaluate the long-term dimensional stability of an acrylic resin used for fabrication of provisional crowns. MATERIAL AND METHOD: Five types of processing techniques were evaluated: I - thermal polymerization using fast polymerization liquid and flask; II - auto-polimerization under pressure in a stainless steel matrix; III - auto-polimerization using the bead brush technique to build the sample; IV - auto-polimerization after mixture (powder + liquid) in a dappen dish and insertion in a stainless steel matrix at the sand stage; V - auto-polimerization after mixture in a dappen dish with insertion in a stainless steel matrix at the plastic stage. For each type of processing technique, 10 samples were made. Dimensional stability was evaluated by means of a steel matrix made following the ADA specification nº19. The samples were stored in distilled water at 37 ºC and examined at the periods of 1 hour, 1, 7, 15, 30, 90 and 180 days, with an optic microscope with 20× magnification. The results were subjected to the 2-way analysis of variance (Tukey Test) at the significance level of 5% for the variables Time and Processing Technique. RESULT: All samples had dimensional alterations from day 7 to the day 15, regardless of the technique used. From day 15 to 180, there were no statistically significant dimensional alterations. CONCLUSION: The dimensional stability of the acrylic resin was not influenced by the different processing techniques tested, however, it was influenced by the storage time.
Denture, partial, fixed; dental marginal adaptation; dental restoration, temporary; polymethyl methacrylate