Thermal Changes at the One-Piece Implant Surface During the Setting of Two Autopolymerized Acrylic Resins

To compare the temperature changes during the setting process of two provisional crown materials, polymethyl methacrylate (PMMA)-based acrylic resin (Ac) and bis-acryl composite resin (Co), at the first thread surface of one-piece implants.

Twenty-two 3.3-mm-diameter one-piece implants were divided into two groups according to the provisional restoration material. Implants were mounted on a Plexiglas apparatus. A K-type thermocouple was fixed at the most coronal thread. Baseline (Bl Temp) and maximal (Max Temp) temperatures of both groups were recorded during the curing process. Total heat flux (THF) at the implant surface and thermal amplitude (Temp-Amp) were calculated. Differences between groups were compared using a t test for unpaired observations.

Upon curing, a statistically significant increase in the Max Temp from the Bl Temp was detected in both groups, with a greater increase in the Ac compared with the Co group. The Temp-Amp and the THF were two times greater in the Ac group than the Co group.

Significant heat is produced during the polymerization of PMMA-based resin and bis-acryl composite resin provisional crowns in one-piece implants. To decrease the risk of thermal challenge at the implant cervical aspect associated with restoration of immediately loaded implants, bis-acryl composite resin should be used.