Heat transfer of impression plasters to an implant-bone interface.
PURPOSE: The purpose of this in vitro study was to measure heat generated at the implant-bone interface caused by exothermic setting reaction of 2 impression plasters. MATERIALS AND METHODS: The study consisted of 20 titanium-alloy abutment impressions connected to a titanium-alloy cylindrical implant embedded in an acrylic-resin mandible in a 37 degrees C water bath. There were 2 types of impression plaster used, Snow-White (Kerr, Romulus, MI) and Xantano (Kulzer, Dormagen, Germany). Temperature changes were recorded via embedded thermocouples at the cervix and implant surface apex. Analysis of variance for repeated measures was used to compare 2 treatment groups. RESULTS: Temperature increased less at the implant apex (1.5 degrees-2.1 degrees C) than at the implant cervix (7.4 degrees-10.5 degrees C). Differences between the 2 impression plasters were statisticallysignificant only at the implant cervical level (P < 0.05). A lower temperature increase was shown with the Snow-White compared with the Xantano. Although both plasters generated an exothermic reaction on setting (mean temperature change 22 degrees C), the increase in the temperature rate of the Snow-White was slower than the Xantano. CONCLUSIONS: Under the conditions of the present study, Snow-White impression plaster appears to be safer to use in implant prosthodontics compared with the Xantano because of its slower and lower exothermic reaction at the implant-bone interface. However, use of the material with the rapid setting time would require more care, such as limiting the volume of material used (e.g., by using a custom tray).