The Effect of Time Intervals on Heat Transfer to the Implant-Bone Interface during Preparation of a Titanium Abutment: An in Vitro Study

Statement of Problem: Thermal injury during dental implant placement and restoration is a clinical concern as it may cause bone damage and compromise osseointegration. The threshold level for heat-induced cortical bone necrosis is 47°C for 60 seconds. Objectives: To measure the amount of heat transferred to the implant-bone interface when a two-piece or one-piece abutment was prepared in vertical and horizontal direction using various time intervals. Materials and Methods: Three groups of samples (n = 24), one-piece and two-piece implant and natural teeth, were used in this study to compare the amount of heat transferred to the implant-bone interface. This study used cooling system in the 10, 20, 30, and 60 seconds time intervals. The Thermo-couples (K type) were attached to each sample at the crestal, middle and apical points. To have a similar condition with the oral cavity, each implant was embedded separately in transparent acrylic resin in a 37°C water bath. To have a constant cutting pressure, the turbine was fixed on the stable stand and a 100 g counterweight hanged to it. Then, the bath was fixed in front of it and cutting started at vertical and horizontal directions for 10, 20, 30, 60 seconds. Results: The maximum decrease from 37°C was observed in two-piece im-plant at the apical point (3.95°C) after 60 seconds and the minimum decrease was seen in one-piece implant at the crestal point (0.6°C) after 60 seconds. Also the minimum increase was observed in the natural teeth at the apical point (0.15°C) at 10 seconds and the maximum temperature increase was seen in one-piece implant at the apical point (1.95°C) at 20 seconds. Conclusions: Within the limitation of this study, it was concluded that to reduce the thermal damage on the bone tissue, an intermittent cut up to 20 seconds is acceptable. Cutting one-piece implant caused more heat transfer than that of two-piece implant.