Heat Transfer to the Implant-Bone Interface During Preparation of a Zirconia/Alumina Abutment

Purpose: Excessive heat at the implant-bone interface may compromise osseointegration. This study examined the heat generated at the implant surface during preparation of a zirconia/alumina abutment in vitro. Materials and Methods: Sixty zirconia/alumina abutments were randomized into 12 experimental groups. The abutments were connected to implants and embedded in an acrylic resin block in a 37°C water bath. The abutments were reduced by 1 mm in height over a period of 1 minute with a high-speed handpiece and then polished for 30 seconds with a low-speed handpiece, both with and without an air/water coolant. Temperatures were recorded via thermocouples at the cervical, middle, and apical part of the implant surfaces. The Mann-Whitney rank-sum test was used to assess the statistical significance of the difference in temperature between the abutment/implant complexes altered with and without coolant. Results: The 1-mm reduction with the high-speed handpiece without coolant resulted in a maximum temperature of 41.22°C at the cervical portion of the implant. Three of four temperatures above 40°C were observed at the cervical part of the implant following use of the high-speed handpiece without coolant. The temperature difference between "with coolant" and "without coolant" during both low-speed polishing and high-speed reduction was statistically significant at the cervical portion of the implant (P = .009). In contrast, the temperature difference between "with coolant" and "without coolant" during both low-speed polishing and high-speed reduction was not statistically significant at the middle and apical parts of the implant (P > .05). Conclusions: Preparation of a zirconia/alumina abutment caused an increase in temperature within the implant, but this temperature increase did not reach the critical levels described in the implant literature. Keywords: heat generation, implant abutment preparation, zirconia/alumina abutment