Transient Heat Transfer in Dental Implants for Thermal Necrosis-Aided Implant Removal: A 3D Finite Element Analysis.

Removal of osseointegrated but otherwise failed (mechanical failure, mispositioning, esthetics, etc) dental implants is a traumatic process resulting in loss of healthy bone and complicating the treatment process. The traumatic effects of implant removal can be reduced by weakening the implant-bone attachment. Thermal necrosis-aided implant removal has been proposed as a minimally invasive method toward this end. In this method, an electrocautery tip is contacted to the implant to increase the temperature to 47°C and generate a limited and controlled thermal necrosis at the bone-implant interface. So far, no controlled studies have been performed to investigate the optimal clinical parameters for this method. In this study, we aimed to investigate, using finite element analysis method, the optimal settings to achieve intentional thermal necrosis on 3 implant systems, at 5 W and 40 W device power and with different size tips. The temperature increase of the implants at 40 W power was very sudden (< 0.5 seconds) and as the bone reached 47°C, the implants were at unacceptable temperatures. At 5 W power, temperature increase of the implants happened at manageable durations (< 1 second). Moreover, the temperature increase was even slower with larger implants and larger tip sizes. Therefore, low power settings must be used for thermal necrosis-aided implant removal. Also, the size of the implant and the tip must be taken into consideration in deciding the duration of contact with the electrocautery tip and the implant.