Infrared thermography vs. thermocouples for temperature measurement during implant preparation

5T2O7 ePOSTER BASIC RESEARCH

Background: During dental implant site preparation, heat is generated due to friction. Overheating of the bone during implant osteotomy can induce cell necrosis and may inhibit successful osseointegration of the implant. Several in vitro studies accessing intraosseous temperature rise with temperature recorded either using thermocouples or infrared thermography. However, few studies have compared these measuring methods and quantified differences in temperature recording.

Aim/Hypothesis: The aim of this in vitro study was to evaluate the intraosseous temperature rise measured by thermocouples and infrared thermography in a standardized setup.

Materials and Methods: A surgical device with a surgical handpiece was mounted on a labside drilling unit. The setup recorded the temperature changes using k-type thermocouples (HH147U, Omega Engineering, UK) at depths of 3 mm, 6 mm and 9 mm and with an infrared thermometer (VarioCAM HD, InfraTec, Germany). Infrared temperature data were evaluated at the same drilling depth. Forty bovine rib samples were divided into four subgroups (n = 10): thermocouple (TC) with external irrigation (TC-1, 50 ml/min) and without irrigation (TC-2); infrared thermography (IT) with external irrigation (IT-1, 50 ml/min) and without (IT-2). The rotational speed was set to 800 rpm and implant preparation was performed using a 2.2 mm pilot drill followed by a 2.8 mm twist drill at a depth of 10 mm both with a load of 2 kg. Kruskal-Wallis test and Mann-Whitney-U test were used for statistical analysis.

Results: The overall mean temperature rises (95%-CI) were 8.5°C (7.0 – 9.9) for group TC and 11.4°C (9.8 – 11.4) for group IT, respectively. This difference is statistically significant (P < 0.001). For the subgroups mean temperature rises were as follows: TC-1: 4.9 (3.4 – 6.3), TC-2: 12.04 (9.9 – 14.2), IT-1: 6.2 (5.5 – 6.9), IT-2: 16.5 (14.1 – 19.0). The differences between measurement methods and between different cooling were significant for all subgroups except for TC-2/IT-2 (P < 0.018).

The setup investigating IT allowed the measurement of peak temperature additional to the standardized measuring spots (3 mm, 6 mm, 9 mm depth). Mostly peak temperature was reached between or above these spots. On average peak temperature was 2.3°C higher than the highest temperature increase recorded at either 3 mm, 6 mm or 9 mm depth.

Conclusions and Clinical Implications: In a standardized setup infrared thermography records are about 30% higher than the measurement with thermocouples. Furthermore, thermography enables to record a thermal profile, whereas thermocouples only allow spot measurement.

Acknowledgements: Drills were provided by Straumann AG (Basel, Switzerland). The authors thank Mr Honné (Medical Research Workshop, UKAachen, Germany) for technical support.

Keywords: intraosseous temperature rise, infrared thermography, temperature measurement, dental implants