Objective: This in-vitro study aimed to examine the change in surface temperature induced by the actions of drills for the placement of dentine pins.
Methods: Ten decoronated extracted premolar teeth were embedded by the apical tip of their roots in orthoresin. They were held in a bench vice and allowed to reach the ambient temperature of 24 degrees C. A thermal imaging camera, Agema Thermovision 900 series, was positioned 0.05 m perpendicular to the decoronated surface. Sequential recording of a series of images was stored at a rate of three per second during each stage of the pin placement procedure. This included a pilot drill, a channel cutting drill and the pin placement. All pins were 0.675 mm diameter x 2 mm in length and were placed 1 mm from the amelo-dentinal junction using a Kavo handpiece rotating at 4000 rpm.
Results: The mean baseline temperature for the thermally stabilized teeth was 23.9 degrees C. The action of the round pilot drill changed the temperature from baseline by 25 degrees C. The action of the channel drill generated the greatest heat, with a mean maximum temperature recorded during these procedures of 94 degrees C +/- 9 degrees C. The pilot drill produced a mean change from baseline of 31.3 degrees C +/- 17.7 degrees C during pin placement.
Conclusions: The placement of dentine pins produced a high temperature increase on the surface of the dentine. All stages of pin placement gave rise to an increased temperature, but this was maximal with the channel drill. Further studies are required to determine whether these surfaces temperatures are transferred to the pulpal chamber.