The purpose of this experiment was to observe and measure the distribution of heat to bones and the maximum temperature that developed when cutting bone with drills. Generation of heat that spread in the presence or absence of irrigation when drilling with IMZ, Brånemark, and ITI implant (F type) drills was observed in the pig rib via thermography. Without irrigation, the condition of heat spread in each drill and bur differed according to bur shape and drilling site. Maximum heat temperature without irrigation was higher than that with irrigation for any IMZ, ITI, and Brånemark drill. Keywords: bone preparation, cutting instrument, heat generation, irrigation, thermography