In 1979, McSpadden introduced a thermomechanical compaction technique. In this technique a rotating condenser creates frictional heat inside the root canal and plasticizes a cone of gutta-percha, which is forced laterally and apically to obturate the root canal space. The condenser, which has an appearance similar to an inverted Hedstrom file, but with the blades directed toward the blunt-tipped end is fixed in a latch type slow-speed contra angle, placed into the root canal as far apically as possible and rotated at the minimum recommended speed of 8000 rpm. Gentle apical pressure is applied to carry the condenser 1 mm short of the working length after the gutta-percha become plastic. At this length, the condenser is slowly removed while rotation is maintained.
REF: JOE ,31, 4, 2005