Heat transfer to the periodontal ligament during root obturation procedures using an in vitro model

It appears to be important to avoid thermal injury to the periodontal ligam ent when using heated gutta-percha techniques such as "System B," An in vit ro model was developed, consisting of an extracted human tooth rooted in an artificial periodontal ligament (PDL) and alveolar socket, which allowed u s to measure the temperature transferred to the root surface. The teeth wer e instrumented and subsequently embedded in alginate to simulate the PDL, M edium gutta-percha points were fit, sealer was applied, and a fine Buchanan plugger was used for condensation. Temperature measurements were taken sim ultaneously at the apex and 5 mm from the apex during obturation with two f ine gauge thermocouples connected to a digital thermometer, The average tem perature increase was similar to 1 degrees C at the apex and similar to 2 d egrees C at the 5 mm mark. The resulting temperature increases appear to be lower than previously reported by other investigators (Hardie, 1986, 1987; Barkhordar et at., 1990; Weller et at., 1991; Lee et al,, 1998), who did n ot allow for the heat disseminating effect of the PDL.