The purpose of this study was to evaluate the thermal expansion characteristics of injectable thermoplasticized gutta-perchas and a Resilon. The materials investigated are Obtura gutta-percha, Diadent gutta-percha, E&Q Gutta-percha Bar and Epiphany (Resilon).The temperature at the heating chamber orifice of an Obtura II syringe and the extruded guttapercha from the tip of both 23-and 20-gauge needle was determined using a Digital thermometer. A cylindrical ceramic mold was fabricated for thermal expansion test, which was 27 ㎜ long, with an internal bore diameter of 3 ㎜ and an outer diameter of 10 ㎜. The mold was filled with each experimental material and barrel ends were closed with two ceramic plunger. The samples in ceramic molds were heated in a dilatometer over the temperature range from 25℃ to 75℃. From the change of specimen length as a function of temperature, the coefficients of thermal expansion were determined.There was no statistical difference between four materials in the thermal expansion in the range from 35℃ to 55℃ (p > 0.05). However, Obtura Gutta-percha showed smaller thermal expansion than Diadent and Metadent ones from 35℃ to 75℃ (p < 0.05). The thermal expansion of Epiphany was similar to those of the other gutta-percha groups. [J Kor Acad Cons Dent 31(5): [344][345][346][347][348][349][350][351] 2006]
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