Heat Generation Changes with Electrically Heated Pluggers after Multiple Autoclave Cycles at Different Operating Temperatures

IntroductionElectrically heated pluggers are the most commonly used instruments during warm obturation techniques. This study aimed to evaluate the effect of sterilization and operating temperature settings on the heat generation of pluggers of various taper sizes.MethodsFifty pluggers were sterilized at 132°C for 25 minutes for a total of 150 cycles. One group (Autoclave200) consisted of 25 pluggers tested at an operating temperature setting of 200°C, whereas another group (Autoclave400) consisted of 25 pluggers tested at 400°C. The heat generation at their tip surface was measured with T-type thermocouples at 0, 50, 100, and 150 autoclave cycles. An unpaired t test was used to compare the time it took the pluggers to reach 60°C and the mean maximum temperature change.ResultsAfter 50 autoclave cycles, all of the 0.04 taper pluggers in Autoclave200 failed to reach 60°C. After 100 autoclave cycles, one of the 0.10 taper pluggers in Autoclave200 did not reach 60°C, and after 150 autoclave cycles, one of the 0.04 taper pluggers failed to generate any heat. The mean increase in the time to reach 60°C ranged from 1071-4004 milliseconds and 510-2074 milliseconds for Autoclave200 and Autoclave400, respectively. The mean maximum temperature change decreased by 13-29°C and 24-116°C for Autoclave200 and Autoclave400, respectively.ConclusionsAfter multiple autoclave cycles and higher operating temperature use, the electrically heated pluggers transferred less heat to the tip surface, potentially making them less effective.     

The effect of immediate versus delayed dowel space preparation on the integrity of the apical seal

This in vitro study evaluated the effect of immediate vs delayed preparation of dowel space on the integrity of the apical seal. Twenty human teeth were obturated by lateral compaction of gutta-percha and cement and stored. Two weeks later, 20 more were similarly filled. Using warm endodontic pluggers, dowel spaces were prepared so that either 3 mm or 7 mm of apical fill remained. The specimens were treated in ⁴⁵CaCl₂, horizontally sectioned, and autoradiographs were made. Analysis of the incidence and degree of microleakage showed that delayed preparations significantly increased leakage (P <.01) if only 3 mm of apical fill remained.