Endodontic diagnosis often requires thermal testing through porcelain fused-to-metal (PFM) and all-ceramic restorations. The purpose of this study was to measure and compare the temperature change during thermal testing by three commonly used methods occurring at the pulp-dentin junction (PDJ) of nonrestored teeth and teeth restored with full coverage restorations made of PFM, all-porcelain, or gold. The methods used to produce a thermal change were (a) an ice stick, (b) 1,1,1,2-tetrafluoroethane (TFE), and (c) carbon dioxide snow. A thermocouple measured temperature changes occurring at the PDJ in 10 extracted premolars when thermal tested by each method over a period of 30 seconds. Temperature reduction was also measured for the same samples restored with full gold crowns, PFM, and Empress crowns. Results showed intact premolars and those restored with PFM or all-ceramic restorations to respond similarly to thermal testing. In these teeth, TFE produced a significantly greater temperature decrease than carbon dioxide snow between 10 and 25 seconds (p < 0.05). In conclusion, application of TFE on a saturated #2 cotton pellet was the most effective method for producing a temperature reduction at the PDJ of intact teeth and those restored with gold, PFM, and all-porcelain when testing for less than 15 seconds.
The purpose of this investigation was to ascertain the prevailing attitudes within the endodontic community regarding smear layer removal. The first survey asked the philosophies and techniques currently being taught to predoctoral dental students and postdoctoral endodontic residents in the United States, whereas the second surveyed some of the members of the American Association of Endodontists currently practicing in the United States. Findings from these surveys revealed that more than three-fourths of the dental students and nearly two-thirds of the endodontic residents are not being taught routine smear layer removal. Slightly more than one-half of endodontists responded they practice smear layer removal. These surveys indicate that there is no clear consensus in the endodontic community, either academically or clinically, as to whether the smear layer should be removed or be allowed to remain before obturation of the root canal space.
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