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.
· Cold testing can be accomplished by individually isolating teeth with a rubber dam. This technique for cold testing is especially useful for patients presenting with porcelain jacket crowns or porcelain-fused-to-metal crowns where there is no natural tooth surface (or much metal) accessible. Frozen carbon dioxide (CO2), also known as dry ice or carbon dioxide snow, has been found to be reliable in eliciting a positive response if vital pulp tissue is present in the tooth.
Multiple issues seem to be present in both the question and the responses. First, the use of pulp sensitivity testing as a term is most appropriate, not endodontic diagnosis, which encompasses so many other issues. Second, the issue of vitality and non-vitality is archaic as many teeth that test "vital" are in a state of degeneration and at some stage in the cyclic inflammatory response. Third, with teeth covered by full crowns, a cold test - generic, is the best to determine the responsiveness of the tissue in the tooth...and if abnormal (severe response, or lingering response, or reflects the patient's chief complaint) the C fibers are being stimulated and the pulp is most likely in some state of degeneration. If there is a response and it subsides rapidly, it is reasonable to think that the tissue is healthy (not vital) and not intervention is indicated. For those who continue to use the terms vital and non-vital I pose a question: Have you ever gone to your physician and asked him or her to check if you are vital or non-vital? You are either sick or healthy...and so it is with the tooth pulp. It seems that in this day of high technology we still have not come up with reiiable way to ascertain the true status of the dental pulp...other than maybe when it is truly necrotic. If you wish to see how far we have come with diagnosis see: J Hist Dent 2011;58(3):126-128.
Dentists perform pulp vitality tests through full coverage crowns frequently in their practices to aid in diagnosis irreversible pulpal involvement. There is insufficient research on whether full coverage restorations can be adequately tested to determine pulpal vitality and the patient’s subjective symptoms become more important in determining the course of treatment.
Characteristically, pulpal symptoms are difficult for patients to localise, and require systematic provocation and reproduction to identify the offending tooth with certainty. If sensitivity is reported to hot or cold, the teeth should be challenged with that stimulus. Cold can be applied with an ethyl chloride soaked cotton pellet, though ice sticks or proprietary refrigerants such as Endo-Frost can give a more profound cold challenge to stimulate the pulps of old or heavily restored teeth. Heat can be applied with a stick of warm gutta percha 'temporary stopping', taking care to coat the tooth first with petroleum jelly to prevent the hot material from adhering. Electronic touch and heat instruments used in thermoplastic gutta percha filling techniques can also be used to deliver a known and reproducible thermal challenge.
As a general rule, thermal tests are more discriminating of pulp condition than electrical. They should be repeated, and contra- lateral and adjacent teeth tested for reference. An exaggerated and lingering response may indicate irreversible pulpal inflammation, whilst a consistent absence of response may suggest pulp necrosis. Pulp sensitivity tests are essential in pre-operative assessment, but their results should not be taken in isolation, and should always be interpreted with caution.
