Hands On

Predictive values

Background

To develop an effective endodontic treatment plan requires knowing the status of the pulp tissues. The sensitivity of pulpal nerves is tested using thermal and electrical tests. Ideally, these tests should be easy to use, fast, inexpensive, noninvasive, painless, reproducible, and accurate. The accuracy of a test is measured by determining its sensitivity, specificity, and positive and negative predictive values. These values were determined, along with accuracy and reproducibility, for thermal

Methods

The thermal tests evaluated were the 1,1,1,2-tetrafluoroethane (cold) test and the hot gutta-percha test. Electrical testing was done using the Analytic Technology Pulp Tester. One hundred ten teeth were tested, of which 60 had vital pulps and 50 had necrotic pulps (a disease prevalence of 45%). Direct pulp inspection was the definitive standard.

Results

The cold test identified 44 of the 50 necrotic pulps as necrotic (true positives) and 6 as sensitive (false negatives). The hot test found 43 of the necrotic pulps were necrotic (true positives) and 7 were sensitive (false positives). Of the 50 teeth with necrotic pulps, electrical testing found 38 were nonsensitive (true positives) and 12 were sensitive (false negatives). All of the tests identified the 60 vital pulps as clinically vital (true negatives).

The cold test was the most sensitive,

Discussion

It is important with diagnostic tests to know the probability that the test will give an accurate, correct result. Sensitivity and specificity do not provide this information, so the positive and negative predictive values are important measures to consider.