A screening test is used for the early identification of a targeted disease in an asymptomatic patient so that the disease can be managed before it progresses any further, which often leads to a better prognosis and thus better patient/population health outcomes. However, the screening process comes with its own risk of incorrectly testing positive when the disease does not exist (ie, a diagnostic false positive) or incorrectly testing negative when the disease truly does exist (ie, a diagnostic false negative). As a result, the clinical interpretation of a screening test is a challenge for every dental hygienist, who is practicing in a world of uncertainty. This article will review the role of probability in analyzing the reliability of a diagnostic tool as a screening test in clinical practice. As long as we live in a world of uncertainty, the challenges of clinical decision making will be based on the science of probability and the art of clinical judgment.
Keywords: diagnostic test, oral health screening, negative predictive value, positive predictive value, probability, sensitivity, specificity