Fissure sealant retention is traditionally considered as a proxy measure for caries prevention. This study investigated the logic behind this proposition, and its validity. A logical framework of the proposition was established. The mechanism of caries development was transferred into a Directed acyclic graph, and this was used to investigate the logical framework. The sensitivity and specificity of full sealant retention in the prediction of dental carious lesion development and the number of false positive/false negative prediction rates were computed. The sensitivity/specificity was statistically compared to that of random values. A contradiction in the logical framework was identified. The mean sensitivity/specificity was 37.9% (SD = 27.8%) and 67.6% (SD = 28.4%), respectively. When these values were compared against random values (30.5%, SD = 25.7% and 58.7%, SD = 31.6%), a non-significant sensitivity (P = 0.06) and a borderline higher specificity (P = 0.04) were observed. The overall false prediction rate was 33.7%, with 16.9% and 16.8% false negative and false positive predictions, respectively. The sensitivity/specificity was too low and the false prediction rate was too high to consider retention a valid proxy for caries prevention. The logic behind the investigated proposition is flawed, contradicted by the current empirical evidence, and thus invalid.
Keywords: fissure sealant; formal logic; predictive accuracy; reductio ad absurdum.