Interrater agreement on subgingival calculus detection following scaling.

Accurate and reliable detection of subgingival calculus is a difficult skill which relies on subjective tactile sensations for determinations. This one year retrospective study examined the interrater agreement among a large, generalized pool of clinical examiners who scored residual subgingival calculus after student scaling. Four thousand one hundred and sixty tooth surfaces were analyzed for examiner agreement. Interrater reliability for all paired clinical ratings was low (Kappa = .33). A second, companion study evaluated accuracy and reliability using raters' assessments about the existence of simulated calculus on the root surfaces of manikin teeth. In the second study interrater reliability also was low (Kappa = .34); the true positive and true negative ratios were 49 percent and 88 percent respectively, while the false positive and false negative ratios were 12 percent and 51 percent. These data suggest that there is a need in periodontics for effective examiner calibration methodologies and objective subgingival calculus detection techniques.