Option‐4 Algorithm for Third Generation Disc Probe: Agreement of Selected Site‐Specific Relative Attachment Level Measurements and Detection of Longitudinal Site‐Specific Attachment Level Change

Background: Longitudinal site‐specific attachment level change (SSAC), identified from serial relative attachment level measurements (RAL), is the principal indicator of progression/regression of periodontal diseases. Many variables confound RAL reproducibility and affect measurement error. The Option‐4 algorithm was designed to reduce measurement error and improve accuracy and sensitivity of SSAC detection. The study aimed to evaluate the performance of the Option‐4 algorithm. Methods: A precalibrated clinician recorded full mouth RAL with a third generation disc probe on 4 occasions over 6 months in 16 subjects (mean age 48.1 years) with moderately advanced chronic adult periodontitis (2,312 sites). Option‐4 allowed up to 4 RAL recordings per site per visit until 2 values had differences ≤ 1.0 mm and their mean was ≤1.0 mm from the previous visit mean: the clinician made the selection if these criteria were unfulfilled. Results: Within‐visit agreement ≤1.0 mm was ≥ 99.6%: all withinvisit correlation coefficients = 0.98 (P < 0.001). At each visit, mean difference in Option‐4 values was < 0.05 mm, mean absolute difference (ignoring direction) was ≤ 0.34 mm. Mean site‐specific variances ranged from 0.092 mm2 to 0.097 mm2 across all visits. Subject thresholds for site‐specific attachment level change (from estimated 95% confidence limits of visit 1 data) ranged from 0.52 mm to 0.67 mm. Linear SSAC (by linear regression) and betweenvisit patterns of SSAC were investigated. SSAC was detected in 100% subjects and at 51.0% measured sites. Linear SSAC (R2 ≥ 0.90: P ≤ 0.05) occurred at 105 sites (4.5%): 32 sites (1.4%) deteriorated, 73 sites (3.1%) improved. Between‐visit SSAC occurred at 1,074 sites (46.5%): 391 sites (16.9%) deteriorated, 295 sites (12.8%) improved, and 388 sites (16.8%) showed exacerbation/remission patterns. Conclusions: The Option‐4 algorithm produced high RAL agreement. Site‐specific attachment level change was detected in both directions in 100% subjects and at 51.0% measured sites. J Periodontol 1999; 70:159‐170.