SOURCES OF ERROR FOR PERIODONTAL PROBING MEASUREMENTS

This study determined the relative contribution to probing measurement reliability of several factors, compared with that of random error. P robing measurements were performed by examiners properly trained and c alibrated. A total of 5771 pairs of replicate pocket depth (PD) and re lative attachment level (RAL) measurements were performed with the Flo rida probe(R). A total of 1488 replicate clinical attachment level (CA L) measurements were performed with the North Carolina 15 mm probe. In addition, longitudinal replicate measurements of RAL were performed a t 0 and 12 months on 816 sites in 11 patients utilizing the Florida Pr obe(R) 20 mm disk probe. Measurement reliability with the Florida Prob e(R) resulted in mean intra-examiner variances of 0.21 and 0.33, for P D and RAL, respectively (s.e.m. 0.46 mm for PD and 0.57 mm for RAL). M easurement reliability with the conventional probe resulted in mean in tra-examiner variances of 0.19 for PD and 0.32 for CAL (s.e.m. 0.44 mm and 0.56 mm). Pocket depth contributed to approximate to 5% of the va riability of the intra-examiner variance with both probes with other c ontributing factors being the individual patient, tooth and site locat ion. Mean intra-examiner reproducibility for duplicate RAL measurement performed at 0 and 12 months was 0.24 and 0.19, respectively (s.e.m. 0.49 mm and 0.43 mm). In conclusion, a mean intra-examiner variance of less than or equal to 0.24 can be achieved for replicate measurements with both electronic and conventional probes for moderate and severe periodontitis patients. Individual examiner, individual patient and si te location contribute up to 10% to the overall variance. Hence, the p attern of variability for intra-examiner variance of probing measureme nts performed with either electronic or conventional probes by trained and calibrated examiners is mostly random error.