A study of inter- and intra-examiner reliability of pocket depth and attachment level.

Factors affecting inter- and intra-examiner variability for probing pocket depth and periodontal attachment level were studied on a sample of 20 patients, each given six full-month examinations, two by each of 3 examiners. The major determinant of both dimensions of variability was the degree of periodontal destruction, measured as either pocket depth or level of attachment: the greater the degree of destruction, the greater the disagreements within and between examiners. Differences in variability were generally minor between sites on anterior and sites on posterior teeth, between midsites and proximal sites, and between sites on the facial and sites on the lingual surface. When differences were found between the average variances for different kinds of sites, they may have been due to corresponding differences between the average depths, and not to any inherently greater difficulty in measuring one kind of site than another.