PERIODONTAL ATTACHMENT LOSS ASSESSED BY LINEAR AND AREA MEASUREMENTS INVITRO

The aim of the present study was to investigate the relationship betwe en linear and area measurements of periodontal attachment loss, and to determine the root surface area on different tooth-types. Extracted p ermanent teeth were collected in a national survey including a systema tic random sample of 500 Norwegian dentists. The response rate was 70% . Altogether 329 teeth were received, 81 of them (excluding 3rd molars ) were subjected to both linear and area measurements of attachment lo ss. Using a dissecting microscope (10 x), 4 to 8 duplicate linear meas urements were recorded per tooth. The areas of both lost and remaining periodontal attachment were measured by a method based on controlled release of Cu and Co metal ions from coatings applied to the root surf ace. Linear loss of attachment for single-rooted teeth (n = 63) was xB AR = 44.0% and the area loss xBAR = 49.2%. The corresponding measureme nts for multi-rooted teeth (n = 18) were xBAR = 30.3% and xBAR = 35.1% , respectively. The correlation between linear and area loss was r = 0 .78 for single-rooted and r = 0.75 for multi-rooted teeth (p < 0.01). The lower correlation in multi-rooted teeth is probably due to the mor e complex root anatomy. It is concluded that there is a strong correla tion between linear loss of attachment and area of periodontal support lost for teeth with early to moderate loss of attachment, and that li near measurements tend to underestimate the remaining periodontal atta chment.