Quantification of root surface plaque using a new 3-D laser scanning method

There are nd published reports in the literature objectively quantifying th ickness of plaque on teeth. The aim of this study was to quantify plaque on a tooth surface and assess if this quantification correlates with a clinic al index of plaque from each of 51 patients. Patients were instructed not t o perform any oral hygiene an the day of the assessment. The Silness and Lo e plaque index was scored and replicas were scanned using a co-ordinate mea suring machine (CMM) and laser scanning probe. A replica was obtained from this surface before and after toothbrushing. Plaque adjacent to the gingiva l margin had a mean thickness of 0.106+/-0.118 mm (mean+/-SD) whilst mean p laque thickness 250 mu m from the gingival margin was 0.053+/-0.052 mm (mea n+/-SD). There was a significant correlation between the plaque index and t he plaque thickness (p less than or equal to 0.002). The finding that plaqu e is present in the greatest amount adjacent to the gingival margin support s a previously reported hypothesis that primary root carious lesions (PRCL' s) may initiate adjacent to the gingival margin. This method quantifies pla que thickness on exposed root surfaces which correlates with the plaque ind ex as well as illustrating how the morphological characteristics of teeth, gingivae and plaque can be studied in vivo from replicas recorded.