ARREST OF ROOT SURFACE CARIES IN-SITU

This study tests the hypothesis that daily oral hygiene combined with topical fluoride arrests active root-surface caries lesions without ch anging the mineral content of the lesions. Therefore, changes in miner al content and distribution were studied in root surfaces during carie s lesion development and subsequent arrest of lesion progression in si tu. In 18 subjects, lesions were developed during 3 months in sound ro ot-surface specimens inserted into lower partial dentures. After 3 mon ths, ground sections were prepared from each lesion prior to re-insert ion of the specimens into the dentures. In addition, one sound root sp ecimen was added per subject. During the following 3 months, half of t he subjects cleaned both sound and carious specimens once a day with a n 1100-ppm fluoride toothpaste, and the specimens were treated twice w ith 2% NaF for 2 min in situ. The other half of the subjects continued the experiment without cleaning. During the initial three-month perio d, all specimens developed subsurface lesions extending 187 to 583 mu m into the dentin. Lesion depth increased somewhat in both experimenta l groups during the following 3 months (P greater than or equal to 0.1 ). There was a non-significant increase in mineral loss in the plaque- covered specimens (P = 0.08). However, the total mineral content of sp ecimens subjected to plaque removal and topical fluoride did not chang e. This treatment resulted in an increased mineral content in the surf ace layer (P < 0.01) and formation of a zone of higher mineral content within the body of the lesion. The sound root surfaces which had been cleaned for a three-month period showed mineral uptake in the surface layer, occasionally associated with subsurface demineralization exten ding 20 to 70 mu m into the tissue. The mineral loss of these specimen s was significantly smaller than that of plaque-covered surfaces (P < 0.001). It is concluded that daily plaque removal and topical fluoride use influence the distribution of mineral in sound and carious root s urfaces and may arrest lesion progression without affecting the total mineral content.