Artificial root caries in amalgam restorations: effect of light-cured fluoride releasing liners

The purpose of this study was to examine artificial root caries when light-cured fluoride releasing liners were placed under amalgam restorations. Class V preparations in extracted third molars were used with gingival margins on root surfaces. Ten restorations were used for each of the following groups: 1) Amalgam alone; 2) Two layers of copal varnish and amalgam; 3) Vitrabond, amalgam; 4) Timeline, amalgam; 5) XR Ionomer, amalgam. The teeth were thermocycled and artificial caries were created using a liquid system acidified to pH 4.20 containing 2.2 mM calcium and phosphate but without fluoride. The teeth were sectioned, polished and photographed using polarized light. Areas of recurrent caries were measured using a sonic digitizing pad. The data were analyzed using ANOVA and Duncan's Multiple Range Test. Areas for root lesions for the different groups were: 1) 2.17 +/- 0.35; 2) 1.90 +/- 0.40; 3) 1.30 +/- 0.18; 4) 1.77 +/- 0.28; 5) 1.50 +/- 0.33. Groups 3 and 5 were statistically different from groups 1 and 2, while no differences were observed for enamel lesions. The use of the photo-activated/fluoride releasing liners significantly reduced lesion area.