Argon Laser and Remineralizing Paste Effect on Root Surface Caries

Objective: In vitro root surface caries formation in permanent teeth was evaluated to determine the treatment effects of argon laser irradiation and a remineralizing paste (casein phosphopeptide-amorphous calcium phosphate) alone and in combination. Methods: Caries-free permanent tooth root surfaces (n=10) underwent debridement and a fluoride-free prophylaxis. Acid-resistant varnish was placed leaving four windows of sound permanent root surface exposed for study. Each sound root surface window was assigned to a treatment group: 1) no-treatment control; 2) argon laser exposure of ~11.5 Joules/cm2 (231 mW, 5-mm beam size, 10 continuous seconds); 3) remineralizing paste for 2 minutes [MI Paste™ GC Corporation]; 4) remineralizing paste and argon laser. The tooth specimens were sectioned into quarters, rinsed in distilled/deionized water, and then exposed to synthetic saliva for 24 hours. In vitro caries were created in the sound root surface windows using a modified ten Cate solution (2.2 mM calcium, 2.2 mM phosphate, 1.0 mM fluoride, pH 3.90, 7 days). Longitudinal sections (5/tooth quarter) were evaluated for mean lesion depths using water imbibition and polarized light microscopy (ANOVA, DMR). Results: Mean lesion depths were 207±16µm for no-treatment control; 166±23µm for argon laser alone; 159±14µm for remineralizing paste alone; and 123±12µm for remineralizing paste and argon laser. All treatment groups had mean lesion depths that were significantly less than that for the no-treatment control (P<.05). The combined treatment with remineralizing paste and argon laser had mean depths significantly less than that for remineralizing paste alone or argon laser alone (P<.05). Conclusions: A topical remineralizing paste with bioavailable calcium and phosphate and argon laser treatment alone enhanced caries resistance against in vitro caries formation in root surfaces. Combining remineralizing paste containing casein phosphopeptide-amorphous calcium phosphate and argon laser irradiation markedly enhanced the caries resistance of root surfaces in vitro. (Funded by GC America, Inc.)