Method: Root surfaces from caries-free permanent teeth (n=10) underwent debridement and a fluoride-free prophylaxis. The tooth roots were sectioned into quarters, and acid-resistant varnish was placed with 2 sound root surface windows exposed on each tooth quarter. Each quarter from a single tooth was assigned to a treatment group: 1) No Treatment Control; 2) Aquafresh Advanced Dentifrice (1500 ppm FL, GlaxoSmithKline, Township, PA 15108); 3) Experimental Xylitol Dentifrice Without Fluoride; and 4) Experimental Xylitol Dentifrice With Fluoride. Tooth root quarters were treated with fresh dentifrice twice daily (3 minutes) followed by fresh synthetic saliva rinsing over a 7 day period. Controls were exposed twice daily to fresh synthetic saliva rinsing over a 7 day period. In vitro root caries were created using an acidified gel (pH 4.25, 21 days). Longitudinal sections (3/tooth quarter, 60/group) were evaluated for mean lesion depths (water imbibition, polarized light, ANOVA, DMR).
Result: Mean lesion depths were 359 ± 37 µm for No Treatment Control Group; 280 ± 28 µm for Aquafresh Advanced dentifrice; 342 ± 41 µm for Xylitol Without Fluoride dentifrice; 261 ± 34 µm for Xylitol With Fluoride dentifrice. Aquafresh Advanced and Xylitol With Fluoride dentifrices had mean lesion depths significantly less than those for No Treatment Controls and Xylitol Without Fluoride dentifrice (P<0.05). There was little difference in mean lesion depths between Aquafresh Advanced and Xylitol With Fluoride dentifrices (P>0.05).
Conclusion: Fluoridated dentifrices provided significant reductions in in vitro root caries lesion depths compared with root surfaces not exposed to dentifrice treatment (no treatment control) or exposed to Xylitol Without Fluoride dentifrice (P<0.05). Xylitol With Fluoride dentifrice reduced lesion depth to a similar extent as a commercially available fluoride dentifrice (Aquafresh Advanced dentifrice, P>0.05).