Cariostatic effect of fluoride-containing restorative systems associated with dentifrices on root dentin.

OBJECTIVE: The aim of this in vitro study was to evaluate the interaction between two sources of fluoride (restorative systems and dentifrices) in inhibiting artificial root caries development.

METHODS: One hundred and eighty tooth segments were embedded in polyester resin, and sanded flat. Cylindrical cavities 1.0mm-deep and 1.5mm-diameter were prepared in root dentin and randomly restored by fluoride-containing restorative systems: Ketac-fil/Espe (Ke), Fuji II LC/GC Corp (Fj), F2000/3M (F2), Surefil/Dentsply (Su) or a control: Filtek Z250/3M (Z2). Ten experimental groups were made to test the association among the five restorative systems and two dentifrices: with F(-) (Sensodyne Baking Soda) or without F(-) (Sensodyne Original) (n=18). After surface polishing, a 1mm-wide margin around the restorations was demarcated and initial dentin surface Knoop microhardness values (KHN(i)) were obtained. The specimens were submitted to a pH-cycling model, and to applications of slurries of dentifrice. Afterwards the final dentin surface Knoop microhardness values (KHN(f)) were measured.

RESULTS: The differences between KHN(i) and KHN(f), and the covariate KHN(i) were considered by the ANCOVA and Tukey's test (alpha=0.05). The interaction between restorative system and dentifrice was statistically significant (p=0.0026). All restorative systems provided some protection against artificial caries challenge when associated with the fluoride-containing dentifrice treatment. The means (standard deviation) of reductions in Knoop hardness values for systems associated with the fluoride-containing dentifrice were: Ke: 40.0(1.02)(a), Fj: 41.9(1.02)(b), F2: 43.3(1.04)(c), Su: 43.5(1.00)(c), Z2: 44.0(1.02)(c); and with the non-fluoride-containing dentifrice were: Ke: 42.9(1.02)(a), Fj: 44.7(1.01)(b), F2: 45.2(1.09)(bc), Su: 46.0(0.99)(c), Z2: 46.6(0.99)(c) (statistical differences were expressed by different letters).

CONCLUSION: The cariostatic effect shown by the fluoride-containing dentifrice could enhance that shown by Ketac-fil and Fuji II LC, and could mask that shown by F2000.