Enamel de/remineralization on teeth adjacent to fluoride releasing materials without dentifrice exposure

Interproximal caries presents a continual clinical concern. The purpose of this study was to evaluate the ability of fluoride-releasing materials to remineralize incipient caries lesions on adjacent teeth, at the interproximal site with and without exposure to a fluoridated dentifrice. Thirty extracted teeth had Class II preparations placed, then equal numbers were restored with amalgam (Tytin (3-Kerr), glass ionomer (Ketac Fil-ESPE) or composite (Heliomolar-Ivoclar). Thirty additional teeth had 1 x 5 mm artificial caries lesions formed at the interproximal contact point. One hundred mu thick sections were obtained at the caries sites and polarized photomicrographs were taken. The sections had varnish placed, leaving only the external section site exposed, and were situated back into the original tooth. These teeth were then mounted with the artificial lesion having an interproximal contact with the adjacent tooth restoration. Specimens were placed in closed environments of artificial saliva for two weeks; the saliva was changed every forty-eight hours. All teeth were cycled through an artificial caries system for thirty minutes, three times per day. Half the specimens in each group were brushed with Crest (Procter and Gamble) for two minutes, twice per day. The same sections were again photographed under polarized light and areas of the lesions were digitized quantitatively. Results demonstrated the mean (+/- S.D.) percent change in lesion size (water imbibition) for each material nonexposed and exposed to fluoridated dentifrice to be: Amalgam -64.1 +/- 22.0, -1.0 +/- 8.5; Glass Ionomer 2.2 +/- 10.6, 14.0 +/- 7.2; Composite -28.1 +/- 11.7, 18.2 +/- 6.7. Negative numbers represent demineralization and positive numbers represent remineralization. Duncan's analysis indicated the nonbrushed fluoride-releasing glass ionomer and composite resin to have significantly greater demineralization inhibition compared to the nonbrushed amalgam group and remineralization enhancement effects on adjacent interproximal lesions (p < 0.05) compared to the brushed amalgam group.