Staining potential of acidulated phosphate fluoride (APF) foam on dental restorations in vitro

OBJECTIVES: To identify the staining potential of acidulated phosphate fluoride (APF) foam on restorations in vitro. MATERIALS AND METHODS: Two hundred ovine molars were used. Except 40 teeth remained unrestored as the controls, each was randomly selected to receive one of four restorative materials including preparation without restoration, glass ionomer cement (GIC), resin modified glass ionomer cement (RMGIC), or composite resin (CR). Following the procedure, topical APF was applied with a predetermined frequency. Staining formation was then evaluated. RESULTS: APF-treated teeth and restorations appeared with a darker shade, an orange-colored surface and/or a brown margin. The staining rates on GIC, RMGIC, and CR were 50%, 27.5%, and 17.5%, respectively. GIC had a higher staining potential than RMGIC (χ(2) = 4.266, df = 1, P = 0.039) and CR (χ(2) = 9.448, df = 1, P = 0.002), whereas the difference between RMGIC and CR was indiscernible (χ(2) = 1.147, df = 1, P = 0.284). Repeated applications of topical APF increased the risk of staining on RMGIC (χ(2) = 8.436 df = 1, P = 0.004) and CR (χ(2) = 6.873, df = 1, P = 0.009) but not on GIC (χ(2) = 0, df = 1, P = 1) and the controls (χ(2) = 4.051, df = 3, P = 0.256). CONCLUSIONS: APF-foam-related staining was confirmed in vitro. GIC was more susceptible to fluoride staining. This study suggested aesthetic implications when applying fluorides to restored teeth.