Anticaries Efficacy of <Phytic Acid-Stannous Fluoride> Primer

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The <Phytic acid (PYA)-Stannous Fluoride (SnF_2)> primer has been developed in our department as a tooth conditioner for bonding dental adhesives to tooth substrates. The treatment with this primer requires two steps, a first treatment with 7% aqueous solution of PYA and a second treatment with 3% aqueous solution of SnF_2. Therefore, it is expected that the caries resistance of teeth treated with SnF_2 at second step is improved. This primer is called 7PYA+SnF_2 primer. In this study, the effect of SnF_2 on the remineralization process of enamel treated with 7PYA+SnF_2 primer was investigated by comparing with the other treatments commonly used in dentistry.The tooth conditioners tested were a 10% and a 40% aqueous solution of phosphoric acid, an aqueous solution containing 10% citric acid and 3% FeCl_3,7PYA+SnF_2 primer, and a 7% aqueous solution of PYA as its control. The bovine enamel treated with each tooth conditioner was stored in the remineralization solution prepared according … More to the prescription of ten Cate et al for seven days. The remineralization process of tretaed enamel was evaluated by Knoop hardness (KHN) measurment and SEM observation. The KHNs of enamel treated with conditioners were down to ab.25-40% of that of sound enamel. However, the KHNs were recovered to ab.60-70% after 1 day storage in the remineralization solution in all treatments except 7PYA+SnF_2 primer and did not increase remakably after that. The formation of crystals like hydroxyapatite was found on these enamel surfaces after 1 day storage by SEM observation. On the other hand, the KHN of enamel treated with 7PYA+SnF_2 primer was recovered to ab 30-40% only after seven days. However, the acid-proof layr, which could not be dissolved even with 0.05-N hydrochloric acid and had ab. 5mum in thickness, was found on its surface by SEM observation. This layr also was found immediately after the treatment with 7PYA+SnF_2 primer, but not found in the other treatment. These results suggested that the acid-proof layr controlled the formation of hydroxyapatite, and the 7PYA+SnF_2 primer had an anticaries efficacy. Less