The Bulletín of Kanagawa Dental College

Vol. 36 No. 1       MARCH- 2008

ISSN: 0385-1443      UBIC: 65

ABSTRACT

In order to develop new calcified material using the calcification mechanism of phosphoserine polymer (Poly[Ser(P)]), a preliminary study was carried out on a reaction of Poly[Ser(P)], calcium ion and/or apatite. Hydroxyapatite (HAP) was added to 1ml of 500 µm/ml of Poly[Ser(P)], and the solution was stirred for 60 mins. After centrifugation, the supernatant was filtered, and Poly[Ser(P)], without adsorption onto HAP in the filtrate, was analyzed with gel permeation chromatography. Copolymers of phosphoserine and aspartic acid (Copoly[Ser(P)50 Asp50]), poly (aspartic acid) (Poly(Asp)), phosphoserine (Ser(P)), and phosvitin were used as the comparative compounds. The reactivity between the calcium ions and the polymers and Ser(P) in aqueous solution was estimated from the determination of free calcium ions in the solution and by potentiometric titration. The enamel surfaces of bovine teeth were treated with Poly[Ser(P)], then immersed in a saturated solution of tricalcium phosphate for 30 days and finally observed with an electron probe microscope analyzer (EMA). The amount of polymer and Ser(P) that adsorbed onto HAP was 100% to Poly[Ser(P)], 78% to Copoly[Ser(P)50 Asp50], 59% to Poly(Asp), 22% to Ser(P) after immersion for 5mins, respectively and 90% to phosvitin after 60mins. The reactivity of Poly[Ser(P)]to HAP was higher and more rapid rather than that of phosvitin. The binding ratio of calcium ions to the polymers and Ser(P) in the aqueous solution was about 41% to Poly[Ser(P)], 20% to Copoly[Ser(P)50 Asp50], 2% to Poly(Asp), and 36% to phosvitin, respectively. PoIy[Ser(P)] was more reactive to calcium ions than any other polymer used in this study. It was recognized from the EMA observation that the enamel surface of the bovine teeth to which Poly[Ser(P)] had been applied was covered with crystalloid. The results of this study suggest that Poly[Ser(P)] is a compound that promotes remineralization on the enamel surface. Key words: Caries prevention / Calcification / Polyphosphoserine.

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