2016 Volume 59 Issue 6 Pages 472-478
Purpose: Calcium phosphate cement (CPC) is converted to hydroxyapatite (HA) as a major product and also has high biocompatibility and osteoconductivity. Thus, CPC has received considerable interest in dental and medical applications as a bone graft material. Recent studies have shown that the inclusion of fluoride (F) in hydroxyapatite enhances bone formation and causes it to be considerably less soluble than HA under an acidic physiological-like environment. Therefore, fluorapatite (FA)-forming CPC may be suitable for not only bone graft materials but also for endodontic applications such as root-end filling, perforation repair, and direct pulp capping. The purpose of this study was to investigate the in vitro properties of FA-forming CPC.
Methods: A conventional CPC powder consisting of equimolar amounts of tetracalcium phosphate (TTCP; median particle size=4.0 μm) and dicalcium phosphate anhydrous (DCPA; median particle size=1.0 μm) was used in this study. Various amounts of sodium fluoride (NaF) powder were added to the CPC powder to obtain F/Ca molar ratios for the FA-forming CPC ranging from 0-0.4. A 0.5 mol/l phosphate (pH 5.6, P/L=2.5) solution was used as the cement liquid. The FA-forming CPC was subjected to measuring setting time (ST), diametral tensile strength (DTS), and porosity. Additionally, two types of F present in the set specimens were determined by sequential extraction: CaF2 (1 mol/l KOH solution) and apatitic F remaining in the specimen (0.5 mol/l HClO4). The reaction products of the samples were identified by powder X-ray diffraction. A one-way analysis of variance (ANOVA), following Tukey’s test, was performed on the ST, DTS, porosity, and F content of the hardened cement (p<0.05).
Results: The addition of F to the cements decreased ST (14.3-16.8 min) and DTS (1.0-3.4 MPa), but increased porosity (40.7-49.0 vol%). Additionally, the amounts of F incorporated into the cement product increased with the F/Ca ratio. The ANOVA of the results revealed significant differences among the groups. A higher F/Ca ratio increased the crystallinity of the apatitic products formed.
Conclusion: Higher crystallinities of the apatitic products formed at higher F/Ca molar ratios. Most of the FA-forming CPC used in this study exhibited valuable in vitro properties for not only bone graft materials but also for endodontic materials that require biocompatibility and osteoconductivity and also non-bioresorbability.
