Synthesis and characterizations of a fluoride-releasing dental restorative material

• Nano-fluorapatite (nFA) was synthesized by sol–gel method.
• Chemically linked PU/nFA composite was synthesized and characterized.
• The nFA and composite showed fluoride release pattern.
• The composite showed adhesion with dentin and sufficient bond strength.
• The resulting composite has potential to be used as endodontic obturating material.

The aim was to develop an obturating material which has the tendency to release fluoride and minimize interfaces with tooth. Nano-fluorapatite (nFA) powder was synthesized by sol–gel. The composite based on polyurethane (PU) was obtained by chemically binding the nFA (10, 15, 20% wt/wt) to the diisocyanate component by utilizing in-situ polymerization. The procedure involved stepwise addition of monomeric units of PU, and optimizing the reagent concentrations to synthesize composite. The structural, phase and morphological analysis of nFA was evaluated. The structural, fluoride release and in-vitro adhesion analysis with tooth structure of PU/nFA was conducted. For fluoride release analysis the samples were stored in artificial saliva and deionized water for periodical time intervals. Bond strength of composites was analyzed by push-out test. Chemical linkage was achieved between PU and nFA without intermediate coupling agent. The insignificant difference of fluoride release pattern was observed in artificial saliva and (p ≥ 0.05) deionized water. The PU/nFA composite provided sustained release of fluoride over a long period of time. The composite showed more adhesion toward tooth structure with the increase in concentration of nFA. Bond strength of composite was in accordance with root canal filling material, hence, the material with anti-cariogenic properties can be used as an obturating material.