Hockin H K Xu1, Michael D Weir, Limin Sun. 1. Paffenbarger Research Center, American Dental Association Foundation, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA. hockin.xu@nist.gov
Abstract
OBJECTIVES: Nanoparticles of dicalcium phosphate anhydrous (DCPA) were synthesized in our laboratory for the first time and incorporated into a dental resin. Our goal was to develop a mechanically strong dental composite that has Ca and PO(4) ion release to combat tooth caries, and to investigate the effects of whisker reinforcement, DCPA particle size and silanization. METHODS: DCPA nanoparticles and two larger DCPA particles were used with nano-silica-fused whiskers as fillers in a resin matrix. Composite mechanical properties were measured via three-point flexure, and the release of Ca and PO(4) ions were measured versus time. RESULTS: Using DCPA nanoparticles with a diameter of 112nm, the composite at a DCPA:whisker mass ratio of 1:1 had a flexural strength (mean+/-S.D.; n=5) of (112+/-17)MPa, not significantly different from (112+/-14)MPa of a commercial non-releasing composite; both were higher than (29+/-7)MPa for the composite at DCPA:whisker of 1:0 (p<0.05). The composite with DCPA particle size of 112nm released Ca to a concentration of 0.85mmol/L and PO(4) of 3.48mmol/L, higher than Ca of 0.67mmol/L and PO(4) of 1.11mmol/L using DCPA with 12microm particle size (p<0.05). Silanization of DCPA increased the composite strength at DCPA:whisker of 1:0 compared to that without silanization, but decreased the Ca and PO(4) release (p<0.05). Increasing the DCPA particle surface area increased the Ca and PO(4) release. SIGNIFICANCE: Decreasing the DCPA particle size increased the Ca and PO(4) release; whisker reinforcement increased the composite strength by two- to three-fold. The nano DCPA-whisker composites, with high strength and Ca and PO(4) release, may provide the needed, unique combination of stress-bearing and caries-inhibiting capabilities.
OBJECTIVES: Nanoparticles of dicalcium phosphate anhydrous (DCPA) were synthesized in our laboratory for the first time and incorporated into a dental resin. Our goal was to develop a mechanically strong dental composite that has Ca and PO(4) ion release to combat tooth caries, and to investigate the effects of whisker reinforcement, DCPA particle size and silanization. METHODS:DCPA nanoparticles and two larger DCPA particles were used with nano-silica-fused whiskers as fillers in a resin matrix. Composite mechanical properties were measured via three-point flexure, and the release of Ca and PO(4) ions were measured versus time. RESULTS: Using DCPA nanoparticles with a diameter of 112nm, the composite at a DCPA:whisker mass ratio of 1:1 had a flexural strength (mean+/-S.D.; n=5) of (112+/-17)MPa, not significantly different from (112+/-14)MPa of a commercial non-releasing composite; both were higher than (29+/-7)MPa for the composite at DCPA:whisker of 1:0 (p<0.05). The composite with DCPA particle size of 112nm released Ca to a concentration of 0.85mmol/L and PO(4) of 3.48mmol/L, higher than Ca of 0.67mmol/L and PO(4) of 1.11mmol/L using DCPA with 12microm particle size (p<0.05). Silanization of DCPA increased the composite strength at DCPA:whisker of 1:0 compared to that without silanization, but decreased the Ca and PO(4) release (p<0.05). Increasing the DCPA particle surface area increased the Ca and PO(4) release. SIGNIFICANCE: Decreasing the DCPA particle size increased the Ca and PO(4) release; whisker reinforcement increased the composite strength by two- to three-fold. The nano DCPA-whisker composites, with high strength and Ca and PO(4) release, may provide the needed, unique combination of stress-bearing and caries-inhibiting capabilities.
Authors: Michael D Weir; Jennifer L Moreau; Eric D Levine; Howard E Strassler; Laurence C Chow; Hockin H K Xu Journal: Dent Mater Date: 2012-03-18 Impact factor: 5.304
Authors: Ling Zhang; Michael D Weir; Laurence C Chow; Joseph M Antonucci; Jihua Chen; Hockin H K Xu Journal: Dent Mater Date: 2015-12-29 Impact factor: 5.304