Effects of incorporating nanosized calcium phosphate particles on properties of whisker‐reinforced dental composites

Abstract

Clinical data indicate that secondary caries and restoration fracture are the most common problems facing tooth restorations. Our ultimate goal was to develop mechanically-strong and caries-inhibiting dental composites. The specific goal of this pilot study was to understand the relationships between composite properties and the ratio of reinforcement filler/releasing filler. Nanoparticles of monocalcium phosphate monohydrate (MCPM) were synthesized and incorporated into a dental resin for the first time. Silicon carbide whiskers were fused with silica nanoparticles and mixed with the MCPM particles at MCPM/whisker mass ratios of 1:0, 2:1, 1:1, 1:2, and 0:1. The composites were immersed for 1-56 days to measure Ca and PO4 release. When the MCPM/whisker ratio was changed from 0:1 to 1:2, the composite flexural strength (mean +/- SD; n = 5) decreased from 174 +/- 26 MPa to 138 +/- 9 MPa (p < 0.05). A commercial nonreleasing composite had a strength of 112 +/- 14 MPa. When the MCPM/whisker ratio was changed from 1:2 to 1:1, the Ca concentration at 56 days increased from 0.77 +/- 0.04 mmol/L to 1.74 +/- 0.06 mmol/L (p < 0.05). The corresponding PO4 concentration increased from 3.88 +/- 0.21 mmol/L to 9.95 +/- 0.69 mmol/L (p < 0.05). Relationships were established between the amount of release and the MCPM volume fraction v(MCPM) in the resin: [Ca]= 42.9 v(MCPM) (2.7), and [PO4] = 48.7 v(MCPM) (1.4). In summary, the method of combining nanosized releasing fillers with reinforcing fillers yielded Ca- and PO4-releasing composites with mechanical properties matching or exceeding a commercial stress-bearing, nonreleasing composite. This method may be applicable to the use of other Ca-PO4 fillers in developing composites with high stress-bearing and caries-preventing capabilities, a combination not yet available in any dental materials.

Hybrid effects of zirconia nanoparticles with aluminum borate whiskers on mechanical properties of denture base resin PMMA

“…By compounding the two fillers together, nano-ZrO 2 suppressed the grain growth of ABWs during polymerization. At the same time, ABWs acted as seeds for the grain growth of nanoZrO2 to form large elongated grains around the whiskers, thus resulting in a good grain mircostructure [27][28][29] . Due to the enormous specific surface area, high surface energy, and active chemical properties, nanoparticles have a strong tendency to aggregate and decrease particle-polymer interactions, thus lowering the reinforcement of PMMA 9,30) .…”

Calcium orthophosphate-based biocomposites and hybrid biomaterials

“…To the author's best knowledge, among calcium orthophosphates listed in Table 3, before very recently only apatites (CDHA, HA and, perhaps, FA) have been available in the nanocrystalline state. However, very recently, nano-DCPA [481][482][483] and nano-MCPM [484] have been synthesized and applied to prepare nano-biocomposites with strong ionic release to combat tooth caries.…”

“…For example, HA was combined with Bioglass Ò (Novabone Products, Alachua, FL) [748,749] and with other glasses [750] to form glassceramics biocomposites. Other reinforcement materials for calcium orthophosphates are differentiated by either shape of the fillers, namely, particles [751,752], platelets [753,754], whiskers [484,755,756], fibers [757][758][759], or their chemical composition: zirconia and/or PSZ [250, 743-746, 755, 760-793], alumina [250,751,754,[793][794][795][796][797][798][799][800][801][802], titania [307,747,752,[803][804][805][806][807][808][809][810][811][812][813][814][815][816][817], other oxides [818-821], silica and/or glasses …”

Nanotechnology In Dentistry - What Does The Future Hold In Store?

“…These nanocomposites have superior hardness, flexural strength, modulus of elasticity, decreased polymerization shrinkage and also have excellent handling properties [23]. A recent study by Xu et al has evaluated the incorporation of nanosized CaPO 4 particles into resin based-composites, with a resulting improvement in stress bearing capacity as well as ion release that could inhibit dental caries [24,25].…”