Nanocomposite containing amorphous calcium phosphate nanoparticles for caries inhibition

Abstract Objectives The main challenges facing composite restorations are secondary caries and bulk fracture. The objectives of this study were to synthesize novel nanoparticles of amorphous calcium phosphate (NACP), develop NACP nanocomposite with calcium (Ca) and phosphate (PO4 ) ion release to co...

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Bibliographic Details
Published in:Dental materials 2011-08, Vol.27 (8), p.762-769
Main Authors: Xu, Hockin H.K, Moreau, Jennifer L, Sun, Limin, Chow, Laurence C
Format: Article
Language:English
Subjects:
Advanced Basic Science
Amorphous calcium phosphate
Bisphenol A-Glycidyl Methacrylate - chemistry
Calcium Phosphates - chemical synthesis
Calcium Phosphates - chemistry
Caries inhibition
Cariostatic Agents - chemical synthesis
Cariostatic Agents - chemistry
Composite Resins - chemical synthesis
Composite Resins - chemistry
Dental Materials - chemical synthesis
Dental Materials - chemistry
Dental nanocomposite
Dentistry
Diffusion
Elastic Modulus
Filler level
Glass - chemistry
Glass Ionomer Cements - chemistry
Humans
Hydrogen-Ion Concentration
Ion release
Materials Testing
Nanocomposites - chemistry
Nanoparticles - chemistry
Pliability
Polyethylene Glycols - chemistry
Polymethacrylic Acids - chemistry
Resin Cements - chemistry
Stress, Mechanical
Stress-bearing
Surface Properties
Time Factors
X-Ray Diffraction
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Summary:Abstract Objectives The main challenges facing composite restorations are secondary caries and bulk fracture. The objectives of this study were to synthesize novel nanoparticles of amorphous calcium phosphate (NACP), develop NACP nanocomposite with calcium (Ca) and phosphate (PO4 ) ion release to combat caries, and investigate the effects of NACP filler level and glass co-filler reinforcement on composite properties. Methods NACP (diameter = 116 nm) were synthesized via a spray-drying technique for the first time. Since the local plaque pH in the oral cavity can decrease to 5 or 4, photo-activated composites were tested with immersion in solutions of pH 7, 5.5, and 4. Composite mechanical properties as well as Ca and PO4 ion release were measured vs. pH and filler level. Results Increasing the NACP filler level increased the ion release. At 28 d and pH 4, the Ca release was (4.66 ± 0.05) mmol/L at 20% NACP, much higher than (0.33 ± 0.08) at 10% NACP ( p < 0.05). Decreasing the pH increased the ion release. At 20% NACP, the PO4 release at 28 d was (1.84 ± 0.12) mmol/L at pH 4, higher than (0.59 ± 0.08) at pH 5.5, and (0.12 ± 0.01) at pH 7 ( p < 0.05). However, pH had little effect on composite mechanical properties. Flexural strength at 15% NACP was (96 ± 13) MPa at pH 4, similar to (89 ± 13) MPa at pH 5.5, and (89 ± 19) MPa at pH 7 ( p > 0.1). The new NACP nanocomposites had strengths that were 2-fold those of previous calcium phosphate composites and resin-modified glass ionomer control. Significance NACP composites were developed for the first time. Their strengths matched or exceeded a commercial composite with little ion release, and were 2-fold those of previous Ca–PO4 composites. The nanocomposite was “smart” as it greatly increased the ion release at a cariogenic pH 4, when these ions would be most needed to inhibit caries. Hence, the new NACP composite may be promising for stress-bearing and caries-inhibiting restorations.
ISSN:0109-5641
1879-0097
DOI:10.1016/j.dental.2011.03.016