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 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.

Demineralization&ndash;remineralization dynamics in teeth and bone

“…However, this significantly reduced the amount of calcium and phosphate ions that could be released. 168 Composites containing HA Coupling agent treatment of calcium phosphate fillers with citric acid, acrylic acid, or methacrylic acid improved the flexural strength of composites containing HA. 169,170 However, γ-methacryloxypropyltrimethoxysilane coupling agent …”

pH-responsive release of chlorhexidine from modified nanoporous silica nanoparticles for dental applications

“…For efficient prevention or treatment of biofilm infections several systems releasing antibacterial and remineralizing agents have been reported, e.g. fluoride (F − ) [3][4][5][6], calcium (Ca 2+ ) and phosphate (PO 4 3− ) [7][8][9][10] or silver (Ag + ) ions [11,12]. Chlorhexidine (CHX) is a widely applied drug because of its high antimicrobial activity against gram-positive and gram-negative bacteria, fungi and viruses [13].…”

Adsorption and desorption behaviors of cetylpyridinium chloride on hydroxyapatite nanoparticles with different morphologies

“…Although the nanoparticles of CaP, including HAp, have been widely studied as filler materials for non-resolvable materials such as resin matrices 10,45) , the mechanical properties of CaP-filled resins will change owing to the dissolvability of CaP under acidic pH conditions. Recently, direct application of HAp nanoparticles to repair damaged enamel has attracted attention because of its dissolvability (i.e., the remineralization effect due to the release of calcium and phosphate ions 46,47) and a neutralization effect 48) ).…”