Rechargeable dental adhesive with calcium phosphate nanoparticles for long-term ion release

J Dent. 2015 Dec;43(12):1587-95. doi: 10.1016/j.jdent.2015.06.009. Epub 2015 Jul 2.

Abstract

Objectives: The tooth-resin bond is the weak link of restoration, with secondary caries as a main reason for failure. Calcium phosphate-containing resins are promising for remineralization; however, calcium (Ca) and phosphate (P) ion releases last only a couple of months. The objectives of this study were to develop the first rechargeable CaP bonding agent and investigate the key factors that determine CaP ion recharge and re-release.

Methods: Nanoparticles of amorphous calcium phosphate (NACP) were synthesized. Pyromellitic glycerol dimethacrylate (PMGDM), ethoxylated bisphenol-A dimethacrylate (EBPADMA), 2-hydroxyethyl methacrylate (HEMA), and bisphenol-A glycidyl dimethacrylate (BisGMA) were used to synthesize three adhesives (denoted PE, PEH and PEHB). NACP were mixed into adhesive at 0-30% by mass. Dentin shear bond strengths were measured. Adhesive specimens were tested for Ca and P initial ion release. Then the ion-exhausted specimens were immersed in Ca and P solution to recharge the specimens, and the recharged specimens were then used to measure ion re-release for 7 days as one cycle. Then these specimens were again recharged and the re-release was measured for 7 days as the second cycle. Three recharge/re-release cycles were tested.

Results: PEHB had the highest dentin bond strength (p<0.05). Increasing NACP content from 0 to 30% did not affect dentin bond strength (p>0.1), but increased CaP release and re-release (p<0.05). PEHB-NACP had the greatest recharge/re-release, and PE-NACP had the least (p<0.05). Ion release remained high and did not decrease with increasing the number of recharge/re-release cycles (p>0.1). After the third cycle, specimens without further recharge had continuous CaP ion release for 2-3 weeks.

Significance: Rechargeable CaP bonding agents were developed for the first time to provide long-term Ca and P ions to promote remineralization and reduce caries. Incorporation of NACP into adhesive had no negative effect on dentin bond strength. Increasing NACP filler level increased the ion recharge and re-release capability. The new CaP recharge method and PMGDM-EBPADMA-NACP composition may have wide application in adhesives, composites and cements, to combat caries and remineralize lesions.

Keywords: Calcium phosphate nanoparticles; Dental adhesive; Dentin bonding; Ion recharge; Ion release; caries inhibition.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Benzoates / chemistry
  • Bisphenol A-Glycidyl Methacrylate / chemistry
  • Calcium Phosphates / chemistry*
  • Composite Resins / chemistry
  • Dental Bonding*
  • Dental Caries / prevention & control
  • Dental Cements / chemical synthesis
  • Dental Cements / chemistry*
  • Dentin / chemistry
  • Ions / chemistry
  • Materials Testing
  • Methacrylates / chemistry
  • Nanoparticles / chemistry*
  • Shear Strength / drug effects

Substances

  • Benzoates
  • Calcium Phosphates
  • Composite Resins
  • Dental Cements
  • Ions
  • Methacrylates
  • amorphous calcium phosphate
  • pyromellitic dianhydride glycerol dimethacrylate adduct
  • ethoxylated bis-phenol A dimethacrylate
  • Bisphenol A-Glycidyl Methacrylate
  • hydroxyethyl methacrylate