title: Mechanical properties and ion release from bioactive restorative composites containing glass fillers and calcium phosphate nano-structured particles.
abstract: OBJECTIVE
  To evaluate the effect of the replacement of barium glass by dicalcium phosphate dihydrate (DCPD) particles on the mechanical properties and degree of conversion (DC) of composites. Additionally, calcium and hydrogen phosphate (HPO4(2-)) release were followed for 28 days.
  
  
  METHODS
  Nine composites containing equal parts (in mols) of BisGMA and TEGDMA and 40, 50 or 60 vol% of total filler were manipulated. Filler phase was constituted by silanated barium glass and 0%, 10% or 20% of DCPD particles. DC was determined by near-FTIR. Biaxial flexural strength (BFS) and modulus (E) were tested using the "piston on three balls" method, while fracture toughness (KIc) used the "single edge notched beam" method. Specimens were tested after 24h and 28 days in water. Ion release was determined using inductively coupled plasma optical emission spectrometry (ICP-OES). Data were analyzed by ANOVA/Tukey (DC and ion release) or Kruskal-Wallis/Mann-Whitney (mechanical properties; alpha: 5%).
  
  
  RESULTS
  DC was not affected by DCPD. The presence of DCPD reduced BFS for both storage times, while differences in E became evident after 28 days. After 24h, KIc increased with the addition of DCPD; after 28 days, however, KIc decreased only for DCPD-containing composites. Calcium release was similar for both DCPD contents and remained fairly constant during the 28-day period. Overall, HPO4(2-) release was higher at 7 days and did not decrease after 14 days.
  
  
  CONCLUSIONS
  The composite with the highest filler level and 10% DCPD represented the best compromise between mechanical properties after aging in water and ion release.
authors.affiliation: Department of Biomaterials and Oral Biology, Univ. of São Paulo School of Dentistry, Av. Prof. Lineu Prestes, 2227, São Paulo, SP 05508-000, Brazil.
authors.forename: Marina D S
authors.initials: MD
authors.lastname: Chiari
authors.affiliation: Department of Biomaterials and Oral Biology, Univ. of São Paulo School of Dentistry, Av. Prof. Lineu Prestes, 2227, São Paulo, SP 05508-000, Brazil.
authors.forename: Marcela C
authors.initials: MC
authors.lastname: Rodrigues
authors.affiliation: Department of Biomaterials and Oral Biology, Univ. of São Paulo School of Dentistry, Av. Prof. Lineu Prestes, 2227, São Paulo, SP 05508-000, Brazil.
authors.forename: Tathy A
authors.initials: TA
authors.lastname: Xavier
authors.affiliation: Department of Biomaterials and Oral Biology, Univ. of São Paulo School of Dentistry, Av. Prof. Lineu Prestes, 2227, São Paulo, SP 05508-000, Brazil.
authors.forename: Eugen M N
authors.initials: EM
authors.lastname: de Souza
authors.affiliation: Department of Biomaterials and Oral Biology, Univ. of São Paulo School of Dentistry, Av. Prof. Lineu Prestes, 2227, São Paulo, SP 05508-000, Brazil.
authors.forename: Victor E
authors.initials: VE
authors.lastname: Arana-Chavez
authors.affiliation: Department of Biomaterials and Oral Biology, Univ. of São Paulo School of Dentistry, Av. Prof. Lineu Prestes, 2227, São Paulo, SP 05508-000, Brazil. Electronic address: rrbraga@usp.br.
authors.forename: Roberto R
authors.initials: RR
authors.lastname: Braga
mesh_terms: D017609:Barium Compounds / Q000737:chemistry*; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002130:Calcium Phosphates / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D055119:Elastic Modulus; D005898:Glass / Q000737:chemistry*; D007477:Ions; D008422:Materials Testing; D053758:Nanoparticles; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D013054:Spectrophotometry, Atomic; D019265:Spectroscopy, Near-Infrared; D013499:Surface Properties
chemical_list: D017609:Barium Compounds; D002130:Calcium Phosphates; D003188:Composite Resins; D007477:Ions; D011109:Polymethacrylic Acids; C102738:barium glass filler; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; D012822:Silicon Dioxide; C494366:calcium phosphate, dibasic, dihydrate
keywords: Calcium phosphate; Ion release; Mechanical properties; Resin composite