title: A new modification for improving shear bond strength and other mechanical properties of conventional glass-ionomer restorative materials.
abstract: OBJECTIVE
  To study the effect of addition of poly(acrylamide-co-sodium acrylate) copolymer and/or TiO2 nanoparticles on the mechanochemical properties of conventional glass ionomer (GIC)-based restorative materials.
  
  
  METHODS
  The copolymer was prepared, characterized and then added, either separately or in combination with different proportions of TiO2 nanoparticles to the conventional GIC powder. The developed composites were characterized using FTIR spectrometry, x-ray diffraction, and scanning electron microscopy. The mechanical properties of the obtained series of modified GIC formulations were investigated in comparison with other formulations containing only TiO2 nanoparticles through testing their compressive strength, flexural strength, and dentin shear bond strength.
  
  
  RESULTS
  The preliminary data of the study showed a significant increase in the compressive strength of the conventional GIC after addition of 3% and 5% TiO2 nanoparticles by weight, but 7% decreased it. Upon addition of copolymer, the compressive strength was lower than that of the conventional GIC. The highest average compressive strength value was obtained upon incorporation of 7% 1:1 combination of copolymer-TiO2 nanoparticles. The results also demonstrated a significant increase in the flexural strength values after addition of both copolymer and TiO2 nanoparticles to the GIC powder. In addition, the results revealed a significant increase in values of dentin shear bond strength after copolymer addition with the highest value noted upon addition of 7% by weight of copolymer.
  
  
  CONCLUSIONS
  The new series of modified glass ionomers developed here can be tailored to act as restorative materials with high quality performance in high stress-bearing areas.
authors.forename: Salwa A
authors.initials: SA
authors.lastname: El-Negoly
authors.forename: Abeer A
authors.initials: AA
authors.lastname: El-Fallal
authors.forename: Ibrahim M
authors.initials: IM
authors.lastname: El-Sherbiny
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D002626:Chemistry, Pharmaceutical; D019245:Compressive Strength; D001840:Dental Bonding; D003799:Dental Stress Analysis / Q000295:instrumentation; D003804:Dentin / Q000648:ultrastructure; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006801:Humans; D006813:Humidity; D008422:Materials Testing; D055595:Mechanical Phenomena; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles / Q000737:chemistry; D018583:Pliability; D033081:Shear Strength; D017550:Spectroscopy, Fourier Transform Infrared; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014025:Titanium / Q000737:chemistry; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction; D000099166:Polyacrylamides
chemical_list: D000180:Acrylic Resins; D005899:Glass Ionomer Cements; D014025:Titanium; D014867:Water; D000099166:Polyacrylamides; C009495:titanium dioxide; C006903:carbopol 940