title: Nanoclay addition to a conventional glass ionomer cements: Influence on physical properties.
abstract: OBJECTIVE
  The objective of the present study is to investigate the reinforcement effect of polymer-grade montmorillonite (PGN nanoclay) on physical properties of glass ionomer cement (GIC).
  
  
  METHODS
  The PGN nanoclay was dispersed in the liquid portion of GIC (HiFi, Advanced Healthcare, Kent, UK) at 1%, 2% and 4% (w/w). Fourier-transform infrared (FTIR) spectroscopy was used to quantify the polymer liquid of GICs after dispersion of nanoclay. The molecular weight (Mw) of HiFi liquid was determined by gel permeation chromatography. The compressive strength (CS), diametral-tensile strength, flexural strength (FS) and flexural modulus (Ef) of cements (n = 20) were measured after storage for 1 day, 1 week and 1 month. Fractured surface was analyzed by scanning electron microscopy. The working and setting time (WT and ST) of cements was measured by a modified Wilson's rheometer.
  
  
  RESULTS
  The FTIR results showed a new peak at 1041 cm(-1) which increased in intensity with an increase in the nanoclay content and was related to the Si-O stretching mode in PGN nanoclay. The Mw of poly (acrylic acid) used to form cement was in the range of 53,000 g/mol. The nanoclay reinforced GICs containing <2% nanoclays exhibited higher CS and FS. The Ef cement with 1% nanoclays was significantly higher. The WT and ST of 1% nanoclay reinforced cement were similar to the control cement but were reduced with 2% and 4% nanoclay addition.
  
  
  CONCLUSIONS
  The dispersion of nanoclays in GICs was achieved, and GIC containing 2 wt% nanoclay is a promising restorative materials with improved physical properties.
authors.affiliation: School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.|FMH College of Medicine and Dentistry, University of Health Sciences, Lahore, Pakistan.
authors.forename: Muhammad A
authors.initials: MA
authors.lastname: Fareed
authors.affiliation: School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
authors.forename: Artemis
authors.initials: A
authors.lastname: Stamboulis
keywords: Glass ionomer; mechanical properties; nanoclay; setting time; working time