title: The Effect of Lucite Glass Reinforcement on the Properties of Conventional Glass-Ionomer Filling Materials.
abstract: BACKGROUND
  The usage of glass ionomer cements (GICs) restorative materials are very limited due to lack of flexural strength and toughness.
  
  
  OBJECTIVE
  The aim of this study was to investigate the effect of using a leucite glass on a range of mechanical and optical properties of commercially available conventional glass ionomer cement.
  
  
  METHODS
  Ball milled 45μm leucite glass particles were incorporated into commercial conventional GIC, Ketac-Molar Easymix (KMEm). The characteristics of the powder particles were observed under scanning electron microscopy. The samples were made for each experimental group; KMEm and lucite- modified Ketac-Molar easy Mix (LMKMEm) according to manufacturer's instruction then were collected in damp tissue and stored in incubator for 1 hour. The samples were divided into two groups, one stored in distilled water for 24 hours and the others for 1 week.10 samples were made for testing biaxial flexural strength after 1 day and 1 week, with a crosshead speed of 1mm/min, calculated in MPa. The hardness (Vickers hardness tester) of each experimental group was also tested. To evaluate optical properties, 3 samples were made for each experimental group and evaluated with a spectrophotometer. The setting time of modified GIC was measured with Gillmore machine.
  
  
  RESULTS
  The setting time in LMKMEm was 8 minutes. The mean biaxial flexural strength was LMKMEm/ 1day: 24.13±4.14 MPa, LMKMEm/ 1 week: 24.22±4.87 MPa KMEm/1day:28.87±6.31 MPa and KMEm/1 week: 26.65±5.82 MPa which were not statistically different from each other. The mean Vickers hardness was LMKMEm: 403±66 Mpa and KMEm: 358±22 MPa; though not statistically different from each other. The mean total transmittance (Tt) was LMKMEm: 15.9±0.7, KMEm: 22.3±1.2, the mean diffuse transmittance (Td) was LMKMEm: 12.2±0.5, KMEm: 18.0±0.5 which were statistically different from each other.
  
  
  CONCLUSIONS
  Leucite glass can be incorporated with a conventional GIC without interfering with setting time. Yet, it did not improve the mechanical and optical properties of the GIC.
authors.affiliation: Dept. of Restorative Dentistry, Dental Branch, Islamic Azad University, Tehran, Iran.
authors.forename: Haleh
authors.initials: H
authors.lastname: Kazemi Yazdi
authors.affiliation: Academic Unit of Restorative Dentistry, University of Sheffield, Sheffield, UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Van Noort
authors.affiliation: Residence of Dept. Operative and Cosmetic Restorative, Dental Branch, Islamic Azad University, Tehran Branch, Tehran, Iran.
authors.forename: Mona
authors.initials: M
authors.lastname: Mansouri
keywords:  Glass ;  Glass Ionomer Cement ;  Mechanical Phenomena ;  Optical Phenomena; Dental material 