title: Effects of N-vinylcaprolactam containing polyelectrolytes on hardness, fluoride release and water sorption of conventional glass ionomers.
abstract: BACKGROUND
  N-vinylcaprolactam (NVC) containing glass ionomers are promising dental restorative materials with improved mechanical properties; however, little information is available on other physical properties of this type of modified glass ionomer, especially their water sorption, fluoride releasing properties and microhardness.
  
  
  OBJECTIVE
  The purpose of this study was to investigate the effects of NVC-containing polyelectrolytes on microhardness, fluoride release and water sorption of conventional glass ionomer cements (GIC).
  
  
  METHODS
  The terpolymer of acrylic acid (AA), itaconic acid (IA) and N-vinylcaprolactam (NVC) with 8:1:1 and 7:1:2 (AA: IA: NVC) molar ratios was synthesized by free radical polymerization and characterized using 1H-NMR and FTIR. Experimental GIC specimens were made from a 50% solution of the synthesized terpolymer with Fuji IX powder in a 3.6:1 P/L ratio. Specimens were mixed and fabricated at room temperature. Vickers hardness was determined using a microhardness tester. Water sorption and fluoride releasing properties were also investigated. Commercial Fuji IX was used as the control group. All specimens were first conditioned in distilled water at 37°C for 1 day up to 1 month. Results for the experimental GIC were compared with the control group, using 1-way and 2-way ANOVA and the Tukey multiple range test (α=.05).
  
  
  RESULTS
  The NVC-modified GIC exhibited higher mean values of Vickers hardness numbers (VHN). However, the data exhibited no statistically significant differences between the experimental and control groups. The experimental cement (TP2) absorbed significantly more water than the control group (P<.034). Additionally, NVC-containing specimens showed comparable fluoride releasing properties with almost the same fluoride burst and continued fluoride release from the bulk of the material.
  
  
  CONCLUSIONS
  It was concluded that a hydrophilic monomer such as NVC might be able to increase the water sorption and decrease the amount of initial fluoride release of the glass ionomers. Hydrophilic monomer such as NVC might be able to increase the water sorption and decrease the amount of initial fluoride release of the glass ionomers.
authors.affiliation: Advanced Prosthodontics Program, Herman Ostrow School of Dentistryof University of Southern California, 925, W 34th St, Rm #102, Los Angeles, CA 90089, USA. moshaver@usc.edu
authors.forename: Alireza
authors.initials: A
authors.lastname: Moshaverinia
authors.forename: Sahar
authors.initials: S
authors.lastname: Ansari
authors.forename: Nima
authors.initials: N
authors.lastname: Roohpour
authors.forename: Mamaly
authors.initials: M
authors.lastname: Reshad
authors.forename: Scott R
authors.initials: SR
authors.lastname: Schricker
authors.forename: Winston Wl
authors.initials: WW
authors.lastname: Chee
mesh_terms: D000327:Adsorption; D002209:Caprolactam / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D003692:Delayed-Action Preparations / Q000737:chemistry*; D004337:Drug Carriers / Q000737:chemistry; D004573:Electrolytes / Q000737:chemistry; D005459:Fluorides / Q000008:administration & dosage / Q000737:chemistry*; D005899:Glass Ionomer Cements / Q000138:chemical synthesis / Q000737:chemistry*; D006244:Hardness; D057927:Hydrophobic and Hydrophilic Interactions; D008422:Materials Testing; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D003692:Delayed-Action Preparations; D004337:Drug Carriers; D004573:Electrolytes; D005899:Glass Ionomer Cements; D011108:Polymers; D002209:Caprolactam; D005459:Fluorides