title: Evaluation of thermal conductivity and flexural strength properties of poly(methyl methacrylate) denture base material reinforced with different fillers.
abstract: BACKGROUND
  Poly(methyl methacrylate) (PMMA) is widely used in prosthodontics as a denture base material. However, it has several disadvantages, including low strength and low thermal conductivity.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to evaluate thermal conductivity and flexural strength after adding powdered Ag, TiO2, ZrO2, Al2O3, SiC, SiC-nano, Si3N4, and HA-nano in ratios of 10 wt% to PMMA.
  
  
  METHODS
  A total of 144 specimens were fabricated and divided into 18 groups. Specimens were left in water for 30 days. Thermal conductivity values were measured using a heat flowmeter, flexural strength was measured with a 3-point bend test, and specimens were investigated with environmental scanning electron microscopy. One-way ANOVA was used to compare means followed by using Duncan multiple range test (α=.05).
  
  
  RESULTS
  The thermal conductivity value of PMMA increased significantly after the addition of Si3N4, SiC, Al2O3, SiC-nano, TiO2, ZrO2, HA-nano, and Ag. Progressive increases in thermal conductivity were observed in Si3N4, SiC, and Al2O3fillers. Flexural strength values of the control group were not significantly different from those of the SiC, Al2O3, or Ag group (P>.05). In the other groups, flexural strength values decreased significantly (P<.05). On the basis of electron microscopy, we observed that Si3N4, SiC, and Al2O3powders had higher thermal conductivity values that are dissipated more homogeneously in PMMA.
  
  
  CONCLUSIONS
  Although the addition of 10 wt% SiC, Al2O3,and Ag powder to PMMA significantly increased thermal conductivity, the flexural strength values of PMMA were not significantly changed.
authors.affiliation: Assistant Professor, Department of Prosthodontics, Faculty of Dentistry at Atatürk University, Erzurum, Turkey. Electronic address: esra.kul@atauni.edu.tr.
authors.forename: Esra
authors.initials: E
authors.lastname: Kul
authors.affiliation: Professor, Department of Prosthodontics, Faculty of Dentistry at Atatürk University, Erzurum, Turkey.
authors.forename: Lütfü İhsan
authors.initials: Lİ
authors.lastname: Aladağ
authors.affiliation: Assistant Professor, Department of Mechanical Engineering, Faculty of Engineering at Atatürk University, Erzurum, Turkey.
authors.forename: Ruhi
authors.initials: R
authors.lastname: Yesildal
mesh_terms: D003819:Denture Bases; D008422:Materials Testing; D018583:Pliability; D019904:Polymethyl Methacrylate; D013499:Surface Properties; D013814:Thermal Conductivity
chemical_list: D019904:Polymethyl Methacrylate