The effect of ceramic and porous fillers on the mechanical properties of experimental dental composites.
OBJECTIVE
The purpose of this study was to investigate the effect of ceramic fillers (containing leucite crystals) and their porosity on the mechanical properties of a new experimental dental composite in order to compare with the properties of composites containing conventional glass fillers.


METHODS
In this study, experimental composites were prepared by mixing the silane-treated fillers with monomers. Experimental composites were divided into four groups according to their filler type, amount and porosity. The monomers were composed of 70% Bis-GMA and 30% TEGDMA by weight for all groups. Glass and leucite-containing-ceramic were prepared as different filler types. In order to make fillers porous, leucite-containing-ceramic fillers were treated with HF acid. Camphorquinone and DMAEMA were used as photo initiator system. Post-curing was done for all groups before mechanical testing. Degree of Conversion of composites was measured using FTIR spectroscopy. The diametral tensile strength (DTS), flexural strength and flexural modulus were measured and compared among the groups.


RESULTS
The results showed that the stronger and more porous filler has a positive effect on flexural strength. Porosity of filler increased flexural strength significantly. No significant difference was found in DTS tests among the groups. Flexural modulus was affected and increased by using ceramic fillers. The type of the filler affected the DC of the composite and DC increased by post-curing.


CONCLUSIONS
Flexural strength is one of the most important properties of restorative dental materials. Higher flexural strength can be achieved by stronger and more porous fillers. Investigation into the effect of filler on dental material properties would be beneficial in the development of restorative dental material.
Zandinejad
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Restorative Department, School of Dentistry, Tehran University of Medical Sciences, P.O. Box 14155-5583, Tehran, Iran. azandinejad@hotmail.com
Atai
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Pahlevan
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D000538:Aluminum Silicates / Q000737:chemistry; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry; D004548:Elasticity; D005898:Glass / Q000737:chemistry; D006801:Humans; D006858:Hydrofluoric Acid / Q000737:chemistry; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D018583:Pliability; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D016062:Porosity; D019163:Reducing Agents / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D013729:Terpenes / Q000737:chemistry
D000538:Aluminum Silicates; D003188:Composite Resins; D003764:Dental Materials; C075815:IPS-Empress ceramic; D008689:Methacrylates; D011109:Polymethacrylic Acids; D019163:Reducing Agents; D013729:Terpenes; D003776:Dental Porcelain; C078519:leucite; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; C048339:camphoroquinone; C049840:2-(dimethylamino)ethyl methacrylate; D006858:Hydrofluoric Acid