The purpose of this study was to evaluate the infulence of incorporation of zirconuim-silicate on diametral tensile strength, shear bond strength to the enamel, and depth of cure of 7 experimental composites. One group contained no filler(group l or control group) , and the other 6 composites contain 75% filler in which zirconium-silicate(Zr-Si) were 0%, 2%, 4%, 6% . 8%, 10% with reduced contents of silica filler resfectively. Both of fillers were treated with 1% silane ( r-methacryloxypropyltrmethoxy silane) . Light curable monomers were prepared by mixing BiS-GMA and TEGDMA with 3 : 1 ratio and adding camphoro quinnone (CQ) 0.6% with tertiary amine 0.3% . Diametral tensile strengths of specimens with 3mm ×6mm were measured with Instron (No.4467, USA) with 1mm/min crosshead speed. Shear bond strengths of composites which bonded to bovine enamel etched with 37% phosphoric acid were measured at Instron Testing Machine with as same speed as in diametric tensile strengths. Depth of cure were measured by a method that composite was filled in cylinder mold, illuminated at one side, and uncured composite was removed with acetone, and the residual thickness of composite was measured.
Following results were obtained :
1.Composites containing 0% , 2% , or 4% zirconium-silicate filler(group 2, 3 and 4) showed the statistically higher diametric tensile strength than the others. (p〈0.05)
2.Increase of zirconium-silicate filler contents reduced the diametric tensile strength of experimental composites. (r2=0.8721, p=0.0002)
3.Increase of zirconium-silicate filler contents did not affect the shear bond strength of experimental composites. (r2=0.2815, p =0.4067)
4.Increase of zirconium-silicate filler contents reduced significantly the depth of cure of experimental composites. (r2=0.9700, p〈0.0001)
These results mean that the mechanical propel-ties of composites could not be improved by incorporation of small amount of zirconium-silicate filler. Also, the increased contents of zirconum-silicates fillers was found to reduce the diametric tensile strength and depth of cure.
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