• Bulletin of the Korean Chemical Society
• /
• v.27 no.1
• /
• pp.27-28
• /
• 2006

• Restorative Dentistry and Endodontics
• /
• v.26 no.1
• /
• pp.23-31
• /
• 2001

The purpose of this study was to search the optimal silane concentrations for filler- silanization of seven experimental composites. Silica filer was a 25micron crushed type. 0.0%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, and 3.0% silane($\gamma$-methacrylooxypropyltrimethoxysilane)were added into silica-filler with weight percentage (wt%). Mixtures(silica filler/silane)were reacted at 6$0^{\circ}C$ for 72hours, and crushed into fine particles those were used as fillers for 7 experimental composites. Monomer was a 3 : 1 mixture of Bis-GMA and TEGDMA containing 0.2% tertiary amine and 0.4% camphoroquinone for light curability. A ratio for mixing the monomer and filler was 75% and 25% respectively. Seven experimental composites was classified with the concentration of silane treated, and the specimen number for each test was 10. Specimens with 6mm diameter and 3mm height dimension for measuring the diametral tensile strength were destroyed with 1mm/min cross-head speed on Instron universal testing machine (No. 4467, USA). Shear bond strength was measured on the specimens bonded to bovine enamel etched with 37% phosphoric acid solution for 1 minute Fractured surfaces were observed by SEM (Hitachi S-3200, Japan) among that of the highest values measured from each groups. Following results were obtained: 1. Experimental composites containing silanized filter showed the significantly higher diametral tensile strength and shear bond strength than the composites containing un-silanized fillers(Group1) (p<0.05). 2. In silanized filler composite resins(Group 2~7), Diametral tensile strength of Group 3 showed the significantly higher than that of Group 2 and Group 6(p<0.05). 3. Shear bond strength was higher in Group 3 than that of Group 7 (p＜0.05)in silanized fillers composite resins. 4. Fracture surface was formed in resin matrixes on the specimens from composites containing the fillers treated with 0.5% 1.0%, and 1.5% silane. These results mean that the optimal silane concentrations are exist for each fillet with its size and surface area, and that 1.0% is a optimal value for concentration to coat the 25$\mu\textrm{m}$ filler with silane.

• Applied Chemistry for Engineering
• /
• v.16 no.1
• /
• pp.117-122
• /
• 2005

The aim of this study was to evaluate the effect of tertiary amine photo-accelerator on the dental properties of visible light-activated, polymeric, dental restorative composites (PDRC) through the measurement of mechanical and esthetic properties. The surface of barium silicate was hydrophobically treated to improve the interfacial behavior with the acrylic resin matrix. Camphorquinone was adopted as a photo-initiator with 0.5 wt% based on the resin matrix. It was discovered that the dental properties of PDRC were primarily dependent on the chemical structure rather than the added content of photo-accelerator.

• Restorative Dentistry and Endodontics
• /
• v.25 no.3
• /
• pp.421-434
• /
• 2000

The purpose of this study was to evaluate the influences of incorporation of zirconium-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 1 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, respectively. Both of fillers were treated with 1% silane (${\gamma}$-methacryloxypropyltrimethoxy silane). Light curable monomers were prepared by mixing Bis-GMA and TEGDMA with 3:1 ratio and adding camphoroquinone(CQ) 0.6% with tertiary amine 0.3%. Diametral tensile strengths of specimens with $3mm{\times}6mm$ 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 diametral 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 diametral tensile strength than the others. (p<0.05) 2. Increase of zirconium-silicate filler contents reduced the diametral tensile strength of experimental composites. ($r^2$=0.8721, p=0.0002) 3. Increase of zirconium-silicate filler contents did not affect the shear bond strength of experimental composites. ($r^2$=0.2815, p=0.4067) 4. Increase of zirconium-silicate filler contents reduced significantly the depth of cure of experimental composites. ($r^2$=0.9700, p<0.0001) These results mean that the mechanical properties of composites could not be improved by incorporation of small amount of zirconium-silicate filler. Also, the increased contents of zirconium-silicates fillers was found to reduce the diametral tensile strength and depth of cure.

• The Journal of Korean Academy of Prosthodontics
• /
• v.41 no.5
• /
• pp.606-616
• /
• 2003

Purpose : The purpose of this study was to research the properties of some chemically cured methacrylate polymers such as MMA, HEMA, TEG-DMA, bis-GMA, GMA. Material and Method : 5 kinds of methacrylates were selected and added 2% tertiary amine and benzoyl peroxide to make a chemically curable polymer 25 micron crushed silicas which are treated with silane were selected as filler, they were added into methacrylate monomer until the consistency did not changed by the load of 500gram. All of the experimental resins were 5 kinds, and a serial test was done with 3 kinds of items including the filler contents, the tensile strength, and the bond strength. The number of specimen were 10 for each group. Filler contents were obtained by reducing the specimens to ashes at $600^{\circ}C$ for 1 hour. The specimens with the dimension of 6mm in diameter and 3mm thick were immersed in $37{\pm}1^{\circ}C$ distilled water for 24 hours before test, and tensile strength were measured with cross-head speed 1mm/min. Shear bond strength were mea sured on the specimens attached to bovine enamel etched with 37% phosphoric acid for 1 minute. Results : 1. Maximum filler incorporation was the highest as 75.5% on MMA, and the least as 53.4% on bis- GMA(p<0.0001). 2. The tensile stregth were MMA 141.3, GMA 154.3, TEG-DMA 157.4, bis-GMA 161.4 MPa, and HEMA showed the highest value, 226.9MPa(p = 0.0004). 3. The bond strength were GMA 10.1, TEG-DMA 11.7, HEMA 12.2, bis-GMA 13.3 MPa, and MMA showed the highest value, 15.3MPa, however statistical significances were not (p =0.3838), 4. TEG-DMA and HEMA were not different on the aspect of maximum filler contents and shear bond strength(p>0.05). Conclusion : HEMA can be used as an another diluent substituting TEG-DMA with the increased strength and with the constant bond strength and the constant filler contents.