PMSE 335 |
| Many dental restorative dental composites still utilize 2,2 bis [4-(2-hycroxy-3-methacryloyloxy propoxy) phenyl] propane (Bis-GMA) as base resin. The high viscosity of Bis-GMA necessitates dilution with dimethacrylate ethers of low viscosity such as triethylene glycol dimethacrylate (TEGDMA). However, increased amounts of the TEGDMA have adverse effects on properties such as water uptake and during shrinkage. The viscosity of the base resin should be as low as possible to enable the preparation of dental composites with a minimum content of diluent. To overcome the disadvantage of Bis-GMA, i.e., its high viscosity caused by hydrogen bonding between hydroxyl groups, hydroxyl group in Bis-GMA was substituted by methoxy groups, ethoxy groups, propoxy groups, and butoxy groups. As an example, 2,2 bis [4-(2-methoxy-3-methacryloyloxy propoxy) phenyl propane (Bis-M-GMA) was prepared by substitution methoxy groups for hydroxyl groups in Bis-GMA. The viscosity of Bis-GMA was dramatically decreased from 574 (Pa.s) to 3.7 (Pa.s) by substitution of methoxy group. Consequently, the amount of TEGDMA included in the resin matrix could be minimized. Dental composites were prepared from Bis-M-GMA (or Bis-GMA) mixtures with TEGDMA filled with 75 wt% filler. Comparing the curing shrinkage of dental composite containing Bis-M-GMA with that prepared from Bis-GMA, the reduction in curing shrinkage was about 47%. Dental composites prepared from new resin matrices also exhibited low water uptake and better properties in mechanical strength. |
|
Joint PMSE/POLY Poster Session
6:00 PM-8:00 PM, Tuesday, 12 September 2006 Moscone Center -- Hall D, Poster
Division of Polymeric Materials: Science & Engineering |