Abstract
Porcelain teeth have various advantages for their use clinically. However, the designs currently used for most porcelain teeth provide mechanical locking with the use of metal pins or undercut wells (diatoric form). These designs weaken the teeth and do not prevent the leakage of fluids along the tooth-resin interface, which has created poor oral hygiene and esthetics. Therefore, if porcelain teeth are bonded chemically to the denture base of acrylic resin without the use of pins, failure in porcelain teeth will decrease significantly in clinical use. So an attempt of creating such chemical bonding between porcelain teeth and acrylic resin was undertaken utilizing a kind of silane coupling agents, gamma-methacryloxypropyltrimethoxysilane. The results were as follows : 1. The chemical bonding of porcelain teeth to the denture base of heat-curing acrylic resin was accomplished by the addition of gamma-methacryloxypropyltrimethoxysilane in the methyl methacrylate monomer for the heat-curing resin. 2. More than 4 wt% concentration solution of the silane in the methyl methacrylate monomer for the heat-curing acrylic resin produced a stable bonding strength, and also a sufficient anchorage was observed after breakage on the surface of test pieces. 3. Inclusions of gamma-methacryloxypropyltrimethoxysilane in the methyl methacrylate monomer for the heat-curing acrylic resin did not create any change in the physical properties of the heat-curing resin. However, a slightly increased sorption of water in the cured acrylic resin was observed by inceasing the concentration of the silane in the methyl methacrylate monomer. 4. By evaluating the effect of the silane bond on porcelain anchorage strength, it was concluded that a 6 wt% concentration solution of the silane in the methyl methacrylate monomer for the heat-curing acryic resin was sufficient. 5. Data indicated that a large difference in the thermal expansion existing between the bonding surfaces can cause a lowering of bonding strength when the bonded specimen was alternately dipped in the cold and the hot water baths and subjected to thermocycles from 5, 000 to 10, 000 times. 6. The bonding strength of the adhesive acrylic resin to the porcelain teeth was not affected by the total immersion in water (36℃) for 90 days. 7. A dye penetration test showed that the firm bonding of the adhesive acrylic resin to the porcelain teeth prevented dye penetration far more effectively than in the case of bonding of non-adhesive ones with the porcelain teeth. On the base of the above results, it was concluded that the porcelain could be bonded stably to the denture base of heat-curing acrylic resin by using the silane added monomer for acrylic resin. This silane added adhesive acrylic resin is much more reliable for clinical use than non-adhesive ones.
