[Studies on design for resin veneered crowns. 1. Adhesive resin luting agents reinforcement effect].
Resin veneered crowns show several drawbacks which affect the veneering resin: peeling, fracture, falling and also discoloration by leakages from the metal-resin border. The purpose of the present study is to find out a principle of resin veneered crown design allowing the solution of the above-mentioned problems. As a preliminary step, the influence of luting cements on the relative rigidity of veneered crowns and metal frameworks was examined by measuring the strain to static and impact charges on several portions of crowns. The investigation led to the following results: 1. The magnitude of the strain to a static charge increased with the number of shocks but beyond 100 shocks, no variation could be observed. 2. The magnitude of the strain to a static charge was proportional to the weight of the charge. 3. The strain of crowns and metal frameworks set with PanaviaEX had a magnitude smaller than the strain of those set with Fitchecker. 4. The strain to an impact charge had a magnitude 1-4 times larger than the strain to a static charge. 5. The adhesive resin luting agent reinforcement effect could be clearly confirmed.
Adhesive 4-META/MMA-TBB Opaque Resin with Poly(methyl methacrylate)-coated Titanium Dioxide
An adhesive opaque resin for veneering on cast metal was developed with 4-methacryloxyethyl trimellitate anhydride and poly (methyl methacrylate)-coated titanium dioxide prepared by aqueous phase polymerization. The opaque resin was a modified 4-META/MMA-TBB resin. The powder consisted of 20% of the encapsulated material and 80% PMMA instead of pure PMMA powder. This resin hides the metal color when the thickness of the resin is as thin as 50 μm. The opaque resin bonded strongly to both cobalt-chromium alloy and visible-light-cured veneering resin. This self-curing opaque resin is applicable not only for bonding veneering resin to an alloy surface but also for bonding fixed partial dentures to enamel surfaces.
Clinical procedures for improving veneered metal crowns.
Satisfactory design and preparation of the veneer window presuppose that a perfect or a near-perfect preparation of the tooth has been made. The window is not just a cutout and is not the responsibility of the laboratory technician. Whenever optimum gingival health, a satisfactory esthetic result, and a long-lasting restoration are desired, it is worthwhile to carefully check and, if necessary, adjust the veneer window directly in the mouth before the veneer is added. This is especially important in restorations that extend below the gingival margin.