2004 Volume 22 Issue 3 Pages 237-244
A new magnetic attachment system was designed that a keeper was fixed directly into a resin root-coping. This study evaluated the bonding of keeper to a buildup composite for root-coping. The experimental post-keeper was made with Fe-Cr magnetic alloy and consist of a disc-keeper (H: 0.8 mm, and ∅: 3.0, 3.5, 4.0, or 4.5 mm) and a tapered-post (L: 1.5 mm, ∅: 1.5 mm). The keeper without post was used as control. The bonding surface of keeper was pretreated with one of three methods (50 μm alumina sandblasting [S], S plus application of metal-primer [S+P], or no treatment). After the keeper was placed in a buildup composite (Clearfil® Photocore) poured into acrylic tube, the composite was photo-polymerized to complete test specimen. The specimens were also fabricated that the post-keeper was bonded to a polymerized composite with the adhesive resin (Panavia® Fluoro Cement or Super-Bond C & B). Five specimens for each experimental group were subjected to 20, 000 thermocycles before tensile bond strengths were measured. The data were analyzed with ANOVA and Fisher's test (p=0.05). From the results, it was founded that the fixation which the post-keeper over the 3.5 mm diameter pretreated with S+P was bonded using Super-Bond C & B could be most effective to increase the bond durability of keeper.
