[Microbeading resin-bonded retainers. 1. Tensile bond strengths and durability]

With the development of adhesive luting resins that adheres both dental alloys and tooth enamel has been widely used the resin-bonded fixed partial denture recently. Since we experienced, however, that the metal retainers without mechanical retention such as channels were often dislodged with metal interface failure, the more durable bonding between a luting resin and a metal has been desired. This study was undertaken to investigate the effect of microbeading onto the adherent metal surface on the tensile adhesive strength between an adhesive luting resin and a dental alloy. Maxgold equivalent to Type IV gold and Panavia EX were used as an adherent metal and a luting resin, respectively. The following conclusions were drawn: 1. Microbeading on the adherent metal surface made no contribution to an increase of the tensile adhesive strength, unless the adherent surface treatment was achieved. However, once 50 microns alumina blasting and tin plating were achieved on the microbeaded metal surface, the tensile adhesive strength was significantly increased. 2. Taking into account the fabrication technique and the tensile adhesive strength, the optimum diameter of microbeads seems to be 150 microns. 3. In the result of various accelerative durability tests (invasion tests in 70 and 100 degrees C water, thermal cycling between 4 and 60 degrees C water), the durability of 150 microns microbeaded metal surface on which 50 microns alumina blasting and tin plating were achieved was much better than that of the smooth metal surface.