REPRODENT relining resin cures very slowly by α-amylase in saliva catalyzed polymerization. The purpose of this study was to evaluate a bonding ability of REPRODENT against denture bases made of acrylic resin and Co-Cr alloy. Ability for adherent of traditional relining material to REPRODENT was also studied. As the method, bonding specimens were fabricated by curing REPRODENT on the chemically and mechanically treated disk surface of denture base resin or Co-Cr alloy. In addition, traditional relining resin was applied on the surface of cured REPRODENT disk. Specimens were thermocycled for maximum 50, 000 times and shear bond strength were measured. As the result, untreated and methylene chloride painted surface of acrylic resin showed excellent bond strength which decreased very slowly with the increase in the number of thermocycles, and alumina-blasted surface showed significantly lower bond strength. The separation of the REPRODENT from Co-Cr alloy specimen occurred within 20, 000 thermocycles. Traditional direct relining material revealed the highest bond strength and durability to cured REPRODENT painted Methyl Methacrylate monomer. In conclusion, sufficient bond between REPRODENT and denture bace resin was achieved without chemical surface treatment.

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The purpose this study was to evaluate the influence of irradiation time of high intensity light on polymerization shrinkage and heat generated during curing of light-cured resins. A high intensity curing unit used was Credi 8000 (3M), and a halogen light curing unit Candelux (Morita) as a control, was used in this study. Resin paste was placed into a Teflon mold, 4mm in diameter and 2 mm in height, and extruded into the dilatometer. Then the specimen was light irradiated and the change in the height of the meniscus of water was recorded using a CCD camera. The temperature rise during curing was also measured according to the method described by ISO 4049. The volumetric shrinkade of light-cured resin obtained with the high intensity light was lower than those obtained with the halogen light unit. The heat generated during polymerization decreased with shorter irradiation times. It was concluded that shorter irradiation time with the use of high intensity light might not be enough for the cure of light-cured resins.

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Retention of posts in post and core technique is a very important factor for the longevity of restorations. Retentive force becomes larger when adhesive resin cements are selected instead of conventional luting cements. However, the larger retention can not be expected without proper manipulation for each resin cement. In the 7^th Clinical Seminar of Japan Society for Adhesive Dentistry, five kinds of adhesive resin cements were used by participants to bond prefabricated metal posts to the bovine teeth and their retentive forces were measured. On the other hand, specimens made by us in the same way were prepared and their retentive forces were measured also and compared with those by the participants. Results were as follows: 1. The preseminar questionnaires made clear that at least onethirds of pa ticipants used adhesive resin cements in their daily practice. 2. Two kinds of resin cements showed significantly lower retentive forces than the other three resin cements. 3. The retentive forces of specimens made by the participants were lower than ours in all resin cements examined. 4. The differences in retentive forces between the participants and us could be attributed to the technique sensitivity of this material.

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