Using modified USPHS criteria, we evaluated annually for ten years 91 cases restored with visible light cured posterior composite resin LFP (Base resin: UDMA; filler: micro crushed type, alumino-silicate, barium glass and silica, 85wt%, 74vol%). The 91 cases restored with LFP decreased to 68 in ten years. Of the 23 cases that were lost, one resulted from a pulpal reaction immediately following restoration, four were extracted owing to periodontal disease or extrusion of third molars, two became abutments owing to loss of an adjacent tooth, eight had recurrent caries, and eight were lost owing to caries on a surface having no relationship to the composite resin restoration. Because we observed comparatively little wear, good marginal adaptability, and no discoloration, we concluded that the ten-year clinical success of LFP was on the whole very good, and that this resin has adequate clinical merit as a restorative material for posterior teeth when restricted to restorations covering comparatively small areas.

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The effects of preserving conditions and time after extraction of human teeth, as specimens for bond strength of composite resin to the dentin, were investigated by the tensile test method and scanning electron microscopy (SEM).When the teeth were stored in physiologic saline solution, bond strength at 15 minutes after extraction showed the lowest value (13kg/cm2), and at 1 to 12 weeks it was elevated to about 35kg/cm2. However pretreatment with citric acid-FeCl3 solution of dentin surface increased the bond strength 3-fold. The teeth stored in formalin for 6 months had the highest bond strength (80kg/cm2). On SEM observation of the dentin and resin surfaces following the tensile test, a clear correlation was found between range of bond strength and appearance of resin tags.

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