Improvement in its durability and surface deterioration of dental restorative materials due to surface-contact fatigue

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The purpose of this paper was to investigate the surface contact fatigue of two PMMAs (AC and SU), tow composite resins (ES and SD), three artificial tooth (LP, SP and AT) and three noble metal alloys (T-1, T-4 and 12GS) in an atmosphere of dripped distilled-water at 37℃. Disk specimen 15mm diameter by 2.0mm thick were set into cavity cut in plate of PMMA, and were ground and polished down using water-proof sandpaper followed by 1.0μm alumina and then stored for 24h in distilled water at 37℃. Test was carried out under 200 gf through a ruby ball 2mm diameter, which was rotated at 500rpm, using a rolling-ball device. A surface profile was determined directly on the test specimen at regular intervals. Fatigue life was defined as the number of cycles to produce a track 5μm deep and was determined by interpolation. The fatigue life of AC, ES, SD and SU was ranged from 5.88×10^3～8.82×10^4 cycles. AC and SU without inorganic filler are very much more resistant to contact fatigue than ES containing inorganic filler more. On the other hand, the fatigue life of three artificial tooth (LP, SP and AT) was ranged from 3.1×10^4～5.88×10^4 cycles and LP is lower resistant to contact fatigue than SP and AT. Furthermore three noble metal alloys was ranged from 10^3～10^4 cycles and the two-dimensional profile had a ductility characteristic that is different from two composite resin and artificial tooth.