| Co-Investigator(Kenkyū-buntansha) |
INOKOSHI Shigehisa Tokyo Medical and Dental University, Faculty of Dentistry, Lecturer, 歯学部, 講師 (60143583)
YAMADA Toshimoto Tokyo Medical and Dental University, Faculty of Dentistry, Lecturer, 歯学部, 講師 (40134712)
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| Research Abstract |
Current commercially available resin composites were examined with the SEM and the elemental composition of their filler particles was analyzed with the EDX. Based on these results, the resin composites have been divided into seven groups (Traditional resin, MFR resin, MFR type resin, SFR type resin, Hybrid resin, Hybrid type resin, Semihybrid resin). Characteristics of each group are described, with clinical indications for selective use of respective resin composites in clinical applications. The degradation process of posterior resin composites in an alkaline solution was examined periodically by the SEM up to one week after immersion in a 0.1N NaOH solution at 60^。 C, focusing on the topographical changes of polished resin surfaces and on the subsurface degradation. The immersion test in a 0.1N NaOH solution at 60^。 C was considered to be an appropriate method to estimate the durability of posterior resin composites in vitro.
The occlusal wear of light-cured posterior composite rest
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orations in vivo was evaluated, investigating a possible correlation of the in vivo results with values from an in vitro wear test developed by us. The amounts of in vitro wear were comparable to those measured in vivo for the Semihybrid and Hybrid type resins as well as for the high copper amalgam. However, a slight difference was found between the amounts of in vivo and in vitro wear of SFR type or MFRtype composite.
The resin composite specimens were aged either in the artificial saliva, or in the mouth using palatal plates for a given period of time up to one year. A subsurface damaged layer of the aged resin specimens was observed by SEM after Ar ion beam etching. The subsurface damaged layer of the resins observed in vitro and in vivo experiments was generally found to be less than 50 mum deep.
According to the results obtained from the studies, the Semihybrid type resin was considered to be the most appropriate resin composite for posterior use, and a new formulation of the resin composite for posterior or anterior use was proposed. Less
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