Clinical Factors which Affect the Shortend Life Span of Abutment Teeth in Removable Partial Denture Mitsuhiro Yoshida Abstract: In order to establish diagnostic parameters for the estimation of prognosis of abutment teeth in removable partial denture, the degree of tooth quality must be determined. Clinical factors which affect the shortened life span of abutment teeth in removable partial denture were investigated by use of statistical analysis, biomechanically and histopathologically. Subjects included patients requiring extraction of abutment teeth, were divided into two groups of vital and nonvital teeth. Data was collected based on clinical examinations assigned to three categories such as periodontal condition factor, occlusion factor and prosthesis factor. The following results were observed in the nonvital group: biomechanical factors such as occlusal and prosthesis factors were shown to be significant risk factors in which affected the shortend life span of RPD abutment teeth by statistical analysis, tooth quality was weakened, and bacterial contamination within enamel of root canal surfaces was observed by electromicroscopy. In contrast, vital group factor contribution to poor prognosis included periodontal condition such as pocket depth and CPITN, which proved to be a significant risk factor. Key words: RPD, life span, abutment teeth, statistics, risk factors, histopathology Iwate Medical Univ., Graduate School, Major in Prosthodontics (Director: Prof. Hisatoshi Tanaka)

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