Multivariate analysis of factors affecting the status of wearing removable partial dentures

PURPOSE: The purpose of this retrospective cohort study was to investigate factors that affected the status of wearing removable partial dentures (RPDs) using a multivariate analysis. METHODS: One hundred and sixty-one patients were treated with definitive dentures that were delivered by dental students under teacher supervision at Tohoku University Hospital between 1996 and 2001. Of the 161 patients, 67 patients who agreed to undergo a follow-up examination participated in this study. The subjects were 18 men and 49 women with a mean age of 66.0+/-9.5 years. They were re-examined 5 years after treatment. The status of wearing the RPDs was categorized into three groups, i.e: successful, wearing their original RPDs constantly for 5 years; replaced, wearing re-fabricated RPDs within 5 years, and failed; interrupted wearing the RPDs within 5 years. Factors that affected the status were also examined. The analyzed variables in this study were sex and age of subjects, previous experience in wearing RPDs, location of RPDs and edentulous area, number of occluding pairs, number of missing teeth, placement of RPDs on opposite jaw, denture base type, number of abutment teeth, type of clasp, and number of rests. A stepwise multiple logistic regression analysis was used to determine factors affecting the status of wearing RPDs. RESULTS: The response rate was 41.6%. Of the 90 RPDs, 55 RPDs were regarded as successful, 21 as replaced, and 14 as failed. Statistically significant correlations were found between denture usage and the age of subjects, the location of edentulous area, number of occluding pairs, and number of rests (p<0.05). CONCLUSION: The results suggest the importance of considering the significant factors mentioned above for treatment planning and designing of RPDs.