FIT OF DIRECT RETAINERS IN REMOVABLE PARTIAL DENTURES AFTER 8 YEARS OF USE

In a cross-sectional study the fit of direct retainers was assessed af ter 8 years of use. A total of 101 metal frame removable partial dentu res (RPD) were investigated, including 54 extension base prostheses wi thout any tooth supported replacement and 47 tooth supported prosthese s that replaced only premolars and molars. Of the frameworks studied, about 60% of the clasps showed a space between retainers and abutments . Logistic regression analyses demonstrated that the age of the RPD an d the type of opposing dentition significantly influenced the fit of t he clasps. The relative risks and a backward regression analysis revea led that the variable nonrigid extention base RPD had the greatest inf luence on clasp fit. It was concluded that in extension base RPDs a ri gid design should be preferred.