Overcontouring in resin-bonded prostheses: Plaque accumulation and gingival health

Abstract

0 ne of the advantages of resin-bonded prostheses is minimum reduction of tooth structure to receive the abutment casting The thickness of metal necessary in retention wings results in a change (overcontour) of the natural lingual and proximal contour of abutment teeth. Plaque accumulation and gingival bleeding on probing has been reported from overcontouring of crowns.‘-3 Impaired periodontal health may also result from overcontouring produced by retention wings of resin-bonded prostheses. It has been suggested that lingual and proximal surfaces of abutment teeth be prepared to allow placement of these restorations without overcontouring.’ The relationship between overcontouring created by resinbonded prostheses and plaque accumulation (and gingival health), although assumed, has not been studied and is unknown. Such knowledge is necessary before valid recommendation for preparation of abutment teeth can be made. Several factors may be reponsible for plaque accumulation and gingival reaction associated with resin-bonded partial dentures. These are (1) overcontouring of the lingual surface of abutment teeth, (2) a cervical niche apical to overcontoured retention wings, (3) contour of the connector between the retention wing and pontic, (4) contour of pontics, and (5) surface characteristics of materials used in fabrication. This study evaluated plaque accumulation in relation to factors 1, 2, and 3 under experimental conditions. Factors 4 and 5, although important, were not considered to be specific to resin-bonded prostheses.