Microbial aspects of preventive regimes in patients with overdentures

The aim of this study was to test effects of preventive regimes using fluoride and chlorhexidine to prevent caries and periodontal diseases in 34 patients with overdentures. The patients, who were treated with immediate overdentures, were distributed at random into three experimental groups. In these groups, different gels--a placebo, a fluoride, and a chlorhexidine-fluoride gel--were tested by daily application. Supragingival plaque samples from selected surfaces of two abutment teeth were taken at one week, and at one, three, and six months after initial insertion of the overdenture. The placebo and fluoride gel influenced neither total CFU nor S. sanguis and A. viscosus/naeslundii counts. In the placebo group, but not in the fluoride group, S. mutans levels increased significantly, indicating the caries risk involved in overdentures. The use of chlorhexidine-fluoride gel resulted in a long-term suppression of total CFU. Further, S. mutans was found to be selectively suppressed to below detection level. A. viscosus/naeslundii was initially strongly suppressed, but after three months a partial return of the population was noticed. S. sanguis was relatively insensitive to the chlorhexidine-fluoride gel. It is concluded that a daily application of a chlorhexidine-fluoride gel is effective against plaque formation and S. mutans on abutment teeth in overdentures.