OBJECTIVEThis study was designed to find out the changes in microflora on the stress-bearing areas after insertion of removable partial dentures, and in turn to explore the difference between such changes caused by metal bases and acrylic resin bases respectively.

METHODSSixteen patients who were ready to accept removable partial dentures were selected and divided into two groups. Eight patients used metal bases while the other eight patients used acrylic resin bases. Then at the following three points: before dentures were inserted, one month after wearing and three months after wearing, the total cultivable flora were counted and the proportions of bacteria detected on the stress-bearing areas were calculated.

RESULTSNo matter what type of bases was selected, the wearing of removable partial denture enhanced the accumulation of microflora on stress-bearing areas. The percentages of Candida albicans and Lactobacilli detected on stress-bearing areas also increased significantly (P < 0.05). When such changes were compared, the authors found that the increment of Candida albicans caused by acrylic resin bases was higher than that caused by metal bases (P < 0.05).

CONCLUSIONThe wearing of removable partial dentures forms new retention areas between the bases and the stress-bearing areas, as a result enhances the deposit of microbe and facilitate the growth of Candida albicans and Lactobacilli. Compared with increment of Candida albicans caused by metal bases, the increment relating to acrylic resin bases is more evident.