Evaluation of microbial flora found in previously worn prostheses from the Northeast and Southwest regions of the United States

Statement of problem: Denture-induced stomatitis is a recognized clinical challenge. The responsible microorganisms have not been delineated and may differ among regions of the United States.

Purpose: The purpose of this study was to identify the microorganisms found in dentures from 2 geographic regions.

Material and methods: Previously worn dentures from 51 available subjects living in the Southwest (41) and Northeast (10) were aseptically retrieved in sterile plastic bags. A posterior piece of the mandibular denture was removed and sampled on appropriate media under anaerobic conditions. The remaining denture material was divided into 7 equal pieces. Each piece was touched to appropriate aerobic media and incubated at 37 degrees C. Bacteria and yeasts were identified using standard clinical laboratory procedures. Data were analyzed by using descriptive statistics. Denture fragments were further analyzed by scanning electron microscopy (SEM).

Results: A total of 916 isolates were carried to final speciation. Of these, 711 were aerobic bacteria, 67 were anaerobic bacteria, 125 were yeasts, and 13 were amoebae. Microorganisms were found on the denture surfaces and interstices (denture pores). Most subjects wore their dentures for extended periods without sanitization. SEM analyses confirmed substantial porosity of the denture material with microbial penetration and biofilm formation within the pores.

Conclusions: A wide range of potentially pathogenic microorganisms was found in dentures. There were also regional differences in the microbial flora.