Microbial community analysis of supragingival plaque in patients with fixed prostheses

Harmony between prostheses and periodontal tissues is essential. The presence of a fixed prosthesis has been reported to increase the risk of periodontal lesion onset in abutment teeth and to affect longevity. However, studies comparing the supragingival plaque biofilm on fixed prostheses and natural teeth are lacking.

The purpose of this clinical study was to investigate the composition of supragingival plaque biofilm microorganisms on the surface of fixed prostheses and to identify differences with those of natural supragingival plaque microorganisms using 16S ribosomal deoxyribonucleic acid (rDNA) sequencing technology.

A total of 40 participants were enrolled, including 20 with fixed prostheses and 20 healthy participants with no prostheses in the mouth; 60 samples of supragingival plaque were obtained. The groups included in this analysis were the cobalt chromium metal-ceramic crown group (P), zirconia ceramic crown group (A), natural tooth group with zirconia ceramic crown control (T_A), natural tooth group with cobalt chromium metal-ceramic crown control (T_P), and healthy group with no prostheses in the mouth (SUPP_A). The DNA of all samples was sequenced by using the 16S rDNA high-throughput sequencing technology, and the sequencing data were then examined bioinformatically using the Qiime, R, and PICRUSt2 software programs.

The microbial composition and structural diversity of supragingival plaque on the surface of fixed prostheses were found to differ from those on natural teeth, with relatively high levels of periodontally related pathogens, including Treponema gingivalis, Selenomonas gingivalis, Porphyromonas gingivalis, and Prevotella_7 gingivalis. Functional analysis revealed that the fixed prosthesis group had relatively active microbial communities. The metabolism was relatively active, characterized by a high percentage of lipopolysaccharide biosynthesis, glycine, serine, and threonine metabolism associated with the development of periodontal disease. The microflora on the surface of ceramic crowns was more similar to that on natural teeth than to that on cobalt chromium metal-ceramic crowns.

The present study found significant differences in the microbiological community composition of supragingival plaque between fixed prostheses and natural teeth. Notably, ceramic crowns exhibited less influence on the microbiological structure of supragingival plaque than metal-ceramic crowns. Therefore, the selection of ceramic materials for fixed restorations should be considered a crucial factor in preserving the health of periodontal tissues around abutment teeth from a microbiological perspective.