Distinct Microbial Community of Accumulated Biofilm in Dental Unit Waterlines of Different Specialties

Abstract

The contamination of dental unit waterlines (DUWLs) is a serious problem and directly affects the dental care. This study aims to explore the microbial community of biofilm in DUWL from different specialties and investigate the associated factors. A total of 36 biofilm samples from 18 DUWL of six specialties (i.e., prosthodontics, orthodontics, pediatrics, endodontics, oral surgery, and periodontics) at two time points (i.e., before and after daily dental practice) were collected with a novel method. Genomic DNA of samples was extracted, and then 16S ribosomal DNA (rDNA) (V3–V4 regions) and ITS2 gene were amplified and sequenced. Kruskal–Wallis and Wilcoxon rank test were adopted for statistical analysis. Microbial community with high diversity of bacteria (631 genera), fungi (193 genera), and viridiplantae was detected in the biofilm samples. Proteobacteria was the dominant bacteria (representing over 65.74–95.98% of the total sequences), and the dominant fungi was Ascomycota (93.9–99.3%). Microorganisms belonging to multiple genera involved in human diseases were detected including 25 genera of bacteria and eight genera of fungi, with relative abundance of six genera over 1% (i.e., Acinetobacter, Pseudomonas, Enterobacter, Aspergillus, Candida, and Penicillium). The biofilm microbiome may be influenced by the characteristics of dental specialty and routine work to some extent. The age of dental chair unit and overall number of patients had the strongest impact on the overall bacteria composition, and the effect of daily dental practices (associated with number of patients and dental specialty) on the fungi composition was the greatest. For the first time, biofilm in DUWL related to dental specialty was comprehensively evaluated, with more abundance of bacterial and fungal communities than in water samples. Biofilm accumulation with daily work and multiple kinds of opportunistic pathogen emphasized the infectious risk with dental care and the importance of biofilm control.

The importance of biofilm contamination control for dental unit waterlines: a multicenter assessment of the microbiota diversity of biofilm in dental unit waterlines

“…In our study, the dominant bacteria at the phylum level were Proteobacteria representing over 91% of the total sequences, which was similar to the results of previous reports [ 14 , 15 , 18 ]. Unsurprisingly, Proteobacteria was a commonly detected phylum in water distribution systems, owing to high tolerance to chlorine [ 25 ].…”

“…Previous reports have informed several environmental factors associated with biofilm accumulation, such as the age of dental unit [ 21 ], disinfectants [ 10 , 13 ], and specialty and daily dental practices [ 15 ]. However, in this study, despite the 29 samples compared in different groups, no significant differences among these samples as shown by alpha diversity indices and the PCoA.…”

“…The bacterial 16S rDNA high-throughput sequencing platform this study used enables the production of highly accurate sequencing data, which can provide new insights into studying the diversity of microbial communities in DUWLs [ 14 ]. Bacterial community structure in DUWL may be influenced by various factors such as the age of DCUs, the number of patients and different dental treatments [ 15 , 16 ]. Therefore, the diversity and composition of microorganisms in DUWLs would be diverse between different hospitals and specialties.…”

Efficiency of a high-speed handpiece with anti-retraction adapter to minimize cross-contamination during the routine dental procedure: A clinical study

“…reported that biofilm in DUWLs is related to dental specialty with more abundance of bacterial and fungi communities. [ 14 ]…”

Biofilm growth and microbial contamination of dental unit waterlines at Kuwait University dental center

“…Microorganisms colonizing DUWL are generally non-pathogenic aerobic and heterotrophic environmental bacteria. However, occasionally, pathogenic and/or opportunistic pathogens such as Pseudomonas , Legionella and Mycobacterium species are found ( 7 , 8 ).…”