Exploring the variation of oral microbiota in supragingival plaque during and after head-and-neck radiotherapy using pyrosequencing

•The head and neck patients were followed up to one year after radiotherapy.•The change of the oral microecology was focused on during and after radiotherapy.•The oral microecologies were studied by Roche/454 pyrosequencing.•The diversity of the oral microecology decreased with increased radiation dose.•The diversity of the oral microecology increased over time after radiotherapy.

ObjectiveThe aim of this article was to study the variation in oral microflora of the subgingival plaque during and after radiotherapy.DesignDuring and after radiotherapy, microbial samples were collected at seven time points (early stage, medium stage, and later stage of radiotherapy, and 1 month, 3 months, 6 months, and 1 year after radiotherapy) in three subjects for a total of 21 samples. Polymerase chain reaction (PCR) amplification was carried out on the 16S rDNA hypervariable V1-V3 region, and then the PCR products were determined by high-throughput pyrosequencing.ResultsThe rarefaction curve indicating the richness of the microflora demonstrated that the number of operational taxonomic units (OTUs) was in decline from the early stage of radiotherapy to the time point 1 month after radiotherapy and then trended upward. The Shannon diversity index declined during radiotherapy (ranging from 4.59 to 3.73), and generally rose after radiotherapy, with the lowest value of 3.5 (1 month after radiotherapy) and highest value of 4.75 (6 months after radiotherapy). A total of 120 genera were found; five genera (Actinomyces, Veillonella, Prevotella, Streptococcus, Campylobacter) were found in all subjects across all time points.ConclusionThe richness and diversity of oral ecology decreased with increased radiation dose, and it was gradually restored with time.