Abstract
Oral malodour is often observed in gingivitis and chronic periodontitis patients, and the tongue microbiota is thought to play a major role in malodorous gas production, including volatile sulphur compounds (VSCs) such as hydrogen sulphide (H2 S) and methanethiol (CH3 SH). This study aimed to examine the link between the presence of VSCs in mouth air (as a marker of oral malodour) and the oral bacterial ecology in the tongue and periodontal niches of healthy, gingivitis and periodontitis patients. Participants were clinically assessed using plaque index, bleeding on probing (BOP) and periodontal probing depths, and VSC concentrations in their oral cavity measured using a portable gas chromatograph. Tongue scrapings, subgingival and interdental plaque were collected from healthy individuals (n=22), and those with gingivitis (n=14) or chronic periodontitis (n=15). The bacterial 16S rRNA gene region V3-V4 in these samples was sequenced, and the sequences were analysed using the minimum entropy decomposition pipeline. Elevated VSC concentrations and CH3 SH:H2 S were observed in periodontitis compared with health. Significant ecological differences were observed in the tongue microbiota of healthy subjects with high plaque scores compared to low plaque scores, suggesting a possible connection between the microbiota of the tongue and the periodontium and that key dysbiotic changes may be initiated in the clinically healthy individuals who have higher dental plaque accumulation. Greater subgingival bacterial diversity was positively associated with H2 S in mouth air. Periodontopathic bacteria known to be prolific VSC producers increased in abundance on the tongue associated with increased bleeding on probing (BOP) and total percentage of periodontal pockets >6mm, supporting the suggestion that the tongue may become a reservoir for periodontopathogens. This study highlights the importance of the periodontal microbiota in malodour and has detected dysbiotic changes in the tongue microbiota in periodontitis.
Highlights
Intra-oral halitosis is often observed in patients with periodontitis, and of the volatile sulphur compounds detected in the breath in association with this condition, an elevated methanethiol to hydrogen sulphide ratio (CH3SH: H2S) has been observed in patients compared with healthy controls.[1,2]
Current surveys employing bacterial rRNA gene sequencing to study oral malodour associated microbiota, have only investigated the tongue and saliva, identifying some important bacterial taxa that may be associated with oral malodour in healthy individuals.13–15 An early study that used pyrosequencing of tongue biofilm samples of healthy individuals reported interpersonal variation in community structure to be smaller when associated with higher volatile sulphur compounds (VSCs) concentrations, with the genera Prevotella and Leptotrichia to be positively associated with higher H2S concentrations in the breath.[13]
Minimum entropy decomposition (MED) was used to partition these sequences into nodes at 1-nt resolution with the minimum substantive abundance parameter at 240.27 A BLAST search of the HOMD (v14.5)[28] and NCBI bacterial 16S databases classified representative sequences of all MED nodes, which was used to map the nodes to the human microbial taxa (HMT) by per cent identities
Summary
Intra-oral halitosis is often observed in patients with periodontitis, and of the volatile sulphur compounds detected in the breath in association with this condition, an elevated methanethiol to hydrogen sulphide ratio (CH3SH: H2S) has been observed in patients compared with healthy controls.[1,2] The severity of oral malodour and methanethiol to hydrogen sulphide ratio is positively correlated with the clinical parameters of periodontitis in individuals complaining of oral malodour.[3,4] Ecological population dynamics involving different bacterial taxa have been known to play a role in the aetiopathogenesis of both gingivitis and chronic periodontitis, with studies utilising sequencing methodologies to identify a number of bacterial taxa as responsible for altering the overall ecology of the oral soft and hard tissue niches in the different disease states.5–8 Of these niches, the tongue biofilm is considered as the primary source of oral malodour in healthy individuals, with some clinical studies suggesting that plaque accumulation in the periodontal niches such as the subgingival and supragingival aspects of teeth may play a role in periodontitis-associated oral malodour.9–11 In addition, an interventional study has reported significant reductions in H2S and CH3SH, in the breath of patients undergoing periodontal treatment as opposed to just tongue cleaning.[11,12]Current surveys employing bacterial rRNA gene sequencing to study oral malodour associated microbiota, have only investigated the tongue and saliva, identifying some important bacterial taxa that may be associated with oral malodour in healthy individuals.13–15 An early study that used pyrosequencing of tongue biofilm samples of healthy individuals reported interpersonal variation in community structure to be smaller when associated with higher VSC concentrations, with the genera Prevotella and Leptotrichia to be positively associated with higher H2S concentrations in the breath.[13]. Intra-oral halitosis is often observed in patients with periodontitis, and of the volatile sulphur compounds detected in the breath in association with this condition, an elevated methanethiol to hydrogen sulphide ratio (CH3SH: H2S) has been observed in patients compared with healthy controls.[1,2] The severity of oral malodour and methanethiol to hydrogen sulphide ratio is positively correlated with the clinical parameters of periodontitis in individuals complaining of oral malodour.[3,4] Ecological population dynamics involving different bacterial taxa have been known to play a role in the aetiopathogenesis of both gingivitis and chronic periodontitis, with studies utilising sequencing methodologies to identify a number of bacterial taxa as responsible for altering the overall ecology of the oral soft and hard tissue niches in the different disease states.5–8 Of these niches, the tongue biofilm is considered as the primary source of oral malodour in healthy individuals, with some clinical studies suggesting that plaque accumulation in the periodontal niches such as the subgingival and supragingival aspects of teeth may play a role in periodontitis-associated oral malodour.9–11 In addition, an interventional study has reported significant reductions in H2S and CH3SH, in the breath of patients undergoing periodontal treatment as opposed to just tongue cleaning.[11,12]. Conclusion: This study highlights the importance of the periodontal microbiota in malodour and has detected dysbiotic changes in the tongue microbiota in periodontitis
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
