Interdental and subgingival microbiota may affect the tongue microbial ecology and oral malodour in health, gingivitis and periodontitis

Background and Objective: 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 Sulfur Compounds (VSCs) such as hydrogen sulfide (H2S) and methanethiol (CH3SH). 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. Methods: 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 analysed using the Minimum Entropy Decomposition pipeline. Results: Elevated VSC concentrations and CH3SH:H2S were observed in periodontitis compared to health. Significant ecological shifts were observed in the tongue microbiota of healthy subjects who had higher 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 who have higher dental plaque accumulation. Greater subgingival bacterial diversity was positively associated with H2S in mouth air. Periodontopathic bacteria known to be prolific VSC producers increased in abundance on the tongue and this was associated with increased bleeding on probing (BOP) and a greater % of periodontal pockets >6mm, supporting the suggestion that the tongue may become a reservoir for periodontopathogens. Conclusion: This study highlights the importance of the periodontal microbiota in malodour and has detected dysbiotic changes in the tongue microbiota in periodontitis.

Chromatographic Examinations in the Gas Network Odourised by Tetrahydrothiophene

The paper presents the results of the spread of the tetrahydrothiophene (THT) - used as odourant - in the gas network. Such analyses allow quick detection of leaks in networks, systems and devices of gas supply directly to consumers. The main goal of the study was to determine the effectiveness of the use of portable chromatograph and comparing it with a stationary odourant concentration analyser. Based on these studies, an attempt to determine the odouration zone for the selected city have been also taken. For this purpose, three series of measurements were made - in each series 13 points were analysed. Obtained results confirmed the effectiveness of the measurement a concentration of odourant in the gas network using a portable gas chromatograph - difference in relation to the stationary chromatograph ranged from 1.91 to 2.55 %.