Oral Microbial Basis of Intraoral Halitosis: The Role of the Oral Microbiome

Background: A respectable amount of the global population is affected by halitosis. Halitosis causes notable social and psychological distress among sufferers. It is primarily caused by the oral microbiota, which converts sulphur containing amino-acid substrate into volatile sulphur compounds. This review aims to elucidate the role of the oral microbiome in intraoral halitosis, emphasising microbial dysbiosis, volatile sulphur compound production, and the potential of microbiome-targeted therapeutic approaches.

Methods: Relevant literatures were searched across PubMed/MEDLINE, Scopus, and Google Scholar using terms regarding the microbial aetiology, biochemical mechanisms, and management of intraoral halitosis and included.

Results: The primary sites for volatile sulphur compounds production are the dorsum of the tongue and diseased periodontal pockets. The main gram-negative bacteria associated with VSC production are Porphyromonas gingivalis, Treponema denticola, Fusobacterium nucleatum, Prevotella intermedia, and Solobacterium moorei. Oral dysbiosis, poor oral hygiene, periodontitis, xerostomia, and some systemic conditions, promotes the growth of these proteolytic bacteria. Microbiome-targeted treatments, such as mechanical cleaning, antiseptic agents, and probiotics, have shown significant clinical benefits in managing halitosis.

Conclusion: Intraoral halitosis is strongly associated with oral microbiome dysbiosis and increased volatile sulphur compound production by anaerobic bacteria. Understanding these microbial mechanisms supports targeted treatments such as antimicrobials, probiotics, and microbiome-modulating therapies to reduce oral malodour.

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