Oral microbiology

See also: Oral ecology
Thrush, a common condition caused by overgrowth of the fungus Candida albicans. Cases are characterized by growth of matted, yellow-white patches of fungus in the mouth.

Oral microbiology is the study of the microorganisms (microbiota) of the oral cavity and their interactions between oral microorganisms or with the host.[1] The environment present in the human mouth is suited to the growth of characteristic microorganisms found there. It provides a source of water and nutrients, as well as a moderate temperature.[2] Resident microbes of the mouth adhere to the teeth and gums to resist mechanical flushing from the mouth to stomach where acid-sensitive microbes are destroyed by hydrochloric acid.[2][3]

Anaerobic bacteria in the oral cavity include: Actinomyces, Arachnia (Propionibacterium propionicus), Bacteroides, Bifidobacterium, Eubacterium, Fusobacterium, Lactobacillus, Leptotrichia, Peptococcus, Peptostreptococcus, Propionibacterium, Selenomonas, Treponema, and Veillonella.[4][needs update] The most commonly found protists are Entamoeba gingivalis and Trichomonas tenax.[5] Genera of fungi that are frequently found in the mouth include Candida, Cladosporium, Aspergillus, Fusarium, Glomus, Alternaria, Penicillium, and Cryptococcus, among others.[6] Bacteria accumulate on both the hard and soft oral tissues in biofilms. Bacterial adhesion is particularly important for oral bacteria.

Oral bacteria have evolved mechanisms to sense their environment and evade or modify the host. Bacteria occupy the ecological niche provided by both the tooth surface and mucosal epithelium.[7][8] Factors of note that have been found to affect the microbial colonization of the oral cavity include the pH, oxygen concentration and its availability at specific oral surfaces, mechanical forces acting upon oral surfaces, salivary and fluid flow through the oral cavity, and age.[8] However, a highly efficient innate host defense system constantly monitors the bacterial colonization and prevents bacterial invasion of local tissues. A dynamic equilibrium exists between dental plaque bacteria and the innate host defense system.[7] Of particular interest is the role of oral microorganisms in the two major dental diseases: dental caries and periodontal disease.[7] Additionally, research has correlated poor oral heath and the resulting ability of the oral microbiota to invade the body to affect cardiac health as well as cognitive function.[9]

  1. ^ Schwiertz A (2016). Microbiota of the human body : implications in health and disease. Switzerland: Springer. p. 45. ISBN 978-3-319-31248-4.
  2. ^ a b Cite error: The named reference Prescotts was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference Wang2014rev was invoked but never defined (see the help page).
  4. ^ Sutter VL (1984). "Anaerobes as normal oral flora". Reviews of Infectious Diseases. 6 (Suppl 1): S62–S66. doi:10.1093/clinids/6.Supplement_1.S62. PMID 6372039.
  5. ^ Deo PN, Deshmukh R (2019). "Oral microbiome: Unveiling the fundamentals". Journal of Oral and Maxillofacial Pathology. 23 (1): 122–128. doi:10.4103/jomfp.JOMFP_304_18. PMC 6503789. PMID 31110428.
  6. ^ Cui L, Morris A, Ghedin E (July 2013). "The human mycobiome in health and disease". Genome Medicine. 5 (7): 63. doi:10.1186/gm467. PMC 3978422. PMID 23899327. Figure 2: Distribution of fungal genera in different body sites
  7. ^ a b c Rogers AH, ed. (2008). Molecular Oral Microbiology. Caister Academic Press. ISBN 978-1-904455-24-0.
  8. ^ a b Lamont RJ, Hajishengallis G, Jenkinson HF (2014). Oral microbiology and immunology (2nd ed.). Washington, DC: ASM Press. ISBN 978-1-55581-673-5. OCLC 840878148.
  9. ^ Noble JM, Scarmeas N, Papapanou PN (October 2013). "Poor oral health as a chronic, potentially modifiable dementia risk factor: review of the literature". Current Neurology and Neuroscience Reports. 13 (10): 384. doi:10.1007/s11910-013-0384-x. PMC 6526728. PMID 23963608.