The emergence of new genomic technologies, including bioinformatics and next-generation sequencing, has significantly increased our knowledge and understanding of the oral microbiome and its importance in health. The oral microbiota in health is very diverse and more than 700 different bacterial species have been identified in the oral cavity. In each healthy individual, it is estimated that the number of resident species is lower, that is, in the range of 250 to 300 different species, of which the genus Streptococcus is the most abundant.
The oral cavity offers a moist and warm environment with host-derived nutrients such as dietary sugar, salivary proteins, glycoproteins and gingival crevicular fluid, making it a suitable residence for the growth of many different microorganisms, mainly bacteria but also fungi, virus. , archaea and protozoa.
The oral cavity offers several different niches for microbial colonization, such as the teeth, gingival sulcus, attached gingiva, tongue, cheeks, lips, and hard and soft palate that display a site-specific microbiota. Furthermore, teeth are the only natural non-shedding surfaces in the human body and therefore provide opportunities for extensive biofilm formation and microbial residency.
Similarly, dental restorations, fillings, fixed prosthesis, dentures, and implants exhibit non-shedding surfaces that may influence biofilm formation and the composition of the resident oral microbiota.
The complex and diverse oral microbial ecosystem plays an important role in promoting and maintaining oral health.
Several factors influence the formation and maintenance of the oral microbiota, including the host (behavior and defense mechanisms), the local environment and the microorganisms themselves, that is, their ability to adhere, coaggregate, interact with other species, as well as its virulence. One of the factors that plays a very important role in oral homeostasis and symbiosis is saliva.
Saliva contributes to the formation of the acquired enamel film and mucosal film, which covers the hard and soft oral tissues, respectively, and therefore helps to modulate the initial adhesion and colonization of microorganisms and shapes the composition of the resident oral microbiota. In addition, saliva facilitates the removal of microorganisms and dietary carbohydrates from the oral cavity, but also provides nutrients to colonizing bacteria through the breakdown of dietary starch, lipids and proteins and the bacterial metabolism of the components. salivary, for example, glycoproteins.
Goals
Provide an update on our current understanding of how saliva and its various components directly and indirectly affect oral bacteria and therefore play a role in modulating and maintaining a healthy oral microbiota and also associations with symbiosis and dysbiosis.
Methods
The search for biomedical literature on saliva and its antimicrobial activities (years 1966 to 2017) was carried out in the PubMed, Embase and Web of Science databases.
Results
This review highlights that saliva plays an essential role in the formation and maintenance of the ecological balance of the resident oral microbiota.
Saliva contributes to the formation of the salivary film, which covers the hard and soft oral tissues and therefore determines the initial adhesion and colonization of microorganisms.
Saliva facilitates the removal of dietary carbohydrates and microorganisms from the oral cavity, but also provides nutrients to bacteria through the enzymatic breakdown of dietary starch and proteins and salivary glycoproteins.
In addition, saliva contains proteins such as mucins, which block the adherence of certain microorganisms to oral surfaces through binding and aggregation mechanisms. Saliva also provides antimicrobial activity through numerous proteins and peptides including mucins, lactoferrin, lysozyme, lactoperoxidase, statherin, histatins, and secretory immunoglobulin A.
Conclusions
Saliva is a key component in maintaining a balanced oral microbiome and performs a wide variety of functions that help promote oral health. The importance of the complex interaction between the host, saliva and oral microbiota becomes evident when salivary flow is reduced and composition is altered, leading to dysbiosis and the risk of associated oral diseases, such as dental caries, gingivitis. and oral fungal infections.
Salivary constituents provide an important nutritional source for various microorganisms, and the complex interaction of many salivary organic and inorganic constituents is essential for the maintenance of a balanced and beneficial microbiota and for symbiosis.
A large number of proteins and peptides have been detected in saliva and some of their functions and complex interactions with the oral microbiome have not yet been clarified. The availability of advanced technologies provides promising possibilities to study the interaction of the host and the microbiome and consequently identify risk predictors in the salivary proteome for common oral diseases such as dental caries or periodontal disease, as well as identify measures to help to prevent dysbiosis.
This article has reviewed some of the most prominent components of saliva and how they directly and indirectly contribute to modulating and balancing the oral microbiome.
A balanced oral microbiome is important for maintaining oral health and symbiosis. Conditions associated with hypofunction of the salivary glands, altered oral clearance, low salivary pH and altered salivary composition, often lead to perturbation of the function and composition of the oral microbiome causing dysbiosis and an associated risk of oral disease. .
Clinical significance Saliva plays an important role in maintaining the relationship between the host and the oral microbiota in a symbiotic state. In conditions with salivary gland dysfunction, the natural balance of the oral microbiome is often disturbed, leading to dysbiosis and associated risks of gingivitis, cavities and fungal infection. |
