The collagen-cleaving enzyme matrix metalloproteinase-8 MMP-8 is present in saliva and acts as measurable indicator of periodontal disease [ 33 ].
Amylase present in human saliva was one of the first enzymes to be recognized and molecular mechanisms involved in amylolysis of starch and even of the physiological role of the salivary amylase itself [ 34 ].
Lactoferrin in saliva represents an important defense factor against bacterial injuries including those related to Streptococcus mutans and periodontopathic bacteria through its ability to decrease bacterial growth, biofilm development, iron overload, reactive oxygen formation, and inflammatory processes [ 35 ].
Lactoferrin is a major component of biologically important mucosal fluids and is essential for mucosal-mediated immunity [ 36 ]. The antimicrobial in vitro effects of the salivary proteins lactoferrin and lysozyme on microorganisms is involved in the carious process, obtaining their minimum inhibitory concentration and minimum bactericidal concentration [ 37 ].
Salivary alpha-amylase has been proposed as a sensitive noninvasive biomarker for stress-induced changes in the body that reflect the activity of the sympathetic nervous system [ 38 ]. Lactoferrin is a multifunctional mammalian immunity protein that limits microbial growth through sequestration of nutrient iron [ 40 ]. Lysozyme in saliva is found to have the antibacterial activity against the pathogen, and there is potential for it to serve an antimicrobial role in the specific application of medical industry [ 41 ].
Lactoferrin may be a useful agent to prevent irradiation effects in salivary glands [ 42 ]. LTF is examined as a first-line mediator in immune defense and response to pathogenic and nonpathogenic injuries as well as a molecule critical for control of oxidative cell function [ 43 ]. Salivary and pancreatic amylases hydrolyze starch and involvement of amylase in adiposity and starch metabolism [ 44 ].
Lactoferrin is a secretory protein with various physiological functions, and oral lactoferrin may mitigate psychological stress in humans [ 45 ]. The complex mix of salivary constituents provides an effective set of systems for lubricating and protecting the soft and hard tissues [ 46 ].
The lubricating and antimicrobial functions of saliva are maintained mainly by resting; saliva results in a flushing effect and the clearance of oral debris and noxious agents [ 47 ]. Saliva is a complex fluid, which influences oral health through specific and nonspecific physical and chemical properties [ 48 ].
Saliva contains numerous antimicrobial proteins that help protect the oral ecosystem from infectious agent [ 49 ]. Proteins can move from blood circulation into salivary glands through active transportation, passive diffusion, or ultrafiltration; some of which are then released into saliva and hence can potentially serve as biomarkers for diseases [ 50 ].
Saliva covers the oral hard and soft tissues with a conditioning film which governs the initial attachment of microorganisms, a crucial step in the setup of the oral microflora [ 51 ].
A high quality of saliva is an essential factor to protect the dental elements against attrition and promote the digestion process [ 52 ]. Saliva is the principal fluid component of the external environment of the taste receptor cells which is involved in the transport of taste substances and protection of the taste receptor [ 53 ]. The role of human saliva and its compositional elements in relation to the GI functions of taste, mastication, bolus formation, enzymatic digestion, and swallowing [ 54 ].
Salivary nonesterified fatty acids NEFA are proposed to play a role in oral health and oral fat detection, and they may hold diagnostic and prognostic potential [ 55 ]. Lingual lipase generates nonesterified fatty acids NEFA from dietary fats during oral processing by lipolysis. Lingual lipase in rodents has strong lipolytic activity and plays a critical role in oral detection of fats [ 56 ]. Physiological role of salivary lipolytic activity in the regulation of the basal FFA concentration could be involved in fat taste sensitivity [ 57 ].
During chewing, saliva helps in preparing the food bolus by agglomerating the formed particles, and it initiates enzymatic food breakdown [ 58 ]. Saliva plays a key role in the eating process and on the perception of flavor.
Flavor corresponds to the combined effect of taste sensations, aromatics, and chemical feeling factors evoked by food in the oral cavity [ 59 ]. Analysis of saliva may be useful for the diagnosis of hereditary disorders, autoimmune diseases, malignant and infectious diseases, and endocrine disorders, as well as in the assessment of therapeutic levels of drugs and the monitoring of illicit drug use [ 61 ].
Fluid addition facilitated chewing of dry foods and feeding disorders caused by hyposalivation [ 62 ]. Saliva has been demonstrated to be a promising bodily fluid for early detection of diseases, and salivary diagnostics have exhibited tremendous potential in clinical applications [ 63 ].
Saliva has the potential to become a first-line diagnostic sample of choice owing to the advancements in detection technologies coupled with combinations of biomolecules with clinical relevance [ 64 ]. Saliva is a useful diagnostic fluid for oral-related diseases. Monitoring salivary biomarkers for oral and systemic diseases could become an important complement to clinical examinations in epidemiological surveys [ 65 ] Figure 1.
Different functions of the saliva [ 60 ]. The high rate of changes in the composition of saliva can be used for the monitoring of various biorhythms in order to study the physiological characteristics of the human body [ 66 ]. The significant influences of the oral environment observed in this study increase the current understanding of the salivary microbiome in caries. These results will be useful for expanding research directions and for improving disease diagnosis, prognosis, and therapy [ 67 ].
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Learn more about our commitment to oral health education. Top Articles. Location and Function You have six main glands three on each side of your mouth that continually produce saliva.
What Is Saliva Made Of? Proteins: The second leading component of saliva after water. Though proteins make up only a fraction of saliva's composition, they serve numerous functions. Proteins work as the first line of defense in eliminating oral bacteria and help form a protective layer on your teeth.
They are thought to aid in taste by interacting with taste receptors in your mouth. Enzymes : The enzymes found in saliva are specific proteins responsible for sparking chemical reactions in your body that help begin the digestive process. For example, these enzymes assist in breaking down starches and fats in your mouth.
Mucin: You might equate mucin to the buildup of mucus that happens when you get a cold, but the mucin found in saliva aids in digestion. This specific protein helps you eat and swallow safely by keeping the mouth lubricated.
Electrolytes: Electrolytes are minerals in your body, such as calcium, phosphorous, and magnesium. Inside your mouth, these particular minerals help strengthen and harden your enamel, which in turn helps reduce your risk of cavities. How to Keep Your Salivary Glands Healthy Follow these simple tips to keep your salivary glands healthy and productive: Avoid smoking and tobacco products.
This movement is made Yet others live barely Their varied lifespans make rockfish a unique genus in which to pinpoint genes An international team of scientists Print Email Share. Most Popular Stories. It's in the Father's Genes. We have seen that the surface of the hydroxyapatite crystal that forms the enamel is sensitive to changes in the composition of saliva and undergoes constant reconstruction. However, our teeth are supposed to stay healthy and functional for many decades.
Therefore, a stable environment on the enamel surface would be desirable. Here, too, saliva has a role: components of it, first and foremost the mucins, firmly settle on the crystal surface and create a protective layer.
The many moist and warm surfaces in our mouth serve as an ideal habitat biotope for microorganisms, mainly bacteria, but also yeasts e.
Candida and protozoa e. Entamoeba gingivalis. Bacteria only stand a chance to survive in our mouth if they manage to hold on and not get swallowed. A few bacterial species, especially streptococci, can bind directly to the pellicle.
On the one hand this happens via positively charged calcium ions that mediate between the negatively charged surfaces of the pellicle and the bacteria. On the other hand, there is also direct, specific binding of bacterial proteins lectins to the pellicle structure. Already five minutes after the tooth surface has been cleaned, the first bacteria start attaching to the newly formed pellicle.
They then proliferate by cell division to form a biofilm. After two to three hours, a plaque visible to the naked eye is established. In protected areas of the mouth, bacterial colonies over the next days grow into thick, complex three-dimensional structures known as mature plaque. If the plaque is undisturbed by tooth brush or floss, it can grow as thick as one millimetre or bacteria. To be able to continue extracting energy from food, these bacteria need to switch to fermentation, a process that yields organic acids instead of carbon dioxide and water.
The resulting acidic microclimate dissolves the hydroxyapatite crystal and caries ensues. After about a week, the plaque begins to mineralise: calcium and phosphate from saliva are deposited in the bacterial colony and harden it, leading to dental calculus. Plaque as thick and firm as this can only form in places in the mouth where bacteria can proliferate undisturbed over many days.
The constant flow of saliva prevents this on most dental surfaces simply by washing away loosely attached bacterial layers. Even in people who neglect brushing their teeth over a prolonged period of time, dental plaque and calculus do not form on exposed surfaces. However, niches such as the interdental space and gum pockets provide sufficient protection against the mechanical rinsing function of saliva.
But saliva can do even more: the proteins that form the pellicle on the tooth surface and to which bacteria can hold on, are also still present in a soluble form in saliva. Bacteria cannot actively discern whether the mucin they bound to is fixed to the tooth surface or free floating in saliva and washed into the stomach with the next swallowing process.
Many bacteria are thus entrapped and swallowed. In addition, saliva contains the enzyme lysozyme that attacks and perforates the cell walls of certain bacteria, eventually making them burst.
Then there are antibodies immunoglobulin A secreted into saliva that prevent pathogens from settling in the oral cavity. Our saliva promotes bacteria that do not produce acids, and it helps kill undesirable and excess bacteria with the use of nitrate.
Nitrate is an important nitrogen source for plants and is therefore used as fertiliser.
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