Bobkova S.A., Kushnir K.G., Severinova S.K.

SI “Crimea State Medical University named after S. I. Georgievsky”

Using of prebiotics in periodontal pathology treatment

Dental plaque is a biofilm that develops naturally on the teeth. Like any biofilm, dental plaque is formed by colonizing bacteria trying to attach themselves to a smooth surface (of a tooth). It has been speculated that plaque forms part of the defense systems that prevent colonization by microorganisms which may be pathogenic.

The oral cavity contains the only known anatomical aspect of the human body that does not have a regulated system of shedding surfaces: the teeth. This allows a numerous amount of microorganisms to adhere to the surface of teeth for long periods of time. These multiple species of bacteria become dental biofilm. Dental biofilm, more commonly referred to as dental plaque, is composed of about a thousand species of bacteria that take part in the complex ecosystems of the mouth. The natural, non-frequent regulation of tooth shedding plays a large role in making dental biofilm the most diverse biofilm in the human body despite the relatively small size of the teeth.

As previously mentioned there are about 1000 species of bacteria that are involved with the formation of dental biofilm. Due to this fairly large number there is fierce competition among the bacteria present on dental biofilm for nutrients present in the mouth. Only about fifty percent of the 1000 species have been cultured for study.

The microorganisms that form the biofilm are mainly Streptococcus mutans and anaerobes including Str. salivarius and Str. sobrinius, with the composition varying by location in the mouth. Examples of other anaerobes include fusobacterium and actinobacteria.

The main ecological factors are pH, saliva, temperature and redox reactions. The majority of microbial organisms prefer neutral pH levels (pH 7). Saliva acts as a buffer, maintaining the pH in the mouth between 6.75 and 7.25. In addition to acting as a buffer, saliva is also a main source of nutrients for the thousands of microorganisms. A 2ºC change has been shown to drastically shift the dominant species in the plaque. The normal temperature of the mouth ranges from 35ºC to 36ºC. Redox reactions are carried out by aerobic bacteria. This keeps the oxygen levels in the mouth at a semi-stable homeostatic condition. This allows other bacteria to survive, which will be discussed in the next section.

Presence of nutrients and suitable pH level are two main factors that are necessary for dental plaque forming because they act on oral cavity microflora. Normal microflora metabolizes one type of nutrients, opportunistic microflora requires other type of nutrients. If to say about their proportion normal microflora should be in bigger amount than opportunistic because dental plaque formed by pathogenic and opportunistic microflora leads to appearance of hardened dental plaque named calculus. Plaque and calculus accumulation causes the gingiva to become irritated and inflamed, and this is referred to as gingivitis. When the gingiva become so irritated that there is a loss of the connective tissue fibers that attach the gums to the teeth and bone that surrounds the tooth, this is known as periodontitis. That’s why correction of bacterial proportion is necessary for preventing of oral cavity diseases caused by microorganisms.

In the year 1995 Prof. Marcel Roberfroid discovered non-digestible food ingredients that stimulate the growth and/or activity of bacteria in the digestive system. They were named prebiotics. One of the main features of prebiotics is their selective action – they act mostly on normal microflora. They are represented by carbohydrates, mostly oligosaccharides. Some oligosaccharides that are used in this manner are fructooligosaccharides (FOS), xylooligosaccharides (XOS), polydextrose, and galactooligosaccharides (GOS). Moreover disaccharids like lactulose or some monosaccharides such as tagatose are also used sometimes as prebiotics.

If to say about oral cavity, prebiotics act on Str. salivarius, Corynebacterium and Peptococcus, catalyzing biochemical processes in microorganisms. Level of pH becomes higher, thus and so mixed saliva becomes unsuitable for Str. mutans and Str. sobrinius which are main dental plaque pathogenic microorganisms. Level of free polysaccharides decreases and lack of nutrients for pathogenic microflora appears. Redox reactions keep the oxygen levels in the mouth at a semi-stable homeostatic condition suitable for anaerobic microorganisms. Dental plaque has almost no harmful influence on oral cavity because biofilm formed by pathogenic bacteria is reduced.

Main prebiotics used for oral cavity microflora normalization are extracted from unrefined wheat, unrefined barley and yacon, Jerusalem artichoke, jicama, and chicory root and can be used in this case, also lactulose (synthetic disaccharide) is widely used as additional component in some milk products and mouth rinses. If to say about lactulose it is also one of the most effective modern prebiotical medicines. This chemical substance is an artificially synthesized disaccharide (it contains chemical residues of galactose and fructose molecules) which has no nutrient value for human cells but it is very useful for Str. sanguinius and other normal microflora microbes. It accelerates growth of Str. sanguinius and Bifidobacterium in oral cavity which normalizes pH and stops multiplication of Str. mutans and Str. sobrinius. The growth of useful bacteria also increases the process of pathogenic microflora metabolites utilization.

The results of modern investigations and biochemical analyzes of dental plaque gives us data about biochemical and microbiological changes in oral cavity. This data proves the efficiency of prebiotics usage for dental plaque normalization.