**1. Introduction**

228 Practical Applications in Biomedical Engineering

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Dental caries is the most prevalent oral disease that affects a significant part of the world population, especially in less developed countries. It is universally accepted that the dental caries is a chronic and multifactorial disease [1-3]. The permanence of the bacterial plaque on the tooth surface will lead to loss of minerals constituents of the dental enamel promoting the installation of the carie disease. The carious lesion is characterized by the tooth structure (hydroxyapatite) demineralization by the production of organic acids, such as lactic acid, resulting from bacterial (dental biofilm) metabolism. This results in loss of calcium and phosphate ions which subsequently diffuse out of the tooth. In this complex process, the microorganisms, particularly *Streptococcus* species, have an important role in its etiology [3-5].

Many oral *Streptococcus* in the presence of carbohydrate produce organics acids and insoluble glucans which serve as binding sites for bacteria on the tooth surface, forming the biofilm. The sucrose plays an important role in carie development, influencing on biofilm acidogenicity and cariogenic microflora. The high cariogenicity of dental plaque formed in the presence of sucrose can be mainly explained by the high concentration of insoluble glucans on its matrix, the low inorganic concentration and its protein composition may have some contribution [6, 7].

Specifics microorganisms are associated with dental plaque formation, development and maturation. The *Streptococcus mutans* is a member of the oral microbial community which plays a key role in formation of cariogenic biofilms. The key factors of *S. mutans* cariogenic are the production of a great variety of carbohydrates, which generate low pH and cause the consequent demineralization of the tooth enamel [3, 8-10].

© 2012 de Campos-Takaki et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2012 de Campos-Takaki et al., licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Recent developments in the areas of biomaterials devices have resulted in a number of advances in the searches of natural substances which may inhibit the dental plaque formation and/or the hydroxyapatite demineralization [11, 12]. In particular, this research is focused on novel macromolecules and biocompatible materials for use in clinical applications. Chitosan is a non-toxic and natural polysaccharide, which have many biological applications, mainly as antimicrobial agent [12].

Microbiological Chitosan: Potential Application as Anticariogenic Agent 231

enzyme chitin synthase and Mg +2 ion as catalyst, resulting in the formation of a long chain of subunits monosaccharide's linked by β-1 → 4. Chitosan is thus obtained by deacetylation

Fungi the chitin and chitosan synthesis simultaneously were occurred. The synthesis of chitin is highly compartmentalized. The enzyme chitin synthase is the zymogen form and distributed in specific regions of the cell surface, vesicles in specialized, chitosome. The macromolecular assembly starts out of the cytoplasm, where the protease enzyme acts on the cell surface activating the zymogenes. In this way the UDP N-acetylglucosamine is produced from glucose, and chitin synthase catalyzes the transfer of N-acetylglucosamine for polymerization chain forming chitin. The chitosan present in cell walls of certain fungi (Mucorales) is formed from the deacetylation (chitin deacetylase) chain chitin source for the biosynthesis of chitin. The regulations of the synthesis of chitin and chitosan are determined

Crustacean chitosan is inconsistent in its physical–-chemical properties due to the variability in raw materials, the harshness of the isolation and conversion processes, the caustic effects of the chemicals used in the isolation process, and variability in the levels of deacetylation

The use of biomass from fungi have demonstrated a great advantages, such as: independence of seasonal factor, wide scale production, simultaneous extraction of chitin and chitosan, extraction process is simple and cheap resulting in reduction of the time and cost required for production, and also absence of proteins contamination, mainly the proteins that could cause allergy reactions in individuals with shellfish allergies. However, to optimize the production of chitin and chitosan from fungi, it's usually used complex or synthetics cultures media, which are expensive. It's becomes necessary to obtain economic culture media that promote the growth of fungi and stimulate the production of the

In order to obtain alternative sources of nutrients and low cost several research projects are being conducted. Table 1 shows the use of various synthetic media and low cost alternative media used for growth of fungi of the order Mucorales, and production of chitin and chitosan. The content of chitin and chitosan from fungal cell wall varies among different species and growth conditions. Many studies have been performed to verify the possibility of using the biomass of fungi, especially Mucorales, class Zygomycetes, as an alternative source of chitin and chitosan. Many of these studies test simple models to verify the production of chitin and chitosan, ie, the approach adopted experiments using only one variable at a time during the fermentation, eg after cultivation, agitation, pH, temperature and concentration of nutrients. However, the literature report in recent years the scientific interest to reduce the numbers of tests and increase the accuracy of the results has been increased. Therefore, multivariate approach, using factorial design, allows the observation of the synergistic effect between the independent variables, since all variables are

considered simultaneously, resulting in the final optimize conditions [30-34].

of chitin by chemical treatment with NaOH at high temperature [20].

by the spatial organization of the synthesis of chitin in the cell surface [20, 21].

and protein contamination [22-24].

polymers [25-32].
