Dental Plaque Biofilm byDr. Mohammed.pptx

Dental plaque biofilm by Dr.Mohammed Kareem
Dental plaque is a biofilm of microorganisms mostly bacteria, that grows on surfaces within the mouth. It is a sticky colorless deposit at first, but when it forms calculus , it is often brown or pale yellow. It is commonly found between the teeth, on the front of teeth, behind teeth, on chewing surfaces, along the gumline (supragingival), or below the gumline cervical margins (subgingival).

1. Dental plaque Biofilm By: Mohammed Kareem Radhi

2. Contents of presentation Introduction Definitions Composition of dental plaque Classification of dental plaque Accumulation of a Dental Plaque biofilm -The formation of the pellicle on the tooth surface - Initial adhesion/attachment of bacteria -Colonization/plaque maturation Factors Affecting Supragingival dental plaque formation Biofilms and Antimicrobial Resistance Detection of plaque build-up Dental Plaque control

3. Introduction Dental plaque is a biofilm of microorganisms mostly bacteria, that grows on surfaces within the mouth. It is a sticky colorless deposit at first, but when it forms calculus , it is often brown or pale yellow. It is commonly found between the teeth, on the front of teeth, behind teeth, on chewing surfaces, along the gumline (supragingival), or below the gumline cervical margins (subgingival). Dental plaque is one of the major causes for dental decay and gum disease.

4. Oral biofilms are functionally and structurally organized polymicrobial communities that are embedded in an extracellular matrix of exopolymers on mucosal and dental surfaces. Definitions Dental plaque is defined clinically as a structured resilient yellow-grayish biofilm that adheres firmly to the intraoral hard surfaces, including removable and fixed restorations. The tough extracellular matrix makes it impossible to remove plaque by rinsing or the use of sprays. Plaque can thus be differentiated from other deposits that may be found on the tooth surface such as materia alba and calculus.

5. Materia alba refers to soft accumulations of bacteria, food deposits, and tissue cells that lack the organized structure of dental plaque and are easily displaced with a water spray. Definitions calculus is formed as a hard mineralized deposit of dental plaque and is generally covered by a layer of unmineralized plaque

6. C ompostion of dental plaque Dental plaque Water 70-80% Solid 20-30% Micro organisms 70% Intracellular matrix 20-30% *Bacterial *Non- bacterial *Organic material *Inorganic material

7. Composition of dental plaque Microorganisms represent the main component of dental plaque, with approximately 10 11 bacteria contained in one gram of plaque (wet weight).

8. Classification of dental plaque

9. Supragingival plaque Supragingival plaque is found at or above the gingiva when in direct contact with the gingival margin it is referred to as marginal plaque. Gram-positive cocci and short rods are predominant at the tooth surface, whereas gram-negative rods and filaments, as well as spirochetes, predominate on the outer surface of the mature plaque mass Marginal plaque is of prime importance in the initiation and development of gingivitis. Supragingival plaque is critical in calculus formation and root caries

10. Subgingival plaque Subgingival plaque is found below the gingival margin between the tooth and the gingival pocket epithelium the subgingival microbiota differs in composition from the supragingival plaque, primarily because of the local availability of blood products and a low reduction-oxidation (redox) potential, which characterizes the anaerobic environment The environmental parameters of the subgingival region differ from those of the supragingival region. The gingival crevice or pocket is bathed by the flow of crevicular fluid, which contains many substances which bacteria may use as nutrients.

11. Subgingival plaque The tooth-associated cervical plaque , adhering to the root cementum, does not markedly differ from that observed in gingivitis Tooth-associated subgingival plaque are critical in calculus formation and root caries Tissue-associated subgingival plaque Mainly consist of gram negative , proteolytic , anaerobic , motile rods. These microorganism had virulence factors enable them to evade immune system , initiation of disease, and invasion of underlying connective tissue and bone. Tissue-associated subgingival plaque is important in the tissue destruction that characterizes different forms of periodontitis.

12. Subgingival plaque

13. Subgingival plaque The composition of the subgingival plaque depends on pocket depth apical part Dominated by spirochetes, cocci and rods Coronal part More filaments are observed . Cervical part Gram + , rods and cocci

14. Accumulation of a Dental Plaque Biofilm The formation of the pellicle on the tooth surface Initial adhesion/attachment of bacteria Colonization/plaque maturation .

15. The formation of the pellicle on the tooth surface All surfaces in the oral cavity including hard and soft tissues, are coated with a layer of organic material known as the acquired pellicle. The pellicle on the tooth surface consists of more than 180 peptides, proteins, and glycoproteins including keratins, mucins, proline-rich proteins, phosphoproteins, histidine-rich proteins, and other molecules that can function as adhesion sites (receptors) for bacteria. Salivary pellicles can be detected on clean enamel surfaces within 1 minute after tooth cleaning .

16. The formation of the pellicle on the tooth surface By two hours, the pellicle is essentially in equilibrium between adsorption and detachment, although further pellicle maturation can be observed for several hours. Consequently, bacteria that adhere to tooth surfaces do not contact the enamel directly but interact with the acquired enamel pellicle.

17. Initial Adhesion/Attachment of Bacteria Tooth brushing removes most but not all bacteria from the exposed surfaces of teeth. However, recolonization begins immediately and bacteria can be detected within 3 minutes of introducing sterile enamel into the mouth. Initial adhesion is performed by specific interactions between microbial cell surface “adhesin” molecules and receptors in the salivary pellicle that determine whether a bacterial cell will remain associated with the surface. Only a relatively small proportion of oral bacteria possess adhesins that interact with receptors in the host pellicle, and these organisms are generally the most abundant bacteria in biofilms on tooth enamel shortly after cleaning.

18. Initial Adhesion/Attachment of Bacteria Over the first 4 to 8 hours, 60% to 80% of bacteria present are members of the genus Streptococcus. Other bacteria commonly present at this time include species that cannot survive without oxygen (obligate aerobes), such as Haemophilus spp. and Neisseria spp., as well as organisms that can grow in the presence or absence of oxygen (facultative anaerobes) including Actinomyces spp. and Veillonella spp. These species are considered the “primary colonizers” of tooth surfaces.

19. Initial Adhesion/Attachment of Bacteria The primary colonizers' function: 1. provide new binding sites for adhesion by other oral bacteria. 2. The metabolic activity of the primary colonizers modifies the local microenvironment in ways that can influence the ability of other bacteria to survive in the dental plaque biofilm. For example, by removing oxygen, the primary colonizers provide conditions of low oxygen tension that permit the survival and growth of obligate anaerobes.

20. Colonization and Plaque Maturation The primary colonizing bacteria adhered to the tooth surface provide new receptors for attachment by other bacteria in a process known as “ co-adhesion .” Together with the growth of adherent microorganisms, coadhesion leads to the development of microcolonies and eventually to a mature biofilm. Different species or even different strains of a single species have distinct sets of coaggregation partners. Fusobacteria coaggregate with all other human oral bacteria while Veillonella spp., Capnocytophaga spp. and Prevotella spp. bind to streptococci and/or actinomyces. Each new cell becomes itself a new surface and therefore, may act as a coaggregation bridge to the next potentially accreting cell type that passes by. The transition from early supragingival dental plaque to mature plaque growing below the gingival margin involves a shift in the microbial population from primarily gram-positive organisms to high numbers of gram-negative bacteria.

21. Colonization and Plaque Maturation Therefore, in the later stages of plaque formation coaggregation between different gram-negative species is likely to predominate. Examples of these types of interactions are the co aggregation of F. nucleatum with P. gingivalis or T. denticola .

22. Factors Affecting Supragingival dental plaque formation Topography of Supragingival Plaque Surface roughness Individual variables influencing plaque formation impact of Gingival Inflammation and Saliva Variation within the Dentition The Impact of Patient’s Age Spontaneous Tooth Cleaning

23. Biofilms and Antimicrobial Resistance the resistance of bacteria to antibiotics is affected by their nutritional status , growth rate , temperature , pH , and prior exposure to sub-effective concentrations of antimicrobial agents . Variations in any of these parameters will thus lead to a varied response to antibiotics within a biofilm. An important mechanism of resistance appears to be the slower rate of growth of bacterial species in a biofilm, which makes them less susceptible to many but not all antibiotics. The biofilm matrix, although not a significant physical barrier to the diffusion of antibiotics, does have certain properties that can retard antibiotic penetration. In addition, extracellular enzymes such as β-lactamases , formaldehyde lyase , and formaldehyde dehydrogenase may become trapped and concentrated in the extracellular matrix, thus inactivating some antibiotics ( especially positively charged hydrophilic antibiotics ).

24. Biofilms and Antimicrobial Resistance The resistance of bacteria to antimicrobial agents is dramatically increased in the biofilm. Almost without exception, organisms in a biofilm are 1000 to 1500 times more resistant to antibiotics than in their planktonic state Recently, “super-resistant” bacteria were identified within a biofilm. These cells have multidrug resistance pumps that can extrude antimicrobial agents from the cell. Since these pumps place the antibiotics outside the outer membrane, the process offers protection against antibiotics that target, for example , cell wall synthesis . The penetration and efficacy of antimicrobials against biofilm bacteria are critical issues for the treatment of periodontal infections.

25. Detection of plaque build-up There are two main methods of detecting dental plaque in the oral cavity: Through the application of a disclosing gel or tablet visually through observation or by using probe

26. Detection of plaque build-up Plaque disclosing gel Plaque disclosing products, also known as disclosants , make plaque clinically visible. Clean surfaces of the teeth do not absorb the disclosant , only rough surfaces .

27. Detection of plaque build-up Disclosing tablets Disclosing tablets are similar to that of disclosing gels, except that they are placed in the mouth and chewed on for approximately one minute. Disclosing tablets are often prescribed or given to patients with orthodontic appliances for use before and after tooth brushing to ensure optimal cleaning. These are also helpful educational tools for young children or patients who are struggling to remove dental plaque in certain areas. Disclosing gels and tablets are useful for individuals of all ages in ensuring efficient dental plaque removal.

28. Plaque Control Plaque control means the regular removal and prevention of accumulations of the dental plaque on the teeth and adjacent gingival surfaces. The two most important objectives of plaque control are: 1- Prevention of gingivitis and marginal periodontitis. 2- Prevention of dental caries.

29. Plaque Control Classification of plaque control Mechanical plaque control Chemical plaque control

30. Plaque Control

31. Plaque Control

32. Plaque Control Chlorhexidine Cationical bisbiguainide was introduced as an antiseptic cream for use in skin wounds in 1975, to human use in the United Kingdom. Since then the use of chlorhexidine has extended to over 20 products that contain chlorhexidine. This agent is commonly used in the management of routine plaques as a chemical supplement. frequently used as a mouth rinse (o. 2% or 0.12% w/v . It caught the dental world as a solution 0.2% of chlorhexidine for managing gingivitis.

33. Plaque Control Clinical applications Application of chlorhexidine is a nonspecific attempt to control microorganism and judicious timings of therapeutic interactions can aid in obtaining a healthy periodontium. Various modes of chlorhexidine delivery techniques have been suggested, and each technique provides different advantages Chlorhexidine can be delivered in the form of mouth washes, tooth pastes, gels, periodontal dressings, sprays, and irrigation.

34. CONCLUSION Dental plaque biofilm cannot be eliminated permanently. However, the pathogenic nature of the dental plaque biofilm can be reduced by reducing the bio burden (total microbial load and different pathogenic isolates within that dental plaque biofilm) and maintaining a normal flora with appropriate oral hygiene methods that include daily brushing, flossing and rinsing with antimicrobial mouth rinses. This can result in the prevention or management of the associated squeal, including the development of periodontal diseases and possibly the impact of periodontal diseases on specific systemic disorders.

35. Thank you

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