Periodontal Microbiology 2025 PDF

Microbiology of Periodontal Diseases  Learning objectives 1. Understand the different tooth deposits, their formation and disease implications. 2. Recognize the different complexes and families of bacteria involved in periodontal disease. 3. Comprehend bacterial interac...

Microbiology of Periodontal Diseases  Learning objectives 1. Understand the different tooth deposits, their formation and disease implications. 2. Recognize the different complexes and families of bacteria involved in periodontal disease. 3. Comprehend bacterial interactions during various periodontal diseases 4. Correlate periodontal treatment modalities to the microbial reasons “ It is obvious that the periodontal microbiota is extremely complex. Because it affects the host, the oral environment, and periodontal treatment and because it is affected by the host, the oral environment, and periodontal treatment, a profound knowledge of periodontal microbiology is necessary ”  Six major ecosystems (niches) The intraoral and supragingival hard surfaces (teeth, implants, restorations, and prostheses) Subgingival regions adjacent to a hard surface, including the periodontal/periimplant pocket (characterized by the presence of crevicular fluid, the root cementum or implant surface, and the pocket epithelium) The buccal palatal epithelium and the epithelium of the floor of the mouth The dorsum of the tongue The tonsils The saliva  Different deposits on teeth Dentalplaque : the soft deposits that form the biofilm adhering to the tooth surface or other hard surfaces in the oral cavity, including removable and fixed restorations. Materia alba: the soft accumulations of bacteria and tissue cells that lack the organized structure of dental plaque and are easily displaced with a water spray. Calculus: a hard deposit that forms by mineralization of dental plaque and is generally covered by a layer of unmineralized plaque Different deposits on teeth Calculus deposits on teeth  Dental plaque is the primary etiologic factor for gingivitis and periodontitis Dental plaque = Dental Biofilm Do we need to study the formation, composition, and characteristics of the dental plaque? Why? Understanding the formation, composition, and characteristics of the plaque biofilm assists in its control Composition of dental plaque Microorganisms Intercellular Matrix (70%) (30%) Bacteria More than 500 bacterial Organic materials strains may be found Non-bacteria Mycoplasma species, yeasts, protozoa, Inorganic and viruses.  Organic materials Glycoproteins derived from saliva an important component of the pellicle Polysaccharides –produced by bacteria –dextran is the predominant form Albumin –derived from crevicular fluid lipid material –consists of debris from the membranes of disrupted bacterial, host cells and food debris  Inorganic materials Calcium & phosphorus (main components) Sodium, potassium, and fluoride (trace amount) derived from Saliva Gingival crevicular fluid Fluoridated toothpaste  How does plaque form on the teeth? Need to know first How do bacteria live in general?  Bacterial Lifestyles Free-floating (Planktonic) Attached to a surface forming a complex community called biofilm  Bacterial Biofilm Communities A biofilm is a well-organized community of bacteria that adheres to surfaces and is embedded in an extracellular slime layer. More than 99% of all bacteria on the earth live as attached bacteria. Can be found on different medical and dental devices (e.g. Implants ,intravenous and urinary catheters, contact lenses, and prosthetic devices such as heart valves, biliary artificial joints)  Bacterial Biofilm Communities Initially formed through bacterial interactions with a solid surface and then through physical and physiologic interactions among different bacterial species within the microbial mass.  Bacterial Biofilm Communities Significance of the Biofilm Increased Resistance of bacteria to antimicrobial agents due to : –limited diffusion of substances into the biofilm matrix –the slow rate of cell growth in the biofilm environment –altered properties of bacteria in response to growth on a surface The Structure of Biofilm Communities Conceptual illustration of dental plaque biofilm The Structure of Biofilm Communities The Structure of Biofilm Communities  Formation of Dental Plaque May be readily visualized on teeth after 1 to 2 days with no oral hygiene measures Appears as white, grayish, or yellow Typically observed on the gingival third of the tooth surface (why?) Form preferentially in cracks, pits, and fissures in the tooth structure; under overhanging restorations; and around malaligned teeth  Formation of Dental Plaque Location and rate depends on: 1- Oral hygiene 2- Diet 3- Salivary composition 4- Saliva flow rate  Formation of Dental Plaque In the absence of oral hygiene measures, plaque continues to accumulate until a balance is reached between the forces of plaque removal and those of plaque formation  Formation of Dental Plaque The process of plaque formation can be divided into three phases: 1- Formation of the pellicle coating on the tooth surface 2- Initial colonization by bacteria 3- Secondary colonization 4- Plaque maturation. Formation of Dental Plaque  Formation of Dental Plaque Pellicle formation: All surfaces of the oral cavity (including all tissue surfaces as well as surfaces of teeth and fixed and removable restorations) are coated with a glycoprotein pellicle This pellicle is derived from components of saliva and crevicular fluid as well as bacterial and host tissue cell products and debris The specific components of pellicles on different surfaces vary in composition  Formation of Dental Plaque Pellicle formation: forms by selective adsorption of the environmental macromolecules function as a protective barrier, providing lubrication for the surfaces and preventing tissue desiccation provide a substrate to which bacteria in the environment attach  Formation of Dental Plaque Initial Colonization Within a few hours, bacteria are found on the dental pellicle Initial bacteria colonizing the pellicle-coated tooth surface are predominantly gram-positive facultative microorganisms (e.g. Actinomyces viscosus and Streptococcus sanguis ) It adheres to the pellicle through specific molecules, termed adhesins, on the bacterial surface that interact with receptors in the dental pellicle  Formation of Dental Plaque Bacteria connect to the pellicle and each other with hundreds of hairlike structures called fimbriae (Fimbriae carry adhesins which attach them to the substratum )  Formation of Dental Plaque Initial Colonization The plaque mass then matures through the growth of attached species, as well as the colonization and growth of additional species There is a transition from the early aerobic environment characterized by gram-positive facultative species to a highly oxygen-deprived environment in which gram- negative anaerobic microorganisms predominate  Formation of Dental Plaque Secondary Colonization and Plaque Maturation Secondary colonizers are the microorganisms that do not initially colonize clean tooth surfaces It includes: Prevotella intermedia, Prevotella loescheii, Capnocytophaga spp., Fusobacterium nucleatum, and Porphyromonas gingivalis These microorganisms adhere to cells of bacteria already in the plaque mass (coaggregation)  Formation of Dental Plaque (Secondary Colonization and Plaque Maturation) Coaggregation: It starts with interactions among different gram- positive bacteria Then between gram-positive & gram-negative species In later stage: between different gram-negative species Formation of Dental Plaque  Microbial ecology and the interactions between periodontal pathogens and their environment o Bacteria have been classified into 5 clusters based on similarities and differences in nutritional and atmospheric environments.  Microbial ecology and the interactions between periodontal pathogens and their environment o Each of the clusters influence the other cluster and is related to a specific periodontal state o Within different periodontal states, either all or none of the species belonging to a particular cluster were found. Very few individual species or pairs of species were found, which further helped show that biofilms were a community of microbes. o Certain clusters were also found to interact particularly well with other clusters. For example, microbial species found in the red cluster were rarely observed without the presence of the orange cluster species  Microbial ecology and the interactions between periodontal pathogens and their environment oSecondary colonizers generally fell into the green, orange or red complexes oThe green and orange complexes include species recognized as pathogens in periodontal and non periodontal infections oThe red complex is associated with bleeding on probing  Microbial ecology and the interactions between periodontal pathogens and their environment Each oral bacterial species colonizes preferred sites within the subgingival plaque architecture. This selective colonization suggests that species organize into communities through communication with their host and with other species that occupy the host’s substrata.  Examples of the interactions between periodontal pathogens Cooperation and Competition Coaggregation bridges are mechanisms of cooperation because they bring together two species that are not coaggregation partners. The bridges are distinct from competition, which occurs when multiple species compete for binding to the same receptor.  Formation of Dental Plaque Microscopic Structure of Dental Plaque Gram-positive cocci and short rods predominate at the tooth surface (tooth associated) It includes Streptococcus mitis, S. sanguis, A. viscosus, Actinomyces naeslundii, and Eubacterium spp Use sugars as an energy source and saliva as a carbon source  Formation of Dental Plaque Microscopic Structure of Dental Plaque Gram-negative rods and filaments as well as spirochetes predominate in the outer surface of the mature plaque mass (tissue associated) Predominant species: S. oralis, S. intermedius, P. micros, P. gingivalis, P. intermedia, Bacteroides forsythus, and F. nucleatum Use amino acids and small peptides as energy sources Nutrients from host or metabolic byproducts of other bacteria  Different plaque regions and associated diseases Supragingival plaque calculus & caries Marginal plaque gingivitis Subgingival plaque Tooth-associated calculus & caries Tissue- associated soft tissue destruction  Microbiologic Specificity of Periodontal Diseases Nonspecific Plaque Hypothesis Specific Plaque Hypothesis Ecological Plaque Hypothesis  Microorganisms associated with specific periodontal diseases Periodontal Health: primarily gram positive facultative species and members of the genera Streptococcus and Actinomyces (e.g., S. sanguis, S. mitis, A. viscosus, and A. naeslundii)  Microorganisms associated with specific periodontal diseases Gingivitis: the bacteria consist of almost equal proportions of gram-positive (56%) and gram-negative cocci, rods and filaments (44%) species  Microorganisms associated with specific periodontal diseases Pregnancy-associated gingivitis: P. intermedia, which use the steroids as growth factors  Microorganisms associated with specific periodontal diseases Chronic Periodontitis: - High percentages of anaerobic (90%) gram-negative (75%) bacterial species - P. gingivalis, P. intermedia, F. nucleatum, and B. forsythus were found to be elevated in the active sites - Herpesviruses including Epstein-Barr Virus-1 (EBV-1) and human cytomegalovirus (HCMV), also have been associated with chronic periodontitis  Microorganisms associated with specific periodontal diseases Localized Aggressive Periodontitis: 90% of the total cultivable microbiota is A. actinomycetemcomitans. Herpesviruses including Epstein- Barr Virus-1 (EBV-1) and human cytomegalovirus (HCMV), also have been associated with LAP.  Microorganisms associated with specific periodontal diseases Abscesses of the Periodontium: microorganisms include F. nucleatum, P. intermedia, P. gingivalis, P. micros, and B. forsythus  How to control dental plaque biofilm? Mechanical removal is the most effective treatment currently available for the control of dental plaque biofilms Plaque index  Acknowledgment Mohammad S. Al-Zahrani, BDS, MSD, PhD Professor of Periodontology, King Abdulaziz University Diplomate, American Board of Periodontology THANK YOU Reference Chapter 8 Pages 134 - 169  Key Points Subgingival niche (ecosystem) Solid–Liquid boundaries, (contact of air and fluid). Gingivitis Vs Periodontitis Dental Plaque = Biofilm + 1ry etiologic factor for GD & PD = Soft & organized Initial colonization Vs Secondary colonization Microbial shifts as health progresses to periodontitis: From gram-positive to gram-negative From cocci to rods (and, at a later stage, to spirochetes) From nonmotile to motile organisms From facultative anaerobes to obligate anaerobes From fermenting to proteolytic species  Key Points Ecological Plaque Hypothesis 5 clusters (colors) Red complex = PTT = BOP PTT = P. gingivalis + T. forsthus + T. denticola = (PBT) Periodontal Health = G+ / Facultative Gingivitis = G+:G- = 56%:44% Pregnency-associated gingivitis = Prevotella intermedia Chronic Periodontitis = G- / Anaerobic Aggressive Periodontitis = Aggregatibacter actinomycetemcomitans (Aa) Periodontitis = Periimplantitis Plaque control = Mechanical Removal  Homework Develop an information flashcard for a bacterium or virus implicated in periodontal disease.  Example for home learning activity BACTERIA OR VIRUS NAME Aerobic/ facultative anaerobic Gram +/- , Cocci Yellow Complex Is one of the primary colonizers of the dental plaque, appears after birth by 2 months. Doesn't contribute to gingivitis but has implications in root caries. Has major fimbriae on its capsule Produces ginigpains enzyme which causes host-protein degradation. MOHAMED ROSHDY - 123456