Pathogenesis of periodontal disease Dr Enas Razzoqi B
Pathogenesis of periodontal disease Dr. Enas Razzoqi B. D. S. , M. Sc. , Ph. D in Periodontics
Pathogen: - is any disease microorganism or material. producing Pathogenesis: - Is the biologic and histologic events that occur in the tissues during the process of conversion from a healthy state to the diseased state.
Periodontal disease: Periodontal diseases are a heterogeneous group of pathologies affecting the periodontium. They include the major conditions periodontitis. gingivitis and Gingivitis: - Is the inflammation of the gingiva which has many No loss of attachment is associated with this condition) types. Periodentitis: Is the inflammation of the supporting tissues of the teeth which is characterized by apical migration of junctional epithelium with associated loss of attachment. Usually progressively destructive changes leading to loss of bone and Periodontal ligament. In other word, it is an extension of inflammation from the gingiva into the adjacent bone and ligament.
Periodontal disease
Periodentitis
Mechanisms of pathogenicity: Gingivitis and periodontitis are caused by bacteria that colonize the gingival crevice and attach to the tooth surfaces. The pathogenic potential of bacteria within the plaque varies from individual to individual and from gingival site to gingival site. Small amounts of plaque in a healthy person can be tolerated without causing P. d. disease. , probably because of the control exerted by host defense mechanisms. When specific bacteria within the plaque increase to significant numbers and produce virulence factors beyond the patient’s control threshold, the balance shifts form health to disease.
Evidence for a pimary role of bacteria in the etiology of periodontal (p. d. ) disease: • The acute phases of certain forms of P. D. disease can be alleviated by any of a number of antibiotics. • intensive plaque control procedures clinical gingivitis • withdrawal of such procedures bacterial plaque gingivitis. eradicated increase in • subjects with destructive periodontal diseases show an elevated serum antibodies against specific subgingival organisms.
In general G-ve, facultative, capnophilic or anaerobic microorganisms are the principal bacteria associated with P. d. d. • P. Gingivalis • A. actinomycetem comitans • Prevotella intermedia • Fusobacterium nucleatum • Campylobacter rectus • Treponema denticola • Eikenella species These are some of the most common bacteria associated with disease, because of their pathogenic capabilities and their increased numbers in disease.
Suspected periodontal pathogens: Actinobacillus actinomycetemcomitans Aggregatibacter actinomycetemcomitans (Aa): small, non motile, G-ve, saccharolytic, round- ended rod and forms small, convex colonies. -presence in higher numbers in lesions of localized aggressive periodontitis (localized juvenile periodontitis previously (LJP)). Soon thereafter, it was demonstrated that the majority of subjects with LAP had an elevated serum antibody response to this species. The species has been isolated from adult periodontitis lesions, but less frequently and in lower numbers than from lesions in LAP subjects.
Porphyromonas gingivalis (P. gingivalis): Bacteroides gingivalis G-ve anaerobic, non motile, asaccharolytic rods that usually exhibit coccal to short rod morphologies. P. gingivalis is a member of much investigated “black pigmented bacteroids” group. Organisms of this group form brown to black colonies on blood agar plates. P. gingivalis has been shown to induce elevated systemic and local immune responses in subjects with various forms of periodontitis; this is demonstrated by elevated antibody in serum or saliva of subjects with various forms of periodontitis.
Virulence factors The periodontopathogen possess numerous factors that enable them to colonize and invade host tissue and permit them to damage the periodontium directly or to trigger a pathogenic host response indirectly, these factors also as referred to (virulence factors).
The possible pathogenic mechanisms are: Bacterial invasion Bacteria were first identified by transmission electron microscopy within the gingival tissues and close to resorbing bone surfaces in mny cases of advanced human periodontitis. In 1965 Listgaarten demonstrated with an electron microscope the invasive nature of spirochetes in acute necrotizing ulcerative gingivitis (ANUG). In localized aggressive periodontitis, A. actinomycetem comitans has been identified within the gingival connective tissue; the presence of this organism within tissues appears to make the disease more resistant to treatment and may necessitate the use of antibiotics or other chemotherapeutic agents in refractory cases.
Exotoxins The production of exotoxins by some plaque microorganisms has been described. A. A. (leukotoxin) because of its toxic effect on human polymorphonuclear neutrophils (PMNs).
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