Multiple Choice Questions Test - VII (Basic Periodontology).
Tetracyclines inhibit connective tissue breakdown by,
- Direct inhibition of active matrix metalloproteinases – dependent on Ca++ and Zn++ binding properties of tetracyclines.
- Inhibition of oxidative activation of pro-matrix metalloproteinases –independent of cation binding properties of tetracyclines.
- Tetracyclines decrease cytokines, inducible nitric oxide synthase, phospholipase A2, prostaglandin synthase.
- Tetracyclines increase collagen production.
- Tetracyclines increase osteoblast activity and bone formation.
Reference: Maria Emanuel Ryan & Lorne M. Golub. Modulation of matrix metalloproteinase activities in periodontitis as a treatment strategy. Periodontology 2000, Vol. 24, 2000, 226–238)
F nucleatum has the potential to be periodontal pathogen because of its number and frequency in periodontal lesions, its production of tissue irritants, its synergism with other bacteria in mixed infections, and its ability to form aggregates with other suspected pathogens in periodontal disease and thus act as a bridge between early and late colonizers on the tooth surface. That is why it acts as a nucleus for plaque formation.
Reference: A I Bolstad, H B Jensen and V Bakken. Taxonomy, biology, and periodontal aspects of Fusobacterium nucleatum. Clin. Microbiol. Rev. 1996, 9(1):55.
The endocrine system plays an important role in the homeostasis of the periodontium. It is a major cause of morbidity and mortality in post menopause women. Osteoporosis, which is defined as a systemic condition characterized by a decrease in the bone mineral density of at least 2.5 times the normal values in a healthy young female, is a major health problem in postmenopausal women.
Reference: Mascarenhas P, Gapski R, Al-Shammari K, Wang H-L: Influence of sex hormones on the periodontium. J Clin Periodontol 2003; 30: 671–681.
Chediak-Higashi syndrome is characterised by a structural defect in which there is fusion of azurophil and specific granules into giant granules called “megabodies”. This is characteristic of neutrophils from individuals with this disease. Neutropenia, depressed inflammation, and the relative lack of neutral serine proteases are observed in CHS. Depressed inflammation is thought to be due to decreased chemotaxis and secretion, not the neutropenia.
Reference: Spicer SS et al. Lysosome enlargement in the Chediak-Higashi syndrome. Fed Proc. 1981 Apr;40(5):1451-5.
Defensins are the antimicrobial molecules. The characterstic features of all defensins are their 3 disulfide bonds via pairs of cystein residues. α- defensins are found in humans in 6 different forms. Both α and β- defensins are encoded in very close approximation on 8p23 chromosome.
Reference: Roderick I. Marshall. Gingival defensins: linking the innate and adaptive immune responses to dental plaque Perio 2000,Vol.35,2004,14-20.
Collagen comprises the major( ~ 80–90%) organic component in mineralized bone tissues. Type I collagen (>95%) is the principal collagen in mineralized bone and, together with type V (<5%) collagen, the type I collagen forms heterotypic fiber bundles that provide the basic structural integrity of connective tissues. In addition to the presence of type I and V collagens in alveolar bone, both type III and XII collagens are also present.
Reference: Jaro Sodek & Marc D.Mckee.Molecular and cellular biology of alveolar bone. Periodontology 2000, Vol. 24, 2000, 99–126.
Azurophilic granules first emerge at the promyelocyte stage, which are recognizable because of their large, prominent cytoplasmic granules that have a deep purple-red color in Wright-Giemsa-stained preparations. Thus, the term azurophil granule, given by early haematologists, is due to their affinity for the azure dyes of blood stains. These granules are also named primary granules, because they are the first granules produced in neutrophil development, or peroxidase-positive granules due to the presence of peroxidase in these organelles. Azurophil granules are the stores of all of the cellular myeloperoxidase and most proteolytic and bactericidal proteins, and therefore these granules have been considered as the microbicidal compartment mobilized during phagocytosis. Azurophil granule degranulation is confined primarily to internalized phagocytic vacuoles during phagocytosis.
References: F. Mollinedo. Human neutrophil granules and exocytosis molecular control. Inmunología Vol. 22 / Núm 4/ Octubre-Diciembre 2003: 340-358.
Leffell MS, Spitznagel JK. Fate of human lactoferrin and myeloperoxidase in phagocytizing human neutrophils: effects of immunoglobulin G subclasses and immune complexes coated on latex beads. Infect Immun 1975; 12: 813-820.
Type IV collagen in mammals is derived from six genetically distinct α-chain polypeptides (α1-α6). n It is the most important structural component of basement membranes integrating laminins, nidogens and other components into the visible two-dimensional stable supramolecular aggregate. The structure of type IV collagen is characterized by three domains: the N-terminal 7S domain, a C-terminal globular domain (NC1), and the central triple helical part with short interruptions of the Gly-X-Y repeats resulting in a flexible triple helix which is 390nm in length.
Reference: K. Gelse et al. Collagens—structure, function, and biosynthesis. Advanced Drug Delivery Reviews 55 (2003) 1531 – 1546.
Plasma half-life (h)
Plasma concentration (mg/L)
Species such as S. Mitis and S. Oralis are considered to be “pioneer species” in subgingival biofilm since they are prominent at 4and 6 hours during plaque formation.
Reference: Clinical Periodontology and Implant Dentistry By Jan Lindhe, Niklaus P. Lang, Thorkild Karring. Fifth edition. Page 241.