Multiple Choice Question Test - XIII (Basic Periodontology).
Epithelial rest cells of Malassez form a latticework in the periodontal ligament and appear as either isolated clusters of cells or interlacing strands. These are distributed close to the cementum throughout the periodontal ligament of most teeth and are most neumerous in the apical areas and cervical areas.
Reference: Carranza 8th edition page 33.
Cementum thickness is most rapid in the apical region of the tooth. Thickness of cementum in the coronal half of the tooth varies from 16-60 µm. It attains the greatest thickness (150-200 µm) in the apical third and the bifurcation and trifurcation areas. The thickness of cementum on the distal surface of root is more than the mesial surface probably from functional stimulation because of functional stimulation from mesial drift over time.
Reference: Carranza 8th edition page38.
Periosteum consists of an inner and an outer layer. The inner layer is composed of cells that have the potential to differentiate into osteoblasts. Outer layer is rich in blood vessels and nerves and is composed of collagen fibers and fibroblasts.
Reference: Carranza 8th edition page 44
Up regulators of MMP production:
- Tumor necrosis factor- α
- Epidermal growth factor
- Platelet derived growth factor (PDGF)
- Transforming growth factor - α (TGF-α )
Down regulators of MMP expression:
- Interferon γ
CD28 molecule is the most effective T-cell co-stimulatory receptor. It is a member of the immunoglobulin (Ig) superfamily, having a single Ig variable-like extracellular domain in addition to its transmembrane and cytoplasmic domains. Expressed as a disulfide-linked homodimer, it is present on most CD4+ and many CD8+ T cells, and binds to the APC costimulatory ligands B7.1 and B7.2. These B7.1 and B7.2 are also Ig superfamily members, with two Ig-like extracellular domains (one variable and one constant), in addition to transmembrane and short cytoplasmic domains. Both of these proteins are expressed as monomers on professional APCs — dendritic cells, activated B cells and macrophages.
Reference: Daniel L. Mueller. T cells: A proliferation of costimulatory molecules.
Underwood’s septum is found in Maxillary sinus. Underwood published a detailed description of maxillary sinus anatomy in 1910, for decades these septa were considered clinically-insignificant anatomical variations. The prevalence of sinus septa varies from 16% to 58% according to the literature. Its knowledge is especially important in implant dentistry. For accurate and safe placement of dental implants, and planning of associated surgery, a full assessment of the surgical anatomy of the maxillary sinus is necessary.
Reference: Underwood AS. An inquiry into the anatomy and pathology of the maxillary sinus. J Anat Physiol.1910;44:354–369.
Crawford F. Gray et al. Advanced imaging: Magnetic resonance imaging in implant dentistry: A review. Clinical Oral Implants Research Volume 14, Issue 1, pages 18–27, February 2003.
The exact defect in Papillon lefevre syndrome(PLS) is still unclear but it seems that the defect lies in myloperoxidase deficiency, low integrin expression, increased superoxide production and defective phagoocytosis and chemotaxis. Neutrophils from individuals of PLS show decreased receptor affinity for chemotaxis such as formyl-peptides. Other features are,
- Increased circulating NK cells.
- Decreased monocyte phagocytosis.
- Diminished lymphocyte responsiveness.
- Periodontal connective tissue clearly shows dominated plasma cells.
Resolvins (resolution-phase interaction products) are endogenous mediators that possess potent anti-inflammatory properties. The known actions of resolvins are reduction of neutrophil trafficking, regulation of production of cytokines and reactive oxygen species, and lowering of the magnitude of the inflammatory response.
Reference: Thomas E. Van Dyke. Control of inflammation and periodontitis. Periodontology 2000, Vol. 45, 2007, 158–166.
Th2 cells produce:
- Assists in the recruitment and maintenance of basophils into lymphoid tissues in response to infection
- Inhibits the proliferation and differentiation of Th1 cells
- Stimulates B cell proliferation and maturation into plasma cells
- Regulates the class switching of antibodies
- Increases IgE production
- Attracts and activates eosinophils
- Critical role in B cell maturation into IgG secreting cells
- Plays a significant role in inflammation and autoimmunity
- Inhibits secretion of various cytokines by Th1 cells, macrophages, and dendritic cells
- Stimulates B-cell production of IgE
- Attracts basophils and mediates the release of granules
- Triggers mast cells to release granules
- Co-mediates production IL-4, IL-5 and IL-13
- Implicated in inflammatory responses in the skin
- Recruitment of PMNs, monocytes, and T cells to the sites of infection
- An EGF family member growth factor with anti-tumor effects
Acellular afibrillar cementum is located over cervical enamel at the cementoenamel junction. Its major structural components are glycosaminoglycans and its functional significance is unknown.
Reference: Moon-Il Cho & Philias R. Garant. Development and general structure of the periodontium. Periodontology 2000, Vol. 24, 2000, 9–27