Introduction to oral pathology.pdf

Oral pathology ‫ نجالء الوشلي‬.‫د‬ 4th level Lecture: 1 Introduction to oral pathology Definition  Oral pathology is the specialty of dentistry and pa...

Oral pathology ‫ نجالء الوشلي‬.‫د‬ 4th level Lecture: 1 Introduction to oral pathology Definition  Oral pathology is the specialty of dentistry and pathology which deals with the nature, identification, and management of diseases affecting the oral and maxillofacial regions. It is a science that investigates the causes, processes and effects of these diseases. Oral pathology fields  The practice of oral pathology includes research, diagnosis of diseases using clinical, radiographic, microscopic, biochemical or other examinations, and management of patients. Main descriptive terms applied to orofacial and skin lesions:  Abscess: A localized collection of purulent exudate.  Vesicle: Fluid filled elevated lesion less than 5mm in diameter.  Bulla: Fluid-filled elevated lesion greater than 5mm in diameter.  Macule: Circumscribed discolored flat lesion not raised above level of surrounding mucosa.  Plaque: Slightly elevated area of mucosa with a flat surface.  Atrophy: Reduction in tissue mass.  Papule: Circumscribed elevated solid lesion less than 5mm in diameter. 1  Nodule: Circumscribed elevated solid lesion more than 5mm in diameter, but less than 2cm.  Mass: Circumscribed elevated solid lesion more than 2cm in diameter “tumorlike.”  Endophytic: A lesion that is growing inwards into the underlying tissue.  Exophytic: An oral mucosal lesion that extends outward from the adjacent mucosa.  Pedunculated: Exophytic lesion whose base is narrower than the widest part of the lesion  Sessile: Exophytic lesion whose base is the widest part of the lesion.  Petechiae: Pin-point red or purple spots caused by submucosal hemorrhage.  Ecchymosis: Macular area of hemorrhage > 2 cm in diameter.  Desquamation: Loss of superficial epithelial thickness (commonly follows a blister).  Erosion: Partial loss of the surface epithelium not extending through the full thickness.  Ulcer: Loss of epithelium with loss of some underlying tissues.  Erythematous: The oral mucosa is red in colour resulting either from erosion of the epithelial surface or from increased vascularity.  Papillary: An oral mucosal lesion with a surface consisting of numerous blunted projections.  Neoplasm: Abnormal new mass of tissue.  Indurated: An oral mucosal lesion that is firm when palpated.  Fistula: Abnormal connection, lined by epithelium between two epithelium lined organs. 2  Microscopes Microscope Care  Always carry with 2 hands  Do not force knobs  Always store covered  Only use lens paper for cleaning. Microscope Parts Types of microscopes  The types of microscopes differ according to the interaction of light with tissue components.  Conventional light microscope.  Differential interference.  Phase contrast. 3   Polarizing.  Confocal.  Flourescence.  Atomic force microscopy.  Electron microscopy. Fact About Microscopes  Light microsocopes are used to see details, and enlarged images of small objects.  Magnification is enlarging an image.  Resolution is the amount of fine detail that can be seen.  Light is focused onto the specimen (i.E. The histology slide) by a condenser.  The image produced is magnified by a combination of the objective lens and the eyepiece lens. Light microscope  Stained preparations are examined by means of light that passes through the section.  Compound microscope:  Image formed by action of 2 lenses (of the objective lens and the eyepiece lens). Phase contrast microscopy  Phase contrast microscopy uses a lens system that produces visible images from a transparent object (unstained). 4 Polarizing microscopy  Allows structures made of highly organized molecules to be observed (e.g. collagen). The Fluorescence Microscope  Exposes specimen to ultraviolet, violet, or blue light.  Specimens usually stained with fluorochromes.  Shows a bright image of the object resulting from the fluorescent light emitted by the specimen. Electron microscopy  Used to observe very small objects: viruses, DNA, parts of cells.  Uses beams of electrons rather than light.  2 types:  Transmission E.M. and Scanning E.M. Transmission Electron Microscope (TEM) Can magnify up to 250,000x 5  Scanning Electron Microscope (SEM) Can magnify up to 100,000x Tissue staining  Most tissues are normally colorless  The dyes stain tissue components selectively.  Tissue that takes basic dyes is called basophillic and appear blue.  Tissue that takes acidic dyes is called acidophillic or eosinophillic and appear red or pink.  Examples of basic dyes: hematoxylin, toulidine blue, methylene  Examples of acidic dyes: eosin, orange G , fuschin.  Basophillic components have acids in its composition e.g. nucleic acids, glycosaminoglycans (cartilage), and acid glycoproteins (acute phase proteins).  Eosinophillic components are basic e.g. collagen, bone, muscles, mitochondria (as in oncocytes), secretory granules, and keratin. 6  H&E (hematoxylin & eosin) is the most popular routine stain used universally.  Some other stains are used e.g. trichromes which are used to differentiate b\w muscle and collagen.  Some methods of metal impregnation are used such as silver and gold which are common methods in studies of the nervous system. 7