THE NORMAL AND PATHOLOGICAL HISTOLOGY OF THE MOUTH: PATHOLOGICAL HISTOLOGY

By JOSEPH THOMAS

SECTION I: ORAL HISTOLOGY 1 PREPARATION OF ORAL TISSUES FOR MICROSCOPIC EXAMINATION 2 CELLS, TISSUES AND STAINS 3 DEVELOPMENT OF TEETH 4 ENAMEL 5 DENTIN 6 PULP 7 CEMENTUM 8 PERIODONTAL LIGAMENT 9 MAXILLARY SINUS 10 ORAL MUCOSA 11 SALIVARY GLAND SECTION II: ORAL PATHOLOGY 12 CYSTS OF ORAL REGION 13 ODONTOGENIC TUMORS 14 DENTAL CARIES 15 PULP AND PERIAPICAL LESIONS 16 BACTERIAL AND FUNGAL INFECTIONS CONTENTS 17 SALIVARY GLAND NEOPLASMS 18 SKIN LESIONS 19 BONE LESIONS 20 BENIGN AND MALIGNANT TUMORS OF ORAL CAVITY 21 DEVELOPMENTAL DISTURBANCES I ORAL HISTOLOGY 1 PREPARATION OF ORAL TISSUES FOR MICROSCOPIC EXAMINATION 2 CELLS, TISSUES AND STAINS 3 DEVELOPMENT OF TEETH 4 ENAMEL 5 DENTIN 6 PULP 7 CEMENTUM 8 PERIODONTAL LIGAMENT 9 MAXILLARY SINUS 10 ORAL MUCOSA 11 SALIVARY GLAND THE NORMAL AND PATHOLOGICAL HISTOLOGY OF THE MOUTH A SOUND KNOWLEDGE OF THE STRUCTURES OF ORAL TISSUE IS VERY MUCH ESSENTIAL FOR UNDER- STANDING OF THIS REGION THE KNOWLEDGE ABOUT THESE STRUCTURES GIVES THE CLINICIAN AN INSIGHT INTO THE UNDERSTANDING OF THE DISEASE MECHANISM THAT MAY DEVELOP IN THESE TISSUES AND PREDICT THE REACTION OF TISSUES TO VARIOUS FACTORS, ETC MICROSCOPIC EXAMINATION IS THE METHOD ADOPTED TO STUDY THE HISTOLOGICAL STRUCTURES OF THE ORAL TISSUES TO STUDY THE HISTOLOGICAL STRUCTURE, THE TISSUE SHOULD BE APPROPRIATELY PREPARED FOR MICROSCOPIC EXAMINATION STUDY OF DENTAL HARD TISSUES THE STRUCTURE OF DENTAL HARD TISSUES CAN BE STUDIED USING GROUND SECTIONS OR DECALCIFIED SECTIONS THE EXCEPTION IS ENAMEL, WHERE DECALCIFIED SECTIONS ARE NOT OF MUCH USE BECAUSE 96% OF ENAMEL IS MINERALIZED, WHICH IS LOST WHILE DECALCIFICATION DECALCIFICATION DECALCIFICATION IS THE PROCESS BY WHICH CALCIUM IN THE MINERALIZED TISSUE IS REMOVED SO THAT THE ?STUDY OF DENTAL HARD TISSUES – DECALCIFIED SECTIONS – GROUND SECTIONS ?STUDY OF ORAL SOFT TISSUES – ROUTINE SOFT TISSUE PROCESSING TISSUE BECOMES SOFT ENOUGH TO MAKE SECTIONS DECALCIFICATION IS ACHIEVED BY USING ACIDS, CHELATING AGENTS OR BY ELECTROLYSIS THE COMMONLY USED METHOD IS ACID DECALCIFICATION FREQUENTLY USED ACID FOR DECALCIFICATION IS 5% NITRIC ACID 15% FORMIC ACID MAY ALSO BE USED NITRIC ACID MAY CAUSE YELLOWING OF THE TISSUE, THAT MAY INTERFERE WITH FURTHER STAINING PROCEDURE TO AVOID THIS 0 1% UREA IS ADDED TO NITRIC ACID PROCEDURE HARD TISSUE TO BE DECALCIFIED SHOULD BE FIXED IN 10% FORMALIN OR FORMAL SALINE TO REDUCE THE TIME FOR DECALCIFICATION TISSUE MAY BE CUT INTO SMALLER PIECES THEN PLACE THE TISSUE IN A CONTAINER WITH 5% NITRIC ACID THE ACID SHOULD BE CHANGED DAILY FOR A FEW DAYS THE SPECIMEN IS THEN TESTED FOR COMPLETION OF DECALCIFICATION METHODS TO CHECK THE COMPLETION OF DECALCIFI- CATION 1 CHECKING THE CONSISTENCY OF THE TISSUE: COMPLETELY DECALCIFIED TISSUE WILL BE SOFT WITHOUT ANY HARDNESS BEING FELT (EXPERIENCED HAND CAN TELL BY THE FEEL OF THE TISSUE ) 2 PIERCING THE TISSUE WITH A NEEDLE: IF IT ENTERS THE TISSUE WITHOUT RESISTANCE, THE TISSUE IS COMPLETELY DECALCIFIED THIS IS NOT RECOM- MENDED BECAUSE IT MAY CAUSE DAMAGE TO THE TISSUE PREPARATION OF ORAL TISSUES FOR MICROSCOPIC EXAMINATION MANUAL OF ORAL HISTOLOGY AND ORAL PATHOLOGY 3 JUDICIOUS BENDING OR TRIMMING OF THE TISSUE: THIS CAN BE DONE TO ENSURE COMPLETION OF DECALCIFICATION 4 TAKING RADIOGRAPH OF THE SPECIMEN: IN THE RADIOGRAPH, IF RADIOPAQUE SPECKS ARE FOUND, TISSUE IS NOT COMPLETELY DECALCIFIED 5 CHEMICAL TEST: THE BASIS OF THIS TEST IS TO IDENTIFY CALCIUM IN THE DECALCIFYING SOLUTION IN WHICH THE SPECIMEN WAS KEPT SODIUM HYDROXIDE OR STRONG AMMONIA IS ADDED TO 5 ML OF DECALCIFYING FLUID, TO NEUTRALIZE THE SOLUTION THEN 5 ML OF SATURATED AMMONIUM OXALATE SOLUTION IS ADDED AFTER THIS, CHECK FOR TURBIDITY ABSENCE OF TURBIDITY AFTER 5 MINUTES INDICATES THE FLUID IS FREE FROM CALCIUM AND THEREBY DECALCIFICATION IS COMPLETE TURBIDITY IS OBSERVED DUE TO PRECIPITATION OF CALCIUM IF PRECIPITATION IS OBSERVED AFTER ADDITION OF SODIUM HYDROXIDE, IT INDICATES LARGE AMOUNT OF CALCIUM IS PRESENT IN FLUID PRECIPITATION SEEN ONLY AFTER ADDITION OF AMMONIUM OXALATE SUGGESTS DECALCIFICATION IS NEARLY COMPLETE CHECKING THE END POINT OF DECALCIFICATION IS IMPORTANT BECAUSE INCOMPLETE DECALCIFICATION MAKES FURTHER CUTTING OF SPECIMENS DIFFICULT PROLONGED DECALCIFICATION IS ALSO NOT DESIRABLE BECAUSE IT MAY AFFECT THE STAINING PROCEDURE ONCE THE DECALCIFICATION IS COMPLETE THE TISSUE SHOULD BE WASHED IN RUNNING WATER TO REMOVE ALL ACIDS THEN THE STEPS OF PROCESSING CAN BE CONTINUED LIKE SOFT TISSUE PROCESSING WHICH INCLUDES DEHYDRATION, EMBEDDING, SECTIONING AND STAINING GROUND SECTIONS GROUND SECTIONS ARE OF PARTICULAR IMPORTANCE IN THE STUDY OF STRUCTURE OF DENTAL HARD TISSUES ESPECIALLY ENAMEL IN THIS METHOD THE TOOTH IS MADE INTO THIN SECTIONS BY GRINDING, USING ABRASIVE STONES PROCEDURE THE TOOTH TO BE EXAMINED SHOULD BE CUT INTO 2–3 SECTIONS USING DENTAL HAND PIECE AND DIAMOND IMPREGNATED OR CARBORUNDUM DISC THESE SECTIONS SHOULD BE GROUND USING AN ARKANSAS STONE OR BY SIMPLY RUBBING ON A GLASS PLATE USING ABRASIVE SLURRY GRINDING SHOULD BE CONTINUED TILL IT IS APPROXIMATELY 25–50 MICRONS THICK FINE ABRASIVES SHOULD BE USED FOR THE FINAL POLISHING MOST SUITABLE ABRASIVE IS DOMESTIC SCOURING POWDERS FOLLOWED BY SOAPY WATER ONCE THE DESIRABLE THICKNESS IS ATTAINED, THE SECTION SHOULD BE WASHED AND DEHYDRATED AND MOUNTED ON A GLASS SLIDE USING SYNTHETIC RESIN OR CANADA BALSAM AS MOUNTING MEDIUM AND IS ALLOWED TO DRY GRINDING OF THE TOOTH CAN ALSO BE DONE USING A LABORATORY LATHE INITIAL GRINDING IS DONE BY HOLDING THE TOOTH IN FINGERS AND PRESSING IT AGAINST THE ROTATING COARSE ABRASIVE WHEEL OF A LATHE WHEN THE TOOTH IS THIN, IT IS DIFFICULT TO HOLD WITH FINGERS THEREFORE, A WOODEN BLOCK WRAPPED WITH ADHESIVE PLASTER WITH STICKY SIDE DIRECTED OUTWARD CAN BE USED STICK THE TOOTH ON TO THE PLASTER AND PRESS THE WOODEN BLOCK TO THE ROTATING WHEEL OF THE LATHE SO THAT THE TOOTH IS GROUND THIN THEN CHANGE THE COARSE WHEEL TO FINE WHEEL AND CONTINUE GRINDING TILL THE SECTION IS SUFFICIENTLY THIN TO REMOVE THE ADHESIVE PLASTER THE SECTIONS CAN BE SOAKED IN WATER THE SECTION REMOVED FROM THE PLASTER IS THEN MOUNTED ON A GLASS SLIDE USING A MOUNTING MEDIUM PRECISION EQUIPMENT LIKE HARD TISSUE MICRO- TOMES ARE NOW AVAILABLE FOR THE PREPARATION OF GROUND SECTIONS STUDY OF ORAL SOFT TISSUES THE MOST COMMONLY USED METHOD OF PREPARING SOFT TISSUE FOR THE LIGHT MICROSCOPIC STUDY IS BY EMBEDDING THE TISSUE IN PARAFFIN, AND CUTTING AND MOUNTING THE SECTION ON SLIDES AND STAINING PREPARATION OF SECTIONS OF PARAFFIN EMBEDDED SPECIMENS (SOFT TISSUE PROCESSING) 1 OBTAINING THE SPECIMEN: SPECIMENS FOR MICROSCOPIC STUDY ARE OBTAINED THROUGH EITHER BIOPSY OR AUTOPSY BIOPSY IS THE REMOVAL OF TISSUE FROM A LIVING ORGANISM FOR THE PURPOSE OF MICROSCOPIC EXAMINATION AND DIAGNOSIS IF TISSUE IS TAKEN THE NORMAL AND PATHOLOGICAL HISTOLOGY OF THE MOUTH