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ORAL PATHOLOGY CystCyst is pathological fluid-filled cavity lined by epithelium.COMPONENT OF CYST:1. Lumen (cavity) Wall (capsule)2. Epithelial lining Lumen (cavity)3. Wall (capsule) Lining In this schematic drawing Arrow A the connective tissue wall that forms the cyst. Arrows B various types of epithelium that can line a cyst developing within the oral regions. PseudoCyst ?
ORAL PATHOLOGY Periapical Cyst - Defination• An odontogenic cyst derived from Cell Rests of Malassez that proliferate in response to inflammation.• Odontogenic Cyst (Defination) A cyst in which lining of the lumen is derived from epithelium involved in tooth development.• Non-Odontogenic Cyst (Defination) The epithelial lining is derived from sources other than the tooth-forming organ
ORAL PATHOLOGY Periapical Cyst - Epidemiology• Worldwide• Common – constitutes approx one half to three fourth of all cysts in the jaws• Relative frequency: 60-70%• Frequent in ages between 20-60 years (rarely in <10years age) (Peaks in third through sixth decades)• M/F ratio: 3:2• Maxilla is 3 times more affected than mandible
ORAL PATHOLOGY Periapical Cyst – Clinical Features• Usually asymptomatic• Slowly progressiveIf infection enters, the swelling becomespainful & rapidly expands(partly due to inflammatory edema)• Initially swelling is round & hard• Later, part of wall is resorbed leavinga soft fluctuant swelling, bluish in color,beneath the mucous membrane.• When bone has been reduced toegg shell thickness a crackling sensationmay be felt on pressure.
ORAL PATHOLOGY Periapical Cyst – PathogenesisPHASES1. Phase of Initiation2. Phase of cyst formation3. Phase of enlargment
ORAL PATHOLOGY Periapical Cyst – PathogenesisRECALL• Epithelial cell rests of Malassez (ERM)are part of the periodontal ligament cells around a tooth.• They are discrete clusters of residual cells fromHertwigs epithelial root sheath (HERS) that didntcompletely disappear.(remnants of HERS that persist in PDL after root formationIs complete)• It is considered that these cell rests proliferate to form epithelial lining of various odontogenic cysts suchas radicular cyst under the influence of various stimuli.• Some rests become calcified in the periodontalligament (cementicles)
ORAL PATHOLOGY Periapical Cyst – Pathogenesis(PHASE 1) Phase of Initiation:• Stimulation of cell rests of Malassez in response to INFLAMMATION elicited by - baterial infection of pulp - direct response to necrotic pulp tissue.(PHASE 2) Phase of Cyst Formation:• Epithelial cells derive their nutrients by diffusion from adjacent C.T, progressive growthof an epithelial island moves the innermost cells of that island away from their nutrients.• Ultimately these innermost cells undergo ischemic liquefactive necrosis, establishingCentral cavity (lumen) surrounded by viable epithelium.(PHASE 3) Phase of Cyst Expansion:• Breakdown of cellular debris (innermost cells) within the cyst lumen raises the protein conc. increased osmotic press. resultingIn fluid transport into the lumen from the C.T side FluidIngress thus assists in outward growth of a cyst.
ORAL PATHOLOGY Periapical Cyst – PathogenesisMajor factors in the pathogenesis of cyst formation• Epithelial proliferation• Hydrostatic effects of cyst fluids• Bone resorbing factors- Infection from pulp chamber induces Inflammation & proliferation of ERM- Internal pressure is imp. for growth of cysts.- Cyst fluid contains proteins which exert osmotic pressure- Hydrostatic pressure within cysts is about 70cm of water (higher than capillary blood pressure)- Net effect is that pressure is created by osmotic tension within the cyst cavity.- Bone resorbing factors PGE2 & PGE3, with osteoclastic bone resorption, the cyst expands
ORAL PATHOLOGY Periapical Cyst – Pathogenesis (SUMMARY) CARIES, TRAUMA. PERIODONTAL DISEASE PULPAL NECROSIS ( Death of Dental Pulp ) Necrotic Debris is Inflammatory Stimulus PERIAPICAL INFLAMMATION PERIAPICAL GRANULOMA Composed of granulation tissue, scar & inflammatory cells PROVIDE RICH VASCULAR AREA TO RESTS OF MALASSEZ RESTS OF MALASSEZ PROLIFERATE FORM LARGE MASS OF CELLS INNER CELLS OF MASS DEPRIVED OF NOURISHMENT UNDERGO LIQUEFACTION NECROSISFORMATION OF A CAVITY IN THE CENTRE OF GRANULOMA RADICULAR CYST / PERIAPICAL CYST Cyst wall separates pulpal irritation from bone
ORAL PATHOLOGY Periapical Cyst – Diagnosis• Diagnosis is by the combination of- Radiographic appearances- A non vital tooth- Appropriate histopathological appearancesBy defination, a non vital tooth is necessary for the diagnosis of a periapical cyst.Clinical FindingsSymptoms and Signs• Small radicular cysts do not usually become acutely infected, are frequently asymptomatic,and can be identified on routine dental x-rays.• Larger cysts may produce expansion of the bone, displacement of tooth roots, and crepituswhen palpating the expanded alveolar plate.• The discoloration of nonvital teeth and a negative response of the affected tooth to electric pulp testing or ice are the presenting signs. In addition, infected radicular cysts are painful, the involved tooth is sensitive to percussion, and there may be swelling of the overlying softtissues and lymphadenopathy.
ORAL PATHOLOGYQ. What are the components of cysts?Lumen, Lining, and wall. Lumen (cavity) of cyst Epithelial lining Wall (capsule) – made of connective tissue
ORAL PATHOLOGY Periapical Cyst – Histopathology• Lumen (cavity):- Contains cyst fluid ; which is usually watery & opalescent- sometimes more viscid & yellowish- sometimes shimmers with cholesterol crystals(typically rectangular shaped cholesterol crystals with a notched corner is characteristic)- Cholesterol crystals are not specific to radicular cyst.- Protein content of fluid – seen as amorphous eosinophilic material• Epithelial Lining:- Non-keratinized stratified squamous epithelium- Lacks a well-defined basal cell layer- Thick, irregular, hyperplastic or net like forming Rings & Arcades- Hyaline Bodies ( Rushton Bodies) may be found.- Mucous cells – as a result of metaplasia• Transmigration of inflammatory cells through epithelium is common with more Neutrophils & less lymphocytes.
ORAL PATHOLOGY Periapical Cyst – Histopathology• Wall/Capsule:- composed of collagenous fibrous connective tissue- capsule is vascular & infiltrated by chronic inflammatory cells- plasma cells are prominent or often predominate- Russel bodies are often found.- Pulse or Seed granulomas are often found in cyst wall.- clefts within cyst capsule left by cholesterol dissolved out during preparation for sectioning. (cholesterol is derived from breakdown of blood cells)- clefts may be seen extending into the cyst contents but are formed in the cyst wall- Small clefts are associated with foreign body giant cells, extravasated blood cells & blood pigments- In the bony wall there is osteoclastic activity (bone resorption), beyond resorption there is active bone formation – net effect cyst expands but retains bony wall this bony wall progressively thins (since repair is slower than resorption) & until it forms a mere eggshell, then ultimately disappears together the cyst then starts to distend soft tissues & appear as soft bluish swelling.
ORAL PATHOLOGY Periapical Cyst – Histopathology- foci of dystrophic calcification May be seen subsequent- cholesterol clefts to hemorrhage in the- multinucleated foreign-body giant cells cyst wall.
ORAL PATHOLOGY Periapical Cyst – HistopathologyHyaline Bodies ( Rushton Bodies) :characterized by a hairpin or slightly curved shaped, concenteric lamination & occasionalBasophilic mineralization.- In small percentage of periapical cysts/radicular cysts- are within the epithelium lining- origin believed to be previous hemorrhage- are of no clinical significanceRussel Bodies:refractile & spherical intracellular bodies representing accumulated Gamma Globulin.
ORAL PATHOLOGY• Cholesterol crystals in form of clefts are often seen in the CT wall, inciting a foreign body giant cell reaction.• Originate from disintegrating RBC’s in presence of inflammation.• Different types of dystrophic calcification are also seen in CT wall.
ORAL PATHOLOGY Periapical Cyst – Radiologically• Radiolucency associated is generally round to ovoid,with a narrow opaque margin that is contiguous with the lamina dura of involved tooth.(peripheral radioopaque component may not be apparent if the cyst is rapidly enlarging)• Majority cysts <1.5cm in diameter• Long standing cysts:- Cause root resorption of offending tooth& occasionally of adjacent teeth.Note: cause bone resorptionbut Generally do not produce bone expansion (?)
ORAL PATHOLOGY Periapical Cyst – Radiologically Periapical cyst is well circumscribed distinct line of cortication separating it from the surrounding bone May b associated with Resorption of apices of teeth, displacement of teeth or both. It is distinctly rounded & unilocular may become v.large erosion of inferior border &Bulging of the buccal & lingual cortical plates.
ORAL PATHOLOGY Periapical Cyst – Treatment• Root canal filling ( removal of necrotic pulp; the inflammatory stimuli)• Extraction of the involved non-vital tooth & curettage of apical zone• Root canal filling in association with apicoectomy(direct curretage of the lesion)• Surgery ( epicoectomy & curretage ) is performed for lesions that are persistent,Indicating presence of a cyst or inadequate root canal treatment.• If incompletely removed residual cystContinued cyst growth can cause significant bone resorption & weakening of maxilla &mandible.EnucleationMarsupialization
ORAL PATHOLOGY Residual Periapical Cyst• A cyst that may persist after the extraction of the causative tooth is calledResidual periapical cyst- are common cause of swelling of the edentulous jaw in older persons- may slowly regress spontaneously
ORAL PATHOLOGY Lateral Periapical Cyst• Are rare• Form at the side of a non vital tooth as a result of opening of a lateral branch of the root canal.NOTE:• Must be differentiated from LATERAL PERIODONTAL CYSTS