Periapical cyst

An epithelial cyst, odontogenic cyst ,inflammatory cyst derived from cell Rest of Malassez , that proliferation in response to inflammation.

1. University of Benghazi Faculty of Dentistry Department of Oral Pathology Radicular cyst (Periapical cyst) By:Hager Mohammed Alfakhri

2. A cyst is defined as a pathological cavity lined wholly or in part by epithelium ,having fluid or semi-fluid content .

3. Classification of cysts of the jaw Epithelial cys t Non-epithelialized primary bone cyst Odontogenic cyst Non- odontogenic cyst Developmental -Odontogenic keratocyst -Dentigerous cyst -Eruption cyst -Lateral periodontal cyst -Gingival cyst -Glandular cyst Inflammatory -Radicular cyst -Paradental cyst - Nasopalatine -Nasolabial cyst -Median cyst - Solitary bone cyst -Aneurysmal bone cyst -Stafnés idiopathic bone cavity .

4. Odontogenic cys t Periapical(radicular cyst) Lateral periodontal cyst Gingival cyst of the newborn Dentigerous cyst Eruption cyst Glandular cyst Odontogenic keratocyst Calcifying odontogenic cyst Nonodontogenic cyst Globulomaxilary lesion Nasolabial cyst Median mandibular cyst Nasopaltine canal cyst Psedocys t Aneurysmal bone cyst Traumatic (simple )bone test Static bone cyst( Stafnésbone cyst) Focal osteoporosis bone marrow defect

5. Periapical cyst - An epithelial cyst, odontogenic cyst ,inflammatory cyst derived from cell Rest of Malassez , that proliferation in response to inflammation. -Odontogenic cyst A cyst in which lining of the lumen derived from epithelium in tooth development. - Non-odontogenic cys t The epithelial lining is derived from sources other than the tooth organ.

6. Periapical cyst/Radicular cyst - Types of Radicular cyst (periapical cyst) 1.Apical 70% 2.Lateral 20% 3.Residua l Most common location: 1.Maxillary anterior region 2.Maxillary posterior region 3.Mandibularposterior region 4.Mandibular anterior region

7. Periapical cyst-Epidemiology -Worldwide -Common-constitutes approx one half to three fourth of all cyst in the jaw -Relative frequency :60-70% -Frequent in age between 20-60years(rarely in <10 years Ago) (Peak in third through six decades) -M/F ratio 3:2 -Maxilla is 3 times more affected than mandible

8. Periapical cyst-clinical features -Usually asymptomatic -Slowly progressive If infection enters, the swelling painful and rapidly expands (partly due to inflammatory edema) -Initially swelling round and hard -Later, part of wall is resorbed…leaving a soft fluctuant swelling ,blush in color ,beneath the mucous membrane .

9. Periapical cyst-Pathogenesis Phases: 1.Phase of initiation 2.Phase of cyst formation 3.Phase of enlargement

10. Periapical cyst-Pathogenesis (PHASE1)phase of initiation : -Stimulation of cell rest of Malassez in response to INFLAMMATION elicited by .Bacterial infection of pulp .Direct response to necrotic pulp tissue . ( PHASE2)phase of cyst formation : -Epithelial cells derive their nutrient by diffusion from adjacent C.T ,progressive growth of an epithelial island moves the innermost cells of the island away from the nutrients. -Ultimately these innermost cell undergo ischemic liquefactive necrosis ,establishing central cavity (lumen)surrounding by viable epithelium . ( PHASE3)phase of cyst expansion: -Breakdown of cellular debris within cyst lumen. -the protein concentration ..increased osmotic pressure -in fluid transport into the lumen from the C.T side. -Ingress thus assist in outward growth of a cyst.

11. Periapical cyst-Pathogenesis Major factors in the Pathogenesis of cyst formation .Epithelial proliferation .Hydrostatic effects cyst fluid .Bone resorbing factors -Infection from pulp chamber induces inflammation . -Cyst fluid contain protein which exert osmotic pressure. - Hydrostatic pressure within cyst is about 70cm of water(higher than capillary pressure). -Bone resorption factors PGE2,PGE3 with osteoclast bone resorption ,the cyst expand.

12. Periapical cyst -Histopathology .Lumen(cavity): -Contains cyst fluid ;which is usually watery ,straw -color and opalescent. -Sometimes more viscid and yellowish. -sometime shimmers with cholesterol crystals. -Protein content of fluid . .Epithelial Lining: -Non-keratinized stratified squamous epithelium. -Lack a well-defined basal cell layer. -Thick,irregular,hyperplastic or net like forming rings and arcades. -Hyaline Bodies(Rushton Bodies)may be found. -Transmigration of inflammatory cells through epithelium is common with neutrophils and less lymphocyte.

13. Periapical cyst -Histopathology . Wall/capsule: -Composed of collagenous fibrous connective tissue . -Capsule is vascular and infiltrated by chronic inflammatory cell. -Plasma cell are prominent or often predominate. -Russell bodies are often found. -Cholesterol crystal associated with multinucleate giant cells(foreign body type).they may erode through epithelial lining and extrude into cyst lumen. -Foam cells(lipid-filled macrophages )

14. Early radicular cyst showing variation in thickness of the epithelial lining Periapical granuloma containing proliferation arcades of squamous epithelium derived from the rest of Malassez showing early cystic break down

15. Cholesterol cleft and hemosiderin deposit (blue ) Epithelial lining of radicular cyst

16. Periapical cyst –Radiology -Periapical cyst is well circumscribed -Distinct line of cortication separating it from surrounding bone. -May be associated with resorption of apices of teeth, displacement of teeth or both.

17. References -Cawson's essentials of oral pathology and oral medicine-8 th edition -Contemporary oral and maxillofacial pathology-2 nd edition - O ral pathology clinical pathologic correlations regezi-5 th edition -Soames and southam oral pathology-4 th edition