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    Odontogenic keratocyst is a common cystic lesionof the jaw which arises from the remnants of thedental lamina.

    The biological behaviour similar to a benign

    neoplasm. A distinctive lining of 6 10 cells in thickness

    Exhibits a basal cell layer of palisaded cells

    A surface of corrugated parakeratin.

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    The term odontogenic keratocyst was introduced by

    Philipsen (1956)

    Described as keratocyst, because of a large extent

    keratin formation.

    It has been renamed as Benign Keratocystic

    Odontogenic Tumour(KCOT).

    WHO 2005

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    Arises from

    rests of the dental lamina

    basal layer of the oral epithelium

    Primordium of the developing tooth germ or

    enamel organs.

    Cystic degeneration of the cells of the stellate

    reticulum in a developing tooth germ ( before its

    calcification starts ).

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    AGE Mostly second and third decade of life.

    SEX Males are more affected than females.

    SITE

    > Mostly in relation to mandible ( 75%) than maxilla.

    50% - angle of the mandible.

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    Aggressive in nature.

    high recurrence risk. may occur in association with nevoid basal cell

    carcinoma syndrome.

    Solitary cystscommon (5% to 15% of allodontogenic cysts); recurrence rate 10% to 30%

    Multiple cysts5% of OKC patients; recurrencegreater than with solitary cysts

    Syndrome-associated, multiple cysts5% of OKCpatients; recurrence greater than with multiple cysts

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    Small OKC lesions Asymptomatic

    Discovered only during the courseof a radiographic examination.

    Large OKC lesions- May be asymptomatic If symptomatic, pain,swelling, along with mobility

    and displacement of teeth, or with discharge. Paresthesia of lower lip. There is often one tooth missing from the dental

    arch.

    OKCs tends to grow in antero-posterior directionwithin the medullary cavity of the bone without

    causing obvious bony expansion.

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    Multilocular radiolucent areas with a typical soapbubble appearance.

    Can be unilocular with a well corticated margin

    Many lesions cross the mandibular midline .

    Demonstrate a well defined round or ovalradiolucent area with smooth margins andsometimes scalloped.

    Can cause pathologic fracture, perforation of the

    cortical plates of the jaw.

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    OKC MULTILOCULAR APPEARANCE

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    Panoramic view of lesions in both jaws from multiple nevoid basalcell carcinoma syndrome.

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    Detail from panoramic radiograph showing homogeneous radiolucencythat surrounds roots of right premolar and molar. The definitive

    diagnosis awaits histopathology in such cases.

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    Odontogenickeratocyst: notelack of jaw expansion

    and lack of toothresorption by thislarge well-delineatedhomogeneous radiolucencycrossing the midline of themandible (topographic

    occlusal view).

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    Extraneous

    Replacemental

    Collateral

    Envelopmental

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    Epithelium:

    Stratified squamous epithelium Parakeratinized (80%) or Orthokeratinized (20%)

    Corrugated epithelium

    5-8 cell layer thick

    No rete ridges (rete pegs)

    Basal cells are columnar to cuboidal & show palisading

    arrangement.

    Connective tissue wall:

    Fibrous capsule of the cyst is usually thin. Few to Many daughter/satellite cysts are seen. Absence of inflammatory cell infiltration.

    HISTOPATHOLOGY:

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    (Neville, Brad Neville. Oral and Maxillofacial Pathology, 2nd Edition. Elsevier, 2002. 15.1.2.1).

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    Dentigerous cyst

    Ameloblastoma

    Odontogenic myxoma

    Simple bone cyst

    Lateral periodontal cyst / Botryoid odontogenic cyst

    Residual cyst

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    Stepwise approach(a) History

    (b) Clinical examination

    (c) Radiographic examination(d) Aspiration

    (e) Biopsy

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    A. History

    previous history of swelling, trauma, surgery

    B. Clinical findings

    Symptoms : pain, swelling.

    Enlargement of jaw bone.

    palpation crepitus / fluctuation, pathologic fractures.

    caries, tooth vitality, displacement, crowding, missing

    tooth, resorption or delayed eruption of teeth.

    Alterations in the function of peripheral sensory nerves.

    Secondary infections.

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    C. Radiographic Examination

    Intra Oral

    Periapical Films

    Topographic occlusal view

    Extra-Oral

    Lateral oblique view

    Posterior-Anterior Projection

    Occipitomental view / Waters view

    Orthopantomograph

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    Gives accurate measurement of the extent ofthe lesion

    Exact localization of areas ofperforation through the cortex

    Assessment of soft tissueinvolvement

    Very helpful in large lesions in

    maxilla, particularly where extension of the

    lesion to the cranial base is suspected.

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    D. ASPIRATION:

    Indications(1) To rule out vascular lesions(2) To collect specimen for culture / sensitivity,

    cytology studies.(3) Insight into possible diagnosis

    Aspiration Findings :Pale yellow inspissated material, dirty creamy / cheesy

    materialProtein content of cystic fluid less than 4gm/100ml

    E. BIOPSY

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    Elimination of cystic lining.

    Decompression of the intracystic pressure.

    Preservation of the teeth.

    Preservation of important anatomicalstructures.

    Prevention of recurrence of cyst.

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    Reasons for treatment of cysts of oral cavity : Increase in size Infection

    weaken the jaw

    Cysts undergo changes

    Cysts can prevent eruption of teeth.

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    1. Marsupialization (decompression)

    2. Enucleation / Curettage

    3. Peripheral osteotomy

    4. Marginal mandibulectomy

    5. Segmental resection of the jaw

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    MARSUPIALIZATION:PRINCIPLE :

    Surgical window in the wall of cyst , evacuation of the

    cystic contents which decreases intra cystic pressureand promotes shrinkage of the cyst and bone fill.

    Only a part of mucosa or bone is removed to create a

    window.

    INDICATIONS:

    Age :

    In young child

    In elderly.

    Proximity to vital structures

    Eruption of teeth

    Size of cyst

    Vitality of teeth

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    ADVANTAGES : Simple procedure.

    Spares vital structures.

    Allows eruption of teeth.

    Prevents pathological fractures.

    Reduces operating time.

    Reduces blood loss.

    Helps shrinkage of cystic lining.

    Alveolar ridge is preserved.

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    DISADVANTAGES :

    Pathologic tissue left in situ.

    Histological examination of entire cystic lining is notdone.

    Prolonged healing time.

    Inconvenience to patient. Periodic irrigation of cavity.

    Regular adjustments of plug.

    Periodic changing of pack.

    Secondary surgery may be needed.

    Risk of invagination and new-cyst formation.

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    WALDRONS METHOD (1941) PARTSCH II

    Two stage technique:

    1st marsupialization

    Enucleation when the cavity becomes smaller.

    Indications: Bone has covered the adjacent vital structures.

    Adequate bone fill.

    Difficult to cleanse the cavity.

    For detection of any occult pathologic condition.

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    ADVANTAGES :

    Development of a thickened cystic lining

    Spares adjacent vital structures

    Combined approach reduces morbidity

    Accelerated healing process.

    DISADVANTAGES:

    Second surgery required.

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    PRINCIPLE :Enucleation allows for the cystic cavity to be covered

    by mucoperiosteal flap and the space fills with blood

    clot, which will eventually organize and form normal

    bone.

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    ADVANTAGES : Primary closure of wound.

    Healing is rapid.

    Post-op care is reduced.

    Thorough examination of entire cystic lining.

    DIADVANTAGES :

    After primary closure, observation of healing of cavity

    not possible.

    Removal of large cysts will weaken the mandible,

    making it prone to jaw fracture. Damage to adjacent vital structures.

    Pulpal necrosis.

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    PERIPHERAL OSTECTOMY :

    Adjunct to enucleation or marginal mandibulectomy

    Remaining bony bed is treated to eliminate any

    residual neoplastic cells.

    Adjacent soft tissue nerves and vessels protected,1-

    2 mm of bone removed from the entire bony bed.

    Methylene blue (1% aqueous solution) used to stain

    the uneven surface of bony bed, reducing risk of

    missing uneven portion, primary closure done under

    antibiotic coverage.

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    CRYOTHERAPY :

    Liquid nitrogen by spray or probe --destroy soft

    tissue When the probe is used a medium such as surgical

    jelly assist in transmitting the low temperature to allregions of bony bed.

    Applied for 2 min After complete thawing, cycle is repeated.

    The medium is removed, before closing wound

    CAUTERY:

    After enucleation or curettage - chemical or thermalcautery

    phenol, carnoys solution.

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    Composition

    Absolute alcohol 6ml Chloroform 3ml

    Glacial acetic acid 1ml

    Ferric chloride - 1gm

    Mechanism

    It enters the bony trabeculae inaccessible to enucleation &causes the charring of epithelium or fixes the tissue. Itdestroys the daughter cyst which is one of the most importantcause for recurrence.

    Application

    cotton pellets soaked in carnoys solution is kept in the cystic

    cavity for 3 -5 minutes. Followed by irrigation with normalsaline.

    Depth of penetration

    Soft tissue 3-5 mm

    Hard tissue 1.5 -3 mm

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    4. EN BLOC RESECTION:

    Removal of lesion together with bony marginsof 1 cm (10mm) of the uninvolved bone. Herebony continuity is disrupted and periosteum isinvolved.

    Intra oral approach is used for lesions anteriorto the ramus of the mandible.

    Extra oral approach used for lesions involving

    the ramus of the mandible.

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    RECURRENCE : varies from 5-62 % It is more often in the mandibular lesions,

    particularly those in the posterior body & ascendingramus

    Recurrence occur usually within 5 yrs of surgery

    Why OKC recur??

    Tendency to multiplicitysatellite cyst formation Incomplete removal of lining because lining is thin& fragile & also attachment between two is weak

    predisposition to form OKC from Dental lamina rests Proliferation of basal cells of oral epithelium to form

    OKC

    Long term clinical & radiographic follow up isnecessary

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    ENUCLEATION/CURETTAGE

    CARNOYS

    SOLUTION

    CRYOTHERAPY

    PERIPHERALOSTECTOMY

    MARSUPLIALIZ

    ATION(DECOMPRESSION)

    ENBLOC/SEGMENTALRESECTION

    SMALLACCESSIBLE

    CYST

    LARGE

    INACESSIBLECYST

    RECURRENTCYST

    DIAGNOSTICPROCEDURE

    HISTORY &CLINICALFINDINGS

    OKC

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