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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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