SURGICAL MANAGEMENT OF BENIGN ODONTOGENIC TUMOURS

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SURGICAL MANAGEMENT OF BENIGN ODONTOGENIC TUMOURS
ODONTOGENIC TUMOURS

• J T AROTIBA
• Department of of Oral Maxillofacial Surgery
• Faculty of Dentistry
• College of Medicine/ University College Hospital,
• University of Ibadan, Ibadan.

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Objectives

• To be able to
• Define and classify odontogenic tumours.
• Describe the common clinical features of
  odontogenic tumours .
• Describe how to examine, evaluate and diagnose a
  patient presenting with odontogenic tumour.
• Discuss the surgical treatment of these tumours

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INTRODUCTION

• Tumour general term for swelling of tissues
• Tumour Neoplasia - New growth
• An abnormal mass of new tissue the growth of
  which exceeds, and is uncoordinated with that of
  the normal tissue and which persists after
  cessation of the stimuli that provoked or evoked
  it(Willis 1957).

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INTRODUCTION

• In the oral cavity, both neoplastic and
  non-neoplastic tumefactions (swellings) arise
  from tissues concerned with tooth formation
  (dental hard tissue) as well as from non-dental
  tissues.
• These are called odontogenic and non-odontogenic
  tumours respectively.
•  Odontogenic tumours are tumours arising from
  dental tissues or their progenitor
  (embryonic)cells.
• They are usually located in the jawbones-
  central- but occasionally may be located in the
  surrounding oral soft tissues- peripheral.

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INTRODUCTION

• They are mostly slowly growing lesions, which are
  benign ( about 95) although a few are malignant
  or have malignant variants.
• They may be locally aggressive (infiltrative)
  and, with the exception of a few (e.g AOT), are
  more commonly seen in the mandible than the
  maxilla.
•  
• They may be purely epithelial, purely mesenchymal
  or mixed.

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PREVALENCE

• There is geographic variation in the incidence of
  odontogenic tumours especially ameloblastoma. 
• Odontogenic tumours constitute 19 to 30 of jaw
  tumours in Asian and African Countries where as
  in North/ South America and Canada they are 1
  to 9. 
• They can occur at any age but more common around
  second to fifth decades with peak in 2nd and 3rd
  decades of life. 
• Equal sex incidence or a slightly higher female
  incidence.

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CLASSIFICATION

• Past efforts
• Broca (1869) suggested a classification of
  odontogenic tumours. He used the term odontome
  for all tumours arising from dental formative
  tissues and divided them into different types
  according to the stage of development of the
  tooth at the inception of the tumour 
• Bland Sutton (1888) modified this by basing
  classification on the tissue from which the
  tumour arose.
• Gabell, James and Payne (1914) modified
  BlandSuttons work but still included
  non-neoplastic cysts of dental origin

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CLASSIFICATION

• 1. Epithelial Odontomesarising from dental
  epithelium eg Amelo, epithelial cysts etc
• 2. Composite odontomes---arising from both dental
  epithelium and dental mesenchyme
•  
• 3. Connective tissue odontomes--- arising from
  dental mesenchyme only
• Thoma and Goldman (1946) classified Odontogenic
  tumours based on tissue of origin into those from
  ectodermal (Epithelium), mesenchymal and mixed
  dental tissues discarding the use of the general
  term odontome .
• They omitted the non-neoplastic cysts
•  

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CLASSIFICATION

• American Academy of oral Pathology (Robinson
  1952) went further to amplify Thomas
  classification
• EPITHELIAL TUMOURS
• Adamantinoblastoma
• Enameloma
• MESENCHYMAL TUMOURS
• Odontogenic fibroma
• Dentinoma
• Cementoma

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CLASSIFICATION

• ODONTOGENIC MIXED TUMOURS (ODONTOMES)
• Soft odontoma epithelium and mesoderm
• Soft and calcified odontomeadamantinoma arising
  with forming or completely formed odontome.
• Completely formed odontome with enamel, dentine,
  pulp, p.d.l,
• Compound
• Complex.

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CLASSIFICATION

• Pindborg and Clausen (1958) Classified OTs based
  on embryonic principle- the inductive changes
  exerted by dental tissues on each other during
  embryonic development which they also thought
  could have some influence on the pathogenesis of
  these tumours.
• WHO established a Collaborating centre for
  Histological Typing of Odontogenic Tumours and
  Allied Lesions in 1966 headed by Pindborg J.J and
  in 1971, Pindborg and Kramer (1971) published the
  first authoritative WHO guide to the
  classification of OTs.
• This was revised in 1992 by Kramer, Pindborg and
  Shear (1992) basing classification on type of
  odontogenic tissues involved and behaviour of
  tumour. The more recent revisions, however are in
  2002 by Philpsen and Reichart and 2005 (WHO
  histological classification).
• ASSIGNMENT Describe the Classification of OTs 
  based on the most recent WHO Classification

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Modified WHO Recommended classification ( 2002,
2005)

• TUMOURS OF ODONTOGENIC EPITHELIUM
• Ameloblastoma solid multicystic,
  extraosseus(peripheral), desmoplastic, unicystic.
• Adenomatoid Odontogenic Tumour.
• Calcifying epithelial odontogenic Tumour.
• Squamous Odontogenic Tumour.
• Keratocystic Odontogenic Tumour.
• Ameloblastic carcinoma Malignant ameloblastoma
• Clear cell odontogenic carcinoma

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Classification

• MIXED TUMOURS.
• Ameloblastic fibroma
• Ameloblastic Fibro-odontoma
• Ameloblaastic fibro - dentinoma
• Odonto-ameloblastoma.
• Compound Odontoma
• Complex Odontoma
• Calcifying cystic odontogenic tumour
• Dentinogenic Ghost cell tumour
• Ameloblastic Fibrosarcoma

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Classification

• TUMOURS OF ODONTOGENIC ECTOMESENCHYME.
• Odontogenic Fibroma
• Granular cell odontogenic Tumour
• Odontogenic myxoma
• Cementoblastoma.

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PRINCIPLES OF DIAGNOSIS MANAGEMENT

• HISTORY Ask patient about
• Duration long /short/prolonged with(out) pain?.
• Mode of onset spontaneous/ following trauma or
  infection?
• Progress of tumour slow/stationary or
  rapid/fast?
• Site, Shape of swelling?
• Surface characteristics smooth, normal overlying
  skin/mucosa, engorged, ulcerated ?etc.
• Consistency hard, firm, soft fluctuant.
• Associated symptoms pain, abnormal sensations,
  anaesthesia/parasthesia, discharge, tenderness,
  lymphadenopathy, trismus, nasal obstruction etc.
• Any similar swelling somewhere else?

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• Associated loss of weight, recurrence,
• Drug history
• Family history hereditary?
• Social History Habit

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PRINCIPLES OF DIAGNOSIS MANAGEMENT

• CLINICAL EXAMINATION
• Thorough and detailed systematic examination from
  extra-oral to intra- oral.
• Inspection
• No, Size, Shape, Colour, Site(anatomical
  location).
• Surface smooth, lobulated , irregular,
  ulcerated, fungating growth.
• Attachments Pedunculated /sessile
• Integrity of overlying skin or mucosa.
• Temperature of overlying skin
• Palpation for
• Consistency- soft , firm, hard/ indurated, bony
  hard, cystic/fluctuant
• Relationship with overlying underlying
  structures.
• Lymph nodes
• Bimanual palpation for large lesions to determine
  extent of tumour

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• Percussion related teeth.
• Auscultation if suspecting vascular lesion.
• Aspiration if cystic or contains fluid.

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INVESTIGATIONS IMAGING

• Plain LO, PA, OMV, OPG
• Advanced imaging tech
• Computerized tomographic Scans -CT Scans
• Three dimensional reconstruction CT
• Complete bone scan / Scintigraphy to detect
  distant metastasis if malignancy is suspected
• Magnetic resonance imaging (MRI) soft tissue
  nodal involvments.
• Angiographic studies(CT angiogram)

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• Fine Needle Aspiration Cytology (FNAC)
• Tissue Biopsy for histological diagnosis is
  confirmatory.
• Techniques Exfoliative , Aspiration, FNAC,
  Excisional, Incisional
• ASSIGNMENT Discuss the various biopsy methods
  available for diagnosis of a benign jaw tumours

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Principles of Treatment

• Goals.
• 1. Complete eradication of tumour.
• 2. Preservation of normal tissue.
• 3. Removal with least morbidity.
• 4. Reconstruction to replace tissue loss and
  form.
• 5. Rehabilitation and Restoration of function.
• 6. Long term follow up to detect recurrence
  early.

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Principles of Treatment

• The treatment of odontogenic tumours requires
  correct histological diagnosis.
• The appropriate choice of surgical treatment
  method is after proper and adequate evaluation
  before surgery and depends on
• (1) Histological type benign Vs
  Malignant
• - encapsulated/ non-infiltrative
• - non-encapsulated/infiltrative 
• (2) Anatomical location/ Site of tumour -
  Oral Cavity -- -- Anterior Vs Posterior
  -- Maxilla Vs
  Mandible

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Principles of Treatment

•  (3) Size of Tumour/ confinement to bone- small
  lesion?Local excision.
• - large or malignant lesion-? Radical/Extensive
  excision.
• (4) Age of Pt - ability to withstand stress
  of radical surgery
• (5) If malignant--Presence/ absence of distant
  metastasis.
• (6) Proximity to adjacent vital structures.
• (7) Rehabilitation or reconstruction methods.

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Treatment methods

• The best and tested modality of treatment is
  surgery.
• Radiotherapy, chemotherapy are usually used as
  adjuncts or palliative measures in malignant
  types and therefore have no role in benign
  odontogenic tumours .

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Surgical Treatment

• Most odontogenic tumours are benign and surgery
  is the first choice.
• Adequate resection with margin of normal tissue
  is the recommended surgical treatment.
•  
• Well-circumscribed (encapsulated)
  non-infiltrative lesions (A.O.T, Ameloblastic
  Fibroma, Fibro-odontomas , odontomas,
  cementoblastoma) may however be treated by
  Conservative surgery .
• - - Enucleation or Local Excision (Curettage)
• with or without saucerization or treatment of
  adjacent bone will suffice.Chemical Cautery
•   --- Thermal
• Locally invasive (infiltrative) Lesions
  (Ameloblastoma , ameloblastic odontoma,
  fibromyxoma, CEOT, KCOT, SOT) a slightly more
  aggressive approach is needed
• Resection with margin of normal bone.

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Resection

• Removal of tumour by cutting through uninvolved
  tissue around the tumour and delivering the
  tumour without direct contact with the tumour
  en bloc resection.
• Marginal Resection (Resection with preservation
  of lower cortical plates if still intact and
  uninvolved). Also called \Resection without
  continuity defect (Peripheral Ostectomy or En
  bloc resection)
• Partial Resection. (Removing a complete segment
  of the jaw) Resection with continuity defect).
• It can vary from a small portion to
  Hemimandibulectomy / partial maxillectomy.

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Resection

• Total Resection Removal of the whole involved
  bone Maxillectomy or Mandibulectomy
• Resections can be
• -- Marginal, partial, total,
• -- with or without disarticulation.
• -- Composite resection for malignant tumours

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Reconstruction

• Surgical resection leads to disfigurement,
  deviation of jaw during movement, disturbance of
  function. Therefore, the need for reconstruction
  to
• Restore movement and equilibrium of mandible
• To maintain normal occlusal plane , floor of
  mouth and tongues anatomical position.
• To restore functioneg feeding.
• To restore aesthetics appearance and a more
  favourable social acceptance

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Reconstruction

• Reconstruction Primary (Immediate) or
  Secondary (delayed)
• IMMEDIATE
• Advantages Single stage surgery, Early return
  to function, Minimal compromise of aesthetics,
  No muscular deformation or scar/ fibrosis
  limitations.
• Disadvantages Recurrence may occur in graft and
  risk of infection leading to loss of graft.
• - Intraoral approach
• .- both intraoral (excision) and Extraoral
  (grafting) approach.
• - extra oral approach only

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Secondary / delay

• -- Steinnmans Pin
• -- Kirschners wires
• -- Acrylic implants
• -- Metallic implant Reconstruction Plates.
• --Bowerman-Conroys mandibular implant. (All
  these are temporary materials to maintain tissue
  space and /or bone continuity if you are planning
  secondary reconstruction
• Bone grafts - autogenic (iliac/ribs)
  alloplastic bone grafts or synthetic materials
• Microvascular Flap Reconstruction

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• Rehabilitations
• Acrylic dentures
• Obturators with teeth(Maxilla).
• Dental Implants following bone (Microvascular)
  grafts.
• May need RCT for related adjacent teeth if the
  apices are at risk.
• Follow up. For many years

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Factors for Consideration before surgery

• Anatomical location of tumour
• Aggressiveness of Tumour
• Size of tumour
• Location of tumour(Confinement to bone).
• Proximity to adjacent vital structures.
• Involvement of mandible/maxilla.
• Rehabilitation or reconstruction methods
• Age of patient

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AMELOBLASTOMA

• A benign but locally invasive polymorphic
  neoplasm consisting of proliferating odontogenic
  epithelium which usually has a follicular or
  plexiform pattern, lying in a fibrous stroma.
• Most often a central tumour of jaw bones although
  peripheral variants are occasionally seen.

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• Aetiology Unknown
• ? Irritation, repetitive trauma or
  inflammation/infection from difficult eruption
  since it occurs often in posterior mandible where
  impaction is common(New 1915, Robinson1934).
• ? Metabolic disorders e.g. Rickets
  (Geschickter1935). 
• ?Viral (Stanley et al 1964 Lucas , 1969,Csiba
  1970)- in experimental animals polyoma virus
  from dental lamina or its derivatives

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• Histogenesis
• From dental lamina or its derivatives
• -enamel organ (Kegel 1932)
• -epithelial cell rests --cell rests of dental
  lamina (glands of Serres)or the roots(cell rests
  of Malassez).
• lining of odontogenic cysts
• basal layer of oral mucosa

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• Clinical features
• . Slow growing usually central jaw lesion
• . Painless- unless infected
• . Expands bone - locally infiltrative and
  erodes cancellous bone.
• Age Can occur at any age
• More common between 2nd 6th decades (10-59)
• Peak between 30-40 years.
•  
• Sex Male Female (Akinosi)
• Male slightly gt female slightly (Adekeye,
  Arotiba, Ladeinde )

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• Site- Mandible gt Maxilla
• Although any part of the jaw may be affected,
  more commonly seen in the anterior mandible in
  Nigerians than in Caucasians in which the
  posterior aspect of the mandible is the
  predominant site.
• Clinical Appearance
• Hx of Slow growth.
• Enlargement of bone (expansion of buccal and
  lingual plates)

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• Tooth mobility / derangement.
• Thinning of cortical plates ? Depressible bone?
  egg -shell cracking sound.
• Local bone invasion makes conservative surgery
  inadequate.

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• The basic clinical types are
• The Solid Multicystic (intraosseous)
  ameloblastoma.
• Peripheral (extraosseous) Ameloblastoma.
• The Unicystic ameloblastoma.
• Malignant variants
• Extragnathic eg craniopharyngioma.

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Radiology

• Multilocular radioluscency - honey comb or soap
  bubble appearance.
• - Unicystic radioluscency.
• . Thinning and expansion of cortical plate
• . Thinning of lamina dura
• . Truncation /Amputation of roots.

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Histology

• Non-encapsulated epithelial lesion, infiltrating
  trabeculae of surrounding bone.
• It consists of odontogenic epithelium arranged in
  islands or processes around a connective tissue
  stroma.
• The peripheral cells-tall columnar / cuboidal
  cells with well polarized nuclei (resembling
  ameloblast)
• The central (core) cells - polyhedral (angular)
  cells resembling stellate reticulum.
•  

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• There are two common basic histologic patterns
• (i) Follicular (ii) Plexiform
• Follicular discrete islands of tumour composed
  of peripheral layer of tall columnar / cuboidal
  cells with polarized nuclei .
• Plexiform- Irregular Masses (sheets, cords or
  strands) which are interlacing in appearance.
  Continuous anastomosing strands

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• Other less common histological variants are 
• (i) Acanthomatous - Squamous metaplasia of the
  central core of sellate reticulum like cells.
  Degeneration of these cells leads to
  formation of keratin.
• (ii) Granular- There are granular changes in the
  cytoplasm of the stellate reticulum like cells.
• (iii) haemangiomatous- there is increased
  vascularization of the stroma
• (iv) Basal cell type- Epithelial cells are
  primitive in appearance resembling the basal
  cells carcinoma of skin.
• Desmoplastic- A lot of collagen deposition in
  the fibrous stroma.
• Clear cell variant. Clear cytoplasm with little
  or no cytoplasmic granules ? Clear cell
  odontogenic tumour/carcinoma

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• Unicystic Ameloblastoma-  Is a clinical Variant
• Essentially a cyst lined by normal cell which may
  show one of the following-
• (i) an area if transformation of part of the
  epithelial lining into cuboidal or columnar,
  ameloblast-like cells with reversed polarity--(
  the tumour is confined to the luminal surface of
  the cystluminal unicystic ameloblastoma
• (ii) A localized nodular projection of
  ameloblastic cells in the lumen of the cyst-
  (sometimes called plexiform unicystic
  Ameloblastoma ) intraluminal unicystic
  ameloblastoma.
• (iii) infiltration of some part of the
  wall(capsule) of the cyst by plexiform or
  follicular ameloblastoma - mural ameloblastoma.

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SQUAMOUS ODONTOGENIC TUMOUR

• Locally infiltrative benign tumour
• - first reported by Pullon and associates (1975).
• - Sometimes, mistakenly diagnosed as
  acanthomatous ameloblastoma or epidermoid Ca.
•  
• Aetiology Unknown
• Histogenesis- Probably arise from rest cells of
  Mallassez or derivatives of dental lamina. 

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• Clinical features
• Age- 2nd 7th decades (peak- 3rd decade)
• Sex- No predilection.
• Site Maxilla most common in the incisor/canine
  area
• When in Mandible ?canine premolar areas
• (Multicentric cases affecting both jaws have
  been reported)
• MCQ
• Usually symptomless at the early stage
• Advanced stage - Mobility of related teeth
• - Pain - Tenderness

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• Xrays-
• Unilocular radioluscency (Semi circular or
  triangular in shape with or without a sclerotic
  border.)
• Usually related to the cervical third of the
  root(s).
•  
• Histology-
• A locally infiltrative tumour consists of
  well-differentiated islands of squamous cells,
  scattered in a fibrous stroma.
• The peripheral layers of these islands are made
  up of highly flattened cells, with no pallisading
  or polarization.

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CALCIFYING EPITHELIAL ODONTOGENIC TUMOUR
(PINDBORGS TUMOUR)

• Is uncommon
• - Locally invasive epithelial tumour
• - First classified separately by Pindborg (1958)
•  
• Histogenesis ? enamel organ / dental lamina
•  
• Clinical features
• Age 20 60 years Peak middle age (40yrs)
• Sex No sex predilection
• Site - mandible gt maxilla
• -molar-premolar area most affected
  part
•  

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• Clinical Appearance 
• - Usually asymptomatic slow but progressive bony
  jaw swelling with associated unerupted tooth /
  impacted tooth.
•  
• Extra-Osseous types have been reported with an
  average age of 35 years.
•  
• X-rays- poorly demarcated irregular
  radioluscency or circumscribed area of mixed
  radiolucencies and opacities.
•  
• There may be irregular bone trabeculations
  multilocular radiolucency or honeycomb appearance
  with flecks of radio opacities. 

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• Histology- locally infiltrative shows a lot of
  variations
• - Sheets or strands of polyhedral epithelial
  cells with well-defined borders and prominent
  intercellular bridges in a bland fibrous tissue
  stroma that may show degenerative changes.
•  
• - Mitosis are rare but theres nuclear
  pleomorphism, giant cells, multinucleated cells
  and cells with prominent nucleoli.
•  
• - Characteristics presence of round homogenous
  eosinophilic intra-epithelial substances (similar
  in staining characteristics to amyloid- ( i.e
  fluoresce with thioflavin T stain and green
  birefringence with congo red stain). Controversy
  does exist as to whether it is a degenerative
  product or it is actively secreted.
•  

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• - These substances are extruded into the
  extracellular spaces later due to cell secretion
  anddegeneration.
• - Deposition of calcific material in the
  concentric eosinophilic masses ? Liesesang rings
  .
• A variant may show clear cells (vacuolated
  cytoplasm).
• - In peripheral or extra osseus types there are
  fewer foci of calcification and the neoplastic
  
  epithelium is less active.

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CLEAR-CELL ODONTOGENIC TUMOUR/CARCINOMA

• This also a locally invasive tumour of
  odontogenic epithelium recently classified as an
  entity. First regarded as benign but now believed
  to be malignant
• Aetiology ? Unknown
• Histogenesis Probably - derivatives of dental
  lamina -
  rest cells of Malassez 
• Clinical Features A central jaw tumour can
  affect either jaw
• Some patients associated with pain
• Age more seen above 50 years
• -More locally aggressive than Ameloblastoma
• - Data too scanty to give a comprehensive
  picture.

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• Radiology- Radioluscent lesion (may be uni- or
  multi- locular) with poorly defined margins
• Histology- Sheets or islands of uniform
  vacuolated and clear cells or finely stippled
  cells in a scanty mature c.t.
  
• -No evidence of amyloid or calcific deposits. 
• -May be similar to clear cell adenocarcinoma or
  intra-osseus mucoepidermoid carcinoma in
  histologic appearance.

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AMELOBLASTIC FIBROMA

• Mixed tumour (both epithelial and messenchymal
  neoplastic elements)
• - Less common
• - occur in younger age group than ameloblastoma
• - Characterized by simultaneous proliferation of
  both epithelial mesenchymal tissues without
  formation of dental hard tissue.
•  
• Histogenesis Epithelial part - Enamel organ
  or its derivative
• mesodermal part - dental papilla or follicle

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• Clinical Features- Slow growth / Painless.
  Slower than amelo jaw expanding but not
  infiltrative.
• Age-Younger age 40 below 10 years (most are
  seen lt 25 years ) Average age 15 years. 
• Sex- Male Female
•  
• Site-Mandible gt Maxilla
• (Canine-prem-molar area of the mandible)
•  
• X-ray Multilocular or unilocular radioluscency
  (similar to amelo).
• Cortical bone expansion, displacement of roots
• may encompass/include unerupted tooth.
• The edges are usually smooth or sometimes
  sclerotic (b/c it does not infiltrate trabeculae)

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• Histology Two components epithelial and
  mesencymal.
• - Epithelial cells arranged in strands, sheets or
  scattered islands in a highly cellular c.t.
  stroma.
• - The epithelial cells which are cuboidal or
  columnar may contain small number of stellate
  reticulum like cells.
• - The c.t. is made up of numerous large round or
  angular cells with little or no collagen and very
  few blood vessels.
• - Occasionally some stroma cells may have fine
  granular cystoplasm (granular cell ameloblastic
  fibroma)
•  
• - Hyalinization around the epithelial cells may
  also be seen.

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AMELOBLASTIC FIBRO-DENTINOMA / FIBRO-ODONTOMA

• - Rare tumours 
• - Similar to ameloblastic fibroma (i.e. mixed
  tumours). 
• They are characterized by stimultaneous
  proliferation of epith and messenchy tissues but
  with inductive changes that lead to dentine or
  enamel and dentine.
• - Should not be confused with self limiting
  developmental anomalies like odontoma.
•  
• Age - Occur in children and teenagers as
  asymptomatic lesions.
• Characterised by Swelling which may be associated
  with failure of tooth eruption.

58

•  
• Sex - Males ? Females
•  
• Site - Maxilla ? Mandible
•  
• X-ray Both appear as well-circumscribed
  expansive radioluscencies with large radiopaque
  masses.
• Histology- Proliferating odontogenic epithelium
  and cell-rich mesencyme with poorly calcified
  dentine / enamel and dentine around the
  epithelial cells.
• Both tumours must not be confused with odontomes
  (developmental) since they are capable of
  continuous growth and can reach a relatively
  large size destroying the jaw bones.

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ODONTO AMELOBLASTOMA (Ameloblastic odontoma)

• Rare
• Characterized by presence of a relatively
  undifferentiated epithelial neoplastic component
  (ameloblastoma) with a highly differentiated
  mesenchymal tissue (Odontoma).
• AGE - Affects any age but more common in children
•  
• SITE - Mandible gt maxilla
•  
• X-ray Similar to composite odontomes
  multilocular or unilocular radioluscency with
  numerous small radiopacities.
•  
• Histology Similar to ameloblastoma but also with
  fibrous tissue stroma containing variable amount
  of cellular odontogenic ectomesenchyme with well
  formed dentine / enamel.

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ADENOMATOID ODONTOGENIC TUMOUR (Adenoameloblastoma
)

• An Intraosseus odontogenic tumour (few
  extra-osseus cases reported)
•  
• - Not common 
• - It is a benign tumour of odontogenic
  epithelium with duct-like structures and varying
  degree of inductive changes in its c.t.
•  
• Histogenesis -Enamel organ or its remnant (REE)
• ? ? from a dentigerous cyst.
•  
• Disturbance must have occurred after completing
  of tooth formation (associated with non-defective
  tooth). 

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• Clinical Features
• Painless progressive swelling expanding bone.
• Age All ages More in 1st 3rd decades peak
  2nd
•  
• Sex Females gt males
•  
• Site Maxilla gt mandible Canine /
  premolar.
• X-RAYS Radioluscent unilocular lesion with or
  without sclerotic borders and most of the times
  enclosing the crown of an unerupted tooth. 
• There may be dense radiopaque foci within the
  lesion.

62

• Histology Usually encapsulated.
• - Whorls of Odontogenic epithelium interspersed
  with duct-like (tubular) structures in a scanty
  c.t. stroma.
• - The duct-like structures are lined by columnar
  / cuboidal (amelobast-like) cells.
• - Eosinophilic Coagulum are sometimes seen in the
  ductal lumen 
• - Deposits of amyloid - like substances in
  between the epithelium cells.
• - Acidophilic hyaline material deposited in the
  c.t. suggestive of dysplastic dentine.
• - Calcific deposits may be scattered throughout
  the tumour.

63
CALCIFYING ODONTOGENIC CYST (Gorlins cyst)

• First described by Gorlin and associates
•  
• - Now agreed as a neoplastic lesion although with
  features of a cyst.
•  
• - Praetorious et al (1981) described 3 cystic
  entities and 1 tumour variant each with peculiar
  histological and clinical features.

64

• Common seen in 2nd/3rd decades of life
•  
• - Equal sex distribution
•  
• - Mandible maxilla
•  
• - Central tumour which occur in jaw bones or in
  soft tissue of tooth bearing areas.
•  
• X-ray well-defined radioluscency with varying
  amount of radiopaque materials. Flecks or nodules
  of radiopaque material.

65

• Histology A cystic lesion with epithelial lining
  which shows well-defined basal layer of columnar
  cells with an overlying layer (many cells thick)
  of stellate reticulum like cells.
•  
• There are pyknotic epithelial cells (ghost cells)
  in the epithelial cyst lining or in the fibrous
  capsule.
•  
• The ghost cells ? dysplastic
  calcification.
•  
• Dysplastic dentine may be laid down adjacent to
  the basal layer of the epithelium.

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ODONTOMAS

• These are harmatomatous rather than neoplastic
  lesions.
•  
• (A) Compound- tooth like structures with
  various layers (dentine, enamel, cementum pulp)
  laid down in regular pattern like normal tooth.
•  
• (B) Complex- tooth-like structures with various
  layers arranged in irregular (harphazard) manner
  with no semblance to normal tooth.
•   Both are enclosed in a fibrous capsule and
  a cystic cavity lined by squamous epith.

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• Clinical features
•  
• - More commonly seen in 1st 2nd decades 
• - Females gt males
• - Mandible gt maxilla
•  
• - Compound more common in anterior region incisor
  / canine while Complex more common in
  molar/premolar region.
• - They are usually associated with secondary
  dentition
• - Self-limiting Asymptomatic
• Xray- Area of well-circumscribed radioluscency
  at early stage with progressive deposition of
  radiopaque masses.

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ODONTOGENIC FIBROMA

• Rare
• - Central or peripheral 
• - A fibroblastic neoplasm 
• Histogenesis dental follicle papilla (the c.t.
  surrounding the enamel region)
• Clinical Features- More in children/young
  adults but can occur at all ages
• - mandible gt maxilla
• Usually asymptomatic, local enlargement of jaw

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• Peripheral- slowly growing, solid, firm,
  attached to gingival between or close to a tooth.
• Central- Very rare. Slowly growing jaw
  lesion.
• Xray- Usually unilocular radiolucency.
• may Resemble dentigerous cyst radiologically if
  related to tooth crown.
• Lesion is however solid and not cystic if
  multilocular may resemble ameloblastoma.
•  
• Histology- Mass of loosely arranged c.t. in
  which strands and islands of epithelium are
  dispersed.
• There may be calcification in form of
  dysplastic dentine, osteoid, or cementum like
  material (calcifying odontogenic fibroma).

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ODONTOGENIC MYXOMA (FIBROMYXOMA, MYXOFIBROMA)

• Benign Locally invasive expansile central tumour
• - Occur exclusively in jaw bones
• - Slowly growing but expands bone and destroy the
  cortex
• - Little or no encapsulation.
• Histogenesis from mesenchymal portion of tooth
  germ dental papilla / follicle or p.d.l.
• Clinical features- slow growth
• Expands bone causes bone destruction
• May be associated with an unerupted tooth 
• Age- 2nd - 3rd decade rarely below 10years or
• Sex- Male female
• Site- Mandible gt maxilla (slightly)

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FURTHER READINGS

• Surgical management of Oral Pathologic lesions by
  Edward Ellis III in Cotemporary Textbook of Oral
  Maxillofacial Surgery. ( Chapter 22)
• Oral Maxillofacial Pathology by BW Neville, DD
  Damm, CM Allen JE Bouquot . Pennsylvania,
  Philadelphia Saunders (2002).
• Malik NA . Textbook of Oral and Maxillofacial
  Surgery Jaypee Medical Publishers ( Chapter
  36).