Quartz 4

Oral Pathology - 13 - Odontogenic Cysts

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Oral Pathology and Odontogenic Cysts

Overview of Odontogenic Cysts1

Odontogenic cysts are a group of lesions derived from the remnants of the dental lamina or the enamel organ. These cysts are classified based on their origin and clinical behavior.

  • Definition: Cysts are cavities lined by an epithelium.
  • Origin: Derived from cells associated with tooth formation (odonto meaning tooth; genic meaning formation).
  • Pathogenesis: Residual odontogenic epithelium can undergo "cystification" at any time, involving residual cells or "rests" from tooth development.

Classification and Types

  • Radicular Cyst

    • The most common type of odontogenic cyst.
    • Typically associated with a non-vital tooth.
    • Results from inflammation of the periapical tissues.

  • Dentigerous Cyst (Follicular Cyst)

    • Originates from the reduced enamel epithelium.
    • Surrounds the crown of an unerupted tooth, most commonly the mandibular third molar.

  • Odontogenic Keratocyst (OKC)

    • Known for its aggressive clinical behavior and high recurrence rate.
    • Histologically characterized by a thin, parakeratinized stratified squamous epithelium.
    • Often associated with Nevoid Basal Cell Carcinoma Syndrome (Gorlin Syndrome).

  • Lateral Periodontal Cyst

    • Occurs on the lateral aspect of a tooth root.
    • Derived from the dental lamina remnants (rests of Serres).

Diagnostic Criteria

  1. Clinical Presentation: Swelling, pain (if infected), or asymptomatic discovery during routine radiography.
  2. Radiographic Features: Well-defined radiolucencies with cortical borders.
  3. Histopathological Examination: Essential for definitive diagnosis and differentiation between cyst types.

Management and Treatment

  • Enucleation: Complete removal of the cyst lining.
  • Marsupialization: Creating a surgical window in the cyst wall to relieve pressure and allow for shrinkage before definitive surgery.
  • Curettage: Often performed following enucleation to ensure all epithelial remnants are removed, particularly in cases of OKCs.

Classification of Oral Pathology

Categories of Oral Pathology2

  • Developmental Conditions
  • Mucosal Lesions—Reactive
  • Mucosal Lesions—Infections
  • Mucosal Lesions—Immunologic Diseases
  • Mucosal Lesions—Premalignant
  • Mucosal Lesions—Malignant
  • CT Tumors—Benign
  • CT Tumors—Malignant
  • Salivary Gland Diseases—Reactive
  • Salivary Gland Diseases—Benign
  • Salivary Gland Diseases—Malignant
  • Lymphoid Neoplasms
  • Odontogenic Cysts
  • Odontogenic Tumors
  • Bone Lesions—Fibro-Osseous
  • Bone Lesions—Giant Cell
  • Bone Lesions—Inflammatory
  • Bone Lesions—Malignant
  • Hereditary Conditions

Inflammatory Odontogenic Cysts

Radicular Cyst

Clinical Presentation and Etiology3

  • Also called a periapical cyst.
  • This is the most common odontogenic cyst.
  • Presents as a radiolucency at the apex of the root.
  • Always associated with a nonvital tooth.
    • ==Always associated with a non-vital tooth (a tooth with a necrotic pulp).==

Pathogenesis

  • Necrotic pulp causes periapical inflammation:
    • Acute inflammation leads to an abscess.
    • Chronic inflammation leads to a granuloma.
      • Chronic inflammation leads to a granuloma involving granulation tissue.
  • Epithelial Rests of Malassez (ERM), derived from Hertwig’s Epithelial Root Sheath (HERS) within the pocket of inflammation, encapsulate the lesion, resulting in the formation of a cyst
  • These rests are residual cells from Hertwig’s epithelial root sheath, a structure in tooth embryology associated with the cervical loop of the enamel organ.
  • Infection and inflammation from the necrotic pulp stimulate these residual cells to encapsulate the lesion, forming a cyst.

Treatment

  • Root Canal Therapy (RCT), apicoectomy, or extraction with curettage.
    • Apicoectomy (direct surgical access to the apex).
    • Extraction of the tooth combined with curettage (scraping the walls of the lesion to remove infection).

Developmental Odontogenic Cysts

Dentigerous Cyst

Clinical Features4

  • Also called an eruption cyst if the lesion occurs over erupting teeth in children.
  • The second most common odontogenic cyst.
  • Presents as a radiolucency attached to the Cementoenamel Junction (CEJ) of an impacted tooth.
    • The CEJ is where the enamel meets the root cementum.
  • Most common with canines and third molars.
    • Third molars are also referred to as wisdom teeth.

Pathogenesis and Treatment

  • Caused by the accumulation of fluid between the crown and the reduced enamel epithelium.
  • Treatment involves excision; however, it may be a source of a future odontogenic tumor.

Lateral Periodontal Cyst

Clinical Characteristics5

  • Most common in the mandibular premolar region.
  • Always associated with a vital tooth.

Treatment

  • Surgical excision.

Gingival Cyst of the Adult

Clinical Characteristics6

  • This is the soft tissue counterpart of the Lateral Periodontal Cyst (LPC).
  • Does not present with a radiolucency.
  • Found in the soft tissue between the roots of teeth, most commonly in the mandibular premolar area.
  • No radiolucency is visible because the lesion is located only in the soft tissue, not the bone.

Treatment

  • Surgical excision.

Gingival Cyst of the Newborn

Clinical Variants7

  • Bohn’s nodules: Located on the lateral palate.
  • Epstein’s pearls: Located on the midline palate.
    • These appear as small white pearls.

Pathogenesis and Treatment

  • Rests of dental lamina epithelialize the small lesions.
    • The rests of dental lamina are residual cells from tooth development.
  • No treatment is required; the lesions will involute as the infant ages.
    • Involute means the lesions will go away on their own.

Primordial Cyst

Clinical Characteristics8

  • Develops in a location where a tooth would have otherwise formed.
  • Most common in the mandibular third molar region.
  • Appears as a radiolucent pocket.

Treatment

  • Complete surgical removal.

Keratocystic Odontogenic Tumor

  • ==Synonyms: Previously known as OKC (Odontogenic Keratocyst).==

Clinical and Histological Features9

  • Aggressive and recurrent in nature.
  • Most common in the posterior ascending ramus of the mandible.
  • Characterized by thin, corrugated, parakeratinized epithelium.

Associated Syndromes

  • Gorlin Syndrome (also called Nevoid Basal Cell Carcinoma Syndrome):
    • Multiple KCOTs.
    • Multiple Basal Cell Carcinomas (BCCs).
    • Calcified falx cerebri.
    • Potentially fatal.

Treatment

  • Aggressive enucleation.
    • Aggressive enucleation involves the removal of the lesion and some surrounding bone.

Audio Appendix

Additional Audio Content

The following sections from the lecture audio did not correspond to any heading in the main document.

Calcifying Odontogenic Cyst

  • Synonym: Also called a Gorlin Cyst (not to be confused with Gorlin Syndrome).
  • Characteristics: Rare and unpredictable.
  • Histology: Features ghost cells (empty spaces where the nucleus used to be, now filled with keratin).
  • Radiographic Features: These ghost cells can undergo calcification, appearing as tiny radiopaque flecks (radiodensities) within the radiolucency.

Footnotes

  1. Original PDF page 1: Oral Pathology - 13 - Odontogenic Cysts, p.1 ↩

  2. Original PDF page 2: Oral Pathology - 13 - Odontogenic Cysts, p.2 ↩

  3. Original PDF page 3: Oral Pathology - 13 - Odontogenic Cysts, p.3 ↩

  4. Original PDF page 4: Oral Pathology - 13 - Odontogenic Cysts, p.4 ↩

  5. Original PDF page 5: Oral Pathology - 13 - Odontogenic Cysts, p.5 ↩

  6. Original PDF page 6: Oral Pathology - 13 - Odontogenic Cysts, p.6 ↩

  7. Original PDF page 7: Oral Pathology - 13 - Odontogenic Cysts, p.7 ↩

  8. Original PDF page 8: Oral Pathology - 13 - Odontogenic Cysts, p.8 ↩

  9. Original PDF page 9: Oral Pathology - 13 - Odontogenic Cysts, p.9 ↩

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