Epithelial cysts

    Developmental odontogenic cysts
        Odontogenic keratocyst
        Dentigerous cyst (follicular cyst)
        Eruption cyst
        Lateral periodontal cyst
        Gingival cyst of adults
        Glandular odontogenic cyst (sialo-odontogenic)
        
        
    Inflammatory odontogenic cysts

        Radicular cyst (apical and lateral)
        Residual cyst
        Paradental cyst
        
    Non-odontogenic cysts

        Nasopalatine cyst
        Nasolabial cyst
    
Non-epithelial cysts (not true cysts)

    Solitary bone cyst
    Aneurysmal bone cyst

Osteoradionecrosis

Clinical features

A reduction in vascularity, secondary to endarteritis obliterans, and damage to osteocytes as a consequence of ionising

Radiotherapy can result in radiation-associated osteomyelitis or Osteoradionecrosis. The mandible is much more  commonly affected than the maxilla, because it is less vascular. Pain may be severe and there may be pyrexia. The overlying oral mucosa often appears pale because of radiation damage. Osteoradionecrosis in the jaws arises most often following radiotherapy for squamous cell carcinoma.
 

Scar tissue will also be present at the tumour site, often in close relation to the necrotic bone.

Radiology
 

Osteoradionecrosis appears as rarefying osteitis within which islands of opacity (sequestra) are seen. Pathological

fracture may be visible in the mandible.

Pathology
The affected bone shows features similar to those of chronic osteomyelitis. Grossly, the bone may be cavitated

And discoloured, with formation of sequestra.
Acute inflammatory infiltrate may be present on a background of chronic inflammation, characterized by formation

Of granulation tissue around the non-vital trabeculae.

Blood vessels show areas of endothelial denudation and obliteration of their lumina by fibrosis.

Small telangiectatic vessels lacking precapillary sphincters may be present.

Fibroblasts in the irradiated tissues lose the capacity to divide and often become binucleated and enlarged.

Management

Prevention of Osteoradionecrosis is vital. Patients who  require radiotherapy for the management of head and

neck malignancy should ideally have teeth of doubtful prognosis extracted at least 6 weeks prior to treatment.

The dose of radiation,
The area of the mandible irradiated and
the surgical trauma involved in the dental extractions.
Surgical management of Osteoradionecrosis is similar to osteomyelitis.

 Streptococcus mutans Mechanism

• Key Substrate: Sucrose
• Metabolic Pathway: Phosphorylation → Glycolysis → Lactic acid
• Enzymes:
  • Invertase: Converts sucrose to glucose + fructose
  • Glucosyltransferase (GTF): Forms sticky glucans
  • Fructosyltransferase (FTF): Produces fructans

Actinomyces naeslundii

• Fimbriated surface → fuzzy texture
• Type 1 fimbriae: Bind tooth surfaces/collagen
• Type 2 fimbriae: Bind galactose/galactosamine (epithelial/bacterial targets)

• Bull Neck: Seen in Diphtheria and Ludwig's Angina.

• Bull's Eye Lesion / Target Lesions: Characteristic of Stevens-Johnson Syndrome and Erythema Multiforme.

• Bull's Teeth: Refers to Taurodontism.

• Circus Rubber Man: Clinical appearance associated with Ehlers-Danlos Syndrome (due to hypermobility and skin elasticity).

• Claw Hands: A physical deformity seen in advanced Scleroderma.

• Coup de Sabre: A linear depression or groove resembling a "saber cut" seen in Facial Hemiatrophy (Parry-Romberg Syndrome) and localized Scleroderma (linear scleroderma).

• CREST Syndrome: A limited form of Scleroderma, characterized by:

  • Calcinosis

  • Raynaud's phenomenon

  • Esophageal dysfunction

  • Sclerodactyly

  • Telangiectasias

• Crowe's Sign: Axillary or inguinal freckling seen in Neurofibromatosis Type 1.

• Frog Facies: A characteristic facial appearance seen in Crouzon Syndrome (due to midfacial hypoplasia and exophthalmos).

• Gorlin Sign: The ability to touch the tip of the nose with the tongue, seen in Ehlers-Danlos Syndrome (due to increased joint laxity).

• Hockey Stick Deformity of Femur and Shepherd's Crook Sign: Radiographic findings typically associated with Fibrous Dysplasia.

• Parrot's Beak Nose: A nasal deformity seen in Crouzon Syndrome.

• Red Strawberry Tongue and Pastia's Lines: Clinical signs characteristic of Scarlet Fever.

• Rodent Facies: A facial appearance often associated with Thalassemia.

• Simian Stance: A stooped posture, reminiscent of an ape, seen in Paget's Disease of Bone.

• Snail Track Ulcers: Serpiginous, grayish-white lesions on mucous membranes, characteristic of Syphilis (mucous patches in secondary syphilis).

• Socks Feet and Mitten Hands: Refers to syndactyly (fusion of digits) appearing like a sock or mitten, seen in Apert's Syndrome.

• Parrot Beak Shaped Nails: A nail deformity (onychogryphosis) seen in Congenital Syphilis.

 General Features

• Caused by mutation in DSPP gene (dentin sialophosphoprotein).

• Teeth appear translucent or opalescent.

• Enamel fractures easily due to poor dentin support.

• Pulp chambers are obliterated or enlarged depending on type.

• Also called Hereditary Opalescent Dentin or Shell Teeth.

Type II DI

• Pulp chambers are normal but rapidly obliterate.

• Associated with progressive hearing loss.

Type III DI

• Pulp chambers are large and shell-like.

• Seen in Brandywine isolate population.

• Derived from Reduced Enamel Epithelium (REE):

  • Dentigerous Cyst

  • Eruption Cyst

  • Paradental Cyst

• Derived from Rests of Serres (remnants of dental lamina):

  • Odontogenic Keratocyst (OKC)

  • Gingival Cyst of Newborn

  • Gingival Cyst of Adult

  • Lateral Periodontal Cyst

  • Glandular Odontogenic Cyst