Gemination

• Attempted division of a single tooth germ before calcification.

• Results in two crowns (complete/incomplete) with one root and canal.

• Tooth count remains normal.

• Difficult to differentiate from fusion with a supernumerary tooth.

 Twinning

• Complete division of a single tooth germ.

• Results in one normal + one supernumerary tooth.

• Tooth count is more than normal.

Fusion

• Union of two separate tooth germs.

• If before calcification → single large tooth.

• If after calcification → roots fused, crowns may be separate.

• More common in deciduous teeth.

Concrescence

• Union by cementum only.

• Occurs after root formation.

• Common in maxillary molars.

• Blood: Aneurysmal bone cyst, Vascular lesion, Vessel puncture.

• Air: Traumatic bony cyst (Simple Bone Cyst/Hemorrhagic Bone Cyst), Maxillary sinus.

• Chocolate Colored Fluid: Warthin's Tumor (salivary gland cyst).

• Café au Lait Spots:

  • "Coast of California": Associated with Neurofibromatosis (Type 1).

  • "Coast of Maine": Associated with Fibrous Dysplasia.

• Carpet Tack Lesions: Characteristic of Discoid Lupus Erythematosus.

• Cerebriform Tongue: Seen in Pemphigus Vegetans.

• Charcot's Triad: Seen in Multiple Sclerosis, characterized by:

  • Intention tremor

  • Nystagmus

  • Dysarthria

• Chipmunk Facies: Seen in Thalassemia.

• Chvostek's Sign: Indicative of Hypoparathyroidism (facial muscle twitching upon tapping the facial nerve).

• Buffalo Hump: A characteristic clinical sign of Cushing's Syndrome (fat pad on the upper back).

• Inverted Pear-shaped Radiolucency: Globulomaxillary cyst.

  • Associated teeth need not be non-vital.

  • Klestadts’s cyst: Soft tissue variant of Globulomaxillary cyst.

• Tear Drop-shaped Radiolucency: Lateral Periodontal Cyst.

  • Associated teeth are vital.

• Cluster of Similar Cysts / Cluster of Grapes: Botryoid Odontogenic Cyst.

Viral Infections

Herpes Simplex Virus (HSV-1)

• Dormancy Sites: Trigeminal > Nodose (Vagus) > Dorsal Root > Brain
• Inclusions: Lipschutz bodies (intranuclear)
• Herpetic Whitlow: Finger lesions in dentists
• Location Difference:
  • Herpangina: Posterior palate
  • Herpes: Anterior palate

Herpes Zoster

• Key Feature: Lesions do not cross midline
• Ramsay Hunt Syndrome: Zoster of geniculate ganglion → facial paralysis

Measles

• Koplik's Spots: Disappear after skin rash onset

Rubella

• First Trimester: Blindness, deafness, cardiovascular defects

Mumps

• Complications: Orchitis, oophoritis (sterility), pancreatitis, meningoencephalitis

Nasopalatine cyst

Radiology

The nasopalatine cyst appears as a well-defined, round radiolucency in the midline of the anterior maxilla . Sometimes it appears to be 'heart-shaped' because of super-imposition of the anterior nasal spine.

Radiological assessment should include examination of the lamina dura of the central incisors (to exclude a radicular cyst) and assessment of size (the nasopalatine foramen may reach a width of as much as 10 mm).

Pathology

The cyst is lined by a layer of pseudostratified ciliated columnar epithelium and/or stratified squamous epithelium. The capsule of the cyst is fibrous and may include the incisive canal neurovascular bundle.

Nasolabial cyst

Radiology

'Bowing' inwards of the anterolateral margin of the nasal cavity has been recorded

Pathology

The nasolabial cyst is lined by non-ciliated pseudostratified columnar epithelium, which is often rich in mucous cells.