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.

• 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

Miescher Cheilitis

• Definition: Granulomatous inflammation confined to the lip

Melkersson–Rosenthal Syndrome

Triad:

1. Facial palsy
2. Cheilitis granulomatosa
3. Fissured tongue

Ascher Syndrome

Triad:

1. Double lip
2. Blepharochalasis
3. Nontoxic thyroid enlargement

Double Lip

• Appearance: Cupid's bow

• Radicular Cysts: Derived from Rests of Malassez.

• Impacted Canine Associations:

  • Most common odontogenic cyst: Dentigerous cyst.

  • Most common odontogenic tumor: Adenomatoid Odontogenic Tumor (AOT).

• Eruption Cyst: Considered an extra-alveolar dentigerous cyst (soft tissue counterpart).

Infective osteomyelitis

• Tuberculous osteomyelitis
• Syphilitic osteomyelitis
• Actinomycotic osteomyelitis

Tuberculous osteomyelitis

• Non healing sinus tract formation
• Age group affected is around 15 – 40 years.
• Commonly seen in phalanges and dorsal and lumbar vertebrae.
• Usually occurs secondary to tuberculosis of lungs.
• Cases have been reported where mandibular lesions were not associated with pulmonary disease.
• Another common entrance is through a carious tooth via open pulp.
• Usually affects long bones and rare in jaws.
• Results when blood borne bacilli lodge in cancellous bone. Usually in ramus , body of mandible. may mimic parotid swelling or submassetric abscess.

Syphilitic osteomyelitis

• Difficult to distinguish syphilitic osteomyelitis of the jaws from pyogenic osteomyelitis on clinical & radiographic examination.
• Main features are progressive course & failure to improve with usual treatment for pyogenic osteomyelitis.
• Massive sequestration may occur resulting in pathologic fracture.
• If unchecked, eventually causes perforation of the cortex.

Actinomycotic Osteomyelitis

• The organisms thrive in the oral cavity, especially tissues adjacent to mandible.
• May enter the bone through a fresh wound, carious tooth or a periodontal pocket at the gingival margin of erupting tooth.
• Soft or firm tissue masses on skin, which have purplish, dark red, oily areas with occasional zones of fluctuation.
• Spontaneous drainage of serous fluid containing granular material.
• Regional lymph nodes occasionally enlarged.
• Mimics parotitis / parotid tumors