Abnormal tooth structures

Supernumerary Tooth

A supernumerary tooth is an abnormally developed extra tooth. It is mostly related to heredity. It can appear at any region of the dental arch, but most commonly erupts in between the upper front teeth, or is completely embedded inside the jaw.

Photograph of a supernumerary tooth erupting in between the upper cental incisors.

Oral problems associated with supernumerary teeth:

  • Failure of eruption of permanent teeth.
  • Delayed eruption of permanent teeth.
  • Displacement of permanent tooth.
  • Irregular alignment of teeth.

If the above situations happen, the supernumerary tooth needs to be extracted. If the supernumerary tooth cannot erupt, surgical extraction of the supernumerary tooth is required.

Leong's Premolar

A Leong's premolar differs from an ordinary premolar by having some tooth structure projecting from its occlusal surface. The structure is very fragile and is liable to fracture. If it is not properly treated after fracture, the pulp may undergo necrosis due to an infection and may lead to dental abscess formation.

Photograph of a Leong's premolar.
Animation showing the process of pulp infection caused by the fractured projected tooth structure of a Leong's premolar.

In order to prevent this from happening, preventive treatment is advocated. The dentist will, according to the tooth condition, either reinforce the fragile structure or remove the structure and restore the defect.

  • Projection strengthened with composite material.
    Animation showing the use of dental material to strengthen the projected tooth structure of a Leong's premolar.
  • Projection removed and restored with composite material.
    Animation showing the removal of the projected tooth structure of a Leong's premolar followed by the restoration with dental material.

Fused teeth

When two teeth are united during the developmental stage by the union of their tooth germs, a fused tooth will be formed. There will be a groove on the surface of the tooth, and it is commonly found on deciduous front teeth.When there is a deciduous fused tooth, a succeeding permanent tooth may be missing.

Photograph showing a deciduous lateral incisor united with a canine to form a fused tooth.
Photograph of a missing permanent lateral incisor in the lower set of teeth.