Last revised by Daniel J Bell on 14 Apr 2021

A mesiodens (plural: mesiodentes) is the most common supernumerary tooth and is located in the palatal midline between the two maxillary central incisors.

It is rare with an estimated prevalence of ~1% (range 0.09 to 2.2%) 3. There is an increased male predilection with a M:F ratio of ~2.5:1.

There is some geographical variation in prevalence ranging from 0.4% in Caucasians to 1.4% in Finnish and 2.2% in Hispanic ethnicities.

  • occur as single (85% of cases), multiple, unilateral or bilateral
  • more commonly seen in permanent dentition than primary dentition
  • possible causes include
    • restricted increase in the activity of the dental lamina (hyperactivity theory)
    • splitting of the tooth bud into two equal or unequal sections (dichotomy theory)

An X-linked inheritance has been documented.

  • classified into eumorphic (similar to a normal-sized central incisor) and dysmorphic
  • three common dysmorphic shapes
    • conical or peg shaped (most common ~70%)
    • tuberculate (more than one cusp or tubercle)
    • supplemental (duplication of a normal tooth)
  • 55% grow in the downward position (35% are inverted and 7% are horizontal)
  • most remain impacted but 25% will erupt (usually eumorphic or conical shape)
  • immediate extraction if there is a complication
  • early extraction before root formation of the permanent incisors
  • late extraction after root formation of the permanent incisors
  • impaction or delayed eruption of adjacent incisors
  • widening of the gap between the incisors (diastema)
  • axial rotation or inclination of erupted permanent incisors
  • abnormal curving of teeth (dilaceration)
  • resorption of adjacent teeth
  • development of dentigerous cysts (5%)
  • eruption into the nasal cavity

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