Supernumerary Causing Displacement

Case History:

A 3-year-old gelding in good condition was brought to the wet lab for routine dental evaluation. There was some foul odor coming from the mouth and the horse seemed moderately head shy while handling. Oral examination revealed abnormalities within the second quadrant. Lateral and dorsal ventral radiographs were taken of the second molar quadrant.


The 206 is displaced rostrally due to pressure from either a supernumerary tooth or a deformed 606. It is highly unlikely that a deciduous tooth would be stabilized enough to cause this much displacement of an erupting permanent tooth. However, a supernumerary tooth would develop at approximately the same time as the adjacent teeth, thus causing misalignment as the teeth mature and erupt, which seems to have occurred in this case. Also, the size, deformity, and density of this tooth is more consistent with a supernumerary tooth than a deciduous tooth.


Extraction of this extra tooth is indicated and should be accomplished as soon as possible to allow repositioning of the 206 caudally. Orthodontic pressure would be difficult to obtain at this time due to lack of clinical crown, but may be considered in 6 months if adequate drifting of the 206 has not occurred. Also, pressure placed on the clinical crown by orthodontic wires or rubber bands causes the tooth to tip and does not move the root and reserve crown at the same rate, which may be undesirable in this case. With time this tooth should reposition itself if care is taken in the future to remove any protuberance formed by the opposing 306 as the teeth erupt and mature.


Dental maintenance every 3 months to prevent any pressure from the opposing lower tooth is very crucial for a favorable outcome of this case. The 306 will erupt quickly in a young horse and form a wedge type protuberance between the 206 and 207, thus preventing the 206 from moving into a normal position. Also, the 206 will not have normal opposing wear as the tooth erupts. The rostral hook will also hinder movement of the 206 caudally. Removing a large protuberance at one time on a young tooth increases the risk of pulp exposure and possible loss of tooth due to infection. Small amounts of reduction at 3- month intervals should be adequate to prevent excessive pressure on the displaced 206 and pulp exposure by normal secondary dentin replacement as the pulp regresses.

B. W. Fletcher, DVM