NTED - Common Incisor Abnormalities
1. Overbites and Underbites (parrot mouth) - This condition is diagnosed when there is a complete displacement of the upper and lower incisors. Upper and lower incisors do not sit on top of one another. Lower incisors sit behind upper incisors while upper incisors overlap lower incisors. Prevents horse from grinding feed freely from side to side resulting in improper and excessive molar wear. Prevents normal anterior, posterior movement of the lower jaw. Front and back hooks, transverse ridges, wave complexes, excessive wear and damage to the molar teeth and sheared molar table angles will become more severe as the horse is forced to grind incorrectly over time. Overbites and underbites will cause dysfunction and pain of the TMJ which, results in poor performance levels, attitudes, training abilities, etc. Since the lower incisors are unable to be worn away, sever tissue damage can be caused to the upper palate. This condition can be found in any age horse.
2. Ventral Curvature (smile) - Prevents horse from properly grinding feed freely from side to side resulting in improper and excessive molar wear. Prevents molar teeth from meeting, occluding and wearing properly therefore, creating mal-occlusions. Can occur if deciduous caps (baby teeth) on upper corner incisors are not shed properly preventing normal growth of permanent incisors. Can also occur due to abnormal grinding secondary to molar mal-occlusions. Can occur when horses are being fed in buckets hanging on stall walls or doors and from horses eating hay from hay racks instead of eating everything from the ground. Can occur when horse is forced to eat with a very tight halter on, restricting normal forwards, backwards and side to side movement of the lower jaw. This condition can be seen in young to geriatric horses.
3. Dorsal Curvature (frown) - Inhibits horse from grinding feed freely from side to side resulting in improper and excessive molar wear. Can occur when deciduous caps (baby teeth) are retained on the lower corner incisors, preventing normal growth of permanent incisors. Often occurs with cribbing, injuries to upper incisor and or pre-maxilla, wood chewing and abnormal grinding secondary to molar mal-occlussions, among other things. This condition can be seen in young to geriatric horses.
4. Offset, Wedge or Diagonal Incisor Bites - Causes horse to excessively wear molars on one side of the mouth. Opposite side molars become excessively long resulting in a sheared molar table angle. Sets horse up for disfunction and pain of the TMJ. Can develop over time as horse grinds food more in one direction and on one side of the mouth, from cribbing, wood chewing and eating from feed buckets on the stall walls or door and eating hay out of hay racks. May occur secondary to molar mal-occlussions or as a result of a missing incisor or incisor damage causing opposing incisors to become excessively long. Can occur from an injury to the TMJ, upper and lower incisor area, lower jaw, among other things. This condition can be seen in mature to geriatric horses.
5. Overjet and Underjets - Is a partial displacement of the margins of the incisor teeth, front to back, in which the incisor teeth do not meet, wear or occlude properly creating an incisor rim and or steep angle. This condition can be seen in younger to geriatric horses.
6. Wry Nose - Is a congenital deviation of the maxilla, incisive bone and nasal septum of newborns. This affects the upper and lower incisors, suckling ability and breathing.
7. Cleft Palate - Is a congenital defect in the hard and soft palate of newborns. It can be present in one or the other, or both. Aspiration of milk, coughing and pneumonia are serious problems associated with a cleft palate.