Many instances occur in which the teeth are too numerous. When this is so they are usually crowded together or appear out of their proper place.

This irregularity of numbers may occur in the incisor teeth or the molars, or both. We have known as many as ten of the former to be present in the upper row instead of six, and we have seen as few as two. Seven molar teeth instead of six on one side of the jaw is not of rare occurrence (fig. 120), and we are aware of an instance where only one molar tooth appeared in each jaw. When numerical excess leads to overcrowding, a good deal of pain is the result; and much inconvenience invariably occurs where the supernumerary teeth spring up, as they sometimes do, in the middle of the palate, or immediately within or without the naturally placed row. In the former position they interfere with the tongue, and in the latter with the cheeks, and in both they render mastication difficult, and in some cases almost impossible.

Where the number of teeth is deficient, grazing and mastication are rendered troublesome in proportion to the extent of the loss.