THE TEETH

The human teeth are arranged in two parabolic arches, the upper arch being larger, its teeth overlapping the lower. The average distance between the centres of the condyles of the inferior maxillary bones is about four inches. which is also the distance from either of these points to the line of junction between the lower incisor teeth

Owing to the smaller sizes of the lower incisors, the teeth of the lower jaw are each one half a tooth in advance of its upper fellow, so that each tooth of the dental series has two antagonists, with the exception of the lower central incisors a.nd upper third molars

The third molars are called the wisdom teeth (dentes sapientia!) from their late eruption: they have threc cusps upon the upper and five upon the lower. The three roots of the upper are frequently fused together, forming a grooved cone, which is usually curved backward. The roots of the lower, two in number, are compressed together and curve backward

The crowns are cuboidal in form, are convex buccally and 1inguall:-; they are flattened mesially and distally. They are formed by the fusion of three primitive cuspids in the upper and four in the lower. '1'0 these are added in the first and . second upper molars a disto-lingual tubercle, and in the first and third molars of the lower jaw a disto-buccal tubercle. The unions of the primiti\'e forms are marked by sulci. The necks of these teeth are large and rhomboidal in form. The roots of the Uppel' molars are three in number-one large lingual and two smaller buccal roots. In the lower, two roots are found, a mesial and a distal, each of which is much flattened from before backward.