The Teeth

The formula for the permanent teeth is:

( 3 1 4 2 )

2 ( I

C

P

M

) = 42

( 3 1 4 3 )

All of the teeth have short crowns and distinct necks; they erupt rapidly. The crowns are white, being destitute of cement.

The incisors are placed almost vertically and close together in the jaw-bones. They do not correspond to an opposing tooth, but rather to parts of two teeth of the other jaw. The crowns are trituberculate, the central projection being the largest. They increase in size from the first to the third. The labial surface is convex, the lingual slightly concave, and marked off from the neck by a V-shaped ridge, the cingulum. The roots are flattened transversely. The lower incisors are smaller than the upper ones. One or two supernumerary teeth may be present.

The canine teeth are large, conical, and curved. The upper canine is separated from the corner incisor by an interval into which the lower canine is received when the jaws are closed. The lower canine is close to the corner incisor. The root is about an inch (ca. 2 to 3 cm.) long and is flattened laterally.

The cheek teeth are typically ⁶⁄₇, but in brachycephalic breeds they are commonly reduced to ⁵⁄₇, and in extreme cases even to ⅘. The reduction occurs at either end or at both ends of the series. The first tooth appears only once. The fourth tooth of the upper row and the fifth of the lower row are much larger than the rest, and termed sectorial or carnassial teeth. From these the teeth diminish in size both forward and backward. The upper and lower teeth do not correspond, but rather dovetail. The teeth behind the sectorial ones are tuberculate, i. e., have rounded eminences on the masticatory surface. The others are all sectorial in character, i. e., have sharp-edged, pointed projections, the middle one being the most prominent. The premolars are laterally compressed, and are separated by intervals from the canines and from each other, except in the brachycephalic breeds. The upper molars have wide, somewhat quadrangular crowns, and three roots. The crown of the upper fourth premolar (Dens sectorius) is divided into two pointed lobes and has an antero-internal tubercle; it has three roots. The crown of the first lower molar (Dens sectorius) is compressed laterally and has two pointed, sharp-edged lobes, behind which are one or two tubercles; it has two roots.

The average periods of eruption are given below.

Tooth Eruption Change

I1 4 to 5 weeks 4 to 5 months

I2 4 to 5 weeks

I3 4 weeks

C 3 to 4 weeks 4 to 5 months

P1 4 to 5 months 5 to 6 months

P2 4 to 5 weeks

P3 3 to 4 weeks

P4 3 to 4 weeks

M1 4 months

M2 upper 5 to 6 months
lower 4 ½ to 5 months

M3 6 to 7 months