Teeth

Dental formula for adult teeth

2-1-2-3

How many teeth do adults have?

32 8 incisors 4 canines 8 premolars 12 molars

How many teeth are in the primary dentition?

20 8 incisors 4 canines 8 molars

How can you determine the side of an upper M1? How about a lower one?

All molar roots angle distally with respect to the crown axis. In the upper molars: the hypocone is lingual, the protocone is the largest/most heavily worn cusp, and is in the mesiolingual crown corner. In the lower molars: Protoconid is the largest, most heavily worn cusp and is in the mesiobuccal crown corner.

How can you distinguish a canine from an incisor?

Canine crowns are conical and tusk-like. The outline of the occlusal dentin patch exposed by wear is diamond-shaped. Roots are longer/larger relative to crown heights than the incisor roots.

Dental formula for primary dentition

I2/2 C1/1 M2/2 = 10 x 2 = 20

How can you distinguish between central and lateral incisors?

In the Upper Incisors: central crowns are larger than lateral crowns, central crowns are more symmetrical in labial view than lateral crowns, and central roots are shorter than lateral roots. In the Lower Incisors: central crowns are slightly smaller than lateral crowns, central crowns are more symmetrical in labial view than lateral crowns, and central roots are shorter than lateral roots.

How can you distinguish incisors from other teeth?

Incisor crowns are flat and blade-like. The outline of the tooth is rectangular and square.

What differences do you see comparing M1, M2, and M3 in the same dentition?

Molars usually go from largest to smallest. M1 shows classic morphology and will become less conforming toward M3. Upper: M1 will have 4 cusps arranged in a rhombus shape, m3 usually lacks a hypocone (4th cusp), M1 has three divergent roots while M3 roots are fused. Lower: M1 will have 5 cusps arranged in a Y-5 pattern, M1 has two divergent roots while M3 tends to have fused roots.

How can you determine the side of a canine?

On both uppers and lowers in canines, the crown is not symmetrical and the distal edge of the cusp is the longer side.

How can you determine the side of a premolar?

The buccal cusp is usually larger than the lingual cusp, roots are angled distally relative to the axis of the crown.

How can you distinguish a premolar from a molar?

There are normally two cusps, premolars are smaller than molars, and they have a more regular cusp pattern.

How can you distinguish an upper from a lower M1 (note the number of cusps and the number of roots)?

Upper: 3-4 major cusps, rhombus-shaped occlusal outline, asymmetrically placed cusps, and usually has three roots if not fused. Lower: 4-5 major cusps, square/rectangular occlusal outline, symmetrically placed cusps, and usually only has two roots.

How can you distinguish between an upper and lower incisor?

Upper: broad relative to height, more lingual relief (bumps on the lingual surface, and their roots are rounder in cross-section. Lower: narrow relative to height, smooth on the lingual surface, and their roots are mesiodistally compressed in cross-section.

How can you distinguish an upper from a lower canine?

Upper: broad relative to their height with more lingual relief. Lower: narrow relative to their height with less lingual relief.

How can you distinguish an upper from a lower premolar?

Upper: have two cusps of nearly equal size, strong grooves oriented mesiodistally between major cusps, and the occlusal circular is more oval. Lower: buccal cusp is much larger than the lingual cusp, relatively weak groove between cusps, and is more circular.