Teeth, Age of dog

There is more variation in small dogs and in dogs with undershot or overshot jaws. Even, bites usually result in excessive wear.

1 ½ yr Cusps worn off lower I 1.
2 ½ yr Cusps worn off lower I 2.
3 ½ yr Cusps worn off upper I 1.
4 ½ yr Cusps worn off upper I 2.
5 yr Cusps of lower I 3 slightly worn. Occlusal surface of lower I 1 and I 2 rectangular. Slight wear of canines.
6 yr Cusps worn off lower I 3. Canines worn blunt. Lower canine shows impression of upper I 3.
7 yr Occlusal surface of lower I 1 elliptical with the long axis sagittal.
8 yr Occlusal surface of lower I 1 inclined forward.
10 yr Lower I 2 and upper I 1 have elliptical occlusal surfaces.
12 yr Incisors begin to fall out (unless care has been taken to maintain healthy gingival and periodontal tissues).

The dental formula for puppies is, 2(Di 3/3 Dc 1/1 Dp 3/3 = 28
The dental formula for adult dogs is, 2(I3/3 C 1/1 P 4/4 M 2/3) = 42