The dental formulas
Permanent dentition: in each half of the upper jaw 3 incisors, 1 canine, 4 premolars and 2 molars; in each half of the lower jaw 3 incisors, 1 canine, 4 premolars and 3 molars. In total 42 teeth: 12 incisors, 4 canines, 16 premolars and 10 molars.
Deciduous dentition: 3 incisors, 1 canine and 3 premolars in each half, upper and lower, that is 28 teeth. The molars and the first premolar have no baby teeth preceding them.
When the teeth erupt
Baby teeth begin to erupt at 3-5 weeks; permanent teeth usually appear from 4-5 months, and by 7 months they are generally all present. The ages are averages, with wide variation: very small breeds tend to be late, and in some breeds (terriers, for example) missing premolars are considered a normal variant.
Rigid timetables (“all teeth by 8 weeks”) ignore the variation between dogs; the atlas uses ranges and does not turn teeth into a tool for estimating age.
Occlusion: veterinary terms and show-ring terms
Normal occlusion: the upper incisors all sit immediately in front of the lower incisors, and the lower canine fits into the space between the third incisor and the upper canine. In show-ring vocabulary this is the “scissor bite”; a “level bite” (pincer bite) means incisors that meet edge to edge.
The AVDC nomenclature describes malocclusions by class: class 2 (mandibular distoclusion, MAL2) — the lower arch sits behind its normal position, “the lower jaw looks shorter”; class 3 (mandibular mesioclusion, MAL3) — the lower arch sits in front of its normal position, “the lower jaw looks longer”. In everyday language they appear as “overshot” and “undershot”.
A type of occlusion accepted by a breed standard (for example class 3 in many brachycephalic breeds) needs no treatment unless it produces a traumatic occlusion, that is teeth that strike the gum or the palate. Conformation and health are two different judgments; treatment is decided by comfort and function, not by looks.
What each category of teeth does
The incisors, at the front, are small; the canines, long and pointed, grip and hold; the premolars and molars, at the back, cut and grind food.