The Dental Anatomy of a Dog

Types of teeth

• The teeth of carnivores, such as dogs, and herbivores are classified as incisors, canines, premolars or molars. The shape of the teeth indicates their function. Incisors are the front (rostral) teeth of the upper and lower jaw. They have a narrow ridge at the tip of the tooth used for cutting and nibbling food. Canine teeth are located next to the incisors, and are longer and pointed at the tip, used for holding and tearing food. Premolars are located behind the canines, further back on the jaw, and have flatter, bumpy surfaces used to grind, cut and shear food. Molars are the teeth furthest back in the mouth and are used for grinding and chewing.

Number of teeth

• Dogs, as many other mammals, are "diphodont," meaning they have two sets of teeth. The deciduous, or baby, teeth set is replaced by a permanent adult set as they age. Typically, puppies have 28 deciduous teeth (14 upper, 14 lower) and adults have 42 permanent (20 upper, 22 lower). The number of each type of tooth is commonly represented by a dental formula, which counts the number of teeth in the upper and lower jaw of one side only. Multiply by two to get the total number of teeth. For puppies, the formula is as follows: i3/3 c1/1 p3/3, where i,c,p represent baby incisors, canines and premolars, respectively. The first number represents the upper teeth and the second number represents the lower teeth. For adult dogs the formula is I3/3 C1/1 P4/4 M2/3, where I, C, P, M represent adults incisors, canines, premolars and molars respectively.

Eruption

• In puppies, deciduous incisors erupt between 4 and 6 weeks of age, canines between 5 and 6 weeks and premolars at 6 weeks. In adult dogs, permanent incisors replace the deciduous teeth at 3 to 5 months of age, canines at 4 to 6 months, premolars when the dog is 4 to 5 months old, and molars at 5 to 7 months of age.

Bone anatomy

• The upper jaw containing teeth is called the maxilla, and the lower jaw is called the mandible. Different breeds of dogs have different skull or jaw shapes which affect the positioning of the teeth. Brachycephalic dogs like pugs have pushed in, short, wide snouts, which sometimes cause their teeth to stick out. Mesaticephalic dogs like retrievers have medium length and width snouts, and Dolichocephalic dogs like greyhounds have long, narrow snouts.

Tooth anatomy

• The different surfaces of dog teeth are classified as follows: The main chewing surface is called the occlusal surface. The inner surface facing the tongue or palate is the lingual or palatal surface (depending on if they are lower or upper teeth). The outer surface is called the labial or buccal surface (facing the cheek or lips). The tooth itself consists of a crown above the gumline and a root embedded in the jawbone. Some teeth, like incisors, have one root, whereas others like the largest premolar may have three. The pulp lies at the center of the tooth, surrounded by protective dentin, which in turn is surrounded by a hard enamel layer, the hardest tissue in the body.