Adult dogs typically have 42 teeth. Like humans, dogs have two sets of teeth in their lifetime. They first have a set of deciduous or "baby" teeth that are eventually replaced by a permanent set. Puppies begin to lose their baby teeth at around 12 weeks of age, and by the time they are 6-7 months old, they should have all of their permanent teeth. The adult dog's teeth include incisors, canines, premolars, and molars, which are used for biting, tearing, and grinding food. It's important to take care of a dog's teeth through regular brushing and dental checkups, as dental issues can lead to pain, infection, and other health problems.