Summarize this article:

All dogs have four basic types of teeth: incisors, canines, premolars, and molars. These are found on the upper and low jaws, on both the left and right sides.  The incisors are the small teeth running along the front of the mouth. Adult dogs have six incisors on the top and six on the bottom jaw. The two  side incisors (next to the canine teeth) are a bit bigger than the middle incisors; on the top these also tend to stick out to the side a bit more. The canine teeth are located behind the incisors, one on each side for a total of four. These are the large, pointed teeth. Premolars come in behind the canines. There are four premolars both on the upper and lower jaw. The fourth premolar on the top is very large. Finally behind the premolars are the molars. On the top of your dog's mouth there are two molars. On the bottom jaw there are three molars. The first one is larger than the other two. Puppies generally have around 28 teeth. For the first two to four weeks, there are no noticeable teeth. Baby canines start coming in after three to four weeks. Baby incisors and premolars start after four to six weeks. By eight weeks, all baby teeth are grown in. For the next three months, there will be no noticeable changes.  After five months, permanent teeth will start coming in, usually canines and molars first. By seven months, all permanent teeth will have grown in. If your puppy has all of its permanent teeth, then it is most likely more that 7 months old. Adult dogs will have around 42 teeth.  After the puppy stage, age is marked by tooth wear. At one year, teeth are white and clean. By the end of the second year, the white will have dulled and tartar will begin building up. This will cause yellowing on the back teeth. After three to five years the yellowing will increase and be visible on all teeth. There will be noticeable tooth wear. Tooth wear is a natural occurrence, but it can be accelerated by certain habits such as aggressively chewing on hard objects (bones, rocks, sticks) or in small dog’s without good dental care. On the other hand, some chewing is great for a dog’s dental health. Rawhides or “dental” chews can help dogs break down plaque and material on the teeth.  Also understand how disease manifests. By age three, nearly 80% of dogs will exhibit signs of gum disease. This can be seen in the buildup of yellow and brown tartar, inflamed gums, and bad breath. Gum disease is more prevalent in small dog breeds.  Food also plays a role in dog dental health. Dry food in strong chewers can help remove some plaque from the teeth slowing tooth decay and loss. There are specially formulated foods specifically for dental health. Your veterinarian can advise you on the proper diet for your dog if you are worried about its teeth. Water additives can also be used to combat teeth destroying and aging bacteria.  Worn teeth can look fractured, though regular wear poses little health risk. Excessive wear can damage the root of the tooth, which can require a root canal.

Summary:
Understand the structure and organization of your dog's teeth. Understand how your dog's teeth grow in. Understand how and why dog teeth wear down and decay.