First we have our baby teeth. These start coming in around the age of 6 months. Young children have about 20 teeth before they begin to lose them. The second set of permanent teeth consist of 32 teeth. Twenty-eight of them appear between the ages of 6 and 12 years. The last four are called the third molars. These are the wisdom teeth. If they do erupt it will be around the age of 20. However it is common for the wisdom teeth not to come through at all. This is often the case in small jaws without room to support the extra teeth. When they do come in the wisdom teeth appear in the rear of the jaw.