Most adults have 32 teeth unless they have had some extracted for orthodontic treatment or their wisdom teeth removed. There are some people, however, that may be congenitally missing a permanent tooth. This condition resulting in the failure of a tooth to develop is called hypodontia. A rare developmental anomaly characterized by the absence of 6 or more teeth is called oligodontia. This can be isolated or often associated with a syndrome.
Twenty percent of all adults are missing at least 1 tooth. This can be genetic, so it is often seen in families. The most commonly missing teeth are: the wisdom teeth, the 2nd bicuspids, the upper laterals, and the lower incisors. Some adults retain baby teeth in their mouth if there is not a permanent tooth to replace it. The baby teeth, however, tend to have shorter roots and may spontaneously resorb over time due to occlusal trauma.
If the baby tooth comes out or is extracted, it is important to replace it or close the space orthodontically. Leaving a space can lead to the adjacent teeth tipping into the space or the opposing tooth extruding vertically into the space. Both of these can change the bite. Also, when there is no tooth, the bone resorbs over time in height and width. There are several ways to replace a missing tooth: a fixed bridge, a removable appliance, or an implant. It is best to have this done as soon as possible to prevent unwanted movement or bone changes in the adjacent teeth. It is also possible in some situations to close the space orthodontically but this is best done at an early age.
Even though teeth can be missing, there are options to restore your bite to function normally and to give you a nice smile.