The total number of permanent teeth per an individual is 32; these include 8 incisors, 4 canines, 8 premolars and 12 molars including the third molars or wisdom teeth. It is not uncommon to have one or more of those teeth missing. This means that the teeth did not develop in the jaws like the other teeth. They are referred to as congenitally missing teeth and those do not include teeth that were lost due to cavities or injury. Luckily, the most commonly missing teeth are the wisdom teeth which are usually a cause of trouble when they are present. On the other hand, other teeth can be commonly missing like the upper lateral incisors (second teeth from the center) and lower premolar teeth. Those teeth can be missing on one side only or they can be missing on both sides. This trait tends to run in families and some genetic factors are implicated. Even though most cases of missing teeth occur in otherwise healthy people, some disorders and syndromes (e.g. ectodermal dysplasia) are associated with several missing teeth (hypodontia - decreased number of teeth). Oligodontia refers to cases when only a few number of teeth are present and Anodontia is the complete absence of teeth, luckily a very rare condition.

Management of missing teeth depends on the age of the person, the tooth that is missing, the condition of other teeth, the bite (occlusion) and alignment of remaning teeth. These cases should be managed with multidisciplinary approach involving the dentist, the periodontist or surgen (for implant placement if needed), the prosthodontics (for restoration of the missing tooth/teeth) and the orthodontist who should make the decision on how the problem should be managed.

Management options include:

1. Closing the space of the missing tooth by braces. For example the canine is moved forward to "substitute" the missing later incisor. Following orthodontic treatment, the canine will be reshaped by the dentist or the orthodontist to look like an incisor.
   Advantages: no implants are placed and a natural tooth substitutes the missing tooth
   Disadvantages: the shape and color of canines and the high gum line may result in an unattractive appearance if the canine substitutes the incisor. Orthodontic treatment can be complicated especially if the teeth are in good occlusion.
2. Opening and maintaining the space for an implant. Braces will be used to open enough space to allow the placement of an implant to restore the missing tooth.
   Advantages: excellent cosmetic appearance. Implants are highly successful.
   Disadvantages: additional cost of implants. It may be necessary to wait few years until jaw growth stops before the implants can be placed.

In conclusion, cases with missing teeth should be managed by an orthodontist who is able to decide the best esthetic outcome by carefully evaluating the case and working with other dental specialties.