Variations in the Number of Teeth
There are two main congenital anomalies of human tooth number: hyperdontia and congenitally missing teeth. Hyperdontia is the condition of having more teeth than the normal set (28, excluding third molars); congenitally missing teeth means fewer teeth than normal. Both conditions can appear as isolated traits or associated with syndromes such as ectodermal dysplasia. Tooth number variations can have negative aesthetic and functional effects such as malocclusion, periodontal injury, impaired alveolar bone growth, reduced chewing efficiency, and speaking problems. Patients who have tooth number irregularities need more dental attention, so these conditions are interesting not only for dentists but also for public health departments and health insurance companies.