Through a study of 68 patients, presenting 84 supernumerary teeth all together and, after a thorough survey of the literature, we can now state accurately about the frequency, location, surgery, X-Ray and heredity involved. After recalling and discussing the various pathological theories already set up, a theory has been put forward, more specifically intent on the explanation of frequent supernumerary teeth in the upper front teeth area. Nevertheless, the theories of extra growth and the overgrowth of the external layer remain worth while to explain some other locations.