Usually seen in molars, premolars and associated with chromosomal syndromes (Down, Klinefertel), some races or descendants of Mayan Indians, Aztecs, Incas, and hypohidrotic ectodermal dysplasia syndrome, tricho-dento-osseous. No treatment. It is due to a failure to sheath Hertwing 7) Pearl Enamel: They consist of enamel formation in spherical form at the root of a tooth which usually can be seen in upper molars, second or third, and it is rather rare, and the main complication would be in the disease and its treatment, to be affected in the root surface that is the pearl of the enamel. 8) Sindesmo crown-root: A characteristic entity characterized by the presence of a fissure that separates the cingulum of the root, and then extended in apically. It is situated mainly in the palatal of the upper lateral incisors, and leads to an untreatable periodontal defect, which eventually lead to tooth extraction. Dentin can communicate well and even the pulp with the tooth surface through the crack, which can also lead to pulpal pathology. B. Size Abnormalities 1) Macrodontia: Any tooth or group of teeth greater than normal, is of unknown etiology when it affects a single tooth, but the widespread Macrodontia may be due to hormonal imbalance in the case of pituitary gigantism, sometimes there is an illusion Macrodontia generalized if the jaws are small relative to the size of the teeth, resulting in an abnormal pattern of eruption, and dental crowding due to lack of space in the dental arch. The Macrodontia true that affects all teeth is rare, it is common to see in a dental group.