Most abnormal tubercles observed in the anterior portion generally occur in the lingual surface. Those tubercles, however, rarely appear in the labial surface.
Here is a case of a 15-year-old male with an abnormal tubercle in the labial surface of maxillary lateral incisor tooth.
His abnormal tubercle appearing at the left second lateral incisor tooth had a conic shape and it was 9.3 mm in length and 5.7 mm in width. As for the aspect of the proximal surface of the abnormal tubercle, the curvature of the labial surface was nearly constant from the cervical part to the top, which was about 2 mm from the labial surface of the tooth.
X-ray radiography revealed that the basement of the abnormal tubercle was positioned around the cervical neck of the lateral second incisor tooth. Further, a broad zone with an increased density, which indicated a composition of enamel, was noted around the abnormal tubercle. Although the morphology of the root canal of this case was similar to that of a normal one for the radicular pulp cavity, the coronal cavity was unclear because of the presence of an abnormal tubercle.
From these results, it was assumed that the occurrence of the abnormal tubercle might be caused by morphological alteration in the basel membrane, constructing a part of tooth germ which would form the border between the enamel and the dentin, in an early stage of the development of tooth germ.
