| Supernumerary Teeth
Slide #1 is an example of an extra incisor. When located in the midline between the two permanent central incisors, they
are referred to as mesiodens. Slide #2 depicts an extra molar tooth (a paramolar) and Slide #3 is an example of a super-
numerary bicuspid tooth. These are the most common supernumerary teeth in the order shown.
Slide 1: mesiodens
Slide 2: fourth molar
Slide 3: supernumerary bicuspid
Hyperdontia and Cleidocranial dysplasia
Count the teeth in Slide #4 — there are more than 50. This patient has cleidocranial dysplasia (CCD). This is inherited
as an autosomal dominant trait, the gene maps to chromosome #6. The gene encodes a protein called Core Binding Fac-
tor Alpha 1 (CBFA1). This protein is essential for the formation of a normal skeleton but its role in tooth formation is
not yet known. The heterozygous state produces the CCD phenotype, the homozygous state is lethal. Main features of
the phenotype include hyperdontia, small or missing clavicles, delayed closure of the cranial fontanelles (soft spots) and
short stature. Slide #5 shows multiple supernumerary teeth removed from a patient with CCD. Gardner syndrome (intes-
tinal polyposis and skeletal osteomas) also features supernumerary teeth but not to the extent seen in CCD. ( J. Med.
Genetics 1999;36 p177-182 and Cell 89; 773-779 May 1997)
Slide #6 is a little tricky. The coin shape radiolucent lesion between the mandibular bicuspid teeth was thought to be a cyst.
It was removed and found to be a tooth germ of a developing supernumerary tooth. It was discovered early in development
before mineralization commenced. Radiographically, it resembles a lateral periodontal cyst.
Dostları ilə paylaş: | 
