<prompt> The following radiograph shows; the total number of teeth present in oral cavity are one less than normal:FusionGeminationConcrescenceDilaceration  <response>: FusionFused teeth arise through union of two normally separated tooth germs. Depending upon the stage of development of the teeth at the time of the union, fusion may be either complete or incomplete. It has been thought that some physical force or pressure produces contact of the developing teeth and their subsequent fusion. If this contact occurs early, at least before calcification begins, the two teeth may be completely united to form a single large tooth. If the contact of teeth occurs later, when a portion of the tooth crown has completed its formation, there may be union of the roots only. The dentin; however, is always confluent in cases of true fusion. The tooth may have separate or fused root canals, and the condition is common in the deciduous as well as in permanent dentition.Radiological signsThe tooth has a notched incisal margin and there is evidence of conjoined dentine between the involved teeth. The fused tooth may present with two distinct pulp chamberspulp canal systems or a joined system. 