Double tooth

Abstract: Double primary teeth were observed in 367 children and their relationship with the permanent successors was studied with the aid of radiographs Double primary teeth involving 2 adjacent teeth and those involving the same tooth have different patterns of association with the permanent successors Double primary teeth involving 2 adjacent teeth are associated more frequently with congenitally missing permanent successors A combination of factors such as decreased hereditary dependent mitotic potential of the tooth germ and presence of an inhibitory zone around the tooth germ might have been responsible for the formation of these anomalies It is suggested that double primary teeth probably result from unseparated rather than fused tooth masses

Abstract: Transducer elements, such as the teeth of a star-wheel are uniformly distributed around the circumference of a disk; one of the teeth is slit to form a double tooth with a gap therebetween, the two-part teeth and the gap, each, taking one third of the space of a tooth; and a circuit, such as a counter counting at a rate much faster than the pulse repetition rate of the pulse source counts forwardly when sensing a tooth, and backwardly when sensing a gap, so that the count state of the counter, after a tooth-gap count will be zero, except when counting backward after the second part-tooth throughout the length of the normal-size gap, the non-zero count state of the counter being sensed by a threshold detector and providing a signal upon presence of the next tooth, so that a reference signal, at a predetermined tooth position, will be provided as well as the pulses representative of the passage of each one of the teeth.

Abstract: In this article we report a case of a mandibular lateral incisor in which 3 separate root canals were located. Clinical and radiographic examinations suggested that fusion had occurred between the mandibular incisor and a supernumerary tooth. The endodontic management of the tooth is described, and repair of an apical periodontitis had occurred after 9 months.