The relationship between crown size and the incidence of bifid root canals in mandibular incisor teeth.

From an initial sample of 729 extracted mandibular incisor teeth a final sample of 286 (172 central and 114 lateral incisors) was used to determine if any relationship existed between crown size, expressed as the M-D/F-L index, and the presence of bifid canals within the root of the tooth. The M-D/F-L index was calculated for each tooth and was matched against the presence of bifid canals as determined from radiographs of the lateral aspect of the teeth. The results indicate that bifid canals occur more frequently in teeth with the smaller M-D/F-L index and from regression equations, which had a high coefficient of correlation, the indications are that the incidence of bifid canals among the teeth with the lowest M-D/F-L index could be as high as 70 percent.