A Radiographic method for determining the actual tooth length

Tooth length determination is a crucial step in endodontic treatment. Traditionally, radiographs are used to confirm working length of the root length. This study was performed to evaluate the radiographic distortion (magnification) and calculate correction coefficients for the object-film distance. Ninety-six radiographs were made of eight extracted teeth (two upper first premolars, two lower first premolars, two upper first molars, and two lower first molars) by using the 16 inch long cone paralleling techniques with 1 mm interval from 5 to 16 mm tooth-film distance. The following results obtained; 1. The least mean radiographic distortion from 5 to 16 mm tooth-film distance was 2.42 ±0.68% (the length of mesiobuccal cusp-mesial root of lower first molars), the greatest distortion was 4.74 ±1.36% (the length of mesiobuccal cusp-mesiobuccal root of upper first molars). 2. The greatest correction coefficient was 0.986 (the mesiobuccal cusp-mesial root of lower molars, the lowest one was 0.937 (the mesiobuccal cusp-mesiobuccal root of upper first molars).