Clinical evaluation of a new method for determining tooth length without radiographs.

A new instrument (the Apexfinder) for measuring tooth length was recently introduced for use in endodontics. The procedure of measuring tooth length with this instrument was found to be simple and easy. It also eliminated the need for radiographs, with their problems. One hundred forty-two teeth were used to compare the new method with two different methods, widely used in endodontics, that employ radiographs. The investigation showed that the new technique offers a direct method for measuring the distance between the coronal and apical ends of the tooth. Statistical analysis of the data indicated that the new method was superior to the others. The Apexfinder was accurate in 90 percent of the cases. When radiographs were used, the results were accurate in 75 percent of the cases, while the use of the radiograph and the tooth-length formula gave 60.4 percent accuracy.