Accuracy of Software-Based Three-Dimensional Root Canal Length Measurements Using Cone-Beam Computed Tomography

Objective: This study aims to evaluate the accuracy of three-dimensional root canal length measurements performed by dentists with different experience levels using a special software based on cone beam computed tomography (CBCT). Methods: A CBCT scan of an artificial resin maxillary molar was used to train dentists (n=65) in using the software (3D Endo, DentsplySirona, Ballaigues, Switzerland) as part of a continuing education course. At the beginning, each participant completed a questionnaire on endodontic and CBCT experiences. After comprehensive instructions, each participant performed an entire three-dimensional treatment plan by tracing the root canal anatomy between the apical foramen and the center of the canal orifice and simulating a straight-line access. The final root canal length was indicated after the virtual rubber stop of a simulated instrument was adapted to the adjoining cusp. To evaluate the individual accuracy in terms of trueness and precision, differences between the three-dimensional planning and the actual root canal length (ARCL) were calculated, and statistically analyzed. Results: Mean absolute differences between the measurements with the 3D Endo (TM) software (n=260) and the ARCL were 0.30 +/- 0.22 mm. All measurements were within a limit of +/- 1 mm. The accuracy of root canal length measurements was significantly influenced by the type of root canal (p<0.0001). The smallest deviations were observed for the palatal root canal (0.18 +/- 0.13 mm), followed by the mesiobuccal (0.26 +/- 0.22 mm), the distobuccal (0.32 +/- 0.17 mm), and the second mesiobuccal root canal (0.46 +/- 0.24 mm). Conclusion: Within the limitations of this study, the 3D Endo software enables reproducible and accurate root canal length measurements as part of a three-dimensional endodontic treatment plan. However, measurements should always be clinically verified, as root canal morphology has a statistically significant influence.