The results showed that the ProPex II was the best measurements with the highest proportion of accuracy in the range of ± 0.5 mm. However, this EAL disagreed with the AL. There were two modalities agreed with the AL, using the CBCT data. Both of them could be considered for alternators for root canal determination.
3D Endo software is developed, especially dedicated to endodontic therapy in the clinical setting. However, with the friendly, intuitive interface and thoroughly clear instructions step-by-step throughout procedure, 3D Endo completely satisfies all requirements from simple to complex cases, especially in the pre-clinical endodontic education. WL determination is one of the most innovative features of the 3D Endo with the function of manual adjusted length by operator should the suggested length be not satisfied. This feature is developed in the effort of maximum reduction of operator’s errors in WL determination. Depending on the curvature levels of the canal after adjusting the pathway of the canal using the appropriate slices in the 3D Endo, the operator can estimate proper length of instrumented canal to correct the WL at ultimate steps. The virtual pathway of the canal lively intuitively displayed on the screen of the computer assists the operator in effective visualization and management of the root canal instrumentation. Although there were many advantages in using the 3D Endo software, the result showed that the proposed length of the program disagreed with the AL. With the voxel size of 0.10 mm, the resolution of the image acquired from the CBCT device might appropriate for WL determination, however, accessed teeth were used for evaluation might lead to occlusal structure missing on the reconstructed image and might lead to inaccurate determination by the software. The result showed that the correct length by the operator agreed with the AL and obtained the highest accuracy between ± 0.5 mm in three CBCT data modalities.
The human extracted teeth are commonly used for studies using CBCT in WL determination in dry mandible or in jaw model [12,13,14]. The setting with the dry mandible is better than other design in controlling of certain clinical variables such as artifacts caused from position or motion of patient, beam hardening from other materials, or noise from other anatomic structures [12, 14]. The arrangement of teeth in the impression tray of the present study induces certain artifacts from the neighboring teeth in the tray. However, CBCT images are clear and anatomic landmarks are defined easily and exactly with no interferences. Although the human extracted teeth seem appropriately for evaluation the accuracy of CBCT WL determination, the artificial endodontic training tooth still completely satisfies requirements of this purpose [15]. Authors of that study just select the actual root canal length of the artificial tooth as the gold standard in evaluation the accuracy of the CBCT WL without EAL measurements [15]. The 3D Endo software can enhance accurate 3D root canal length determination, however, the working length has to be checked, controlled, and maintained continuously during the preparation phase to detect possible length changes, especially in the severe curved canal [15].
CBCT is an added method for determination of WL, particularly valuable with retreatment when removing gutta-percha to save time and prevent over-instrumentation [6]. One of the important shortcomings when using the CBCT for endodontic WL determination on the heavily metallic restored tooth is the significant artifact [6]. More artifact means a greater approximate range of length, and in these cases, CBCT provides only an estimate of the length. Sometimes neighboring structure assists in estimation of an approximate length [6]. In the present study, the Romexis Viewer measurements agreed with the AL, although the accuracy in the range of ± 0.5 mm was lowest among all other methods. The voxel size of 0.10 mm in the present study seemed appropriate for endodontic length measurements with the acceptable result.
With the advance of technology in production of more and more modern root canal instruments [16, 17], and the complexity of the root canal morphology [18], the more important role of the endodontic length determination is.
Knowledge of root canal anatomy and morphology is essential for every clinician in endodontics in identifying the root canal orifices. CBCT imaging has offered a precise, noninvasive, real-time approach for clinical chairside evaluation of root canal anatomy and morphology [5]. The 3D Endo software, dedicated endodontic program using CBCT data, is an effective, quick, and easy modality for identification and visualization of canal trajectories and confluences in three dimensions. This Endo software shows promise in help for operators quantifying anatomical complexities preoperatively [19].
Diagnostic examinations should be performed at the lowest dose of radiation, following the ALARA principle: as low as reasonably achievable [20]. Therefore, CBCT scans should only be performed when indicated, and consideration should be given to alternative modalities. The American Association of Endodontists statement suggests that the risk-benefit ratio is too high for CBCT to be used as a screening tool, even though the radiation levels are low with focused-field imagers [21]. Therefore, CBCT scans used as a routine procedure for endodontic diagnostic should be strictly indicated and application of CBCT only for root canal length measurement is not recommended [15]. In cases with the pre-existing CBCT owing to the other reasons but endodontics, the 3D Endo software is an invaluable instrument in root canal morphological investigation, treatment planning, and especially in working length determination [15].
The EAL still had the highest accuracy in the range of ± 0.5 mm, as shown by the result of the present study. However, this modality disagreed with the AL that could lead to overemphasize this device’s capability.
