Effects of CBCT acquisition protocol and additional superimposed computerized optical impressions on the accuracy of root canal length measurements: an ex vivo study

Aim: The purpose of the present investigation was to evalu-ate the accuracy of root canal length (RCL) determination according to CBCT acquisition protocol and evaluate the influence of additional superimposed computerized optical impressions. Materials and methods: CBCT scans with low-dose (LD) and high-definition (HD) protocols as well as computerized opti-cal impressions of 30 extracted human molars were acquired. Sicat Endo software (Sicat) was used for CBCT RCL measurements with (LD+, HD+) and without (LD-, HD-) a superimposed optical impression. To evaluate the accuracy, absolute differences between test groups and the actual root canal length (ARCL) were calculated and statistically ana-lyzed using the Wilcoxon rank sum test. Results: Absolute differences between the ARCL and the tested measurement methods varied significantly (P < 0.05). Both higher resolution and additionally superimposed com-puterized optical impression improved measurement accur-acy. Mean differences compared with the ARCL were 0.26 mm (HD+), 0.34 mm (HD-), 0.43 mm (LD+), and 0.66 mm (LD-). 93.4% of all measurements in the HD+ group were within the limits of ± 0.5 mm. Conclusion: Both resolution and superimposition of addi-tional computerized optical impressions have a significant influence on RCL measurements using CBCT.