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 evaluate 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 optical 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 analyzed 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 computerized optical impression improved measurement accuracy. 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 additional computerized optical impressions have a significant influence on RCL measurements using CBCT.