Root Canal Location Accuracy: Dynamic Navigation Verses Freehand in Extracted Human Molars – A Randomized In Vitro Study

OBJECTIVES: To compare the accuracy, instrumentation time, and success rate of three dynamic navigation systems (DNSs)-infrared-active (IA), infrared-passive (IP), and visible light-passive (VP)-with freehand (FH) operation in locating root canals of maxillary and mandibular molars, providing a basis for technique selection in complex endodontic treatments. METHODS: Ninety-six extracted human mandibular molars were randomly assigned to four groups (n = 24/group): IA-DNS, IP-DNS, VP-DNS, and FH (control). Specimens were embedded in plaster and scanned with CBCT (0.3 mm slice thickness). In DNS groups, fiducial markers enabled real-time tracking of the bur position. The FH group used a microscope with CBCT reference. Recorded parameters included: angular deviation (°), three-dimensional deviations at entry and target points (mm), instrumentation time (s), tooth structure loss (mm³), and success rate of canal location. Data were analysed using ANOVA and chi-square tests (α = 0.05). RESULTS: DNS demonstrated significantly higher accuracy than FH. Angular deviations in DNS groups (IA: 0.64° ± 0.34°, IP: 0.59° ± 0.32°, VP: 0.63° ± 0.24°) were 94.3% to 94.7% lower than FH (11.03° ± 4.70°) (P < .001). Three-dimensional deviations at entry (0.57-0.70 mm) and target (0.59-0.80 mm) were significantly smaller than FH (1.64 mm and 1.26 mm, respectively; P < .001). Tooth structure loss in DNS groups (9.79-11.03 mm³) was reduced by 26.8% to 34.6% compared to FH (14.98 mm³; P < .001). No significant difference in operative time was observed among groups (176-183 s, P > .05). Success rate was significantly higher in DNS groups (99.54%, 215/216) than FH (93.06%, 67/72; P = .004). No significant differences were observed among the three DNS types for any parameter. CONCLUSION: DNS significantly enhanced accuracy of root canal location in molars, reducing angular deviation by >94%, minimizing tooth structure loss by >26%, and increasing success rate to 99.5%. Performance was consistent across different optical principles and signal mechanisms, supporting DNS as a viable option for precise management of calcified canals and other nonsurgical endodontic procedures.