Influence of Depth and Choice of Operating Instruments on the Precision of Dynamic Navigation Systems.

Objective: To evaluate the precision and efficiency of dynamic navigation-assisted trephines and fissure drills at varying depths utilising a 3D printed model.

Methods: A computer-designed in vitro standardised model was 3D printed using photosensitive resin, with hemispherical cavities reserved at depths of 5, 10 and 15 mm from the outer surface of the model. CBCT scans were taken before the procedure, and the data were imported into dynamic navigation software. Navigation paths were planned and executed using a trephine with a diameter of 4 mm and a fissure drill with a diameter of 1.2 mm guided by the dynamic navigation system. Ten procedures were performed at each depth. Postoperative CBCT scans were taken to reconstruct the navigated trajectories, and the platform deviations, end deviations and angular deviations were calculated by comparing the actual paths with the planned paths. The operating time was recorded.

Results: Under the guidance of the dynamic navigation system, the mean platform, end and angular deviations for trephines were 0.34 ± 0.17 mm, 0.25 ± 0.15 mm and 1.02 ± 0.49 degrees, respectively. For fissure drills, the mean deviations were 0.29 ± 0.13 mm, 0.31 ± 0.18 mm, and 1.33 ± 0.98 degrees, respectively. No significant differences were found with different depths or instrument types (P > 0.05). High-speed handpieces with fissure drills showed superior efficiency to low-speed handpieces with trephines (P < 0.001).

Conclusion: Dynamic navigation technology achieved good accuracy within a 15-mm depth range. The use of a trephine or fissure drill did not affect the accuracy of the dynamic navigation technique. High-speed handpieces with fissure drills showed superior efficiency.