Evaluation of Cone Beam Computed Tomography Resolution, 3D Printing Resolution and Drilling Depth on Drilling Accuracy in Guided Endodontics: An In-Vitro Study

Objective: The aim of this study was to evaluate the influence of cone-beam computed tomography (CBCT) resolution, 3D printing resolution, and drilling depth on drilling accuracy in guided endodontic access. Methods: Fifty-six printed canines were designed, fabricated, and mounted in maxillary arch models. Preoperative CBCT and 3D surface scan were matched and used to design a surgical guide with different planning parameters: 1) reference (high-resolution CBCT (80 mu m) and 3D printing (50 mu m), shallow drilling (14 mm), 2) low-resolution CBCT (120 mu m), 3) low-resolution 3D printing (100 mu m) and 4) deep drilling (high-resolution CBCT (80 mu m) and 3D printing (50 mu m), deep drilling (21 mm). Guided access into the printed canines was performed in a simulated clinical setting. A postoperative CBCT was matched with the planning data in order to determine the angular and linear (total, mesiodistal, buccolingual and depth) deviation between the planned and performed cavities. Mann-Whitney test was used to analyse differences between the reference group and each test group. Results: Angular, total linear and buccolingual deviations were significantly higher in the low-resolution CBCT group than in the reference group (median: 3.10 degrees and 2.0 degrees (p<0.01), 1.41 mm and 1.06 mm (p<0.05) and 0.77 mm and 0.41 mm (p<0.05), respectively). Depth deviation was significantly higher in the low-resolution 3D printing group than in the reference group (median: 0.90 mm and 0.45 mm (p<0.01), respectively). No other significant differences between the groups were noted (p>0.05). Conclusion: Higher CBCT resolution resulted in lower angular and total linear deviation during guided endodontic access. Higher 3D printing resolution yielded lower vertical linear deviation.