Targeted Endodontic Access Preparation: Comparing Grid-guided and Freehand Cone-beam Computed Tomography Techniques.

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Endodontic access is often one of the most challenging aspects of treatment, particularly in cases involving locating calcified or missed canals, or when performing selective retreatments of a targeted root. Therefore, the purpose of this study is to compare the accuracy of targeted accesses made using prefabricated grid to those made using freehand techniques with cone-beam computed tomography (CBCT) measurements. Twenty extracted maxillary molars were mounted into the TrueJaw maxillary model (PlanB Dental, Goleta, CA). To replicate a clinical scenario where the tooth is extensively restored or has a calcified pulp chamber, the build-up material was intentionally placed directly over the canal orifices. Each of the teeth were prepared for zirconia crowns and once fabricated, these crowns were cemented. The teeth were randomly assigned to either the CBCT freehanded group or the grid-guided group. Preoperative CBCT scans were taken to determine the preplanned drill path, and these scans were superimposed on the postoperative CBCT's taken after the targeted access was completed. The factors evaluated included deviations from the preplanned drill path, procedural times, and adjustments if necessary. The grid-guided technique achieved a significantly smaller deviation from the planned access target (median 0.3mm) compared to the freehand technique (median 0.95mm, P=.00001). However, the grid-guided approach required significantly more procedural time (417seconds) than the freehand method (P=.00008). The grid-guided technique is a viable and accurate method for achieving targeted access to hard-to-reach canal orifices. Further studies are needed to evaluate its application in clinical settings.