Oblique or orthoradial CBCT slices for preoperative implant planning: which one is more accurate?

Aim: To assess which slice inclination would be more accurate in measuring sites for implant placement: the oblique or the orthoradial slice. Methods: Five regions of eight edentulous mandibles were selected (incisor, canine, premolar, first molar and second molar). The mandibles were scanned with a Next Generation i-CAT CBCT unit. Two previously calibrated oral radiologists performed vertical measurements in all the selected regions using both the oblique and orthoradial slices. The mandibles were sectioned in all the evaluated regions in order to obtain the gold standard. The Wilcoxon signed rank test compared the measurements obtained in the oblique and orthoradial slices with the gold standard. Results: The bone height measurements for the first and second molar regions using the orthoradial slices were statistically different from the gold standard. Conclusions: Using the orthoradial slices to obtain cross-sectional images may offer insufficient accuracy for implant placement in the posterior region.