Contrast-to-noise ratio with different settings in a CBCT machine in presence of different root-end filling materials: An in vitro study

Objectives: To compare the contrast-to-noise ratio (CNR) of multiple acquisition settings for four types of retrograde filling materials in CBCT images taken for endodontic surgery follow-up. Methods: 20 maxillary central incisors were endodontically treated and obturated with 4 different root-end filling materials: Amalgam, mineral trioxide aggregate, SuperEBA™ (Harry J Bosworth Company, Skokie, IL) and Biodentine™ (Septodont, Saint-Maur-des-Fausśes, France). Teeth were placed in a skull and scanned, one by one, with the Planmeca ProMax® 3D Max (Planmeca, Helsinki, Finland); at different voltages: 66, 76, 84 and 96kVp; with low, normal and high resolution and high definition (HD); with and without metal artefact reduction (MAR). Images were analyzed using ImageJ software (National Institutes of Health, Bethesda, MD) to calculate the CNR. The dose-area product was registered, and the effective dose calculated. Results: No statistically significant difference was noted between the four materials. 84 and 96 kVp with low resolution and the use of MAR-generated images that have statistically better CNR than 66 and 76 kVp with HD, normal and high resolutions and without MAR. The use of low resolution also generated the smallest value of effective dose. Conclusions: The best setting for radiographic follow-up in an endodontic surgery with retrograde filling on the Planmeca ProMax is 96 kVp with low resolution and high MAR; this setting produced one of the lowest effective doses.