Measuring Peri-implant Bone Lesions Using Low-dose CBCT

Objectives: Low dose cone beam computed tomography (LD-CBCT) protocols are used for three-dimensional dental imaging. High definition CBCT (HD-CBCT) offers improved image quality at the cost of a higher radiation dose. The aim of this in-vitro study was to investigate whether peri-implant bone lesions can be accurately quantified using LD-CBCT. Moreover, the influence of surrounding hard tissues should be evaluated.
Methods: Twelve titanium dental implants with all-ceramic single crowns were placed in bovine bone. Four different types of peri-implant bone lesions were prepared. The lesions (1mm in width and depth) were created with a round diamond bur and exposed to 70% perchloric acid for four hours. Radiographic imaging was performed using small field-of-view HD-CBCT and LD-CBCT. Subsequently, all samples were placed inside a dry human mandible, i.e. adjacent to natural teeth and bone. In this set-up, additional LD-CBCT imaging was indicated as LD-CBCT*. In random order, the datasets were presented to four observers. Maximum lesion depth and width were measured in a standardized CBCT slice in HD-CBCT, LD-CBCT, and LD-CBCT*.
Results: Mean lesion depth and width measurements using HD-CBCT served as the reference. The deviation in LD-CBCT without surrounding hard tissues was 0.20±0.16mm for depth and 0.21±0.14mm for width. For LD-CBCT*, the deviation was 0.28±0.33mm for depth and 0.29±0.34mm for width. A significant difference between LD-CBCT and LD-CBCT* was detected for both measurements.
Conclusions: Although surrounding hard tissues decrease LD-CBCT image quality, the absolute differences to HD-CBCT were minor. Given the usual limitations of an in vitro trial, LD-CBCT might be an interesting tool for monitoring peri-implant lesions at a substantially decreased radiation dose.