Low-dose, standard, and high-resolution cone beam computed tomography for alveolar bone measurements related to implant planning: An ex vivo study in human specimens.

AIM: To evaluate the performance of low-dose cone beam computed tomography (CBCT) protocols with regard to linear bone measurements in the posterior mandible for implant planning compared with higher dose protocols. MATERIALS AND METHODS: Forty-two edentulous posterior sites in human cadaveric mandibles were imaged in three CBCT scanners using three or four protocols with varying exposure parameters to achieve lower dose. Co-registration was performed to generate sagittal and cross-sectional image sections representative of the implant site. Three observers measured bone height, from the alveolar crest to the mandibular canal, and width, three mm from the top of the alveolar crest. Intra- and interobserver reproducibility were assessed for the cases rated as nonmeasurable as well as for completed measurements. The measurements were analyzed using paired t-tests for differences among the CBCT protocols and the frequency distribution of nonmeasurable cases with a Pearson Chi-square test. RESULTS: Reproducibility for registering nonmeasurable cases varied among observers; however, no consistent significant differences were found in the frequency distribution of these cases among observers, units, and protocols. Intraclass correlation coefficients (ICC) were >0.9 for all measurements of bone height and width. Mean differences of <0.5 mm were found regardless of protocol; however, one observer did in some cases produce larger differences. CONCLUSION: Linear bone measurements did not differ significantly and could be performed with excellent reliability, using low-dose CBCT protocols compared with standard and high-resolution ones. Varying approaches for rating nonmeasurable cases were found, indicating differences in diagnostic strategies related to implant planning among observers.

Low-dose CBCT protocols in implant dentistry: a systematic review.

OBJECTIVE: To evaluate the state-of-the-art evidence for applying low-dose CBCT protocols in 3 stages of implant therapy (planning, insertion, and follow-up examination of peri-implantitis) and assess the overall body of evidence presented in the literature. STUDY DESIGN: The search was conducted in the MEDLINE/Pubmed and Scopus databases. Studies comparing low-dose CBCT protocols to a relevant reference standard in relation to any stage of implant therapy were included. Data extraction and quality assessment were performed for all included studies. RESULTS: Sixteen studies were included. Low-dose protocols were reported to result from reduction of the exposure parameters of kV, mA, resolution (through increased voxel size), exposure time, and scanning trajectory. The current literature suggests that low-dose CBCT protocols perform similarly in the 3 stages of implant therapy compared to higher resolution protocols regarding objective measurements, with adverse impacts mostly on subjective assessment of image quality. The results also suggest that CBCT-based bone measurements are similar to direct measurements, independent of the imaging protocol. Reduction in all parameters except kV seems feasible as the basis of low-dose CBCT protocols for implant therapy. CONCLUSIONS: The use of low-dose CBCT protocols does not impact objective image quality assessment in any stage of implant therapy. Clinical studies are needed to indicate if the reported results can be extrapolated to improve patient care in relation to the responsible use of ionizing radiation.