Evaluation of a new low dose CBCT imaging protocol for measuring circumferential bone levels around dental implants

Abstract

The objective of this study was to evaluate whether linear accuracy and metallic scatter artifact generated between 360 degree and 180 degree Cone Beam Computed Tomography (CBCT) acquisition protocols were significantly different during evaluation of peri-implant bone levels. On ten dentate dry human skulls, dental implants were placed at two posterior mandibular implant sites in each skull, one on left and one on right, totaling 20 sites for each protocol. CBCT scans using both acquisition protocols were made on each site. The conventional 360 degree protocol contained: (Parameters: (90 kV -10 mA), 120mm x 100mm focused field of view (FOV) and 17.5 (s) exposure). The low radiation dose 180 degree protocol contained: (parameters: (80kV -2mA), 120x 100mm FOV and 9.0 (s) exposure). There was a significant difference between metallic scatter acquired by pixel intensity values during bone density measurements between 360 degree acquisition and the 180 degree acquisition (Mesial Left p=0.00; Mesial Right =0.00; Distal Left 0.51; Distal Right p=0.02; Buccal Left p=0.00; Buccal Right p=0.43; Lingual Left p=0.00, Lingual Right p=0.03). There was no significant difference in linear accuracy of measurements (Mesiodistal Left p=0.36; Mesiodistal Right p=0.13; Buccolingual Left p=0.70; Buccolingual Right p=0.92). Sensitivity and specificity of both acquisition protocols were comparable. These results dictate that low dose acquisition protocol has comparable linear measurement accuracy to conventional acquisition protocol. Additionally, there is a significant decrease in the metallic scatter, thus making the low dose 180 degree protocol significantly better for evaluating peri-implant bone levels following dental implant placement.