Volumetric bone measurement around dental implants using 3D image superimposition: a methodological and clinical pilot study

Purpose: This study describes the development of a methodology for using three-dimensional (3D) image superimposition to measure volumetric changes in bone level around dental implants in comparison with linear measures. Materials and Methods: The sample was comprised of 46 dental implants of 6-mm length and 4.1-mm diameter placed in the posterior maxilla and posterior mandible in 20 patients. All implants received screw-retained single crowns. Radiographic images were taken using cone beam computed tomography (CBCT) and digital periapical radiography after implantation and after 12 and 24 months of functional loading (after crown placement). Tridimensional reconstructions of the bone perimeter closest to the implant were developed, superimposed, and volumetrically measured. Linear measures of bone levels were recorded in periapical radiography images. A multilevel regression model tested volumetric and linear bone loss. Results: The mean peri-implant linear bone loss for the first and second years was 0.2 ± 0.4 mm and 0.1 ± 0.2 mm, respectively, and the mean volumetric bone loss for the first and second years was 7.2 ± 6.1 mm3 and 6.4 ± 7.8 mm3, respectively. It was estimated that an increase of 1 mm of linear bone loss was associated with a mean volumetric bone loss of approximately 14 mm3 (P < .001). Conclusion: The findings showed that linear and volumetric bone loss measures are related. Measuring volumetric bone changes around implants is possible provided that the CBCT images have proper contrast and sharpness, particularly around the implant outline. Improvements in image quality and in the filters for bone tissue detection would be important for this methodology to be made faster and used clinically.