BACKGROUND: Long-term success of implant treatment depends on the integrity of bone-implant interface. Besides clinical features, imaging exams are used to monitor changes in this area. 2D images are commonly used but they have distortions and generate image
superimposition between buccal and lingual bone. Development of CBCT in Dentistry provide a detailed volumetric reconstruction (3D), of a region of interest. Afterwards, superimposition techniques may be used to detect dimensional changes in this area.

AIM/HYPOTHESIS: To present a dental informatics methodology to measure volumetric changes in the bone level around dental implants.

MATERIALS AND METHODS: Sample composed of 46 dental implants (6mm length and 4.1 mm diameter) placed in the posterior maxilla and mandible in 20 patients. All implants received screw-retained single crowns. Two distinguished radiographic images were used: cone beam
computed tomography (CBCT) and digital periapical radiography; at three different times: after implantation and 12 and 24 months of
functional loading. Tridimensional (3D) reconstructions of the bone perimeter closest to the implant were developed, superimposed and volumetrically measured. Linear measures of bone levels were made in periapical radiography images. Multilevel regression model tested volumetric and linear bone loss data.

RESULTS: Due to deviations in the methodology, some patients were dismissed / excluded from this research. Volumetric changes during the
first year of function were measured in 30 implants, in 34 implants during the second year of function, and accumulated changes during both years were measured in 27 implants. Mean peri-implant linear bone loss was 0.2±0.4 mm in the first year, and 0.1±0.2mm in the second year. Mean volumetric bone loss was 7.2±6,1 mm3 for the first year, and 6.4±7.8 mm3 for the second year of function. The 2D and 3D analysis estimated that an increase of 1 mm of linear bone loss was associated with a mean volumetric bone loss of approximately 14 mm3 (p < 0.001).

CONCLUSIONS AND CLINICAL IMPLICATIONS: Measuring volumetric bone changes around implants is possible with CBCT images, as long as they have proper contrast and sharpness, specially around the implant outline. Improvements in the image quality for bone tissue detection may allow a faster analysis to be easily applied in the dental office, and not so depended on the examiner skills. The findings showed that linear and volumetric bone loss measures are related.

Volumetric bone changes around dental implants – the use of 3D image superimposition