A new standardized-automatic method for bone-to-implant contact histomorphometric analysis based on backscattered scanning electron microscopy images.

AIM To establish an image analysis procedure for measuring the bone-to-implant contact (BIC) by a systematic non-subjective approach based on backscattered scanning electron microscopy (BS-SEM) images. MATERIAL AND METHODS A total of 36 dental implants (9 mm length, Ø 4.0 mm with a SBM surface) were implanted in six beagle dog mandibles. The implants were removed after 1, 2, 4, 6, and 8 weeks and then embedded in resin and cut along their long axis. Sample observation was performed by BS-SEM, acquiring 10 to 16 images per sample. Image processing and BIC determination were performed using the Fiji image processing package. Images were stitched, filtered, and thresholded to obtain a binary image of the whole implant that finally was dilated and outlined. The length of this outline was measured as the maximum possible BIC. The regions of coincidence between this line and the bone were measured as the real BIC. RESULTS The proposed methodology for BIC determination, based on SEM, which has a much higher resolution than optical microscopy, allows the acquisition of highly discriminative images with great contrast between implant and bone. The high resolution and high contrast in SEM images provide more accurate results than those obtained by classical methods. Furthermore, the methodology of image analysis described in this study delineates precisely and automatically the contour of the implant, which results in non-biased measurements. The average percentage of BIC was 35%, ranging from 24.7 to 45.5%. These values were similar to the results documented in the literature for implants of similar roughness in animal models. CONCLUSIONS A novel, non-subjective, and systematic method for measuring BIC is described based on BS-SEM images. The proposed methodology minimizes the shortcomings of the results obtained by previously described methods.