Bone microstructure evaluation near unloaded dental implants combining confocal scanning laser microscopy, circularly polarized light microscopy, and SEM backscattered electrons imaging.

The aim of this report is to present a new investigative approach to implant dentistry based on the correlation of qualitative and quantitative data reported on the same figure by overlapping different images collected on the specimen with different investigative systems. Six unloaded titanium dental implants retrieved with peri-implant bone from the mandible of 2 patients after a 6 month period were used in this study. Samples of the peri-implant tissues embedded in resin were imaged by scanning electron microscopy using backscattered electrons signal (SEM BSE), confocal scanning laser microscopy (CSLM) and circularly polarized light microscopy (CPLM). The SEM BSE images were used to identify the different levels of mineral density. The CSLM images provided all the information on cells and bone marrow spaces. The CPLM images gave the collagen fibre orientation. To overlap the images we used a program introduced by Alan Boyde, based on a linear transformation matrix which projects one system onto the other. The total bone area investigated was of 695x10(3) pixels. The low mineral density index was 40.1, with an extension area of 344x10(3) +/- 23x10(3) pixels (mean +/- SD) while the high mineral density index was 54.8 with an extension area of 317x10(3) +/- 22x10(3) pixels (mean +/- SD). Transverse collagen fibers showed an extension area of 201x10(3) +/- 25x10(2) pixels (mean +/- SD) (28.9%), while the area for longitudinal orientation was 282x10(3) +/- 19x10(2) pixels (mean +/- SD) (40.6%). The marrow spaces showed an extension of 113x10(3) +/- 24x10(2) pixels (mean +/- SD) (16.3%). This method demonstrated that bone near unloaded implants showed almost the same extension for longitudinal and transverse collagen fibre with a predominantly low mineral density index closest to the implant surface.