Histology of periimplant bone: confocal-laser-scanning-microscopy (CLSM) and conventional light microscopy

Objectives: The standard technique for the histologic evaluation of dental implants is light microscopy of stained thin sections using the sawing/grinding technique (Donath and Breuner 1982). A less time and resources consuming method would be desirable. The aim of this study was to correlate the histology of the periimplant organic structures in 1) non- decalcified, unstained bone-implant blocks using CLSM in reflection mode and 2) stained thin sections using the standard sawing/grinding technique and conventional transmission light microscopy. Methods: 60 dental implants (6 different types) implanted in the mandible and maxilla of beagle dogs were studied. The implants were embedded in PMMA (Technovit) and hemi-sectioned along their long axis. The non-decalcified, unstained blocks were studied by CLSM (Leica) in reflection mode (633nm). With 10x magnification a series of individual images was recorded (squares of 1,5 mm, 1024 * 1024 pixel). By animated computer reconstruction the whole implant could be mapped. Subsequently the identical samples were grinded to 70µm thickness and stained with hematoxillin and eosine. Conventional light microscopy (same specifications as CLSM with respect to lateral resolution) was performed. Results: High contrast images for qualitative histologic evaluation of the periimplant bone were obtained by both technologies. Intercomparison of both techniques revealed similar assessment of the periimplant bony structures. Histomorphometric analysis of the unstained samples was possible using a simple threshhold technique. Conclusions: The CLSM technique in reflection mode can be used as a semi-automatic, standard technique for evaluation of peri-implant bone. As the evaluation of unstained, non-decalcified bone blocks requires fewer preparation steps, it is less time consuming and might reduce possible effects of the grinding and staining process.