Calcification at the interface between titanium implants and bone: observation with confocal laser scanning microscopy.

It has not been previously possible to observe bone formation in undecalcified sections with titanium implants at high magnification because of the difficulty in sectioning bone together with implants. A method for examining the bone-implant interface in undecalcified sections is described in which implants are left in situ and confocal laser scanning microscopy (CLSM) is used to examine both the implant surface and adjacent bone. Pulsing of animals at different times with the fluorescent dyes calcein and alizarin red permitted assessment of temporal patterns of bone formation by CLSM. Reflectivity of the polished implant surface permitted accurate assessment of the position of the implant relative to labeled bone. The analysis showed that bone first formed as thin processes towards and across the implant surface, followed by further bone formation behind these processes. The interface between calcified bone tissue and the implant surface was characterized by a 10-microm space. The CLSM technique enabled detailed observations of new bone formation at the titanium implant interface.