HISTOLOGIC ANALYSIS OF CLINICALLY RETRIEVED TITANIUM MICROIMPLANTS PLACED IN CONJUNCTION WITH MAXILLARY SINUS FLOOR AUGMENTATION

In this study, a new approach involving placement and subsequent retri eval of titanium microimplants was employed for the histologic investi gation of the implant-tissue interface in conjunction with maxillary s inus floor augmentation. Nine patients scheduled for sinus floor augme ntation and simultaneous placement of Branemark implants were included in the study. After a sinus graft procedure and placement of implants , an additional microimplant was placed into the graft through the lat eral wall of the sinus. At abutment connection, the microimplants were retrieved using a 3- or 5-mm-wide trephine drill. Six specimens were retrieved after 6 to 14 months from sites augmented with particulate r adiated mineralized cancellous allograft. Another six implants were re trieved after 6 to 12 months from maxillary sinuses augmented with par ticulate autogenous bone grafts. The histologic analysis showed distin ct differences between the two types of grafts. The sites with autogen ous bone grafts displayed a normal morphology of bone and bone marrow including formation of bone on the surfaces of the grafted particles a nd remodeling of newly formed as well as grafted bone. The bone was mo re mature after 11 to 14 months than at 6 months. The allografted site s had a mixed morphologic appearance of newly formed bone and nonviabl e allograft particles (about 75% of the total bone area) in loose conn ective tissue. Significantly more bone was found at the autografted th an at the allografted implants. The use of autogenous bone for augment ation of the maxillary sinus floor resulted in a greater amount of via ble bone surrounding the implant; however, simultaneous placement of i mplants apparently resulted in a low proportion of bone-implant contac t after 6 to 14 months irrespective of graft type.