Measurement of the interface between bone and immediate endosseous implants: a pilot study in dogs

This study developed methodology to evaluate the healing of 15 IMZ implants placed in the sockets of freshly extracted mandibular premolars in three adult mongrel dogs. Six surgical sites were prepared in each animal and one site was left as a control. Porous hydroxyapatite was placed around the top half of two implants in each animal; one implant was also covered with polytetrafluoroethylene membrane. All implants were covered with a mucoperiosteal flap and sutured closed. Upon animal sacrifice, the mandibles were retrieved for block dissection and the blocks were embedded in plastic. Serial longitudinal wafers were ground to 50 to 100 microns and stained. Standard photomicrographs were taken so that tracings of the implant-bone interface could be measured on a sonic digitizer. The mean percent amount of bone to plasma-sprayed portion of the implant on the longitudinal sections was 47.9% +/- 5.2% with a range of 17.4% to 84.7%. The horizontal sections were measured at 53.5% +/- 3.7% with a range of 0.0% to 100%. This pilot study suggests that IMZ implants placed in fresh extraction sockets can achieve a degree of intimate contact with bone; however, wide variation in the implant-to-bone interface was found even in the same specimen.