Experimental Study of Changes in Mobility and Surrounding Bone with Immediately Placed Implants

Abstract

Implant placement into the extraction socket immediately after extraction has been attempted. It is important to determine the condition of the bone surrounding the implants, using X-ray images and mobility measurements. In the present study, we determined the mobility of implants which were placed into extraction sockets immediately after extraction,and observed the changes of bone tissue surrounding the implants over time and investigated the relation among three categories. Furthermore, we examined whether such findings could be used to specify the time of osseointegration and of superstructure set.
Implants were placed into extraction sockets immediately after extraction of upper lateral incisors for experimental animals and mobility was measured over time starting just after implant placement. In addition, the tissues surrounding the implants were observed using bone-microvascular corrosion cast specimens and bone volume was analyzed using soft X-ray images.
Implant mobility was decreased just after implant placement to 2 weeks, and then increased to 4 weeks and was stable to 12 weeks after implant placement.Bone formation was partly observed surrounding implants from 2 weeks after placement, and bone formation became vigorous at 4 weeks after placement. In addition, bone volume was increased at 4 weeks after implant placement.
From these findings, we considered that the mobility of implants placed immediately after extraction corresponded to postoperative changes of the bone tissue surrounding the implants. Accordingly, we concluded that the time of osseointegration could be determined on the basis of mobility measurements, and that such measurements are useful for determining the time of superstructure set.