Effect of alendronate on healing of extraction sockets and osseointegration of implants in the maxilla of rats : histologic analysis

Abstract

Purpose: Bisphosphonates related osteonecrosis of the jaw (BRONJ) has been observed following tooth extraction. The causes of BRONJ are not yet clearly revealed. There are many possible contributing factors to BRONJ. Because of BRONJ, there are rising concerns of the effects of bisphosphonates on the osseointegration of implants. The effect of bisphosphonates on the healing of extraction sockets has been studied by many other researchers. However, very little is known on its effect on osseointegration of implants, and this remains controversial. The purpose of this study was to evaluate the effects of bisphosphonates (alendronates) on healing of extraction sockets and osseointegration of implants in the maxilla of rats. Materials & Methods: 24 Male Sprague-Dawley rats (4weeks old) were divided into the bisphosphonate (bispho) and control groups. In the bispho group, rats were subcutaneously injected with alendronate (5.0 ㎎/㎏) 3 times a week for 4 weeks. Following the injections for 4 weeks, both sides of the maxillary first molars were extracted, and customized titanium implants (Ø1.5 X 2.0 ㎜) were placed immediately into the right extraction sockets after osteotomy. Rats were sacrificed at 3, 7, 14, or 28 days following surgery. The specimens were collected by perfusion fixation with 4% paraformaldehyde. The healing of the extraction sockets and osseointegration of the implants were evaluated by radiographic and histologic analyses.Results: New bone area in the extraction sockets did not differ between the bispho group and control group at any observation time points, however, the empty lacuna was observed significantly more in bispho group than in control group at 7 days after extraction. Bone implant contact did not differ between them, however, bone area around the implant was significantly larger in bispho group at 14 days after implantation, and the number of empty lacuna was observed significantly more in bispho group than in control group at 14 days and 28 days after implantation. Conclusion: Based on the limited outcomes, alendronates did not delay the healing of extraction sockets and osseointegration of the implants. Although the function of osteoclast seemed to be decreased in the bispho group, bone formation seemed not to be decreased in the bispho group. The significant differences of the amount of empty lacuna were occurred more later time of healing in implants compared to the healing of extraction sockets. Therefore, long term effects of alendronate on osseointegration of implants are needed for the further studies.