Insulin-Like Growth Factor I Inhibits Alveolar Bone Loss Following Tooth Extraction in Rats

Background Alveolar bone is often lost after tooth extraction. Few studies have assessed the longitudinal changes in bone volume that occur within these extraction sites. Purpose To investigate the longitudinal morphological changes in extraction sockets following sustained continuous subcutaneous infusion of human recombinant insulin-like growth factor I (IGF-I). Materials and Methods Fourteen rats were subjected to right mandibular first molar extraction. Experimental rats (n = 7) received a continuous subcutaneous infusion of human recombinant IGF-I (320 mg/day) for 3 weeks by osmotic minipump. Control animals were treated with saline via the same method (n = 7). All rats were then housed for an additional 3 weeks. Micro-CT scanning was performed immediately after tooth extraction and at 1, 2, 3, and 6 weeks after extraction. Results New bone formation was markedly higher in the IGF-I-treated group as compared with the control group. The loss in alveolar ridge height in the IGF-I group was significantly lower than that in the control group at each time point after extraction on the buccal side and at 2, 3, and 6 weeks on the lingual side. Conclusions IGF-I treatment increases the volume of newly formed bone and reduces the loss in alveolar ridge height following tooth extraction.