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 (320mg/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.