Excessive lateral dental arch expansion in experimentally developed acromegaly-like rats

Objective: To investigate morphological changes in the dental arches of acromegaly-like rats recently developed by means of exogenous IGF-I administration. Design: Human recombinant IGF-I (640 μg/day) was continuously administered subcutaneously for 4 weeks by osmotic mini-pumps to 10-week-old male rats (n = 6). Control animals were injected with saline alone (n = 6). After administration, all the rats were housed for 4 more weeks. Arch width (W), length (L) and angle (θ) in the mandible and maxilla were measured once a week during and after IGF-I administration. Results: The concentration of circulating IGF-I, and W and θ in the mandible were significantly increased as compared with the control rats. Although the mandibular dental arch stopped expanding once administration ended, it did not return to the control size. Conclusions: In our acromegaly-like rat model, mandibular dental arch growth is greater in the lateral than antero-posterior direction during and after IGF-I administration.