IADR Abstract Archives
Excessive Lateral Dental Arch Expansion in Experimentally Developed Acromegaly-like Rats
Objectives: Insulin-like growth factor-I (IGF-I) acts downstream of growth hormone and promotes growth in various tissues in patients with acromegaly. We have previously shown that exogenous administration of IGF-I stimulates acromegaly-like specific mandibular enlargement in rats. Information about changes in the size and form of the dental arch is important for clinicians in orthodontics, prosthodontics and oral surgery. Hence, the aim of this study is to investigate morphological changes in the dental arches of the acromegaly-like rats developed by means of exogenous IGF-I administration.
Methods: Human recombinant IGF-I (640mg/day) was continuously administered subcutaneously for 4 weeks by osmotic mini-pumps to 10-week-old male rats (IGF-I group; n=6). Control animals were injected with saline alone (control group; n=6). After administration, all the rats were housed for 4 more weeks. Arch width (W), length (L) and angle (q) in the mandible and maxilla were measured on a plaster dental model of the animal, and rat and human IGF-I serum levels were measured by radioimmunoassay once a week during and after IGF-I administration.
Results: Human IGF-I was detectable in the IGF-I group during administration, whereas the rat IGF-I decreased. Total IGF-I (human + rat) increased significantly during administration, and thereafter returned to the control level. In the mandible, W and q were significantly greater in the IGF-I group as compared with the control group from age 12 weeks to the end of the experiment; whereas, L showed no significant intergroup difference throughout the experiment. In the maxilla, no intergroup differences were present for W, L nor q, during and after IGF-I administration. Although the mandibular dental arch stopped expanding after 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.
Methods: Human recombinant IGF-I (640mg/day) was continuously administered subcutaneously for 4 weeks by osmotic mini-pumps to 10-week-old male rats (IGF-I group; n=6). Control animals were injected with saline alone (control group; n=6). After administration, all the rats were housed for 4 more weeks. Arch width (W), length (L) and angle (q) in the mandible and maxilla were measured on a plaster dental model of the animal, and rat and human IGF-I serum levels were measured by radioimmunoassay once a week during and after IGF-I administration.
Results: Human IGF-I was detectable in the IGF-I group during administration, whereas the rat IGF-I decreased. Total IGF-I (human + rat) increased significantly during administration, and thereafter returned to the control level. In the mandible, W and q were significantly greater in the IGF-I group as compared with the control group from age 12 weeks to the end of the experiment; whereas, L showed no significant intergroup difference throughout the experiment. In the maxilla, no intergroup differences were present for W, L nor q, during and after IGF-I administration. Although the mandibular dental arch stopped expanding after 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.