Orthopedic protraction of the maxilla may affect cranial base synchondroses indicated by increased expressions of growth factors

Feng J., Zhao N., Zhao J., Rabie A. B., Shen G. Orthopedic protraction of the maxilla may affect cranial base synchondroses indicated by increased expressions of growth factors. Orthod Craniofac Res 2012; 15 :62–70 © John Wiley & Sons A/S Structured Abstract Objectives – To examine the biological adaptation of cranial base synchondroses (CBS) when the maxilla was forward positioned by orthopedic force. Setting and Sample Population – The Department of Orthodontics at Shanghai Jiao Tong University. 50 Sprague–Dawley rats, 4 weeks of age, were divided into experimental (n = 30) and control groups (n = 20). Material and Methods – An orthopedic appliance was fitted to the cranio‐maxillary complex to advance the maxilla forward. The animals in the experimental group, together with the counterparts in the control group, were sacrificed at days 1, 3, 5, 7, and 14, respectively. The whole cranial base housing both the spheno‐ethmoid (SES) and spheno‐occipital synchondroses (SOS) was removed for tissue processing and immunotest of Sox9, Core‐binding factor α 1 (Cbfa1), and vascular endothelial growth factor (VEGF), three carefully selected growth factors that are markers of chondrogenesis in different stages and its transition to endochondral ossification. Semiquantitative analysis was also conducted by using a computerizing imaging system. Results – The temporal tendency of the changes in the expressions of the three growth factors featured an increase from Day 3 and onwards for Cbfa1 and VEGF, and a following decline after Day 5 for Sox9. In both SES and SOS, the expressions of the three growth factors were significantly stronger in the experimental groups than that in groups ( p < 0.05). Conclusions – Protractive orthopedic force imposed on the maxilla provokes an enhancement of chondrogenic process in CBS.