Expression and Function of Hypoxia Inducible Factor‐1α and Vascular Endothelial Growth Factor in Pulp Tissue of Teeth under Orthodontic Movement

Abstract

Orthodontic force may lead to cell damage, circulatory disturbances, and vascular changes of the dental pulp, which make a hypoxic environment in pulp. In order to maintain the homeostasis of dental pulp, hypoxia will inevitably induce the defensive reaction. However, this is a complex process and is regulated by numerous factors. In this study, we established an experimental animal model of orthodontic tooth movement to investigate the effects of mechanical force on the expression of VEGF and HIF-1α in dental pulp. Histological analysis of dental pulp and expressions of HIF-1α and VEGF proteins in dental pulp were examined. The results showed that inflammation and vascular changes happened in dental pulp tissue in different periods. Additionally, there were significant changes in the expression of HIF-1α and VEGF proteins under orthodontic force. After application of mechanical load, expression of HIF-1α and VEGF was markedly positive in 1, 3, 7 d, and 2 w groups, and then it weakened in 4 w group. These findings suggested that the expression of HIF-1α and VEGF was enhanced by mechanical force. HIF-1α and VEGF may play an important role in retaining the homeostasis of dental pulp during orthodontic tooth movement.

Gene expression of growth factors with angiogenic potential in human dental pulp tissue from teeth with complete and incomplete root development

“…This may be explained due to the increased activity of odontoblasts, fibroblasts and odontoblast-like cells, involved in dentine production as a response to stimuli such as mastication, bruxism and occlusal trauma. This increased VEGFA expression in pulp tissue constitutes the mechanism to initiate new blood vessels formation (Roberts-Clark & Smith 2000, Ceradini & Gurtner 2005, Muz et al 2015, Wei et al 2015, Roth et al 2016, Caviedes-Bucheli et al 2017.…”

“…VEGFR2 had similar expression in both groups, which could be explained by the vessels in the pulp tissue actively sprouting and these sprouts are dependent on the amount of VEGFR1 which has an inhibitor effect in the angiogenic process. (Roberts-Clark & Smith 2000, Mattuella et al 2007, Wei et al 2015, Rombouts et al 2016, Caviedes-Bucheli et al 2017.…”

Effect of microRNA‑21 on hypoxia‑inducible factor‑1α in orthodontic tooth movement and human periodontal ligament cells under hypoxia

“…Franzen et al (20) applied 50 g force to move rats' first molars, and then removed the orthodontic appliances to study the periodontal tissue reaction to during orthodontic relapse in rats. Wei et al (22) used 30 g force to study the reaction of dental pulp tissues by examining HIF-1α and vascular endothelial growth factor; they revealed that the expression of HIF-1α was markedly increased in the 1, 3, 7 day and 2 week groups. In the present study, 50 g force was also applied between the maxillary right first molar and incisors of rats, and hypoxia-sensitive factor HIF-1α was highly expressed in PDL, which could also indicate that the model used was suitable.…”

Effect of Hypoxia on the Induction of Premature Cellular Senescence in the Cells of Periodontium during Orthodontic Tooth Loading

“…Hypoxia describes the reduction of oxygen level in tissue due to decreased oxygen partial pressure beyond the physiologic level [5]. Hypoxic cells release cellular mediators, such as the hypoxia-inducible factor 1 (HIF-1), a heterodimer composed of HIF-1 and HIF-1 [6,7].…”