Role of growth hormone in orthodontics

Abstract

Human growth hormone (Somatotropin) is produced by acidophilic growth hormone cells in the anterior pituitary gland, stimulated by hypothalamus. Its production is regulated by several complex feedback mechanisms in response to stress, exercise, diet, sleep and growth hormone itself. Growth hormone plays a major role in linear body growth and craniofacial growth. In Orthodontics, it induces orthodontic tooth movement by activating specific cytokines to regulate osteoclast & osteoblast activity. It mediates STAT signalling in liver & pancreas to produce JAK-IGF-1. IGF-1 has stimulatory effects on osteoblasts and chondrocytes for endochondral ossification to promote bone growth. Growth hormone mediates mitogenic stimulus to odontoblast lineage cells by epidermal growth factor (EGF) to differentiate into odontoblasts. It also stimulates production of alkaline phosphatase and osteocalcin in osteoblasts to improve osteoblast proliferation and differentiation. It also induces osteoclastic activity indirectly by production of IGF-1 and IL- 6 thereby activating RANK-RANKL/OPG phenomenon. It also promotes myofibrillar diameter expansion so it increases muscle mass with strength. Growth Hormone Replacement therapy reduces facial convexity and its main effect appears to be on condylar growth. Since deficiencies of growth hormone can adversely affect orthodontic treatment, effects of growth hormone treatment on craniofacial structures should be considered in order to maximize the effectiveness of orthodontic treatment with appliances and it is more important to understand.