The molecular markers for condylar growth: Experimental and clinical implications

Abstract

The outpour of new research has led to the identification of several factors that play an important role in condylar growth. The objectives of this review are to present the molecular markers that regulate the growth of different cells in the mandibular condyle and their impact on clinical use of functional appliance. The proliferative layer in the mandibular condyle houses a great number of undifferentiated mesenchymal cells that provide the pool of chondrogenic cells. Therefore, it is important to understand the factors that regulate the cell cycle of these replicating mesenchymal cells as well as the factors that control their differentiation to chondroblasts. These chondroblasts in turn are engaged in cartilage matrix synthesis. Therefore, it is critical to present the factors that regulate matrix formation. The process of maturation of chondrocytes into hypertrophic chondrocytes directly impacts the number of cell replication cycles and indirectly affects growth. Therefore, it is of great importance to review the factors that regulate chondrocytes maturation. Hypertrophic chondrocytes secrete hypertrophic matrix with its type X collagen that marks the onset of endochondral ossification. Angiogenesis is regulated by vascular endothelial growth factor (VEGF), and the new blood vessels are rich depository of mesenchymal cells. Factors that regulate the differentiation of these cells into osteogenic cells are critical to growth of the condyle. Understanding of these markers and their levels of expression provides the basis for application of different treatment modalities in the area of growth modification. Furthermore, the identification of factors critical to condylar growth provides us with candidate genes for future gene therapy. © 2009 Elsevier Ltd and the Japanese Orthodontic Society.