OBJECTIVE: During orthodontic tooth movement, various mechanical stresses are loaded on the periodontium, such as compressive and tension forces, and periodontal remodeling takes place in response to these stresses. The application of excessive orthodontic force produces excessive compressive force, which results in cell death in the periodontal ligament. However, the nature of compressive force-induced periodontal tissue remodeling is not clear. Therefore, we examined the cell-type-specific effects of compressive force on gene expression in human osteoblasts and periodontal ligament cells by gene profiling using microarray analysis.
METHODS: Cultured human osteoblastic cell line MG-63 cells and human primary periodontal ligament (PDL) cells were subjected to continuous compressive force directly for 24 hours before isolating total RNA for hybridization to whole human genome arrays. The data were analyzed using the software program GeneSpring.
RESULTS: The in vitro compressive force induced the expression of chemokine, cytokine, and apoptosis-related genes in osteoblasts and PDL cells. The genes up- or downregulated two-fold or more in response to compressive force were listed. Cell-type-specific gene expression patterns were observed. Furthermore, several putative signaling molecules were detected, including nuclear factor kappa B and the wnt signal.
CONCLUSIONS: This study identified a cell-type-specific gene expression response in osteoblastic cell line MG63 cells and periodontal ligament cells to compressive force. Some of these genes likely contribute to periodontal remodeling.