Effect of Compression Force on Apoptosis in Human Periodontal Ligament Cells

Abstract

The effect of compression force on periodontal ligament (PDL) plays a critical role in orthodontic tooth movement. However, little is known about this effect on apoptosis and the underlying reactive mechanisms in PDL cells. This study focuses on the application of compression force associated with reactive oxygen species (ROS)-induced apoptosis in PDL cells. Following the application of orthodontic force to maxillary first molars, the molars were investigated using immunohistochemical analysis. The cell cycle and apoptosis were assessed in compression force-treated PDL cells using flow cytometry. Furthermore, we assayed the effect on ROS generation by DCFDA fluorescence. In vivo study revealed an increased number of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and caspase 8-positive cells in the orthodontic force group. In our in vitro study model, the compression force increased the G1 phase and apoptotic cells. A large increase in the intracellular ROS levels in human (h) PDL cells was observed in the compression force group. Taken together, these results provide new information on compression force-induced G1 arrest and apoptosis in hPDL cells.

Osteoclast-like activity of U937 cells, peripheral blood mononuclear cells, and periodontal ligament fibroblasts subjected to mechanical stress by centrifugal force

“…Our results show that centrifugal force or PEG-induced cell fusion increases via oxidative stress by generating ROS. Likewise, exposure of PDL 昀椀broblasts to mechanical compression increases intracellular ROS production [26]. Our results support the idea that the oxidative stress in cultured cells, subjected to centrifugal force or PEG-induced fusion, triggers biochemical pathways leading to TRAP and bone resorption activities characteristic of osteoclasts.…”

Reactive oxygen species‐mediated endoplasmic reticulum stress contributes to osteocyte death induced by orthodontic compressive force

“…These findings are consistent with previous in vivo and in vitro studies, which have demonstrated that osteocyte apoptosis occurs under the orthodontic compressive force (Hoshi et al, 2014; Sakai et al, 2009). Moreover, compression can trigger apoptosis in other periodontal tissue cells like cementoblasts, osteoblasts and periodontal ligament cells (PDLCs) (Funakoshi et al, 2013; Goga et al, 2006; Yamaguchi et al, 2018). Intriguingly, the minimum force that caused osteocyte apoptosis (0.125 kPa, equivalent to 1.275 g/cm 2 ) is relatively close to that of cementoblasts (2.0 g/cm 2 ) and PDLCs (1.0 g/cm 2 ), but much higher than that of osteoblasts (2.04 × 10 −4 N/cm 2 , nearly 0.01 g/cm 2 ).…”

“…The non‐physiological mechanical stimuli are known to promote apoptosis through the mitochondrial‐ or death‐receptor‐mediated signaling pathways in several periodontal cells (Funakoshi et al, 2013; Song et al, 2016; Yamaguchi et al, 2018). However, there have been few mechanistic studies on compressive force‐induced osteocyte apoptosis.…”

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

“…High level of cementocytes/cementoblasts apoptosis is associated with adverse orthodontic root resorption and upregulation of caspase 3 and caspase 8 which were induced by heavy or optimum orthodontic force [22,23]. Extreme levels of reactive oxygen species were observed on the compression zone that subsequently resulted in cell cycle arrest and apoptosis of the cells involved in the zone [24]. Stretching force may also cause apoptosis.…”