Objective  Tooth eruption requires the presence of the dental follicle（DF） around the unerupted tooth. This study is to investigate programmed cell death on

human dental follicle cells and changes of programmed cell death under different hydrostatic pressures: 0, 50 and 100 kPa. Methods  Human dental follicles from third mandibular molars were surgically removed from adolescents who need for orthodontics treatment after informed con-tent, then trypsinized and cultured. Human dental follicle cells were divided into three groups according to different hydrostatic pressures: 0, 50 and 100 kPa and their programmed cell death were labeled by using TdT-medi-ated-dUTP nick and labeling（TUNEL）. Results  Dental follicle cells cultured were elongate shape and exhibited fibroblastic
characteristics. Compared with 0 kPa, programmed cell death cells on human dental follicle cells were increased 0.23% and 31.65% under 50 kPa and 100 kPa

hydrostatic pressures respectively. 100 kPa group increased signnificantly （P<0.01）. Conclusion  It suggested that programmed cell death occured in human dental follicle cells cultured in vitro and was influenced by different hydrostatic pressures. Hydrostatic pressure may improve tooth erup-tion through dental follicle.