1Faculty of Dentistry;
University of Hong Kong;
Hong Kong;
China 2Orthodontics;
Tianjin Stomatological Hospital of Nankai University;
Tianjin;
China 3Taizhou Polytechnic College;
Taizhou;
China;
Human; Periodontal; Ligament; Cells; Tension; Force; Lipopolysaccharides; Proliferation; Differentiation;