A NEW EXPERIMENTAL-MODEL FOR STUDYING THE RESPONSE OF PERIODONTAL-LIGAMENT CELLS TO HYDROSTATIC-PRESSURE

An apparatus was developed to apply positive or negative hydrostatic p ressure dynamically to periodontal ligament (PDL) cells in vitro, The objective of this investigation was to construct this apparatus and to determine its effects on PDL cells. Human PDL cells were collected fr om freshly extracted premolars. At the sixth passage, the cells were m echanically stimulated by this apparatus at different magnitudes of co ntinuous positive or negative hydrostatic pressures (PHP or NHP, respe ctively). The application of PHP between 0.3 and 30 gm/cm(2) significa ntly enhanced prostaglandin E (PGE) production and intracellular cycli c AMP (cAMP) of the cells. In contrast, perturbation by NHP significan tly decreased PGE production and intracellular level of cAMP. Prolifer ation rate increased significantly at 24 and 48 hours due to stimulati on of these cells with -30 gm/cm(2) of NHP. Challenging these cells wi th +30 gm/cm(2) of PHP significantly decreased the proliferation rate of these cells at 24 and 48 hours. Stimulation by PHP between +30 to 600 gm/cm(2) increased cell length and width and appeared to increase surface area attachment to the bottom of the culture dishes. in contra st, NHP (between -30 and -600 gm/cm(2)) decreased these dimensions and appeared to reduce the surface area of attachment. These results indi cate that this type of mechanical perturbation of PDL cells produces p hysiologic responses and is not detrimental to their vitality.