Expression of heat stress proteins by human periodontal ligament cells

Abstract

The purpose of the present report was to document the stress response produced by physical and chemical abuses to human periodontal ligament cells, and to review some of the known functions of stress response proteins produced as a result of such treatments. For these studies human PDL cells were exposed to sublethal challenges of 43°C heat, sodium arsenite and the amino acid analog L‐azetidine‐2‐carboxylic acid (AZC). The cells were labelled with [35S]‐methionine and the proteins produced were examined by autofluorography of SDS‐PAGE gels. Heat challenges were shown to induce hsps with an apparent mol. wts. of 90K, 68‐72K, 41–47K, and 36 K. Arsenite‐treated cells produced similar hsps including a 30k protein not produced by other forms of stress. AZC treatment resulted in the production of apparent functionless hsps with apparent molecular weights of 90,000, 72,000, 68,000 and 36,000. The function of these proteins and their possible role in periodontal disease is discussed.

Thermal Effects from Modified Endodontic Laser Tips Used in the Apical Third of Root Canals with Erbium-Doped Yttrium Aluminium Garnet and Erbium, Chromium–Doped Yttrium Scandium Gallium Garnet Lasers

“…6 A threshold temperature increase of 78C is commonly regarded as the highest biologically acceptable value in order to avoid periodontal ligament damage. 8,18 The present results regarding thermal stress from lasing compare favorably with earlier work. For the Er,Cr:YSGG laser, reported temperature elevations on the root surface range from as high as 378C when lasing was undertaken without cooling to 88C when cooling was employed.…”

Heat Release, Time Required, and Cleaning Ability of Mtwo R and ProTaper Universal Retreatment Systems in the Removal of Filling Material

“…The temperature that increased during the use of NiTi instruments dropped as soon as they stopped, whereas the temperature that increased during the use of the Gates Glidden drills dropped only approximately 1 minute after the instruments had stopped. However, the temperatures registered in this experiment do not offer risk to the periodontal ligament (9,31). It has been shown that a 10 C rise is necessary to produce an irreversible thermal damage to the supporting periodontal structures (9,32).…”

The Effect of Ultrasonic Post Instrumentation on Root Surface Temperature

“…Sauk et al found that exposing the periodontal ligament to a temperature of 43°C resulted in protein denaturation and elaborated that ankylosis and bone resorption may develop (9). Atrizadeh et al delivered heat through an electrosurgery tip to prepared root canals in monkeys and found localized areas of necrosis within the periodontal ligament at 3 days.…”