EFFECT OF VARIOUS IRRIGANT AND AUTOCLAVING REGIMES ON THE FRACTURE-RESISTANCE OF RUBBER DAM CLAMPS

Rubber dam clamps are known to break during clinical use in endodontic s. This in-vitro study examined some of the variables which may contri bute to the fracture. Stainless steel rubber dam clamps were subjected to various cleaning and autoclaving regimes and exposure to various s olutions of sodium hypochlorite (NaOCl). Each clamp was examined after four cycles of cleaning and exposure to NaOCl. During environmental e xposure to NaOCl, the clamp was stressed over a perspex rod to simulat e placement onto the crown of a tooth. Clamps were examined after each test cycle visually and microscopically, or immediately after breakag e. Results suggested that the fractures were because of a stress corro sion cracking phenomenon. There was evidence of intergranular and tran sgranular cracking of the metal. Corrosion spots were seen on the surf ace of the clamps and fracture occurred mainly through these spots. A number of recommendations to reduce breakage of clamps have been sugge sted.