EFFECT OF DISINFECTION OF CUSTOM TRAY MATERIALS ON ADHESIVE PROPERTIES OF SEVERAL IMPRESSION MATERIAL SYSTEMS

The effects of impression tray disinfection procedures on the bond str ength of impression-material adhesives to two types of resin trays wer e evaluated with a tensile test. Autopolymerizing acrylic resin and a visible light-curing resin were formed into one-half inch cubes. A scr ew eye was attached to each cube before polymerization. Perforated tra ys were fabricated with stops to maintain an even one-eighth inch of i mpression material over the resin block. Hooks on the opposite side pe rmitted attachment of the metal plate to a mechanical testing machine. Before adhesive was applied, one third of the resin specimens were im mersed in a 1:213 iodophor solution; one third in a 10% sodium hypochl orite solution, and one third were kept in the ''as fabricated'' condi tion. Polysulfide, polyether, and polyvinyl siloxane impression materi al-adhesive systems were evaluated, The resin-impression material-meta l plate couples were attached to a mechanical testing machine and tens ile forces were applied at a separation rate of 5 inches per minute. M ean values for adhesive strength ranged from 3.49 kg/cm(2) for the aut opolymerizing acrylic resin/iodophor/polyether combination to 10.55 kg /cm(2) for the autopolymerizing acrylic resin/untreated/polyvinyl silo xane combination. Differences were detected among materials and disinf ecting procedure. Clinically, disinfection of resin trays may adversel y affect retention of the impression material to the tray.