The use of polymethylmethacrylate to compare the adsorption and staining reactions of some cationic antiseptics.

This study assessed the value of acrylic, in powder and optically clear forms, to measure the adsorption and staining properties of some cationic antiseptics. The uptake of chlorhexidine gluconate, chlorhexidine acetate, alexidine and cetyl pyridinium chloride onto acrylic powder was measured spectrophotometrically. Similarly, tea staining of perspex blocks exposed twice daily to the antiseptics and hexetidine, was measured over a 5 day period. The adsorption of chlorhexidine gluconate and acetate was similar and greater than alexidine but less than cetyl pyridinium chloride. Desorption of the adsorbed antiseptics was minimal after 48 hours soaking in water. Acid produced a variable desorption of antiseptics. Tea staining of blocks was significantly greater with antiseptic treated specimens compared to control specimens. However, staining resulting from alexidine was greater than cetyl pyridinium chloride which was greater than chlorhexidine. Hexetidine produced the least staining. Saliva treatment of specimens only increased the tea staining of control blocks. The results indicated that adsorption levels alone would not explain the differences in antiplaque and staining activity reported for the cationic antiseptics.