An evaluation of an antiadhesive copolymer agent on plaque inhibition by chlorhexidine.

The high molecular weight copolymer M239144 has proven antiadhesive action in vitro but clinically lacked effect, even when combined with chlorhexidine. This latter result was thought to arise from inactivation of chlorhexidine by the copolymer. The aim of this study was to determine whether improved activity might arise if the copolymer and chlorhexidine were applied sequentially rather than combined. The study was a double-blind, randomised crossover design balanced for carryover using a 24-h plaque regrowth method. 2 groups of 25 subjects from a zero plaque baseline rinsed 1x with 15 ml volumes of the allocated paired rinses for 60 s. Subjects abstained from toothcleaning for 24 h and were scored for plaque by area. The paired regimens were: 1. placebo: placebo; 2. placebo: 0.03% chlorhexidine; 3. 1% co-polymer and 0.03% chlorhexidine; 4. placebo: 1% co-polymer; 5. placebo: 0.12% chlorhexidine. Plaque regrowth was greatest with regimen 1 and least with regimen 5. However, regimens 3 and 4 were not significantly different from regimen 1, whereas regimen 2 was significantly more effective than regimen 3. The results indicate that the copolymer alone is ineffective, and even delivered sequentially, inactivates chlorhexidine.