Comparative effects of quaternary ammonium mouthrinses on 4-day plaque regrowth

Background: Quaternary ammonium compounds constitute a large group of antib acterial chemicals with a potential for inhibiting plaque and gingivitis. O ne compound, benzalkonium chloride (BC), may be of value, although there is a dearth of evidence to support efficacy. The aim of this study was to mea sure the ability of 2 BC mouthrinses (0.05% and 0.1%) to inhibit de novo pl aque reformation. Method: A 4-day plaque regrowth model. For comparative purposes, a commerci al mouthrinse containing cetyl pyridinium chloride (CPC) and a positive con trol chlorhexidine (CX) mouthrinse were also evaluated. Results: Compared to water control, a reduction in plaque scores of 52% was noted for the CX mouthrinse, 22.5% for CPC and 5% and 6% for the 2 BC rins es. For plaque area, reductions of 84%, 47%, 16% and 15% were found for CX, CPC, and the 2 BC rinses, respectively. Significant reductions in plaque a rea compared to the water rinse were also seen with the 2 BC rinses (p<0.05 ). However, for both plaque score and plaque area, the CX and CPC rinses si gnificantly reduced plaque compared to the BC rinses (p<0.0001). Conclusions: These findings would suggest that the 2 benzalkonium rinses wo uld only have a limited value at inhibiting plaque formation.