Objectives: Fluoride is an effective agent in the protection of enamel, mainly by interfering with enamel dissolution. Chlorhexidine(CHX) is an effective agent by it's antimicrobial properties. A combination therapy could target both the hard tissues and the oral microflora. But it is possible that interference between the positively charged chlorhexidine and the negatively charged fluoride might influence their efficacy.

Methods: In a pH-cycling setup experimental rinses with different fluoride concentrations in the presence or absence of 0.2% chlorhexidine were tested. In the second study the formulated final products were tested in comparison with the commercially available mouthrinse Parodontax®.

Results: Results of the first experiment indicated that the addition of chlorhexidine to a fluoride rinse resulted in a small but significant decrease of the fluoride efficacy.

cumulated net calcium loss data (reduction to corresponding control in %)
	0 ppm F rinse	100 ppm F rinse	300 ppm F rinse
without CHX	12.7	8.7 (31.1% reduction)	3.9 (69.2% reduction)
with CHX	12.7	9.8 (22.5% reduction)	5.9 (53.7 % reduction)
statistics	p=0.98	p=0.16	p=0.017

This observation was not confirmed in the second experiment. The tested products showed a reduction of the net calcium loss in the range of 51-66% and were not mutually significantly different.

Treatment	net calcium loss	% reduction compared to H2O-control
0.2% CHX + 250ppm F pH4. 5	-3.11	63
250ppm F pH 4.5	-2.91	66
0.2% CHX + 250ppm F pH 5.9	-3.14	63
250ppm F pH 5.9	-4.12	51
Parodontax (0.12% CHX, 225ppm F)	-3.69	56
H2O	-8.48

Conclusions: From these two studies it can be concluded that the inhibitory effect of chlorhexidine on fluoride efficacy is only small and depends on the product formulation.

This study was supported by GABA International, Switzerland.