Changes in pH and Lactate Concentration During ex-vivo Salivary Glycolysis

Objectives: Preliminary ex-vivo salivary glycolysis investigations showed a significantly reduced pH drop after brushing with Blend-a-med Complete 7 dentifrice compared to brushing with water. The objective was to establish whether this methodology is applicable to broader populations and investigate the relationship between changes in salivary pH and lactate concentration ([lactate]) during glycolysis. Methods: In this 2-treatment 2-period cross-over study, 25 volunteers were randomised to two sequences. Subjects brushed with a fluoridated dentifrice during the run-in and wash-out phases. On the two treatment days subjects provided saliva samples before brushing with either the dentifrice containing Triclosan, pyrophosphate and fluoride (TPF dentifrice) or water. Saliva samples were collected in the 90 minutes following brushing during which subjects did not eat or drink. The saliva samples were incubated with 5% glucose for 2 hours and changes in pH and [lactate] were measured. Changes in pH and [lactate] were compared using ANOVA for crossover designs. Results: Brushing with the TPF dentifrice led to a statistically (p=0.011) smaller pH reduction in saliva collected 90 minutes after brushing relative to the water control, with means (standard errors) of 0.82(0.13) and 1.13(0.13), respectively. Similarly, saliva collected after using the TPF dentifrice generated a significantly (p=0.008) smaller increase in [lactate] 90 minutes after brushing relative to the water control, with means (standard errors) of 1.52(0.20) mMol and 2.02(0.50) mMol, respectively. Statistically significant (p<0.0001) correlations were observed between reduction in pH and increases of [lactate] ranging from 0.90-0.94. Conclusions: Brushing with the TPF dentifrice resulted in a significantly smaller fall in salivary pH 90 minutes after brushing compared to brushing with water only. This was presumably due to inhibition of bacterial activity (metabolism or viability) as evidenced by strong correlations with increased lactate concentration. Thus, the results show that brushing with TPF dentifrice reduces bacterial acid production during glycolysis.