Sodium Lauryl Sulfate (SLS) Reduces Salivary and Plaque Fluoride Uptake

Plaque fluoride concentrations ([F]) are directly related to plaque calcium concentrations. Our attempts to increase salivary and plaque F uptake from 1000-ppm dentifrices by pre-rinsing with 20mM (Caries Res 39:100-107,2005) or 150mM (Eur J Oral Sci 114:489-493,2006) calcium solutions were unsuccessful. Ca pre-rinses, however, caused large increases in F uptake from aqueous NaF rinses (Caries Res 40:449-454,2006; JDR 86, Sp Iss A:Abst 1873,2007). Objective: To test the hypothesis that, when added to a rinse, SLS (anionic detergent in dentifrices) reduces F uptake by saliva and plaque. Methods: Subjects (n=11) rinsed with 20mL of 150mM Ca-lactate for 1.0 min, then with 20mL of 228-ppm F. Plaque was collected 15 and 60 min later; whole saliva was collected 60 min after the F rinse. After one week the procedure was repeated with 0.5% SLS in the F rinse. F was analyzed with the electrode after five extractions with pH-4.8 acetate-buffer (plaque) and after HMDS-facilitated diffusion (plaque and saliva). The results were analyzed for statistically significant differences using RM-ANOVA and Fisher's LSD post-hoc test. Results: Mean salivary [F] (mean±SE) at 60 min after rinsing with or without SLS were 0.18±0.05 and 1.40±0.48 mmol/L (p=0.031). The plaque [F] are shown in the table (‘Without SLS' vs ‘With SLS', p<0.01).

Amounts of F Extracted from Plaque (mmol/kg)
Extractor	Without SLS		With SLS
	15'	60'	15'	60'
Acetate buffer	43.06±6.92	30.88±3.08	23.32±4.85	19.52±2.29
HMDS	79.55±24.35	57.47±13.22	10.51±4.18	15.09±8.59
Total	122.61±30.00	88.35±13.50	33.83±6.39	34.61±9.17

Conclusion: SLS (0.5%) in the F rinse significantly reduced salivary and plaque F uptake, an effect presumably due to calcium binding by SLS. We suggest that dentifrices formulated without SLS could have [F] substantially below 1000 ppm but have the same cariostatic effect and reduce the risk of dental fluorosis.