The erosive potential of saliva-stimulating tablets with and without fluoride

Objective: Xerodent™ is a commercially available saliva-stimulating tablet for use in dry mouth patients. Xerodent™ is available on the Scandinavian market in formulations with fluoride (0.25 mg per tablet) and without fluoride. The tablet also contains malic acid, phosphate and orange flavour. The main purpose of fluoride in the tablet is for caries control. However, fluoride may also influence a possible erosive potential (EP) of the tablet caused by its acid content. The aim of this study was to determine saliva stimulating effects and EP of Xerodent™ with and without fluoride in dry mouth cancer patients in vivo. Materials and Method: Ten cancer patients (7 males and 3 females with a mean age of 55 yrs) unilaterally irradiated on head and neck sucked Xerodent™ tablets with and without fluoride. Saliva collections were divided into three 10 min sessions one hour apart in the sequence: unstimulated whole saliva (baseline), Xerodent™ stimulated whole saliva without fluoride, and finally Xerodent™ stimulated whole saliva with fluoride. Saliva was collected in closed systems and saliva pH and P_CO2 were determined immediately after collection. Saliva pH, in combination with inorganic measures, was then used to calculate the degree of saturation with respect to hydroxyapatite (DSHAp) and fluorapatite. Furthermore, EP was determined directly in all saliva samples by monitored dissolution of HAp crystals. Results: Saliva flow rates increased significantly when sucking both tablets (p<0.001), but no difference was obtained between Xerodent™ with (1.02±0.29 ml/min) and without fluoride (1.04±0.27 ml/min). Mean saliva pH became lower (p<0.001) in response to Xerodent™ without fluoride (pH 5.15±0.21) compared to with fluoride (pH 5.28±0.25). Neither of the two types of Xerodent™ eroded HAp crystals when exposed to the collected saliva samples. This was most likely due to high salivary phosphate concentrations (>80 mmol/l) caused by the phosphate content in the tablets. Thereby saliva collected in response to both tablets became supersaturated with respect to HAp (DSHAp 1.08±0.96 without and 1.20±1.07 with fluoride). Conclusion: Both Xerodent™ with and Xerodent™ without fluoride seem to be safe for saliva stimulation in dry mouth patients, although, the variant without fluoride may lack caries protection.