Optimizing Glycerin Concentration for Xerostomia Treatment via Refractive Index Measurements

Xerostomia is also commonly referred to as dry mouth, this is a condition that is characterized by a reduced salivary flow that can negatively impact things like overall oral health, swallowing, or even speaking. The current artificial saliva substitutes vary widely in their composition, physical chemical properties, and effectiveness, many or the products available now as treatment do not disclose the concentrations included in their ingredients. Glycerin is a known saliva substitute that is frequently used due to its abilities to retain moisture. The optimal concentration of glycerin is required in order to best mimic natural saliva. The purpose of this study is to loom into the refractive indices of glycerin water mixtures to identify formulations that closely resemble the properties of a healthy human’s saliva. Glycerin solutions used ranged from 3% to 25% by weight then further analyzed using a digital refractometer at 20 degrees Celsius. The result found showed a linear relationship between glycerin concentrations and refractive index, the mixtures that contained a range of 3%-5% of glycerin showed refractive indices that were almost identical to those of healthy male and female saliva ranges. A commonly used commercial dry mouth product Biotène had a significantly higher refractive index which suggested differences in formulations of products. These findings suggested low concentrations of glycerin water mixtures could be helpful in providing more physiologically relevant alternatives to current artificial saliva substitutes on the market, as well as highlighting the potential of refractive index being used as a practical analytical tool to produce Xerostomia treatments. Additional future research should include lubrication, clinical effectiveness, and viscosity.