This in vitro study analysed the efficacy of salivary substitutes used in the treatment of xerostomia following head neck irradiation. The researchers applied the products under evaluation onto a synthetic surface and onto cellular gingival models. The products were then removed by a defined washing procedure simulating the mouth wash out by natural saliva. The washing solution was then analysed for traces of the products using mid infrared technology. The authors could detect tested products even in dilutions as low as 1:500 and could differentiate the dwell time (time for which the product remained in contact) of the different products. They found that the dwell time of gels was longer compared to sprays, which were immediately washed off. The authors conclude that mid infrared spectroscopy along with three dimensional gingival models is a very sensitive method to detect in vitro the adhesion properties of salivary substitutes. It may eventually help to identify oral care products/saliva substitutes with short dwell times that do not improve quality of life.