The objective of this study was to identify the properties of oral moisturizing gels under experimental conditions that simulate the oral cavity.Oral moisturizing gels were studied under the following three conditions: (1) a drying experiment that tests the water-retention properties of emollients which reduce water loss from evaporation; (2) an dissolution of the gel`s protective layer to assess the hydration properties of oral gel moisturizers in relation to its elution from the oral mucosa; (3) A filtration test to assess an oral moisturizing gel`s degradation in the oral cavity. Three oral gel moisturizers were studied: Peptisal gentle mouth gel (T&K Corporation, Tokyo), Refre-care H (EN Otsuka Pharmaceutical Corporation, Iwate), and Concool mouth gel (Welltec Corporation, Osaka).
The results of the gel drying test using a dried filter paper showed that Refre-care had a higher drying rate than Peptisal and Concool, however, in the moist filter experiment no major difference were observed between the three gel moisturizers. Based on these results, it was shown that every gel moisturizer has emollient properties . The gel dissolution test showed that the retention residue % of the cream after elution increased initially due to water absorption; however, it was observed that, over time, the retention residue % decreased until the cream dissolved into water. Of the oral moisturizing creams tested, Peptisal gentle mouthgel maintained a high retention residue % after elution with high water absorption property, high adhesion property, low disintegration and dissolution property. In the filtration tests, Peptisal gentle mouthgel was retained in a net basket with a 8～14mesh sieve at a higher rate which may explain the results of the dissolution experiments.These results show that Peptisal gentle mouthgel has the potential of providing a long term moisturizing effect.
