Review of the use of polymers in saliva substitutes for symptomatic relief of xerostomia.

It is clear from the many clinical studies carried out on currently available saliva substitutes, that the main factors limiting the success of polymers in treating xerostomia is their short duration of action and/or their lack of acceptability by users. The most effective formulations for severe sufferers of xerostomia contain relatively viscous, thixotropic polymers, which mild to moderate sufferers in particular tend to dislike. Relief can also be extended by increasing concentrations of non-thixotropic polymers; however, this also has to be balanced by the decrease in palatability resulting from higher polymer levels. In addition, gels rather than solutions tend to result from higher polymer concentrations, which are only employed by the most severe sufferers of xerostomia, and in fact, have been suggested to offer little improvement in efficacy over oral sprays. It would be highly advantageous to improve the duration of relief without impacting negatively on the sensory profile of the product. This would provide a longer lasting effect that is acceptable to all sufferers of xerostomia. The essential role of polymers in saliva substitutes is to provide lubrication, hydration, and protection of the oral mucosa, providing symptomatic relief to sufferers of xerostomia. However, saliva substitutes should also be of neutral or near neutral pH, to prevent demineralization of the oral hard tissues. These products should always be used in conjunction with a thorough oral health regimen, but may also contain appropriate levels of electrolytes for remineralization of enamel and dentine.