​Most oral hygiene products contain surfactants that are needed to stabilise the combination of active ingredients, keep the surface of the teeth wet and produce the foam that consumers like to have when cleaning their teeth.​ For more detail on surfactants, read our explainer article.

The most commonly used is the ionic surfactant sodium dodecyl sulfate, known as SDS. However, its use has been related to the development of medical conditions such as mouth ulcers. Other options that are thought to be less of an irritant to the tissues in the mouth are non-ionic or amphoteric surfactants. This study, published in Scientific Reports, looks in detail at these to investigate how they work, and whether this can be improved to compete with those already used in industry.

By studying their interactions with salivary pellicles, which are nanometre-thin films that form rapidly on the surfaces in the mouth upon exposure to saliva, the researchers hope to understand the effect of the surfactants on the tissues themselves.

Using neutron reflectivity on the Surf and Inter instruments, alongside other experimental techniques, the group found that the nonionic and amphoteric surfactants interacted with the salivary pellicles in a gentler way than SDS.

They also saw that the mechanism of the interaction itself was different for these types of surfactant. This is important, as it could affect the other ways that oral hygiene products protect the teeth and gums.

“We have now gathered extensive information on how non-ionic and amphoteric surfactants affect the structure of salivary pellicles, which they do in a significantly gentler way than anionic ones," explains lead researcher, Javier Sotres Prieto from Malmö University.

“Future work will address how these structural modifications relate to changes in aspects of salivary pellicles like lubrication performance, diffusion barrier properties and interaction with bacteria. Overall, we foresee that this research will allow the rational development of more effective oral health products."

Further information

The full paper can be found at DOI: 10.1038/s41598-021-92505-4