In this blog, we’ll be looking at the importance of testing oral care products to make sure they are sufficiently mild for the intended use, and how other claims regarding their benefits can be supported with in vitro tests.
Oral irritation potential: an important part of the safety assessment process
A wide range of products and devices come into contact with the mouth area. Some of these – such as toothpastes, mouthwashes and chewing gums – are used by millions of people daily, heightening the probability of exposure by sensitive individuals, who may experience irritation as a result of single or repeat use. Others, including specialist dental formulations and surgical instruments, may only contact the mouth and gums on an occasional basis. And of course, there are longer term, continuous exposures to items such as dental braces and wires to consider.
Irritation potential forms an important part of the safety assessment process for oral care, personal care, healthcare, pharmaceutical and medical device companies. Human oral and gingival epithelia can be reconstructed in vitro to provide a close simulation of these tissues in real life, in terms of both structure and function. The models are well suited to testing ingredients, formulations or devices using protocol modifications designed to suit the test material and to mimic real-life exposure.
So how do in vitro oral and gingival irritation tests work?
The item is applied to the surface of the model and incubated for defined exposure times. Damage to the tissue is measured using a dye (MTT) that’s converted by healthy cells to a blue product which is measured using spectrophotometry. This method results in an “ET50” value – the time taken to cause 50% cell death in the underlying tissue.
The ET50 approach has been widely used by industry for many years and applied to a variety of tissue types – including skin and eye – as a reliable indicator of irritation potential. Now available for oral and gingival epithelia, these tests can be used to assess the rank order of irritation potential or mildness of a range of formulations or ingredients. The approach is ideally suited to new product development or benchmarking against competitor products. We build in appropriate controls and benchmarks to the test and are building a reference database to further enhance the interpretation of the ET50 result.
As well as the ET50 determination, histological changes and cytokine expression can be assessed using these human oral and gingival epithelial models. Additionally, inflammation can be induced within the models to look at protective or anti-inflammatory effects of formulations or ingredients.