Oral care: The Latest in Vitro Tests Supporting Safety and Efficacy Claims
Dr Carol Treasure
The Why?
If you’ve ever been burned by eating food that’s too hot, you’ll appreciate first-hand just how sensitive the lining of the mouth can be. In this blog, we’ll be looking at the importance of testing oral care products to make sure they don’t irritate the mouth or gums and are sufficiently mild for the intended use.
Our physiology varies between the lining of the mouth cavity (the oral epithelium) and that of the gums (the gingival epithelium). The gums are protected by a cornified protective layer similar to the skin barrier, but in the oral cavity, this is absent, leaving the area more exposed and easily damaged.
As a result, there are markedly different sensitivities between the oral lining and the gums, so it’s important to consider the right approach when testing for possible irritant reactions.
What can be tested?
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. Overall, a wide variety of acute and chronic exposure scenarios exist.
Irritation potential forms an important part of the safety assessment process for oral care, personal care, healthcare, pharmaceutical and medical device companies. For many ingredients, human skin irritation data may be available, but due to the physiological differences described above, this data can’t be assumed to translate to the lining of the mouth or gums. While there are currently no non-animal, in vitro tests with regulatory approval for human oral or gingival irritation, tissue engineering technology can provide sophisticated yet accessible solutions in a non-regulatory context, supporting new product development and providing weight of evidence for regulatory submissions.
About the tests
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.
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.
At XCellR8, we regularly go beyond the standard irritation protocols. Our team of scientists is highly experienced in the design of bespoke studies to model specific exposure scenarios for a wide variety of product types. For example, inflammation can be induced within the models to look at protective or anti-inflammatory effects of formulations or ingredients. As well as the ET50 determination, we often measure impact on barrier function, using transepithelial electrical resistance (TEER). Histological changes and cytokine expression can be assessed using the human oral and gingival epithelial models, resulting in a comprehensive package of data.
A word about regulations…
Globally, regulations can vary considerably. A product may be classed as a medical device in some regions while being covered by cosmetic regulations elsewhere, so the safety assessment needs to include careful consideration of the anticipated geographical markets. While we’re not covering regulatory aspects here, we partner with well-established consultants and can provide bespoke advice if needed. The data obtained from the non-regulatory tests described here may be useful as weight-of-evidence support for some regulatory submissions.
The big picture
Oral care products are considered essentials in our daily self-care routines at home – making the sector comparatively resilient even in volatile economic times. In a bid to avoid costly dental bills, consumers are paying more attention to the latest claims by oral care brands, seeking out the most innovative products to protect their oral and gingival care for the long-term. A 2020 survey cited Colgate as the most chosen personal care brand in the world, and across all categories of fast-moving consumer goods (FMCG), it even tallied up more shoppers worldwide than Coca Cola! Oral care products have a vast reach, highlighting the critical need to ensure their high level of safety for those using them daily around the world, from mass market to premium brands.
Special opportunity to access the tests this month
We’re very proud of all the research that has gone into irritation and mildness testing for oral and gingival care at XCellR8, and we love helping companies across the global industry to support their claims for oral care products! If you’d like to find out how to join the rapidly growing number of companies trusting in our animal-free data, our expert scientists would love to chat with you, and we’re great listeners! We’ll always put your needs at the centre of the conversation and give you the best possible advice on how to get that all-important claim support data, whether you’re an ingredient supplier, global leader, or brand-new start-up. We understand your products are as unique as you are! 😊
To celebrate our “test of the month”, we’re offering special discounts on our oral and gingival irritation tests, for orders placed throughout the month of February. If you’re not ready to test yet, you can place your order now to secure your lab slot and take advantage of the lower price. Discounts vary according to the number of items to test. So, whether you’re trying out this test for the first time, or already familiar with the method, feel free to get in touch!
Email info@x-cellr8.com
Call +44 (0)1925 607 134.
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