Scientists often look to fellow experts, other professions and published work for inspiration, or more simply, stand on the shoulders of giants. This is exactly what the oral health team at WALTHAM did to improve methods to measure dental plaque in pets. In human dental research, a painless technique that involves shining light on teeth and taking specialised digital photos is commonly used. But no one had tried this on cats and dogs before.
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Over 80% of dogs and most cats suffer from gum disease, also known as periodontal disease. Whilst reversible in the early stages, as it progresses it can cause pain and ultimately result in tooth loss. Understanding how we can help prevent this condition developing is crucial for pet health, as is developing effective preventative care and treatment. The current method for measuring plaque deposits on the teeth requires assessment by a trained technician. This is time-consuming and open to human error. So the team turned to the approach used by human dentists, Quantitative Light-induced Fluorescence (QLF), to see if it could work in pets too.
QLF imaging detects the natural fluorescence of plaque, it can, therefore, pick up differences between healthy and plaque covered teeth and these differences can be accurately analysed by a computer. This gives a highly visual representation of where plaque covers the tooth surface, allowing dentists to diagnose problems and recommend effective interventions. In pets, however, the use of QLF has not been widely explored. Corrin Wallis and Judi Allsopp, from the WALTHAM Oral Health team, initially wanted to see if QLF was a technique that could be used on dogs. The first task was to modify the software to enable the annotation of dog’s teeth, which is different to humans. But dogs also offered another unique challenge: their big slobbery lips. It took a bit of improvisation, but the floppy lips were eventually managed using a lip retractor commonly used by dentists for children. Combining these two methods, and using a specially adapted camera, clear images of plaque on the dog's teeth were obtained.
The team then compared the QLF technique with more traditional assessment methods done by eye to see if it was more accurate. Overall the computer analysis far outperformed a purely visual assessment. Plaque in pets is most effectively addressed by regular tooth brushing, but there are a variety of oral care chews on the market that has also been shown to reduce plaque build-up if used regularly. Testing these to make sure they work properly could become much easier with QLF imaging. Fewer animals are required to demonstrate efficacy and, as the method simply involves shining a light using a specialised camera, dogs habituated to the process by WALTHAM's positive reinforcement training are happy to show off their pearly whites to the lens.
With a huge tick in the box for canine QLF, it was time for the next challenge: QLF for cats. “Dogs have much larger, relaxed lips which allowed us to open the mouth to photo their teeth," explains Judi. "It was much more difficult in cats, especially to be able to picture the large molar teeth at the back of the mouth. But we got there in the end”. The team have now shared their results in two recently published papers in veterinary journals.
“Improving the methods that we use in our science on pets is so important,” explained Corrin. “We always need to review what we do and apply the 3Rs guidelines that underpin animal research. Reduce the number of animals we need, Refine the techniques we use and Replace animals with alternatives whenever possible. By demonstrating how effective this new method is, it means that we have refined our techniques and can reduce the number of cats and dogs we need to help with our research in the future”.
“The welfare of cats and dogs is at the core of WALTHAM science. We always take a caring science approach, but it is fantastic that we are able to share this with our peers in pet oral care research” added Zoe Marshall-Jones, lead scientist on the cat QLF research.