Cuttlefish ink is key to painless test for gum disease

Cephalopod-derived food ingredient could banish painful prodding in dentist’s chair

Going to the dentist is no one’s idea of fun. There’s very little about the experience that could be described as comfortable; from lights in your eyes to the whine of the drill, the whole thing is an unpleasant assault on the senses. But the unlikely ingredient of cuttlefish ink could help make a one particular procedure less of an ordeal.

cuttlefish ink
Cuttlefish use their ink defensively and in mating displays

Gum disease (gingivitis) is, as toothpaste adverts never fail to tell us, one of the most common reasons for tooth loss. Caused by bacterial plaque, its first sign tends to be inflammation of the gums at the margin with the teeth, followed by recession of gum tissue. To check for this, dentists employ a relatively crude technique of pressing a tool called a periodontal probe in between the teeth and the gum. If the probe sinks into a depth of 2 mm, the gums are healthy; if it sinks further, this can indicate gum disease. Basically, it’s poking the gum with a sharp bit of metal, and as most of us know, it’s every bit as uncomfortable as it sounds.

Nanoengineer Jesse Jokerst of the University of California San Diego (UC San Diego) was trying to relax at the dentist’s when it occurred to him that things could be better. “I realised that the tools that are currently being used to image teeth and gums could use significant updating,” he said. The method he and his team have developed does away with physical probing altogether.

gum disease
Photoacoustic image obtained after cuttlefish ink staining; the red signal comes from gum pockets. Image: Jokerst Bioimaging Lab at UC San Diego

The method uses a technique known as photoacoustic ultrasound. It begins by having the patient rinse their mouth with the paste made from food-grade cuttlefish ink – the type used to colour pasta or risotto black – mixed with water and cornstarch. The cuttlefish ink contains melanin which acts as a contrast agent; when illuminated with a pulse of laser light at the correct frequency, it heats up and expands, generating an acoustic signal that specialised equipment can detect and analyse. “Light in, sound out,” Jokerst explained.

If there is a pocket at the tooth margin whether gum has receded, the cuttlefish ink paste gets caught in it and generates a characteristic signal when the laser probe is used, whose frequency correlates to the depth of the pocket. This allows the dentist to create a map of the entire mouth, revealing the location of suspect gum recession and indicating the presence and extent of gingivitis. “Using the periodontal probe is like examining a dark room with just a flashlight and you can only see one area at a time. With our method, it’s like flipping on all the light switches so you can see the entire room all at once,” Jokerst said.

In an article in the Journal of Dental Research, Jokerst explains that the cuttlefish ink technique is significantly more consistent and accurate than using a periodontal probe. Testing the technique on pigs, they observed much less variation from one test to another. “It’s remarkable how reproducible this technique is compared to the gold standard,” Jokerst said.

The team is now working on improving the taste of the rince, which is currently unpleasantly salty and bitter, and developing an LED-based light source to replace the bulky and expensive laser, with the ultimate goal of incorporating the technique into a mouthpiece.