Squid Ink Enables More Accurate Pocket Measurements

Dentistry Today
Image courtesy of Jokerst Bioimaging Lab at UC San Diego.


 Image courtesy of Jokerst Bioimaging Lab at UC San Diego.

By combining squid ink with light and ultrasound, researchers at the University of California (UC), San Diego, and UC Irvine have developed dental imaging technology that non-invasively, more accurately, and more comprehensively measures pocket depth than the current state of the art, according to the team. 

“The last time I was at the dentist, I realized that the tools that are currently being used to image teeth and gums could use significant updating,” said Jesse Jokerst, PhD, a nanoengineering professor at UC San Diego and senior author of the study.

Dentists use periodontal probes to measure pocket depth and diagnose gum disease, though this process can be invasive, uncomfortable, and even painful for the patient. Measurements also may vary greatly between dentists, and the probe can only measure one spot at a time.

“Using the periodontal probe is like examining a dark room with just a flashlight and you can only see one area at a time,” said Jokerst. “With our method, it’s like flipping on all the light switches so you can see the entire room all at once.”

The new method is designed to image the entire pocket depth around the teeth consistently and accurately without any painful poking and prodding. It begins by rinsing the mouth with a paste made of commercially available food-grade squid ink mixed with water and cornstarch.

The rinse serves as a contrast agent for photoacoustic ultrasound, which shines a light signal such as a short laser pulse onto a sample that then heats up and expands, generating an acoustic signal that researchers can analyze. 

“Light in, sound out,” Jokerst said.

Squid ink includes melanin nanoparticles, which absorb light. During the rinse, they get trapped in the pockets between the teeth and gums. When researchers shine a laser light onto the area, the ink heats up and quickly swells, creating pressure differences that can be detected using ultrasound. The researchers then can create a full map of the pocket depth around each tooth.

The researchers tested their method in a pig model with a mix of shallow and deep pockets. While their results closely matched measurements taken using a periodontal probe, they also were consistent across multiple tests. However, measurements with the periodontal probe varied significantly from one test to another.

“It’s remarkable how reproducible this technique is compared to the gold standard,” said Jokerst. 

Next, the researchers will collaborate with dentists and test their method in human beings. They also hope to minimize the taste of the squid ink oral rinse, which is salty and bitter, and replace the lasers with inexpensive and more portable lights like IEDs. Ultimately, they want to create a mouthpiece that uses this technology to measure periodontal health. 

The study, “Photoacoustic Imaging for Non-Invasive Periodontal Probing Depth Measurements,” was published by the Journal of Dental Research.

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