Searching for a Better Way to Numb Kids’ Gums Before an Injection

little boy in dentist's chair, smiling and showing a thumbs up

Katharine Gammon


25 Jun 20

USC researchers are looking for ways to create a less painful injection for kids at the dentist. It takes a collaborative, interdisciplinary team to get the research done.

IN DENTISTRY, injecting local anesthetic represents the greatest source of fear and anxiety, especially in children. Alleviating that injection pain is one of the main struggles in appointments for children, Associate Professor of Clinical Dentistry Thomas Tanbonliong said. “The numbing agent we use is kind of hit or miss with kids,” he added. “It’s an eternal struggle.”

That’s why Tanbonliong teamed up with two former pediatric dental residents, Lydia Park PEDO ’17 and Nicole Bui PEDO ’18, as well as Associate Professor of Research Preventive Medicine Melissa Wilson PhD ’05 to test the efficacy of a new numbing compound. The hope was to find something better than the standard for pain-free injections. Children are a special case when it comes to numbing agents – they need an effective medicine, but the researchers also have to consider any potential system absorption of the numbing agent, since children have a lower body mass than adults.

The normal standard of care is a 20 percent benzocaine solution, and the team went about testing a compound that included 10 percent lidocaine, 10 percent prilocaine and 4 percent tetracaine. Since testing on kids is more challenging to get approved, they created a pilot study to test the compound on adults first.

The team didn’t have much experience with creating a randomized, double-blind trial – the standard of research – so they brought in Wilson, who is a biostatistician. With Wilson’s help, the researchers designed and conducted a study of 52 participants — 26 being treated with the new compound and the other 26 being treated with the traditional benzocaine. The dental researchers asked patients to rate their pain on a scale, and they also took measurements of their heart rate at four different points along the procedure – which often tells if a person is stressed even if they don’t react with pain. “We were able to look at two measurements,” Wilson said, “a subjective pain score and an objective heart rate.”

The heart rate measurements were the same between the two groups. The control group, those being treated with benzocaine, actually had lower pain scores than the experimental group that received the new compound. In addition, there were more complications with the new numbing compound. “We were hoping that we’d see a big difference between the compounds that will lead us to a follow-up on children,” Tanbonliong said. “But we saw no significant differences.” The paper was published in the journal Anesthesia Progress this month.

Still, the group is undeterred in their mission. They are still considering further testing. And it wouldn’t have been possible without the teamwork and expertise of residents Park and Bui, and Wilson. More and more, dental researchers are finding that interdisciplinary collaboration is the way to go, Tanbonliong said. “You get points of view from different people, and you can tap into the expertise of others.”
He added that this approach is common in medicine, but just starting to grow in dentistry. “Hopefully this will be a catalyst to tap on expertise of other dental specialties.”

Going to the dentist can be anxiety-provoking, but research like this is ongoing to make the experience more comfortable, Tanbonliong explained. “We want to advance science and teach our students and residents evidence-based techniques: that’s the goal of this kind of research.”


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