A simple test commonly used to diagnose the health of a tooth during a checkup may work better than the usual criteria to assess anesthesia and prevent pain during one of the most sensitive of all dental procedures, a root canal, reports Grace Hsiao-Wu and her co-authors at HSDM.
In a randomized, placebo-controlled study of 83 men and women with an average age of 40, those who could not feel a cold stimulus on an anesthetized tooth were about 80 percent less likely to feel pain during a root canal procedure than those whose providers used soft-tissue numbness (such as a lip or tongue with no feeling) as a guide.
“Contrary to popular belief, dentists don’t like to cause people pain,” said Hsiao-Wu, a clinical instructor in restorative dentistry and biomaterials sciences. “It’s important to make sure the tooth is fully anesthetized. If it’s not completely numb, a patient feels it.”
In a root canal procedure, an endodontist makes an opening in the crown of a tooth, removes the inflamed or infected pulp, cleans and shapes the canals, and fills and seals the space. The procedure can save an infected tooth and relieve the severe ache caused by the damaged tissue.
The latest technologies and anesthetics have transformed what was an admittedly painful procedure decades ago to one that is no more uncomfortable than having a filling replaced, according to patient information posted on the website of the American Association of Endodontists. Yet some people may still feel pain at some point during the hour or longer procedure, Hsiao-Wu said.
There is no gold standard to assess the level of anesthetic effect, she explained, but most dentists check soft tissue signs, such as lip and tongue numbness, for lower teeth, which are more difficult to anesthetize fully.
For their study, Hsiao-Wu and her colleagues selected Green Endo-Ice, a precision spray of –26 degrees C (–15 degrees F). Dentists normally use a cold test to aid diagnosis during checkups. The sensation quickly disappears in healthy teeth, but a lingering ache in a particular tooth indicates a potential problem.
In this study, patients but not clinicians were blinded. In the analysis, the researchers controlled for the severity of inflammation and damage, age, gender, tooth location, and amount of local anesthesia.
The common, easy, inexpensive cold test should become the new standard of care preceding endodontic therapy, concluded Hsiao-Wu and her co-authors.
Hsiao-Wu conducted the study during her endodontic residency when she was also earning her MPH from the Harvard School of Public Health. The findings are reported in the April Journal of Endodontics.