Over the years, I have noticed the same trends while working as a public health dentist and researcher. Patients with serious infections deep in their teeth are more likely to suffer from broader health issues, especially diabetes. At the time, the connection was unclear. Now, a growing body of scientific evidence is beginning to explain it. Treating deep tooth infections may also improve your body’s ability to control blood sugar levels.
A tooth infection may seem like a small, localized problem, but researchers have found that its effects can spread throughout the body. A recent study found that people who underwent root canal treatment for chronic infections at the root tips of their teeth had lower blood sugar levels and less inflammation over the next two years.
Researchers observed the same trend in a longitudinal metabolomics analysis that follows people over time and uses sophisticated blood tests to examine hundreds of small molecules that reflect the body’s functioning. This type of analysis helps scientists understand how treatment affects overall metabolism, not just the infected tooth itself.
The patients in this study had apical periodontitis, a deep infection located around the edge of the tooth root. In most cases, there is little or no pain, so many people do not realize they have pain until it shows up on an x-ray.
Blood tests taken before and after treatment showed long-term improvements in blood sugar levels and markers related to heart and metabolic health. Simply removing infected tissue from inside the tooth appears to have benefits far beyond the inside of the mouth.
How tooth infections cause inflammation
One reason may be that these infections do not necessarily remain isolated. When bacteria spreads to the tissues around the root of the tooth, the immune system responds. If the infection persists, the body can enter a state of low-grade inflammation, a continuous immune response that never completely shuts down.
This ongoing inflammation can circulate through the bloodstream. Over time, chronic inflammation can interfere with your body’s ability to regulate blood sugar levels because it affects how insulin works and makes it harder for cells to absorb sugar from the blood.
To better understand how localized dental infections affect the entire body, researchers looked at the results of various studies. Their narrative review outlined several biological pathways that may link apical periodontitis to broader systemic disease.
Relationship between diabetes and oral infections
Many studies have been conducted on the relationship between diabetes and oral infections. A review of seven studies found that people with diabetes were more likely to develop persistent lesions around root-treated teeth.
In these cases, it is thought that the tooth infection does not directly cause diabetes, but rather that diabetes increases the risk of poor healing. High blood sugar weakens immune defenses, interferes with bone repair, and lesions near the root of the tooth (which appear on X-rays as dark areas where the bone has not healed properly) can become more common.
Another review reported that people with diabetes have a higher risk of developing new apical periodontitis in teeth that have already undergone root canal treatment compared to people without diabetes. Similar results were obtained in a clinical study involving hundreds of treated teeth.
Patients with diabetes often have longer-lasting lesions than patients without diabetes, reflecting poor glycemic control. This means that blood sugar levels are consistently higher than recommended, which is known to slow healing throughout the body, including bones and connective tissues.
Additional evidence from clinical guidelines and research on wound healing and glycemic control points to the same conclusion that hyperglycemia can impair immune function and slow tissue repair.
Root canal treatment and overall health
Researchers are now focused on what happens if these infections are successfully treated. One study using advanced metabolic testing found that root canal treatment not only eliminates infection, but is also associated with improved blood sugar control and lower levels of inflammatory markers.
Root canal treatment removes infected tissue inside the tooth and seals the area to prevent bacteria and toxins from spreading to surrounding tissue. Another study found that lesions tend to heal more slowly in people with diabetes, but lesions improve once the infection is treated. Even if healing is slow, it can still benefit your overall health.
Scientists say these findings are similar to those already observed in periodontal disease. Treating gum infections has been shown to improve blood sugar control in people with diabetes. Research suggests that periodontal therapy (specialized treatment that removes plaque, tartar, and subgingival infection) can moderately lower HbA1c levels.
Because HbA1c reflects average blood sugar levels over several weeks, even small decreases may improve long-term blood sugar control. Researchers believe that by reducing chronic inflammation in the mouth, blood sugar levels may be managed more effectively.
Silent dental problems often go unnoticed
One reason periapical infections are of particular concern is that they are often difficult to detect. Unlike periodontal disease, which typically causes pain, swelling, and bleeding, infection at the root tip exists silently, and the inflammation gradually spreads throughout the body. A review on apical periodontitis highlights how often these infections go unnoticed.
Researchers caution that this does not mean root canal treatment is a cure for diabetes. The improvements seen in studies are modest and vary depending on factors such as the severity of the infection and overall health.
The scientists also stress that a direct cause-and-effect relationship has not yet been proven and more controlled studies are still needed. Still, growing evidence suggests that oral health may play a much larger role in metabolic health than many people realize.
This finding may be particularly important for people living with diabetes or at risk of developing diabetes. If your tooth hurts or just feels unusual, it could indicate a non-dental problem.
The research also highlights broader issues. Dentistry and medicine are often treated as completely different fields, even though the body does not function that way. Research on root canal infections suggests that the two are closely related. Treating an infected tooth may do more than keep you smiling. It may also help improve your overall health.
