Dental implants deceive the immune system!

It is estimated that between 10 and 20 percent of dental implant patients eventually develop peri-implantitis, a serious infection that damages the surrounding jawbone, and antibiotics often fail to control it. ScienceDaily reported that researchers at Rutgers University’s School of Dental Medicine in the United States have identified a potential explanation for this phenomenon in a study published in the journal PNAS Nexus.

The researchers relied on human tissue samples, studied human immune cells in the laboratory, and conducted experiments on genetically engineered mice. They discovered that bacteria gradually erode the implants, releasing microscopic titanium particles into the surrounding tissue. These particles confuse the immune cells responsible for fighting infection, trapping them in a state of excessive inflammation that destroys the jawbone.

The puzzle lies in the similarity between this inflammation and periodontitis around natural teeth; both begin with the same types of oral bacteria, yet the response to treatment differs. In natural teeth, antibiotics combined with professional cleaning can treat the infection, whereas around implants, the same medications succeed in less than half of cases, and jawbone deterioration may continue even with treatment.

For two decades, scientists focused on the bacteria causing the infection. However, a team led by George Kotsakis decided to investigate another factor: the implant material itself. It was found that bacteria accumulating on surfaces form acidic biofilms that slowly corrode titanium, releasing billions of metallic particles over time, each smaller than a red blood cell. Other particles may detach during routine cleaning, especially if tools designed for natural teeth are used, which can scratch the metal surface.

Macrophages, which are white blood cells that engulf microbes, attempt to ingest these particles but cannot digest the titanium.

Laboratory experiments revealed the extent of the dysfunction: macrophages exposed to titanium particles ingested less than half the number of bacteria compared to cells that had not encountered the particles. Kotsakis, the study’s senior author and Associate Dean for Clinical Research at the school, described the particles as “tiny magnets” that attract bacterial toxins and hijack the immune system, preventing it from eliminating the bacteria. He added that this creates a “perfect storm” that defies antibiotics.

The team traced the molecular pathway to TRPC1, a calcium channel—a porous protein structure in cell membranes—found in macrophages that plays a central role in the inflammatory response triggered by titanium particles and bacterial toxins. When genetically engineered mice lacking this channel were exposed to the same mixture of particles and bacteria, their immune systems responded much better; they developed significantly smaller abscesses, produced fewer inflammatory signaling molecules, and regained the ability to eliminate bacteria, thereby preventing the disease observed in mice with the channel.

According to the researchers, this discovery offers the first reliable drug target for a condition affecting up to one in five implant recipients and costing global healthcare systems more than $1 billion annually. Kotsakis explained that understanding the cause allows for the development of treatments, and his team is currently evaluating potential drugs that target the same pathway in human cells, funded by the U.S. National Institutes of Health.

Until such treatments become available, regular professional cleaning remains the most effective known preventive measure, but the type of tools used makes a significant difference. Even about a decade ago, many physicians cleaned implants with the same metal instruments used for natural teeth, and research from Rutgers and others has shown that these can damage titanium surfaces and release additional particles. Today, non-abrasive cleaning methods are the standard.