Antibiotics often fail to control the condition, and scientists have struggled to understand why. Now, researchers believe they have uncovered the mechanism responsible.

A new study published in PNAS Nexus Scientists at the Rutgers School of Dental Medicine have revealed that bacteria can slowly degrade dental implants, releasing microscopic titanium particles into nearby tissues. These particles interfere with the immune cells responsible for fighting infection, trapping them in a state of excessive inflammation that slowly destroys the jawbone.

Researchers examined human tissue samples, studied human immune cells in the laboratory, and conducted experiments using genetically engineered mice. Their research identified a calcium channel in macrophages, the immune cells that surround the bacteria, that was activated by the titanium particles. When this channel was disabled in mice, the disease was prevented.

The discovery provides the first credible drug target for a condition that affects one in five dental implant recipients and costs healthcare systems worldwide more than $1 billion annually.

"For the first time, we show why not all antibiotic treatments that work around teeth work around implants," said Georgios Kotsakis, senior author of the study and assistant dean of clinical research at Rutgers School of Dental Medicine. "Now that we know the cause, we can start developing a cure."

Why do dental implant infections resist antibiotics?

One of the biggest mysteries surrounding peri-implantitis is its similarity to periodontitis, the gum disease that develops around natural teeth. Both conditions start with the same type of bacteria found in the mouth, yet they respond very differently to treatment.

For natural teeth, antibiotics combined with routine professional cleanings can clear up the infection. Around dental implants, however, the same drugs are successful in less than half of cases. Even when treatment is attempted, the underlying jawbone may continue to deteriorate.

For the past two decades, scientists have largely focused on the bacteria responsible for these infections. Researchers in Kotsakis' laboratory decided to investigate another possible contributor: the implant material itself.

Their work shows that bacteria that accumulate on implant surfaces form an acidic biofilm that slowly damages the titanium. Over time, this corrosion can release billions of microscopic metal particles, each smaller than a red blood cell.

Titanium particles can also be removed during routine dental cleanings. This is especially concerning when appliances designed for natural teeth are used on implants, as they can scratch and damage the metal surface.

How titanium particles hijack the immune system

Once inserted into the gums, the tiny pieces of titanium attract a bacterial toxin called lipopolysaccharide, which coats their surfaces. This combination creates a deceptive target for the immune system, making the particles resemble unusually large bacteria that cannot be broken down.

Macrophages, white blood cells responsible for engulfing and destroying harmful microorganisms, attempt to consume these particles. But because cells can't digest titanium, they get stuck in a prolonged state of excessive inflammation.

As a result, macrophages produce large amounts of inflammatory signaling molecules, including interleukin-1 beta. This protein is also associated with inflammatory processes involved in rheumatoid arthritis and Alzheimer's disease.

The resulting immune response slowly breaks down the bone supporting the dental implant. At the same time, macrophages become less effective at fighting the bacteria that triggered the infection in the first place.

Laboratory experiments show how severely their defenses are compromised. Macrophages exposed to titanium particles engulfed less than half of the bacteria as immune cells not exposed to the particles.

"These particles are little magnets that attract bacterial toxins, and they hijack the immune system, preventing it from clearing the bacteria," Koutsakis said. "You have a perfect storm that refuses antibiotics."

Scientists identify a potential new therapeutic target.

After learning how titanium particles disrupt immune defenses, the researchers investigated the molecular pathways responsible for the harmful response.

They traced the process to TRPC1, a calcium channel (a specialized, pore-forming protein structure within cell membranes) found in macrophages. This channel plays a central role in inflammatory responses induced by titanium particles and bacterial toxins.

To test its significance, the team used genetically engineered mice that lacked TRPC1. When these animals were exposed to the same combination of titanium particles and bacteria, their immune systems responded more effectively.

The mice developed dramatically smaller abscesses, produced fewer inflammatory signaling molecules, and regained the ability to clear bacteria. Inactivation of the channel prevented the catastrophic disease process when TRPC1 was present.

The findings point to a potentially new approach to treating peri-implantitis by targeting the immune system response rather than relying exclusively on antibiotics.

With funding from the National Institutes of Health, Kotsakis and his colleagues are now evaluating potential drugs that work on the same molecular pathway in human cells.

Why Proper Dental Implant Cleaning Matters

While the research opens the door to future treatments, it also reinforces an important safety measure for those who have already had dental implants.

Regular professional cleanings are the strongest known protection against peri-implantitis. However, there can be a significant difference in the equipment and techniques used during these appointments.

Until about a decade ago, many dentists routinely cleaned implants with the same metal scalers used to remove plaque from natural teeth. Research by the Rutgers team and other scientists has since shown that these tools can damage and corrode titanium surfaces, potentially releasing excess particles and accelerating disease.

Today, non-abrasive cleaning methods have become standard practice, helping to protect implant surfaces while reducing the risk of complications.

By showing how degraded titanium can interfere with immune defenses, the findings offer a new explanation for why some dental implant infections are difficult to treat and point to a promising direction for developing more effective treatments.