For tens of millions of people, dental implants have replaced missing teeth with a full set of fixed, functioning teeth rather than removable dentures. However, an estimated 10 to 20 percent of implant patients eventually develop peri-implantitis, a serious infection that damages the surrounding jawbone.
Antibiotics often fail to control this disease, and scientists struggle to understand why. Today, researchers believe they have discovered the mechanism responsible.
A new study published in Nexus PNAS by scientists at the Rutgers School of Dental Medicine reveals that bacteria can gradually corrode dental implants, releasing microscopic particles of titanium into nearby tissues. These particles interfere with the immune cells responsible for fighting infections, trapping them in a state of excessive inflammation that gradually destroys the jawbone.
Researchers examined human tissue samples, studied human immune cells in the laboratory, and conducted experiments on genetically modified mice. Their investigation identified a calcium channel in macrophages, the immune cells that engulf bacteria, that is activated by titanium particles. When this channel was deactivated in mice, the disease was prevented.
The discovery represents the first credible drug target for a disease that affects up to one in five dental implant recipients and costs health systems around the world more than $1 billion per year.
“For the first time, we show why not all antibiotic treatments that work around teeth work around implants,” said Georgios Kotsakis, lead author of the study and assistant dean for clinical research at the Rutgers School of Dental Medicine. “Now that we know the cause, we can begin to develop treatments.”
Why dental implant infections are resistant to 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 types of bacteria found in the mouth, but they respond very differently to treatment.
For natural teeth, antibiotics combined with routine professional cleaning can resolve the infection. On the other hand, regarding dental implants, the same medications work in less than half of the cases. Even when treatment is attempted, the underlying jawbone may continue to deteriorate.
Over the past two decades, scientists have focused largely on the bacteria that cause these infections. Researchers in Kotsakis’ lab decided to study another possible contributor: the material of the implant itself.
Their work showed that bacteria accumulating on implant surfaces creates acidic biofilms that slowly damage 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 dislodged during routine dental cleaning. This is of particular concern when instruments 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 released into the gums, the tiny titanium fragments attract a bacterial toxin called lipopolysaccharide, which coats their surface. This combination creates a misleading target for the immune system, making the particles look like unusually large bacteria that cannot be broken down.
Macrophages, the 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 the inflammatory processes involved in rheumatoid arthritis and Alzheimer’s disease.
The resulting immune response gradually destroys the bone that supports the dental implant. At the same time, macrophages become less effective in fighting the bacteria that started the infection.
Laboratory experiments revealed how severely disrupted their defenses were. Macrophages exposed to the titanium particles engulfed less than half as many bacteria as immune cells that had not encountered the particles.
“These particles are little magnets that attract the bacterial toxin and hijack the immune system, preventing it from eliminating the bacteria,” Kotsakis said. “You have a perfect storm that defies antibiotics.”
Scientists identify potential new treatment target
After discovering how titanium particles disrupt immune defenses, researchers studied the molecular pathway responsible for this damaging reaction.
They traced the process back to TRPC1, a calcium channel (a specialized protein structure that forms pores in cell membranes) found in macrophages. This channel plays a central role in the inflammatory response triggered by titanium particles and bacterial toxins.
To test its importance, the team used genetically modified mice lacking TRPC1. When these animals were exposed to the same combination of titanium particles and bacteria, their immune systems responded much more effectively.
The mice developed significantly smaller abscesses, produced fewer inflammatory signaling molecules, and regained the ability to eliminate bacteria. Deactivation of the channel prevented the destructive disease process observed when TRPC1 was present.
The results 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 colleagues are currently evaluating potential drugs that act on the same molecular pathway in human cells.
Why Proper Cleaning of Dental Implants is Important
While the research opens the door to future therapies, it also reinforces an important preventative measure for people who already have dental implants.
Regular professional cleaning remains the most effective known protection against peri-implantitis. However, the instruments and techniques used during these appointments can make a significant difference.
Until about a decade ago, many dentists routinely cleaned implants with the same metal scalers used to remove deposits from natural teeth. Research by the Rutgers team and other scientists has since demonstrated that these tools can damage and corrode titanium surfaces, potentially releasing additional particles and accelerating disease.
Today, non-abrasive cleaning methods have become common practice, helping to protect implant surfaces while reducing the risk of complications.
By revealing how corroded titanium can interfere with immune defenses, the findings offer a new explanation for why some dental implant infections are so difficult to treat and identify a promising direction for developing more effective therapies.
Gn Health
