For tens of millions of people, dental implants have provided a way to replace missing teeth with a full set of fixed, functional teeth rather than removable dentures. However, an estimated 10% to 20% of implant patients eventually develop peri-implantitis, a serious infection that damages the surrounding jawbone. Antibiotics frequently fail to control this condition, and scientists have struggled to understand why.
Now, researchers believe they have uncovered the mechanism responsible. A new study published in PNAS Nexus by scientists at the Rutgers School of Dental Medicine reveals that bacteria can gradually corrode 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 progressively destroys jawbone.
The researchers examined human tissue samples, studied human immune cells in the laboratory, and conducted experiments using genetically engineered mice. Their investigation identified a calcium channel in macrophages, the immune cells that engulf bacteria, that becomes activated by titanium particles. When this channel was disabled in mice, the disease was prevented.
This discovery provides the first credible drug target for a condition that affects as many as one in five dental implant recipients and costs healthcare systems worldwide more than $1 billion annually. "For the first time, we show why all the antibiotic treatments that work around teeth do not work around implants," said Georgios Kotsakis, senior author of the study and assistant dean for clinical research at Rutgers School of Dental Medicine. "Now that we know the cause, we can start developing therapeutics." Why Dental Implant Infections Resist Antibiotics One of the biggest mysteries surrounding peri-implantitis has been its similarity to periodontitis, the gum disease that develops around natural teeth.
Both conditions begin with the same types of bacteria found in the mouth, yet they respond very differently to treatment. For natural teeth, antibiotics combined with routine professional cleaning can resolve the infection. Around dental implants, however, the same medications are successful in fewer than half of cases.
Even when treatment is attempted, the underlying jawbone may continue to deteriorate. For the past two decades, scientists have largely concentrated on the bacteria responsible for these infections. Researchers in Kotsakis' laboratory decided to investigate another possible contributor: the implant material itself.
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