Titanium microparticles prevalent in oral tissue around dental implants, study shows microbiologystudy

Titanium micro-particles in the oral mucosa around dental implants are common. This is shown in a new study from the University of Gothenburg and Uppsala University, which also identified 14 genes that may be affected by these particles.

Registry data indicate that about 5% of all adults in Sweden have dental implants—and potentially also titanium particles in the tissue surrounding the implants. According to the researchers, there is no reason for concern, but more knowledge is needed.

“Titanium is a well-studied material that has been used for decades. It is biocompatible and safe, but our findings show that we need to better understand what happens to the micro-particles over time. Do they remain in the tissue or spread elsewhere in the body?” says Tord Berglundh, senior professor of periodontology at Sahlgrenska Academy, University of Gothenburg.

Previous research has shown that titanium particles may occur in inflamed tissues around dental implants. The new study, published in Communications Medicine, showed that titanium micro-particles were consistently found at all examined implants—even those without signs of inflammation.

The researchers analyzed tissue samples from 21 patients with multiple adjacent implants. Samples were taken both at healthy implants and at implants affected by peri-implantitis, an inflammatory disease in the tissue around the implant. Each patient thus served as their own control. The density of particles varied between patients, but not between sites with and without peri-implantitis within the same patient.

The analyses were conducted in collaboration with Uppsala University, where researchers used an advanced method called µ-PIXE to map the distribution of titanium particles in the tissue samples.

“µ-PIXE is an extremely sensitive, non-destructive microscopy method providing information on the elemental composition of samples that, however, requires a particle accelerator. In Sweden, the Tandem Laboratory is unique in offering µ-PIXE measurements,” says Daniel Primetzhofer, director of the Tandem Laboratory and professor at the Department of Physics and Astronomy at Uppsala University.

To make this type of study possible, the researchers had to develop the existing µ-PIXE system further. Now much larger sample areas can be scanned and microparticles can be identified automatically.

“µ-PIXE was well suited for this study, because its high sensitivity and spatial resolution enabled the efficient detection of the microscopic particles, while the high throughput ensured that we could collect data from a large population,” adds Gyula Nagy, second author of the study and former postdoc at the Department of Physics and Astronomy.

Affected genes

Peri-implantitis is a microbial biofilm-associated inflammatory disease around dental implants, with features similar to those of periodontitis around teeth. The inflammatory process is complex and the resulting destruction of supporting bone in peri-implantitis may lead to loss of the implant.

“We observed that tissue samples with higher concentrations of titanium particles had an altered gene expression, especially genes related to inflammation and wound healing. We identified 14 such genes, but it is unclear whether the particles influence the local immune response or if the difference in gene expression reflects inter-individual variability in inflammatory conditions,” says Carlotta Dionigi, specialist in periodontology and researcher at the Department of Periodontology, Sahlgrenska Academy, University of Gothenburg.

The researchers suspect that titanium particles are released during the surgical installation procedure, when the screw-shaped implant is inserted into the prepared canal in the alveolar bone. In this context, the observation of differences in micro-particle densities between various implant systems deserves attention, since the surface structure of the implant may influence the deposition of micro-particles. This is now an important topic for continued research.