Dental Implants Found Prone to Fractures

Keren Shemtov-Yona (American Technion Society)

22 July 2015. A review of manufactured dental implants discarded because of bone loss in the jaw of their wearers, indicates more than 6 in 10 of the devices had cracks or similar mechanical defects. The findings from the study by Keren Shemtov-Yona, a dentist and engineering doctoral student at Technion-Israel Institute of Technology in Haifa, Israel appears online in Journal of the Mechanical Behavior of Biomedical Materials (paid subscription required) and will appear in the journal’s September 2015 print issue.

Dental implants are prescribed to replace missing teeth, from decay or old age. A cylindrical or tapered post made of titanium or titanium alloy is placed in the jaw bone, with one or more crowns affixed to a piece connecting to the post after it fuses with the jaw bone. According to American Academy of Implant Dentistry, some 3 million people in the U.S. have dental implants, with that number growing by 500,000 a year as the population ages.

Shemtov-Yona, working in Technion’s Dynamic Fracture Laboratory in the mechanical engineering faculty, investigated the frequency of metal fatigue in dental implants, structural damage that happens when objects experience repeated cycles of loading and unloading. She retrieved and examined 100 of these devices removed from patients with peri-implantitis, inflammation of soft tissue around the implant that leads to progressive bone loss, but the implants themselves were considered in good condition when discarded.

The examinations were conducted with energy dispersive X-ray spectroscopy and scanning electron microscopy, techniques offering extreme magnification needed to reveal the composition and structure of elements in objects.

The results show the implant posts were made of commercially pure titanium or a titanium alloy made with small amounts of other metals. Shemtov-Yona found 62 percent of the implants had surface defects, either full cracks or defects resembling cracks. More defects were found in implants made of commercially pure titanium than the titanium alloy.

The analysis indicates embedded particles in the implants were associated with occurrences of cracks in the implants. The particles, say the authors, likely combined with wear and tear of daily use to contribute to development of cracks and eventual failure of the implants.

Shemtov-Yona notes in a Technion statement that “every individual has both different chewing habits and oral environment,” where the constant chewing action “can cause a repeated loading, leading to degradation of the implant materials and metal fatigue.”

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