Blowing the Whistle on Dental Implants

Dental implants are a viable tooth replacement solution for most people, and the question one may ask is not whether you have one of those, but when will you have a dental implant. The use of dental implants is constantly growing, and Israel has become superpower in terms of implant production.

However, like everything else in life, things can go wrong and implants happen to break after sometime, although this is fortunately not too frequent. Extracting and replacing a broken dental implant is a complex surgical procedure for both the dentist and the patient.

Dr. (DDS) Keren Shemtov-Yona started to study the fracture of dental implants in 2010, for her masters of Medical Sciences, in both the School of Dentistry (Rambam Hospital) and in the Department of Mechanical Engineering at Technion. Her results showed the influence of time on the degradation of the implants’ strength until a crack forms that causes final fracture by a mechanism known as metal fatigue.

Upon completion of her degree, Dr. Shemtov-Yona was so passionate about her research that she decided to enroll in a PhD program in 2013, under the supervision of Prof. Daniel Rittel (Mechanical Engineering).

A mother of two, living in Tel Aviv, she would not hesitate to travel twice a week to Haifa to carry out her research with utmost dedication.

Back to early 2014, she managed to collect one hundred dental implants from four Israeli dental clinics. Those implants were particularly precious because they had been extracted for biological reasons, but none of them was broken and otherwise appeared to be in pristine condition. Every implant was thoroughly and patiently examined using the scanning electron microscope of the Materials Mechanics Center, and the picture that emerged rather soon was rather awkward: many of the implants contained cracks and flaws at various stages of development. More precisely, 62% of the intact implants were actually flawed, as reported recently in the highly regarded Journal of the Mechanical Behavior of Biomedical Materials.

Reporting such troubling results did not go smoothly for obvious reasons. Dentistry journals, with a lesser engineering inclination, reacted negatively and perhaps not always objectively to the bad news. By contrast, the Bioengineering community welcomed the results and accepted the publication quite enthusiastically.

Are those such bad news for those of us who have implants for a few years already? According to Dr. Shemtov-Yona “it is too early to reach such a conclusion, since every individual has different mastication habits and oral environment, mastication causing a repeated loading leading to fatigue”. Which means that what will take several years in individual A may take less or not happen in individual. However, as she emphasizes, “time has come for both the dental community and the manufacturers to come to grips with the problem, learn to identify it and look for ways to improve the fatigue life of dental implants”.

And indeed, her research is now focusing on the causes leading to the development of cracks, some of which related to implant manufacturing procedures, in an attempt to devise a viable solution that will prolong the service life of the implants.

Technion has long emphasized interdisciplinary research, including the interface between Engineering and Life Sciences.

Dr. Shemtov-Yona’s research is precisely at this interface, since, as Prof. Rittel puts it, “dental implants without Dentistry make no sense on the one hand, but we have learned that dental implants without Engineering are very incomplete”.


Dr. (DDS) Keren Shemtov-Yona

Dr. (DDS) Keren Shemtov-Yona



Prof. Daniel Rittel

Prof. Daniel Rittel

Scanning Electron Microscope (SEM) micrographs of defects defined as "full cracks" on the surface of dental implants retrieved due to biological complications

Scanning Electron Microscope (SEM) micrographs of defects defined as “full cracks” on the surface of dental implants retrieved due to biological complications