Study determines reasons for dental implant failure and removal techniques
ZURICH, Switzerland: Dental implants have become a great treatment option to replace missing teeth, and various treatment concepts have reported high success rates. Nevertheless, like in every medical procedure, biological complications can occur which may lead to complete implant failure and, consequently, in the worst-case scenario, to the removal of the implant. A recent study by researchers from the University of Zurich has revisited the reasons for implant failure and compared different removal techniques.
A literature search included 28 studies which had been conducted up to 2018. The studies assessed titanium implant failure, removal techniques and the reinsertion of implants in a previously failed site.
The research team identified different categories of factors causing implant failure. Biological factors include peri-implantitis and failure to attain or to maintain osseointegration. Implant fracture is an example of a mechanical factor. Medical errors causing implant failure include bone overheating, site contamination and malpositioning. Functional reasons for implant failure include design of prosthesis and functional overload.
The researchers found that early implant failure is normally caused by the lack of attaining or maintaining osseointegration, or bone overheating or site contamination. Late implant failure is triggered by implant fractures, malpositioned implants and progressive peri-implantitis. The last causes 81.9% of late implant failures. Early implant failure results in implants that are normally mobile and easy to remove. Late implant failure means the implants can be at least partly osseointegrated and, therefore, more difficult to remove.
As options for implant removal, the study determined tooth extraction, trephine burs, piezo-surgery, laser surgery, the counter-torque ratchet technique (CTRT) and electrosurgery. Even though trephine burs seem to be the best-known method for implant removal, the CTRT method, alone or combined, should be the first choice for the clinician because of its low invasiveness.
Furthermore, the research team found that implantation in previously failed sites, irrespective of early or late failure, results in a 71–100% survival rate over five years.
Regarding zirconia implant removal, little data is available. Because of zirconia’s physical properties, it is supposed that these implants require a different approach to removal compared with titanium implants.
“If removal is required, interventions should be based on considerations regarding minimally invasive access and management as well as predictable healing. (Post)Operative considerations should primarily depend on the defect type and the consecutive implantation plans,” concluded the authors in their paper.
The study, titled “Removal of failed dental implants revisited: Questions and answers”, was published online in Clinical and Experimental Dental Research on 21 August 2019, ahead of inclusion in an issue.