Identification of failure mechanisms in retrieved fractured dental implants

• A protocol for analyzing fractured implants and implant’s parts was developed.
• The main failure mechanism for dental implants is metal fatigue.
• For the first time failure mechanisms in implants made of Ti–6Al–4V were identified.
• Implants and implant’s parts might be broken at relatively low cyclic load levels.

Dental implants treatment complications include mechanical failures. These complications were considered minor until now but several clinical trials showed that mechanical complications are common in implantology and in implant rehabilitation. The aim of the study was to perform a detailed systematic failure analysis on Ti–6Al–4V and CP-Ti retrieved dental implants.A total number of 10 CP-Ti and 8 Ti–6Al–4V retrieved fractured dental implants and implant parts were collected and there metal composition was identified using SEM–EDX (energy dispersive X-ray spectroscopy).The identification of the implants failure mechanisms was done by comparing the fracture surfaces of retrieved fractured dental implants to fracture surfaces of implants fractured in lab conditions in room air, and also in an environment mimicking the intraoral environment, which includes artificial saliva and fluoride (exemplar testing). The analysis was done by using Scanning Electron Microscopy (SEM).The overall fracture mechanisms that were identified on the retrieved Ti–6Al–4V and of CP-Ti dental implants were identical to those found on fatigue fracture surfaces of the specimens’ fractured in lab conditions. No evidence was found for corrosion products on the metal surface, which might suggest the operation of a corrosion processes participating in the crack formation.This study clearly shows that fatigue is the main failure mechanism for Ti–6Al–4V and CP-Ti retrieved dental implants. The fractographic analysis showed that implants and their parts might be broken at relatively low cyclic load levels, of the kind that matches the load levels generated during mastication.