There are two types of implant failure
Early Failures and Late Failures
This type of failure occurs shortly after the implants are placed. They can be caused by:
Generally caused by:
Early failures can be dealt with at the stage of treatment planning, and diagnostic work up, by ensuring an adequate surgical protocol, and a thorough knowledge and understanding of the implant system being placed.
It goes without saying that implant surgery, like any invasive procedure, has to follow strict surgical and sterilization protocols, with emphasis being placed on minimal interval time between exposure of the implant from its sterile packaging to its insertion and primary fixation in the Osteotomy site.
Implants should never be manipulated by gloved fingers, or the surface contaminated by external sources during the implant placement. Epithelial invagination in the Osteotomy site is a certain precursor to implant failure. Most instances of crestal bone loss usually occurring within a few weeks of placement with an improper protocol of handling.
A large percentage of failures of implants occur in the late phase or the phase of loading. The most significant factor affecting stability of an implant is occlusal loading. Having mentioned that all implants are eventually prosthetic driven, it is imperative that the occlusal scheme has to be designed to ensure axial loading, and avoid excessive occlusal forces on the implant. Early signs of excess load fatigue are manifested by loosening of abutment screws, and may eventually lead to implant fractures.
The ratio of implant to crown should be ideally 1:1 to ensure proper dissipation of occlusal forces.
Short implants, with an inadequate diameter should be avoided to the greatest possible extent to prevent secondary failures due to inadequate loading.
Cantilever design, especially posterior cantilevers is a precursor to failure too, and may place excessive load on the implant.