Failed dental implant: causes, diagnosis and retreatment options

Not all implant failures have the same origin. Before placing a new implant, it is essential to understand why the previous one failed.

A dental implant that fails to achieve osseointegration, or that undergoes progressive bone loss after a period of apparently regular function, is not simply a “failed implant”. It is a signal that something in the biological, mechanical or behavioural system did not work as intended. Identifying that something is the prerequisite for any rational retreatment.

Primary causes of implant failure

Implant failures are traditionally classified as early, within the first months of placement during the osseointegration phase, or late, after the loading phase, often months or years after prosthetic delivery. The causes are varied and rarely attributable to a single factor.

Biological causes

• Peri-implant bacterial infections (peri-implantitis), often facilitated by inadequate oral hygiene or prosthetic configurations that make cleaning difficult.
• Systemic conditions that compromise bone healing: uncontrolled diabetes, prolonged corticosteroid therapy, osteoporosis treated with bisphosphonates, heavy smoking.
• Inadequate bone quality and quantity, not correctly assessed during the planning phase.

Biomechanical causes

• Occlusal overload: the prosthesis transfers excessive forces to the implant or the peri-implant bone crest.
• Unfavourable implant positioning relative to the loading axis.
• Absence of a diagnostic provisional prosthesis: the patient was loaded with the definitive prosthesis without a functional verification phase.
• Bruxism not diagnosed or not managed prior to implant loading.

Iatrogenic and procedural causes

• Bone overheating during drilling, with necrosis of the peri-implant tissues.
• Bacterial contamination during surgery.
• Excessive or insufficient insertion torque.
• Inadequate management of peri-implant soft tissues.

Why simply replacing the implant is not enough

The instinctive response to implant failure is often the same: remove the implant and place a new one. This approach is rational only if the cause of the previous failure has first been identified and resolved. A new implant placed under the same conditions, with the same prosthetic rationale, in the same unmanaged biological context, is exposed to the same risks as the first. Often with a worse outcome, because the residual bone is more compromised.

In implant retreatments, the correct sequence is: causal analysis of the failure, management of the compromised tissues, a regenerative phase where indicated (bone and/or mucogingival), verification of systemic and behavioural conditions, correct prosthetic planning before the surgical phase, and only then implant re-placement.

Assessment of the post-failure site

After the removal of a failed implant, the residual site almost always presents vertical and/or horizontal bone loss relative to the original crest. The extent of this loss determines the retreatment options available: immediate re-placement, delayed re-placement with a preliminary regenerative phase, or alternative rehabilitation without an implant.

The decision cannot be made without updated radiographic documentation (cone-beam CT), an assessment of the peri-implant soft tissues, and an analysis of the cause of failure. Only after assembling a complete picture is it possible to plan the retreatment.

Implant retreatment

Retreatments represent the most distinctive area of clinical specialisation at Studio Calesini. The approach begins systematically with a causal analysis of the failure, proceeds with the management of compromised tissues, and develops into a sequential plan shared with the patient before any surgical intervention. Morphogenic Tissue Management (MTM) is employed when a regenerative phase is a necessary part of the retreatment plan.