Classification According to Timing of Implant Failure

A clinician has to base the diagnosis only on the clinical and radiographic findings as microbiologic and histologic techniques are restricted to the experimental conditions. Considering the stages at which these failures can occur, it is advisable that we first divide the failure as:

• Before Prosthesis placement.

• After Prosthesis placement.

 Before Prosthesis Placement
On the basis of the stage when problems occurs implant failures can be classified as :

i)Before Abutment Connection.

ii) During Abutment Connection.

iii) After Abutment Connection.

1) Before Abutment Connection: There can be wound dehiscence, and the presence of signs of infection such as swelling, fistula, pain prior to stage to surgery.It is important to clinically examine and sequential radiographs to be taken to ascertain the cause distinguish soft tissue and bone problems which could be:

• Complications due to any remaining suture material.
• Improperly seated cover screws.
• Wound dehiscence caused when the denture is worn early or if the denture has been inadequately relieved.
• Bone loss — radiolucent line around the implant or localized rarefaction in the bone. On the radiograph relationship of the implant to vital anatomic structures should be assessed.

Sometimes there is radiographic evidence of periapical radiolucency with normal appearing bone coronally. It is important to distinguish between these inactive lesions  from active pathologic bone loss by correlating the clinical findings (evidence of infection— tenderness, persistent pain, swelling, fistula etc).

2) During Abutment Connection: Implants should be tested for the presence of any mobility and the radiographs should be taken. These radiographs are very vital as they serve as the baseline data to monitor any further bone loss. Any presence of bone loss at this stage is of concern and should be monitored and  investigated for any associated infection.

3) After Abutment Connection: The patient may complain of pain during screw tightening. Any clinical evidence should be looked into. It is important not to overtighten and overtorque the abutment to prevent the loosening of the implant and breaching the osseointegrated interface and leading to a “Spinner”.Also a radiograph should be taken to verify the complete and proper seating of the abutment.

After Prosthesis Placement
Patient should be put on a regular maintenance programme as we have seen in the previous unit and the monitoring done for clinical signs regarding soft tissue, prosthesis stability, occlusion and radiographic survey for bone loss should be done. It is important to look for ailing, failing implants or failed implants and manage them accordingly.