Risk factors for the failure of re-implanted dental implants: A 20-year retrospective study.

The survival rate of second-time-placed implants was lower than that of first-time-placed implants. The risk factors for second-time-placed implant failure were smoking, implant surface, and timing of reimplantation. To prevent further failure, previous failure factors should be analyzed and modifiable risk factors must be controlled before reimplantation.