Background: The aim of this study was to assess the clinical effectiveness of single dental implants placed in sites of previously failed implants.

Methods: The study consisted of a consecutive cohort of 1,215 patients who received 1,387 single implants for single-tooth replacement during a 6-year period (1999 to 2005). Inclusion criteria were a single implant replacing a previously failed implant and follow-up data ≥6 months. Data were recorded and analyzed regarding implant survival and location, need for bone augmentation, and implant dimensions.

Results: A total of 75 patients experienced the failure of 96 implants. Of those, 31 implants in 28 patients were replaced by a similar implant placed in the same location. Nine of the replacement implants failed, resulting in an overall survival rate of 71%. Follow-up ranged from 6 to 46 months (mean, 19.4 ± 11.4 months). Replacement of maxillary and mandibular failed implants was similar. All failures occurred during the first year after implant replacement. On average, implant replacement occurred 5.8 ± 5.2 months after original implant removal; three implants were placed immediately after implant removal. A third attempt for single implant replacement was made in two patients. However, one failed.

Conclusions: Replacement of a failed implant presents a challenge to achieve osseointegration in a healed bone site and may result in a decline in the survival rates. Patients and clinicians should be aware of these results before a replacement attempt is considered. The success of replacement may be increased by the use of wider implants or with improved surfaces.