Failure causes, timing, and cluster behavior: An 8-year study of dental implants

The aim of this study was to analyze implant failure, causes, time of failure, and cluster behavior of implant failure among patients referred to a private surgical center. Methods: All failed implants placed during the years 1997-2004 were analyzed. Data collected included age, gender, smoking habits, implant type and dimensions, timing of implantation (immediate or nonimme-diate), time to failure, and failure causes. Results: Overall, 99 of the 3609 implants placed between the years 1997 and 2004 failed in 61 patients resulting in a 97.3% survival rate. Patients with implant failure ranged in age from 21 to 78 years (average 54 years); 34% were men, 66% women; smoking was reported by 32.8%, pastsmoking 16.4%; time from implant placement to failure ranged from 1 to 99 months (average 24 months, SD = 24.8). Common causes for implant removal were bone loss and/or inflammation (52.5%), and implant mobility (43.4%). Cluster behavior (ie, more than one implant failure per patient, not necessarily in the same area or quadrant) was shown in one-third (32.8%) of the patients in which 56.6% of all failures were found. This cluster pattern was evident in both the surgical and prosthetic phase failures. Conclusion: There is a higher probability for a cluster pattern among patients with implant failure. Common signs for failure are implant mobility (surgical phase) and infection and marginal bone loss (prosthetic phase).