Implant Failure Characteristics: a 9-Year Retrospective Study

Objectives: Dental implant is considered a predictable procedure with high success and survival rates. Nevertheless it is important to analyze implant failure. The aim of the study was to analyze implant failure, reasons and time of failure. Methods: All failed implants placed during the years 1997-2004 were analyzed. Data collection included age, gender, smoking habits, implant type and dimensions, bone quality, timing of implantation (immediate and non-immediate), type of rehabilitation, time to failure, failure cause and complications. Results: Overall, 99 failed implants in 61 patients included in the study. The average age was 54 years (range 21 to 78 years). There were 34% males and 66% females. Smoking and past-smoking were reported by 32.8% and16.4% of the patients, respectively. The average time from implant placement to failure was 24 months (SD=24.8), ranging from 1 month to 99 months. The most common cause for implant failure was bone loss or inflammation (52.5%) followed by implant mobility (43.4%). One-third (32.8%) of the patients showed cluster behavior (more than one implant failure per patient). Of all failures, 56.6% were found in that group of patients. This cluster pattern was evident in both the surgical and prosthetic phase failures. Conclusions: There is a higher probability to cluster pattern in patients with implant failure. Implant mobility is the most common cause for implant failure in the surgical phase while infection and cervical bone loss are common during the prosthetic phase.