Abstract: Objective To analyze impact factors of failed dental implant cases, and provide the theoretical guidance for clinical operation. Methods Cases in the Center of Oral Implantology from January 2012 to January 2021 with complete medical records were selected. The differences of gender, age, periodontal disease status, location of implants, implant, and surgical factors were compared between failed implants and successful implants. Statistical analysis software was SPSS 24.0. Statistical methods were the χ² test, Fisher’s Exact Test, and binary logistic regression. The level of statistical significance is expressed as P< 0.05. Results A total of 6124 implant cases were included in this study including 82 failed cases. The implant failure rate was 1.34%. There were 72 early failed cases and 10 late failed, with failure rates of 1.18% and 0.16%. Statistics results showed that the failure risk of men was higher than that of women (P< 0.001). Cases with implant diameter < 4.0 mm, implant length < 10 mm, and bone quality type Ⅳ showed a higher failure rate (P< 0.01). The failure risk in cases with internal sinus floor elevation (ISFE) was higher than those without the surgery (P< 0.001). The implant surface which were not sandblasted, large-grit, acid-etched (SLA) had a higher failure rate than those of SLA and SLActive (P=0.001). Age, upper or lower jaw, surgical site, the shape of implants, lateral approach of sinus floor elevation (LASF), and guided bone regeneration (GBR) had no statistical significance for dental implant failure. Conclusion The risk factors for the failure of dental implants were male, bone quality typeⅣ, implant diameter< 4 mm, implant length< 10 mm, non-SLA implant surface, ISFE surgical treatment, and periodontal disease.

Key words: Dental implant, Failure, Reasons, Risk factors