Risk factors for early implant failure: a retrospective-multicentric study of 2323 implants in screw retained fixed full arch rehabilitation

Objectives: The aim of this retrospective study was to investigate possible risk factors for early implant failure in screw retained fixed full-arch rehabilitation. Methods: data of 487 patients (2323 implants) treated with full-arch rehabilitation supported by same implants brand were collected for the time period from 2017 to 2020 and examined to evaluate early implants failure rates. The following data were collected for statistical analysis: sex, age, health disorders (diabetes and hypertension) and bad habit (smoke) of the patient, location of the implant (maxilla or mandible, anterior or posterior site), type of implant's healing and bone regeneration procedures. Chi-squared test, bivariate comparison analysis and univariate mixed model analysis were used to estimate the effect of both patient-related and implant related variables on early implant failure as a potential risk factors. Results: 487 patients were included, 218 females (62.3 ± 9.14 of age) and 269 males (62.8 ± 10.11 of age) in 30 private institutions for a total of 2323 implants placed and a total of 526 screw retained fixed full arch rehabilitation. A total of 40 out of 2323 (1.7%) implants failed prematurely within 1 year, 32 in the maxilla 8 in the mandible. Bivariate comparison analysis and univariate mixed model analysis showed that female patient, implant placed in maxilla, age <61 years and submerged healed implants showed a statistically significant higher failure rate among the risk factors considered. Conclusions: Implants placed in the upper jaw and their modality of healing seems to be associated with a higher risk of early implant failure.