(26) A retrospective cohort study on implant failure in a dental school setting

Introduction: The aim of this retrospective study was to assess the potential risk factors that lead to implant failure in a dental school setting.

Methods: A retrospective review of dental records for 130 failed implants was evaluated. The failed implants were removed in a post-graduate periodontal clinic and specialty private practice. This review includes patients with one or more implants removed between 2019 and 2021. The following medical and dental records are evaluated through electronic health records: gender; age; medical histories; implant position; implant design and size; primary insertion torque; single or two stages implant; complications; time elapsed between placement date and date of removal; type of the implant restoration; medications; reason for failure.

Results: 64 patients and 130 implants were included in the study. All patients identified were over the age of 37, with the average being 64 years of age. 46% of the subjects were male, and 56% were female. 39% of subjects were Caucasian, 34% were African American, 7.8% were Asian, 1.5% were Hispanic, and 34.3% were unreported. The implant survival period ranged from 21 days to 11 years, with 28% of implants lasting fewer than one year. 27.3% of implants survived between one and five years, and 12.2% survived greater than five years. 32.5% had an unknown survival period. Regarding the patients’ medical histories: 29.6% reported tobacco use; 20.3% had a history of diabetes; 53.1% had a history of heart disease; and 32.8% reported drug allergies. 57% of the reported drug allergies were to Penicillins. Moreover, 37.5% of patients had a history of periodontitis, with 21.8% diagnosed as having Stage II periodontitis and 15.6% as having Stage III Periodontitis. Of the 64 patients included, there were 130 implant failures. This indicates that if a patient had one failed implant, they were likely to experience another implant failure. 35% of the failed implants were located in the posterior maxilla, 33.3% in the posterior mandible, and 20.5% and 11.1% in the anterior portions of the maxilla and mandible, respectively. The most common reason for implant failure was lack of osseointegration (31.9%) or peri-implantitis (68%). 31.5% of implants experienced a complication, such as grafting, at the time of placement. Cover screws were utilized in 36.8% of implants at initial placement, and healing abutments were chosen in 13.9% of cases. 50% of the implants were restored as part of a fixed dental prosthesis (FDP), and 36.9% of the implants were never loaded. Additionally, 17.1% of implant failures came from the specialty private practice.

Conclusions: Within the limitations of this study, potential risk factors for implant failure in a dental school setting include patients of advanced age, a history of periodontitis, and a previous implant failure. Furthermore, the implant’s final restoration may also affect implant survival, as more failures were seen in implants restored with fixed splinted prostheses. Finally, the amount of surgical experience of the clinician may also play a role due to the more significant number of failures seen in the post-doctoral clinic versus the specialty private practice. Logistic regression will be used to analyze the risk factors of a failed implant. In addition, a future study will focus on the treatment modality of peri-implantitis.

Lead Author’s Contributions to the Research Project: The lead author was responsible for the data collection, performing the data analysis and for the composition of the abstract.