Comparison of immediate versus delayed implant placement in a failed implant site: A retrospective analysis of early implant survival

Purpose: To compare immediate and delayed implant replacement at failed implant sites to evaluate the factors associated with early failure of second implants after replacement. Materials and methods: Data regarding early implant failure followed by replacement with another fixture in a private practice setting between 2003 and 2019 were analysed retrospectively. Early failure was defined as loss of the dental implant within 6 months of placement. The impact of patient-level (age, sex, diabetes, smoking history) and implant-level (timing of implant replacement, timing of prosthetic loading, bone grafting) variables on the early failure rate of second implants after replacement was evaluated. Due to the hierarchical structure of the data, a multivariate multilevel mixed-effects Poisson regression analysis was performed. Results: A total of 109 patients (63 men and 46 women) diagnosed with early implant failure at 124 implant sites were included in the present study. Fifty-eight implants were immediately replaced at the time of removal of the failed implant (test group), whereas 66 were replaced after a healing period of 2 to 4 months (delayed approach; control group). A total of 15 implants failed after replacement in 11 patients during the first 6 months of follow-up. Of these, nine failures (15.25%) occurred in seven patients (13.21%) after immediate replacement, and six (9.09%) occurred in four patients (7.02%) who underwent delayed replacement. No statistically significant differences were detected between the two groups (P = 0.431). Conclusions: No significant differences in implant survival at sites of previous failure were found according to the timing of implant replacement.