A Retrospective Cohort Study on Site-Specific Early and Late Implant Failure in Single Teeth

To explore the association between specific implant site locations and early and late implant failure when replacing single teeth and to investigate possible local and systemic risk factors that could influence these failures.

The study design was a retrospective cohort study. A chart review was conducted based on records of patients who had received implants replacing single teeth at the University of Toronto, Faculty of Dentistry, between January 2005 and December 2021. In addition to implant location, systemic, local, and prosthetic factors were evaluated as potential risk factors contributing to implant failure.

A total of 78 (2.3%) implant failures were identified from a total of 3,460 single implants. The prevalence of early implant failure (1.4%) was significantly higher than late implant failure (0.9%; z = 2.05) (P = .040). The maxillary lateral incisor location (12/22) demonstrated the highest site-specific early implant failure rate (3.4%) relative to all other locations (Fisher exact test; P = .026). All implants placed in the anterior region of the jaw (2.3%), especially those placed in the maxilla (2.4%), had significantly higher rates of early failure when compared to posterior sites (1.1%; χ²[1] = 6.21) (P = .013). Early implant failures were significantly associated with patients whose health history was positive for a systemic condition other than type 2 diabetes (Fisher exact test, P = .034). There was a significantly higher late implant failure rate in mandibular implants (1.3%) compared to maxillary implants (0.6%; χ²[1] = 5.17) (P = .023). There was a significant association of late implant failures with wide-platform sites (≥ 4.6 mm) (χ²[2] = 11.57; P = .003) or wider-diameter implants (4.51 ± 0.6 mm) (t[76] = 3.19, P = .002).

The prevalence of implant failure was 2.3%, with maxillary lateral incisor sites demonstrating the highest rate of site-specific early implant failure. Early implant failures were associated with patients with a systemic medical condition, whereas late implant failures were associated with healthy individuals, mandibular implants overall, and in sites with wide-diameter implants.