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

Purpose: Research has identified several factors associated with early and late implant failure, however site specificity as a potential risk factor has not been investigated previously. The purpose of this research was to explore the association between specific implant site location as a potential risk factor for early and late implant failure when replacing single teeth, and to investigate possible local and systemic risk factors that could influence these failures. Materials and Methods: 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 to December 2021. In addition to implant location, systemic, local, and prosthetic factors were evaluated as potential risk factors contributing to implant failure. Results: 78 (2.3%) implant failures were identified from a total of 3460 single implants. The prevalence of early implant failures (1.4%) was significantly higher than late implant failures (0.9%), z=2.05 (p=0.040). 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=0.026). All implants placed in the anterior region of the jaws (2.3%), especially those placed in the maxilla (2.4%), had significantly higher early failure when compared to posterior sites (1.1%), χ²(1)=6.21, p=0.013. Early implant failures in the study were significantly associated with patients whose health history was positive for a systemic condition other than type II diabetes (Fisher exact test, p=0.034). There was significantly higher late implant failure rate in mandibular implants (1.3%) compared to maxillary implants (0.6%), χ²(1)=5.17 (p=0.023). There was a significant association of late implant failures in the study with sites with a wide platform (4.6mm or greater) (χ²(2)=11.57, p=0.003) or wider implant diameter implant (4.51±0.6mm) (t(76) = 3.19, p=0.002). Conclusion: The prevalence of implant failures was 2.3% with maxillary lateral incisors sites demonstrating the highest site specific early implant failure. Early implant failures were associated with patients with a systemic medical condition while late implant failures were associated with healthy individuals, mandibular implants overall, and in sites with wide diameter implants.