Delayed Versus Immediate Loading of Implants: Survival Analysis and Risk Factors for Dental Implant Failure
Purpose
The purpose of this study was to estimate 1-year survival for delayed versus immediately loaded implants and identify risk factors for implant failure.
Materials and Methods
This was a retrospective cohort study, consisting of a sample of subjects who had greater than or equal to 1 Bicon dental implant (Bicon, Boston, MA) placed over a 13-year period. The primary predictor variable was method of implant loading: delayed (3 to 6 months after placement) or immediately after insertion. Secondary predictor variables were classified as demographic, anatomic, implant/abutment, and reconstructive. The outcome variable was implant failure, defined as removal of the implant, and was recorded as months of survival. Descriptive, Kaplan-Meier, and univariate Cox proportional hazards statistics were computed. Univariate associations with P ≤ .15 and biologically relevant variables (eg, age, gender) were included in a marginal multiple Cox regression model. In the multiple model, a P value of ≤ .05 was considered statistically significant.
Results
The study sample consisted of 677 subjects who had 2,349 delayed-loaded dental implants and 178 patients who had 477 immediate-loaded implants. The unadjusted 1-year survival estimates for the delayed and immediate loading groups were 95.5% and 90.3%, respectively (P < .01). In the marginal multiple Cox regression model, immediate loading, current tobacco use, maxillary implants, and shorter implants were associated with failure (P ≤ .05).
Conclusion
In this study, implants loaded immediately were 2.7 times (after adjusting) more likely to fail at 1 year compared with delayed-loaded implants.
⁎Resident-in-Training, Department of Oral and Maxillofacial Surgery, Massachusetts General Hospital, Boston, MA.
†Assistant Professor, Department of Oral and Maxillofacial Surgery, Massachusetts General Hospital, Boston, MA.
‡Associate Professor and Director, Center for Applied Clinical Investigation, Department of Oral and Maxillofacial Surgery, Massachusetts General Hospital, Boston, MA.
Address correspondence and reprint requests to Dr Susarla: Massachusetts General Hospital, 55 Fruit Street, Warren 1201, Boston, MA 02114
This project was supported and funded in part by the Center for Applied Clinical Investigation and the Education and Research Fund, Department of Oral and Maxillofacial Surgery and the Massachusetts General Physicians’ Organization, Massachusetts General Hospital, Boston, MA.
ABSTRACT