Part I of this study describes the survival of a wide-platform, wide-diameter implant (Wide-Platform Mk II). Beginning in January 1997, 85 Wide-Platform Mk II implants were placed in the jaws of 63 patients (35 males and 28 females). Male patients experienced 10 implant failures, and female patients lost 9 implants. The mean time of implant follow-up was 286 days (median, 280), with a maximum of 734 days and a minimum of 0 days. Implant loss was 19% in the mandible and 29% in the maxilla. Kaplan-Meier analysis showed a probability of implant failure after 1 year of 0.649 (confidence interval, 0.455 to 0.926) in the maxilla and of 0.751 (confidence interval, 0.616 to 0.915) in the mandible. No apparent relationship was noted between implant survival and implant length. Part II of this study evaluated the association between the survival of a new implant design and a number of potential risk factors. A retrospective chart review was conducted for all patients who received Wide-Platform Mk II implants and who agreed to allow a medical records review for research purposes. Kaplan-Meier survival curves were used to assess the probability of implant survival relative to time. The relationships between implant survival and implant location, history of tobacco use, current tobacco use, sinus grafting, bruxism, and root canal therapy were assessed by Cox proportional hazards modeling. Although the hazard ratio showed an increased risk of implant failure with some factors, particularly a history of root canal therapy in the site of implant placement (hazard ratio 3.2, P = .10), none of the factors were statistically significant. The Wide-Platform Mk II implant used in this population group was associated with a high failure rate, but the failure rate was not related to any specific risk factors reviewed.