7-year Clinical Performance of Immediately Loaded Single-Tooth Implants

Objectives: This study retrospectively evaluated the survival rates of immediately loaded implants supporting single crowns, and investigated causes of failures.

Methods: Between April 2000 and May 2007, a total of 90 dental implants (Brånemark System® and Replace® Select) supporting single-crowns, were placed in 88 patients (35 male, 53 female, mean age: 51.9 years) in a private dental implant clinic (São Paulo, Brazil). Implants were loaded by provisional crowns within 24 hours after surgery, and definitive metal-ceramic crowns were cemented after 3 months. A comprehensive list of factors that could influence survival rate of implants, with all possible complications, was compiled. Patient charts were retrospectively screened for possible events related to failure. The median observation time was 25.5 months (range: 1-87 months). Implant survival data were evaluated according to Kaplan-Meier in addition to frequency counts and Fisher's Exact Test. Results: Of the 90 dental implants, 86 (95.6%) were still in situ. Three implants (3.3%) were lost after 1, 12 and 19 months, respectively. These implants were inserted in bone of quality type II or III with a torque of more than 32 Ncm to get primary stability. Only one implant was inserted with a torque under 32 Ncm without optimum primary stability. The three lost implants were placed in the maxilla. The only prosthetic problem was related to one crown that had its abutment screw loose after 5 months' of insertion. Reasons for failures are speculative, due to sample size and high success rate of this procedure, but parafunction seems to be a risk factor. The mean survival time was 18.8 months. Conclusion: This study on the success rate of immediately loaded single-tooth implants yielded 95.6%. Due to the small number of failures no definitive conclusion can be drawn concerning the factors leading to failures of implants supporting single crowns. This study, nevertheless, illustrates that immediate-loading of single-tooth implants is successful, and that it is a reliable treatment option to replace missing natural teeth to restore aestethics and/or function.