MkII--a modified self-tapping Brånemark implant: 3-year results of a controlled prospective pilot study

A modified self-tapping implant (MkII) with improved cutting characteristics has been designed for use in both maxillae and mandibles. Four sequential studies were conducted to evaluate the outcome of the MkII implant compared to the standard implant. The results presented here are from the extended pilot study that has been conducted as an intra-individual study of 103 patients; ie, each patient received both test (MkII) and control (standard Brånemark System) implants. Seventy patients were treated in the mandible and 33 in the maxilla. The cumulative survival rates and marginal bone resorption showed equivalent results for both test and control implants. Three-year cumulative survival rates were 87.9% and 86.8% for test and control implants in maxilla, respectively, and 99.5% and 100% in mandibles, respectively. The mean marginal bone resorption was approximately 0.5 (control) to (MK II) 0.6 mm after 3 years of function. A total of 288 test implants and 275 control implants were placed. All implants, both test and control, could be placed in an appropriate implant position, but 21.2% of the implants were not fully seated by machine power only; the use of a manual cylinder wrench for the final turns was necessary. During the last phase of the study, however, with an increase in twist-drill diameter from 3.0 to 3.15 mm and an increased motor torque, the prerequisites of successful implant placement into final position were met.