This study was independently designed by the investigators but was supported by Nobel Biocare Services AG, Kloten, Switzerland in the form of free surgical kits, implants and prosthetic components. No other financial contribution was received by any of the authors or their institutions. The authors declare that there is no affiliation or any other conflict of interest to the sponsor and that Nobel Biocare did not in any way interfere with the conduct of the trial or the publication of its results.

ITVs of variable-thread implants were significantly influenced by variations in bone quality and implant position in the posterior maxilla. Despite the influence of bone quality on primary stability, the mean ITVs attained with variable-thread tapered implants in poor bone quality were within the recommended range for immediate loading.