In a retrospective study, all patients with immediately loaded implants in an edentulous maxillae with limited posterior ridge dimensions that received an equal concept were included if they had a follow-up of at least 3 years. The concept contained immediate loading with distal tilted implants and six implants per edentulous maxillae of a single implant system (blueSky™ implants, Bredent GmbH, Senden, Germany), and it includes an equal lab-side-prepared provisional fixed prosthesis.

All patients have received implant stability parameter measurements that were routinely collected at immediate loading directly after implant insertion and after first removal of the provisional restoration 3 months after surgery. The ISQ after RFA and PT values were measured.

The retrospective data analysis was conducted in accordance with the Helsinki Declaration of 1975, as revised in 2008, and all patients signed an informed consent. After consulting the local ethic committee, the decision was that due to the retrospective character of this study with no additional data acquisition, no ethical approval is needed according to the hospital laws of the appropriate state (Landeskrankenhausgesetz Rhineland Palatinate, Germany).

Patients who were treated with this concept had to have the desire and the indication for an implant-supported full-arch prosthesis and concerns regarding bone-grafting procedures. They had to be physically and psychologically capable of undergoing conventional implant surgery. They had to have a reduced bone volume in the molar region of the maxilla that would not allow placing dental implants of at least 6 mm in length without bone augmentation. But placement of tilted implants in the area of the premolars with an implant length of at least 10 mm had to be possible so that the implant was surrounded by bone. All patients had to be treated by the same maxillofacial surgeon and the same prosthodontist.

The exclusion criteria were an active infection or inflammation at the intended implants sites; major systemic disease, e.g., uncontrolled diabetes mellitus, radiation, or chemotherapy within 5 years prior to the surgery; bone-physiology-changing drugs such as bisphosphonates, severe bruxism, or clenching habit; and poor oral hygiene.