This study reports cross-sectional, correlational data of a prospective clinical research project [2] approved by the university Institutional Review Board (10/05074). The research protocol followed the precepts of the Declaration of Helsinki and its amendments. All patients signed an informed consent form.

A consecutive, non-probabilistic sample consisted of 45 implants placed in 20 patients treated by experienced specialists in oral implantology in a private clinic setting. Inclusion criteria were adult patients in need for implant-supported single crowns in the posterior region of the maxilla and mandible and indication of 6-mm long implants, with 2 mm of safety margins for the mandibular canal, lingual cortex of submandibular fossa, and maxillary sinus. Patients were excluded according to the following criteria: previous osseointegration failure or pathologic lesions in the region of interest, use of bone graft or biomaterials, use of bisphosphonates, heavy smoking habit (up to 10 cigarettes/day), non-controlled diabetes, immunosuppression, local radiotherapy, active periodontal disease, poor oral hygiene, or use of removable prosthesis in the antagonist arch.

Clinical data were collected by means of anamnesis, physical examination, and preoperative CT images for surgical planning. Data on implant characteristics and insertion torque were collected at the surgery session.

A total of 45 Standard Plus Regular Neck SLActive® implants (Straumann AG, Basel, Switzerland), 6-mm long and 4.1-mm diameter, were installed in 20 patients. The non-submerged, one-stage surgical protocol was adopted.

Preoperative asepsis of the face and oral cavity was performed with 0.12% chlorhexidine. After local anesthesia with 4% articaine hydrochloride with adrenaline 1:100,000, an incision was made on the ridge crest with total detachment of the flap.

With a 16:1 counter-angle (KaVo Dental®, Biberach, Germany) coupled on an electric motor (Smart® Driller, Jaguaré, São Paulo, Brazil), at a rotation speed of 900 rpm, the surgical milling sequence (1.4-mm spherical drill, 2.3-mm spherical drill, 2.2-mm helical drill, 2.8-mm helical drill, and 3.5-mm helical drill) was performed, with no use of a countersink drill or bone tap. The implant was inserted to the limit between the treated surface of the threads and the smooth platform surface, by using the contra-angle with adapter, at a speed of 18 rpm (Fig. 1a).