Results from the present study clearly show that it is possible to insert an implant using a one-step concept for the surgical preparation of the bone bed in cancellous bone.

Guazzi et al. [24], comparing the clinical outcome of implants inserted in sites prepared with a simplified protocol consisting of one large single drill versus multiple conventional drilling steps, demonstrated less surgical time which led to less postoperative morbidity in the test group.

Gehrke et al. [25] failed in finding differences in implant stability (RFA analysis) between implant inserted with a drill sequence or single large drill.

In the present study, the single-drill protocol was essentially different from that used from previous authors because the osteotomic sites resulted in undersized preparation with respect to the implant diameter. In this way, it is possible to keep more bone inside the implant bed with respect to a large final drill. Also, the significant thermal changes highlighted by some studies [26, 27] when only final large drill is used as single step are avoided by the present surgical protocol which involved the use of only one low-diameter bur.

Undersizing the osteotomic site is a well-documented [28, 29] surgical technique that allows to increase primary implant stability in poor bone density. From the biomechanical standpoint, an undersized drilling protocol is demonstrated to be effective in increasing insertion torque in low-density bone [30].

Some authors [31] theorized that a 10% undersized protocol, in poor density bone, is sufficient to improve the primary stability of the implant.

In the present study, the undersized bone preparation of the implant site of about 2 mm compared to a 4-mm-diameter implant (almost 100%) allows to obtain an excellent implant primary stability with insertion torque peaks greater than 45 N/cm. The implant geometry characterized by self-tapping threads helps the implant body to penetrate into the bone trabeculae without creating excessive bone dust that could delay the osseointegration processes. The high percentage of bone-implant contact (% BIC), almost double compared to the initial bone density, demonstrates an effective action of bone compaction.