Prior to the experiment, the protocol was approved by the Ethics Committee of Valencia University, Spain (A1434714637496). The guidelines indicated by the Council Directive of the European Union (53/2013; February 1, 2013) for animal experimentation and the ethical rules proposed by Royal Decree 223, March 14 and October 13, 1988, were fulfilled. The study was reported following the ARRIVE guidelines.

Sixteen New Zealand rabbits of about 24 weeks of mean age and 3 to 4 kg of weight were used for the experiment. The animals were divided into two groups, eight animals per group, based on the period of euthanasia that was fixed to 1 and 8 weeks from the surgery.

The randomization was performed electronically (www.randomization.com) by an author that was not involved in the selection of the animals and in the surgical procedures (DB). The surgeon (JVA) was informed about the allocation treatment at the access window after having performed the sinus lift.

Data from a study in rabbits [18] showed differences in the bone formation of about 10%. Considering this value as clinically relevant, and supposing a slightly greater variability (standard deviation ± 6%), a power of 0.8, and α = 0.05, a sample of 7 animals was considered sufficient to disclose differences. The number was then increased to 8 to compensate for the possible loss of animals.

Before surgery, a premedication was performed in all animals using 22 mg/kg of ketamine (Ketolar®; Pfizer, Madrid, Spain) and 2.5 mg/kg of xylazine (Rompun®, Bayer, Germany). As general anesthesia 1.5 mg/kg of propofol (Diprivan®, IL, USA) endovenous and maintained subsequently with isoflurane 2% and oxygen. During surgery, an intramuscular injection of 2.5 mg/kg of morphine 1%, (Braun®, Melsungen, Germany) was administered. As local anesthesia, 4% articaine with epinephrine 1/100.000 (ULTRACAIN DS forte®, Hoechst GmbH, Frankfurt, Germany) was used both in the tibia and in the nasal dorsum regions.

The skin at the proximal tibia was shaved and disinfected with Betadine (MEDA Pharma S.L., Madrid, Spain), and an incision was performed several millimeters below the anterior tibial tuberosity. The flaps were elevated to expose the tibial bone of the proximal region (Fig. 1a). Bone particles were collected using a Savescraper Twist curve (CGM spa, Divisione Medicale META, Reggio Emilia, Italy) and maintained in saline. The wounds were sutured with nylon (Aragó®, Barcelona, Spain).