For this purpose, the minipig model was chosen because the embryologic development of pigs generally is recognised as comparable to that found in humans, with the similarities extending to the anatomy, physiopathology, and molecular structures.11, 12 and 13 The experimental procedures and care of animals are in accordance with European Convention for the Protection of Vertebrate Animals. Additionally, the ethics committee GPCR Compound Library on animal research of Bauru School of Dentistry, University of São Paulo, approved
the protocol of this study. Six 12-month-old male minipigs (Minipig BR-1), weighing approximately 35 kg each, were used in the experiment. The animals were kept individually and fed pig food equivalent to 2% of the animal’s weight and water ad libitum on a daily basis. The titanium–aluminium–vanadium alloy mini-implants presented a cylindrical
screw design and a hexagonal head (9 mm × 1.5 mm, ExoproLA™). The same researcher performed all surgeries under sterile conditions. Examinations and surgical procedures were performed under systemic (1 mg/kg intramuscular Azaperone and 5 mg/kg Ketamine) and local (2% lidocaine with 1:80,000 epinephrine) anaesthesia. The surgical sites were located in the maxillary and mandibular premolar regions. A guide drill with an outer thread diameter of 1.1 mm was click here used to mark the insertion site and ascertain the appropriate direction of mini-implant placement. A total of 72 mini-implants were inserted. Each animal received 12 mini-implants, 3 in each quadrant. One mini-implant in each region of the six animals (n = 24) was used as an unloaded
control (G1); the other 2 were loaded at three different time intervals, with a total of 16 mini-implants in each of three different experimental groups (G2, immediate loading; G3, loading after 15 days, or G4, loading after 30 days), equally divided between maxilla (n = 8) and mandible (n = 8). The control mini-implant was inserted in the position distal to the first Linifanib (ABT-869) premolar, while the other two experimental mini-implants were inserted distal to the second and fourth premolars, respectively ( Fig. 1A–C). All animals received mini-implants used as controls, but each one received mini-implants from only one experimental group (G2, G3 or G4), both in the maxilla and the mandible. The most anterior mini-implant remained unloaded, while force was applied to the other two implants at varying intervals. After placement, the 2 adjacent experimental mini-implants were loaded according to their groups with reciprocal forces. A nickel-titanium closed-coil spring was attached to the head of the mini-implant, thus providing a standardised force of 150 g, which was kept until the end of the experiment (120 days).