## 2 Materials and Methods  
_Implants and groups formation:_ Eighty conical implants were prepared in pure titanium grade IV (Implacil De Bortoli Ltd.a, Sao Paulo, Brazil) which were 9 mm in length and 4 mm in diameter. The macrogeometry of the implants used presented the traditional design and threads configuration (Figure 2a) and, the new macrogeometry implant with the presence of decompression chambers in the threads design (Figure 2b). Based on the initial proposed hypothesis, both implant macrogeometries were prepared with and without (machined only) surface treatment. The surface treatment used was performed by blasting with microparticles (\(\sim\)100 \(\upmu\)m) of titanium oxide and followed by application of maleic acid, showing a roughness with Ra = 0.56 \(\pm\) 0.10 \(\upmu\)m [8]. Figure 3 shows the scanning electronic microscopy (SEM) of the two surfaces used for the comparison. Figure 1: Schematic image of the space created after drilling to generate the healing chamber inside of the threads to facilitate the osseointegration. Figure 2: Representative image of the implants and thread closed: (**a**) Traditional conical implant macrogeometry and (**b**) new conical implant macrogeometry. Then, the implants were divided into four groups in accordance with the macrogeometry and the surface condition (with or without treatment), as the following: Group 1 (G1), traditional conical implants with surface treatment; group 2 (G2), traditional conical implants without surface treatment (machined surface); group 3 (G3), new conical implant design with surface treatment; group 4 (G4), new conical implant design without surface treatment. All implants were subjected to washing, decontamination, sterilization, and packaging in accordance with the requirements for commercialization of these materials. _Animal procedures:_ Twenty New Zealand white rabbits, weighing 4 \(\pm\) 0.5 kg, were used for the present experimental study. The animals received the standards care and management applied in the previous studies performed and described by our research group [10; 11]. The international guidelines of animal studies were applied. The study was approved by the Animal Experimentation Committee (Number 02-17 UnRV), University of Rio Verde (Rio Verde, Brazil). A total of eighty implants (\(n\) = 20 per group) were installed in both tibias (\(n\) = 2 per tibia). The implants distribution was made by the randomization program (www.randomization.com). Initially, the animals were anesthetized using a combination of 0.35 mg/kg of ketamine (Ketamina Agener(r); Agener Uniao Ltd.a., Sao Paulo, Brazil) and 0.5 mg/kg of xylazine (Rompum(r) Bayer S.A., Sao Paulo, Brazil), with intramuscular application. Both tibias were scraped of hairs and cleansed with antiseptic solutions before the surgical procedures to avoid a contamination. Then, an incision was performed initiating \(\sim\)10 mm from the knee at distal direction with a length of \(\sim\)30 mm. The bone tissue was exposed and the osteotomy to install the implant was performed using a predeterminate drilling sequence propria of the implant system (Figure 4), under intense irrigation with saline solution. The implant introduction in the bone site was made with manual technique, ending with a torque of \(\sim\)20 N. Distances of 10 mm between the implants and from the knee articulation were maintained. Finally, a simple point suture was performed using an Ethicon nylon 4-0 (Johnson & Johnson Medical, New Brunswick, NJ, USA). After the surgeries, all medication was administered intramuscularly as follows: A single dose of 0.1 ml/kg of Benzetacil (Bayer, Sao Paulo, Brazil); three doses (one per day) of 3 mg/kg of ketoprofen (Ketoflex, Mundo Animal, Sao Paulo, Brazil). Euthan  
Figure 3: Representative SEM images of the two surface models used in both implant macrogeometry: (a) Without treatment (machined surface) and (b) with surface treatment. using an overdose of anesthesia two times after the implantations, at 15 and 30 days.