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Journal of Oral Science & Rehabilitation No. 3, 2017

T a p e r e d i m p l a n t s f o r b u n d l e b o n e p r e s e r v a t i o n antibiotics (enrofloxacin, 5 mg/kg, bid) and anal- gesics (meloxicam, 0.2 mg/kg, tid) via the sys- temic route. S u r g i c a l p r o c e d u r e The animals were pre-anesthetized with ace- promazine (0.12%, 0.25 mg/kg), buprenorphine (0.01 mg/kg) and medetomidine (35 μg/kg). The mixture was injected intramuscularly into the femoral quadriceps. The animals were then taken to the operating theater, where, at the earliest opportunity, an intravenous catheter was inserted (diameter of 22 or 20 G) into the cephalic vein, and propofol was infused at a slow, constant infusion rate of 0.4 mg/kg/min. Con- ventional dental infiltration anesthesia (artic- aine, 40 mg; 1% epinephrine) was administered at the surgical sites. These procedures were carried out under the supervision of a veterinary surgeon. Mandibular premolar and molar extractions (P2, P3, P4 and M1) were performed bilaterally. The teeth were sectioned in the buc- colingual direction at the bifurcation using a tungsten carbide bur so that the roots could be extracted individually without damaging the remaining bony walls with a contra-angle hand- piece (W&H, Bürmoos, Austria). The surgical device used for odontosection was the Implantmed (W&H). Crestal incisions were performed bilaterally in the premolar–molar region of the mandible. Full-thickness mucoperiosteal flaps were ele- vated, and recipient sites in the molar regions on both sides of the mandible were prepared for the present experiment, while the other regions were used for different experimental purposes, the results of which are reported elsewhere. The healed bone was prepared to place cylindrical, self-tapping implants with BIONER’s Top DM expansive core (BIONER Sistemas Implantológi- cos, Sant Just Desvern, Spain; 8.0 mm in length, 3.5 mm in diameter). A total of 48 implants were installed, 8 in each dog in healed and post- extraction bone (Figs. 1a–d). The implants had a bioetch surface characterized by a moderate, acid-etched without sandblasting, roughness along the implant body. The crestal or subcrestal positioning of the implants and the type of placement (healed bone or immediately post-extraction) were deter- mined randomly by the randomization plan gen- erator at www.randomization.com. The sub- crestal position was 2 mm below the buccal and lingual bone crests. After insertion of the implants, the healing abutments were con- nected to evaluate the periimplant soft tissue. The flaps were sutured with 4-0 silk (Lorca Marín, Lorca, Spain). After the surgical procedures, the animals received antibiotic treatment (amoxicillin, 500 mg, bid) and analgesics (ibuprofen, 600 mg, tid) systemically. In addition, the dogs were fed a soft diet for 7 days and plaque control was maintained through the application of Sea4 (Blue Sea Laboratories, Alicante, Spain). The wounds were inspected daily for postoperative clinical complications. Two weeks after surgery, the sutures were removed. H i s t o l o g i c a l a n d h i s t o m o r p h o m e t r i c a n a l y s i s Three animals were sacrificed at 8 weeks and the other 3 animals were sacrificed at 12 weeks through an overdose of Pentothal Natrium (Lab- oratorios Abbot, Madrid, Spain) and perfused through the carotid arteries with a fixative con- taining 5% glutaraldehyde and 5% formalde- hyde. The specimens were washed in saline and fixed in 10% buffered formalin. The specimens were processed to obtain thin sections of soil with the Precise 1 automated system (Assing, Rome, Italy). The specimens were dehydrated in ascending series with alcohol and embedded in a glycol methacrylate resin (Technovit 7200 VLC, Kulzer, Wehrheim, Germany). After polym- erization, the specimens were sectioned along their longitudinal axes with a high-precision diamond disk, at about 150–30 μm. A total of 2 slides were obtained for each implant. The slides were stained with toluidine blue and observed under a normal transmitted light microscope and a polarized light microscope (Leitz, Wetzlar, Germany). The histological preparation evaluated the distance from the top of the implant collar to the first contact with buccal and lingual bone (A-Bc and A-Lc), as well as the heights of the buccal and lingual bone ridges with respect to the neck of the implant (Fig. 2). Resorption of the buccal bone wall compared with resorption of the lin- gual bone wall was expressed as a linear mea- sure. The buccal and lingual bone plates were measured from the implant shoulder to the first BIC and to the top of the bony crest. The per- centage of BIC of native bone was also measured along the perimeter of the implant between the coronal end of osseointegration at the buccal and lingual aspects. The apical portion of each 30 Volume 3 | Issue 3/2017 Journal of Oral Science & Rehabilitation

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