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ePaper created 2015-11-17, 15:11:47 | version 1.38.0
Volume 1 | Issue 1/2015 17Journal of Oral Science & Rehabilitation β-TCP b ov in e b iph a s ic b iom a teria l i ncre ase s bo ne f o rmati o n i n do g mo de l Among the alternatives available (allografts, xenografts or synthetic bone substitutes), syn- thetic materials can be ideal for bone regenera- tion giventhat manycharacteristics ofsuch ma- terials—mechanical properties, porosity, degra- dation rate and composition—can be modified accordingtothespecificclinicalrequirements.13,14 Biomaterialofporcine origin,which has high biocompatibility, stimulates the formation of new bone in contact with biomaterial particles. This material is used for maxillary sinus eleva- tion priorto implant placement.15–17 According to Tadic and Epple, synthetic cal- cium phosphate bone substitutes, such as hy- droxyapatite (HA), tricalcium phosphate (TCP) and biphasic calcium phosphate (BCP), offerex- cellent biocompatibility and are in common use as alternatives to autologous bone.18 In particu- lar, BCP ceramics, consisting of mixtures of HA and beta-tricalcium phosphate (β-TCP), are widely used as bone substitutes. Although BCP and β-TCP are more resorbable than HA bio- ceramics,anevenhigherresorptionrateisdesir- ableforbonerepairapplicationswhenevercom- plete implant osseointegration and bone re- placement are required inthe midterm. Recently, ceramics doped with silicon at dif- ferent rates have become a subject for research because of the biological benefits of silicon in their chemical composition.19 Zou et al. have re- ported that silicon-doped BCP enhances osteo- conductivity and has been found to be nontoxic invivoatconcentrationsashighas50,000 ppm, producing no adverse effects in rats.20 Furthermore,ithasrecentlybeenpostulated that silicon in the form of nanoparticles could even be bioactive and beneficialto the skeleton, although the mechanisms by which silicates regulate skeletal development and function re- main unknown.21 The addition of silicon to TCP can improve stability, provide better structural properties and stimulate new bone formation in small animal models.22, 19 The literature, how- ever, includes few examples of in vivo research into the benefits of incorporating 3% silicon nanoparticles into HA/β-TCP porous granular structures. The purpose ofthis invivo studywasto eval- uatethebiologicaleffectsoftheincorporationof 3% silicon nanoparticles into HA/β-TCP by histological and histomorphometric analysis, scanning electron microscopy and X-ray micro- tomography (μCT) evaluation in canine bone defects. Materials&methods Ani mals Six male beagle dogs of 1.5 years of age and weighing 12–13 kg each were used in the study. The experiment protocolwas designed in accor- dancewiththeSpanishandEuropeanguidelines for animal experiments. The experiment was approved by the Ethics Committee for Animal Research of the University of Murcia (Spain), in accordancewiththeEuropeanUnionCouncilDi- rectiveofFeb.1,2013(R.D.53/2013). Su rgi cal pro ce du re Theanimalswerepre-anesthetizedwithacepro- mazine (0.12%–0.25 mg/kg), buprenorphine (0.01 mg/kg)andmedetomidine(35 mg/kg).The mixture was injected intramuscularly into the femoral quadriceps. Then an intravenous ca- theter was inserted (22- or 20-gauge diameter) into the cephalic vein, and propofol was infused ataslowconstantinfusionrateof0.4 mg/kg/min. Conventionaldentalinfiltrationanesthetic (arti- caine 40 mg, 1% epinephrine) was adminis- tered at the surgical sites. These procedures were carried out under the supervision of a vet- erinarysurgeon. Te e th e xtracti o n and graf ti ng pro ce du re s In both quadrants of the lower jaws, the sec- ond, third and fourth premolars (PM) and first molars (M1) were used as experimental sites. The alveoli corresponding to PM2, PM3 and PM4were classified as smalldefects and M1 as large defects, respectively. Teeth were sectioned with a carbide tung- sten drill;the rootswere removedwithforceps, without damaging the remaining bony walls. Sulcular marginal incisions were made along the vestibular and lingual areas adjoining the alveoli, separating tissues to make the crestal hard-tissue walls visible (Figs. 1a & b). Prior to graft placement, the external di- mensions of the post-extraction sockets (di- ameter) were measured using a caliper and recorded. The mean alveolar ridge measure- ments of the extraction sockets were as fol- lows: 3.8 ± 0.21 mm (PM2), 4.0 ± 0.5 mm (PM3), 4.1 ± 1 mm (PM4) and 5.6 ± 0.07 mm (M1).