Space Maintenance and New Bone Formation with Polyurethane Biocomposites in a Canine Saddle Defect
ARMY INST OF SURGICAL RESEARCH FORT SAM HOUSTON TX
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Large mandibular defect reconstruction presents a continual challenge in oral and maxillofacial surgery. Growth factors such as recombinant human bone morphogenetic protein-2 rhBMP-2 incorporated in scaffolds for tissue engineering promote cellular infiltration, induce osteoblast differentiation, and enhance new bone formation. Biodegradable polyurethane PUR biocomposites containing allograft bone particles are reported to be effective carriers for rhBMP-2 and support new bone growth.1 Moreover, incorporation of allograft bone particles increases the mechanical properties of the graft, which is important for space maintenance in mandibular defects. However, allograft presents biological challenges, as even a low dose of rhBMP-2 combined with allograft can result in transient resorption.2 Additionally, combining recombinant human growth factor with allograft bone introduces regulatory concerns. Mastergraft MG is an osteoconductive, biphasic ceramic composed of 85 -tricalcium phosphate -TCP and 15 hydroxyapatite HA that is similar in mineral content to natural bone.3 45S5 Bioactive glass BG is a resorbable material that has been used effectively in a variety of bone regeneration applications.4 In the present study, we investigated the ability of injectable PURMG and PURBG biocomposites with two doses of rhBMP-2 to heal saddle defects in the canine mandible. Methods The biodegradable polyurethane was synthesized from a lysine triisocyanate LTI and polyethylene glycol PEG prepolymer, a polyester triol 450 gmol, and triethylene diamine catalyst. Treatment groups included the biocomposite containing 45 MG or 45 BG with a low dose of 100 gmL rhBMP-2 or a high dose of 400 gmL rhBMP-2 n4group. The lyophilized rhBMP-2 was hand-mixed with the PUR and injected into saddle defects 4animal measuring approximately 7-8 mm apicocoronal by 8-10 mm mesiodistal.
- Anatomy and Physiology
- Medicine and Medical Research
- Laminates and Composite Materials