RESUMO
PURPOSE: This research evaluated clinical, histological, and radiological osseous regeneration in a critical-sized bilateral cortico-medullary osseous defect in model rabbits from New Zealand after receiving a hydroxyapatite matrix and polylactic polyglycolic acid (HA/PLGA) implanted with human dental pulp stem cells (DPSCs). METHODS: Eight New Zealand rabbits with bilateral mandibular critical-sized defects were performed where one side was treated with an HA/PLGA/DPSC matrix and the other side only with an HA/PLGA matrix for 4 weeks. RESULTS: An osseointegration was clinically observed as well as a reduction of 70% of the surgical lumen on one side and a 35% on the other. Histologically, there was neo-bone formation in HA/PLGA/DPSC scaffold and angiogenesis. A bone radiodensity (RD) of 80% was radiologically observed achieving density levels similar to mandibular bone, while the treatment with HA/PLGA matrix achieves RD levels of 40% on its highest peaks. CONCLUSIONS: HA/PLGA/DPSC scaffold was an effective in vivo method for mandibular bone regeneration in critical-sized defects induced on rabbit models.
Assuntos
Implantes Dentários , Polpa Dentária , Animais , Regeneração Óssea , Polpa Dentária/diagnóstico por imagem , Durapatita , Xenoenxertos , Humanos , Nova Zelândia , Coelhos , Células-Tronco , Alicerces TeciduaisRESUMO
(57)Fe Mössbauer spectroscopy has been used to investigate the structural and magnetic phase transitions of CaFe2As2 (T(N) = 173 K) single crystals. For this compound we found that V(ZZ) is positive and parallel to the c-axis of the tetragonal structure. For CaFe2As2 a magnetic hyperfine field B(hf) was observed at the (57)Fe nucleus below T(N) ~173 K. Analysis of the temperature dependence of B(hf) data using the Bean-Rodbell model shows that the Fe spins undergo a first-order magnetic transition at ~173 K. A collinear antiferromagnetic structure is established below this temperature with the Fe spin lying in the (a, b) plane. Below T(N) the paramagnetic fraction of Fe decreases down to 150 K and for lower temperatures all the Fe spins are magnetically ordered.
RESUMO
(57)Fe Mössbauer spectroscopy has been used to investigate the magnetic order of non-superconducting NdFeAsO (T(N) = 140 K) and superconducting NdFeAsO(0.88)F(0.12) (T(c) = 45 K). A magnetic hyperfine field B(hf) was observed at the (57)Fe nucleus below T(N)â¼140 K for NdFeAsO. Below â¼2 K an increase of B(hf) relative to the saturation value was attributed to the transferred B(hf) at the Fe site resulting from the collinear antiferromagnetic (AF) spin structure of the Nd moments. The analysis of the spectra is consistent with a commensurate AF order of Fe spins. No B(hf) is observed in superconducting NdFeAsO(0.88)F(0.12) down to 1.5 K.