Osteoconductive Properties of beta-Tricalcium Phosphate Matrix, Polylactic and Polyglycolic Acid Gel, and Calcium Phosphate Cement in Bone Defects

Extensive bone defects in maxillofacial region can be corrected with autogenous grafts; otherwise, the disadvantages of the therapeutics modality take the research for new bone substitutes. The aim of the study was to evaluate and compare the osteoconductive properties of 3 commercial available biomaterials. A total of 30 calvarial defects (5-mm diameter) were randomly divided into 5 treatment groups, with a total of 6 defects per treatment group (n = 6). The treatment groups were as follows: 500 to 1000 Km beta-tricalcium phosphate (beta-TCP), polylactic and polyglycolic acid (PL/PG) gel, calcium phosphate cement, untreated control, and autograft control. The evaluations were based on histomorphometric analysis at 60 postoperative days. The results have shown that beta-TCP and autograft control supported bone formation at 60 postoperative days. beta-Tricalcium phosphate showed the highest amount of mineralized area per total area and statistically significant compared with PL/PG, calcium phosphate cement, and untreated control groups. The PL/PG gel does not have osteoconductive properties and performed similar to empty control. Calcium phosphate cement showed higher number of multinucleated giant cells around the sites of the biomaterial and showed newly formed bone only at the edges of the biomaterial, without bone formation within the biomaterial. The findings presented herein indicate that bone formation reached a maximum level when rat calvarial defects were filled with beta-TCP at 60 postoperative days. Further studies should be conducted with beta-TCP to understand the potential of this biomaterial in bone regeneration.

Histometric Analysis of Bone Repair in Bone-Implant Interface Using a Polylactic/Polyglycolic Acid Copolymer Associated With Implants in Rabbit Tibia

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The use of polylactic and polyglycolic copolymer biomaterial in a pre-clinical model of compromised primary stability

Aim Primary implant stability can be compromised by overdrilling of the implant bed. Filling the gap between the implant and the bone with a highly viscous copolymer of polylactic and polyglycolic acid (PLA/PGA) might stabilize the implant and thus supply osseointegration. The aim of this study was to evaluate implants installed in overdrilled beds associated with PLA/PGA in rats tibia model by means of removal torque test and fluorochrome analysis. Materials and methods For this experiment two groups were selected: in the test group 0.4 mm overdrilled defects (2.0 in diameter and 3 mm long ) were produced in the right tibia of seven rats and implants were placed covered with PLA/PGA biomaterial to fill the gap; the control group was not overdrilled and the implants were placed without the biomaterial. Implants of 1.6 mm in diameter and 3 mm long where placed into all defects. Calcein, alizarin and oxytetracyclin were injected at 7, 15 and 21 postoperative days, respectively, and the animals were sacrificed at 35 postoperative day. Results The results showed that all the implants achieved osseointegration. There were no statistical significance differences in torque-reverse and fluorocrome analysis (P>0.05). Conclusion We can conclude that overdrilled defects filled with PLA/PGA did not disturb osseointegration in this experimental model. © ARIESDUE.

The effect of BMP-2 on the osteoconductive properties of beta-tricalcium phosphate in rat calvaria defects

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Rigid internal fixation with titanium versus bioresorbable miniplates in the repair of mandibular fractures in rabbits

The purpose of this study was to compare by qualitative histology the efficacy of rigid internal fixation with titanium system and the Lacto Sorb® system in mandibular fractures in rabbits. Thirty male adult rabbits Oryctolagus cuniculus were used. Unilateral mandibular osteotomies were performed between the canine and first premolar. The animals were divided into two groups: for Group I - rigid internal fixation was performed with titanium system 1.5 mm (Synthes, Oberdorf, Switzerland), with two screws of 6 mm (bicortical) on each side of the osteotomy. For Group II-rigid internal fixation was performed with PLLA/PGA system 1.5 mm (Lacto Sorb®, WLorenz, Jacksonville, FL, USA). The histological analysis evaluated the presence of inflammatory reaction, degree of bone healing and degree of resorption of the Lacto Sorb® screws. The results of both fixation systems were similar, only with a small difference after 15 and 30 days. In Group I a faster bony healing was noted. But after 60 days, bony healing was similar in both groups. It is concluded that both PLLA/PGA and titanium plates and screws provide sufficient strength to permit mandibular bone healing. The resorption process of PLLA/PGA osteosynthesis material did not cause acute or chronic inflammatory reaction or foreign body reaction during the studied period. © 2004 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Thermoanalytical study of praziquantel-loaded PLGA nanoparticles

Polymeric nanoparticles have received great attention as potential controlled drug delivery systems. Biodegradable polymers has been extensively used in the development of these drug carriers, and the polyesters such as polylactic acid, polyglycolic acid and their copolymers as poly-lactide-co- glycolide are the most used, considering its biocompatibility and biodegradability. Thermal analysis techniques have been used for pharmaceutical substances for more than 30 years and are routine methods for screening drug-excipient interactions. The aim of this work is to use thermal analysis to characterize PLGA nanoparticles containing a hydrophobic drug, praziquantel. The results show that the drug is in an amorphous state or in disordered crystalline phase of molecular dispersion in the PLGA polymeric matrix and that the microencapsulation process did not interfere with the chemical structure of the polymer, mantaining the structural drug integrity.

Avaliação do copolímero de ácido polilático e poliglicólico associado ao vidro bioativo no processo de regeneração óssea: análise histomorfométrica e imunoistoquímica em ratos

Pós-graduação em Odontologia - FOA

Cultura de condrócitos para o uso terapêutico: reconstituição de cartilagem

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação da interface osso/implante após o uso do copolímero de PLA/PGA associado a osso autógeno em coelhos: estudo biomecânico e imunohistoquímico

Pós-graduação em Odontologia - FOA

O efeito da BMP-2 sobre as propriedades osteocondutoras do beta-tricálcio fosfato em defeitos de calvária de ratos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Uso do copolímero de PLA/PGA no processo de reparo de defeitos ósseos em tíbia de coelhos: análise histomorfométrica

Pós-graduação em Odontologia - FOA