Emily Correna Carlo

Comparison of in vivo properties of hydroxyapatite-polyhydroxybutyrate composites assessed for bone substitution.

This study compared 3 composites made of hydroxyapatite and polyhydroxybutyrate to determine their biocompatibility, osteointegration, and osteoconduction in rabbits bone defects. Hydroxyapatite-polyhydroxybutyrate was tested in a 10:90 vol/vol ratio for composite 1, 25:75 for composite 2, and 50:50 for composite 3, whereas defects in the control group remained unfilled. Limbs were clinically and radiographically evaluated, and samples were taken 8, 45, and 90 days after surgery for histologic and histomorphometrical analysis. No significant difference was found in the clinical parameters: pain, lameness, dehiscence, infection, and edema among the 4 groups. No signs of osteolysis or periosteal reaction were observed. Bone regeneration in groups 1, 2, and 3 occurred histomorphologically similar to the control group. No inflammatory infiltrate was present on any date of observation. More bone than connective tissue was significantly found in the defects of the 3 groups on all observation dates, and the percentage of bone tissue in the interface was similar for composites 2 and 3. Bone and connective tissue were observed in pores of composites 2 and 3. Osteoclasts were found in the bone-composite interface, and multinucleated giant cells were seen on the surface of composite fragments, found among mesenchymal tissue on the 45th and 90th days. No significant difference was observed in osteoclast number among the 4 groups. In summary, composites were considered biocompatible and able to integrate to bone. They also showed signs of biodegradability, and composites 2 and 3 were osteoconductive, the first displaying best characteristics for bone substitution.

Membrana amniótica canina utilizada como bandagem em úlcera superficial de córnea de coelhos - aspectos clínicos

Twenty-eight rabbits were submitted to superficial keratectomy. The treated group consisted of 14 animals received canine amniotic membrane as a bandage, sutured in a way that its epithelial surface was in contact with the corneal surface. The control group did not receive any treatment. The animals were submitted to clinical evaluations 24 hours after surgery, at each two-day interval during one week and at each four-day interval during 180 days. The amniotic membranes were evaluated as a bandage comparing the time needed for corneal epithelization in the treated and non-treated groups and determining the period necessary for the cornea to become completely transparent. The corneal opacity was present during the entire time of observation. The treated animals presented more opaque cornea in the early period of regeneration, with neovascularization and more pain and discomfort than the animals from control group, showing a delayed epithelization.

Compósito para fabricação de implantes reabsorvíveis para osteossíntese: avaliação da biocompatibilidade em coelhos

Biocompatibility, osseointegration, and resorption of a 10% hydroxyapatite (HAP-91®) - 90% polyhydroxybutyrate composite were analyzed after implantation in rabbits´ bone defects. Clinical, radiographic, histologic and histomorphometric data were collected on the 8th, 45th, and 90th days after surgery and the results were compared to those of unfilled defects. No significant differences between groups for the evaluated clinical parameters existed. Radiographs showed bone-composite direct contact. Bone tissue was formed normally in the defect and at the composite-tissue interface when compared to the control. No inflammatory infiltrated was observed. For each sampling day, the percentages of bone were greater than those of connective tissues (P=0.001 on the 8th and 45th days and 0.022 on the 90th day) inside the defect. Bone and connective tissues were seen at the interface with the composite, being the last one significantly greater than the first on the 90th day (P=0.004). Composites resorption signs were evident: giant cells on the surface of composite fragments separated from the original bloc. Data support that such composite is biocompatible in rabbits, resorbable and integrate to bone.

Osseointegração clínica-radiológica do compósito hidroxiapatita-lignina entre implante metálico e tecido ósseo em coelho

This study evaluated a sinthetic hydroxyapatite-lignin composite for osseoingration between metallic implant and bone tissue. Twenty New Zealand rabbits were used. A defect was made a the proximal region of lateral surfaces of both tibias. An intramedullary pin was inserted in the medullary cavity of the left tibia after filling the cavity with 1,000mg of the composite and covering the thread part of the pin with the composite. The same procedure was made in control tibias without the composite. Clinical evaluation was based on inflammatory reaction, dehiscence, lameness, pain, and tibial circumference. Radiographs were made immediately after surgery and then on days eight, 30, 60, 90, and 120. Most of the animals presented normal clinical progression. Radiographies of treated group showed decrease in the defect and medullary cavity radiopacity to the same pattern of the surrounding bone, while the contrary happened in control group; but, in this group, the medullary cavity remained radioluscent at the last observation date. It can be concluded that the hydroxyapatite-lignin composite did not show clinical signs of rejection and that radiopacity of the tissue in the bone defect and surrounding the pin was similar to bone radiopacity, suggesting that the material promoted osseointegration.

Tissue response to the composite 50% hydroxyapatite: 50% polyhydroxybutyrate for bone substitution in rabbits

Avaliaram-se a biocompatibilidade, a osseointegracao, a osseoconducao e a biodegradacao de compositos de 50% hidroxiapatita (HAP-91®) e 50% poli-hidroxibutirato. O composito foi implantado em defeitos osseos em 12 coelhos (grupo experimental), sendo comparado a defeitos nao preenchidos (grupo-controle, de igual numero). Os parâmetros clinicos dor, claudicacao, infeccao, deiscencia e edema foram avaliados nos primeiros oito dias apos a cirurgia e aos 45 e 90 dias. Radiografias foram realizadas aos oito, 45 e 90 dias apos a cirurgia em quatro animais por grupo que, em seguida, foram submetidos a eutanasia para coleta de amostras destinadas a analises histologica e histomorfometrica. Nao ocorreram diferencas entre os grupos para todos os parâmetros clinicos. Radiografias demonstraram um composito com radiopacidade semelhante a do osso vizinho e contato direto entre osso e composito aos 45 e 90 dias. Diferenca significativa foi observada entre a porcentagem dos tecidos osseo e conjuntivo dentro do defeito nos dias oito, 45 e 90, assim como na interface aos 45 e 90 dias. Foram observadas projecoes dos tecidos osseo e conjuntivo no interior do composito e sinais de biodegradacao na ausencia de infiltrado inflamatorio. Pode-se concluir que o composito e biocompativel, osseocondutor, biodegradavel e se integra ao tecido osseo.

Utilização experimental de hidroxiapatita sintética em alvéolos dentários de gatos domésticos (Felis catus): estudo clínico, radiográfico e histomorfométrico

The biocompatibility of a material depends on its characteristics, as well as the species and the environment recipient. In order to evaluate the biological response of the synthetic hydroxyapatite (HAP-91) in feline dental alveoli, it was implanted in the right inferior third premolar after extraction in 12 cats and maintained through a bacterial cellulose membrane. On the left side the alveoli was covered with a bacterial cellulose membrane (control group). During clinical evaluations it was observed that the animals started to eat after the anesthetic recovery time, without clinical signs of pain. There was a satisfactory cicatrization of the surgical wound and the bacterial cellulose membrane aided in repairing the gum, avoiding the loss of the hydroxyapatite. Radiographs taken 50 days post surgery presented homogeneous bone radiopacity on both sides. The histological and histomorfometrical analysis showed a positive progress of the alveolar repair in the first 8 days in the treated group when compared to the control group and a delay at 30 days, however at 50 days both presented a similar and morphologically normal percentage of bone tissue. These findings suggest that HAP-91 is biocompatible and integrates into the feline alveolar bone.