Papers by Author: Monica Calasans-Maia

Abstract: The study aimed the evaluation of the effect of osseous repair in the synthetic hydroxyapatite cylinder (HA) implanted in rabbit’s tibia. Fifteen adult animals, weighing around 2.5 and 3.0 Kg, sourced by the Fluminense Federal University Animal Lab were anesthetized with spinal anesthesia, and two perforations were created in right tibia and filled with cylinders (2 x 6 mm) of HA. The animals were killed after 28 days for evaluating the HA cylinder through attenuated total reflection infrared microscopy (ATR-FTIR). The two fragments of tibia with the cylinder were collected and fixed in alcohol 70° prior to dehydration in successive alcohol solutions and then impregnated and embedded in methyl-methacrylate. Not stained neither pasted to lamina, sections of 200 µm thickness were analyzed in a Shimadzu IRPrestige-21 Automatic Infrared Microscope (AIM-8800) with ATR Objective Mirror (ATR-8800M). Prior to implantation, HA cylinder was characterized by X-Ray diffraction (XRD), Attenuated Total Reflection- Infra Red microscopy (ATR-FTIR) and X-Ray Fluorescence (XRF). After the implantation, the spectrum of the ATR-FTIR at the interface to neoformed bone was acquired. The hydroxyapatite synthesized was crystalline and stoichiometric with Ca/P ratio of 1.66, becoming carbonated after 28 days of implantation. We conclude that attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) is a useful tool for biomaterial evaluation and able to detect the modification of the chemical HA cylinder pattern occurred probably by ions migration in the biological environment.

Abstract: Biomaterials for treatment of bone defects have been studied for a long time. Alloplastic materials, mainly hydroxyapatite (HA), are under intense investigation due to its biocompatibility and osteoconductive properties. The HA can be modified by the incorporation of bivalent cations as Zn2+ known as a positive effectors for bone repair. The purpose of this study was to evaluate comparatively the effectiveness of 5% zinc-containing hydroxyapatite (ZnHA) in the treatment of critical size defect (CSD) in rat’s calvaria. CSD (8mm diameter) created in the skull of forty-five Wistar rats were filled with autogenous bone, HA and ZnHA. Skulls harvested after 30, 90 and 180 days were submitted to histological processing for paraffin embedding. Sections of 5 µm-thick stained with hematoxylin and eosin (HE) allowed histomorphometric analysis. The area of neoformed bone increased (p<0.001) from 30 to 180 days irrespective to treatment groups. ZnHA and the control group showed a large at 180 days but no significant difference compared to HA. Therefore, we concluded that both biomaterials are biocompatibles and osteoconductors, promoting new bone formation and apposition of bone on the surface throughout the periods and the addition of zinc improved the osteogenesis.

Abstract: Hydroxyapatite (HA), widely used as bone graft, can be modified by the incorporation of bivalent cations (Mg2+ and Zn2+) and its gradual release could favor the bone repair. The purpose of this research was to evaluate the effect of the HA and zinc-containing hydroxyapatite (Zn-HA) in the bone repair in rat calvaria in comparison to autogenous bone. Critical size defect in the calvaria was filled with the graft material and the samples were harvested at the 30, 90 and 180 days. The light microcopy observations showed the biocompatibility of the graft materials. In the Zn-HA group the area of neoformed bone was larger than in the HA group, but smaller than in the autograft. A fibrous connective tissue was more evident around HA granules. It could be conclude that the presence of zinc ions in HA crystal accelerated the osteogenesis and increased the area of newly formed bone in relation to HA.

Abstract: The study was carried out aiming the evaluation of the effect of hydroxyapatite (HA) and zinc-substituted hydroxyapatite (ZnHA) on osseous repair of rabbit’s tibia. For the study, 15 adult animals, weighing around 2.5 and 3.0 Kg, sourced by the Fluminense Federal University Animal Lab were acquired. Two perforations were created in each tibia and filled with cylinders (2x6 mm) of HA (group 1, right) or ZnHA (group 2, left). The animals were killed after 7, 14, and 28 days for evaluating the histological aspects of the interface site and bone repair. No sign of inflammatory reaction surrounding the cylinders area were observed, neither giant cells. Osteogenesis was evidently accelerated in all healing periods for the ZnHA group in regards to the HA group. Randomly dispersed areas of neoformed bone among wide areas of fibrous connective tissue was observed in the HA group. We conclude that both biomaterials are biocompatible, but zinc-containg HA enhanced and accelerated the osteogenesis in relation to HA.