Comparison of Demineralized and Deproteinized Bone
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COMPARISON OF DEMINERALIZED AND DEPROTEINIZED BONE Ana B. Castro-Ceseña1, Ekaterina Novitskaya2, Po-Yu Chen2, M. del Pilar Sánchez-Saavedra1, Gustavo Hirata3, and Joanna McKittrick2 1 Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Carretera Tijuana-Ensenada No. 3918, Zona Playitas, 22860, Ensenada, Baja California México 2 UC San Diego, 9500 Gilman Dr., La Jolla, CA 92093, U.S.A. 3 Centro de Nanociencias y Nanotecnología, UNAM (CNyN-UNAM), Km 107 Carretera Tijuana-Ensenada, Apo. Postal, 356, CP. 22800, Ensenada, México. ABSTRACT Cortical and cancellous bones were demineralized and deproteinized using 1 N HCl and 6% NaOCl, respectively. Experiments were performed at 37°C. The rate constants were calculated and the structural features of untreated and completely demineralized and deproteinized samples were studied by scanning electron microscopy, showing that intact, contiguous structures were obtained. For both cases, the rate constant was higher for cancellous bone than the cortical bone. INTRODUCTION There is a particular interest in the study of demineralized and deproteinized bovine bone since both, protein and mineral obtained from it have important applications on bone repair. Protein obtained from bone, i.e. by means of a demineralization process, has been used as a scaffold and for tissue engineering in bone repairing [1-5]. On the other hand, mineral obtained from deproteinized bovine bone has been used as a surface for deposition of new bone mainly in periodontology and oral implants [6-8]. Bone is a composite that poses a complex hierarchical structure. There are two types of bone: cortical (compact) and cancellous (trabecular or spongy). The cancellous bone consists of a highly porous structure and is surrounded by cortical bone, which is denser. Bones are mainly composed of collagen type I protein. Collagen fibrils have hydroxyapatite (Ca5(PO4)3(OH)) dispersed between or along them. Water, non-collagenous proteins (NCP’s) and lipids are also present [9-12]. Bone demineralization and deproteinization processes have been individually studied by several authors [13- 17]. Birkedal-Hansen [13-14] studied the diffusion of HCl in elephant ivory dentine. The distance penetrated by the HCl solution was directly proportional to the square root of time depending on the geometrical shapes of the samples. Castro-Ceseña et al. [15] studied bone demineralization kinetic parameters (rate constant and activation energy) using different concentrations of HCl and temperatures. The physical and chemical properties of bone deproteinization using hydrazine were analyzed by Termine et al. [16]. Broz et al. [17] evaluated the effects on the mechanical behavior of NaOCl deproteinized bone using macroscopic and microscopic techniques. This is the first study that simultaneously evaluates kinetics and structural features of demineralized and deproteinized bone.
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EXPERIMENTAL DETAILS Sample preparation A bovine femur bone (24 months old) was purchased from a local butcher. The bone was first c
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