title: Effects of enzymatic treatments on the biomechanical properties of screws made of bone.
abstract: Nowadays, bone tissue employed to manufacture screws used as osteosynthesis material is obtained from organ donors. But in different medical fields there is an increasing need to use xenogenic grafts and implants, which still imply risks of transmission of some diseases and antigenicity. Two different autoclaving programs (A1, A2) and an alternative to reduce the antigenicity of screws made of xenogenic bone based on enzymatic treatment are analyzed from a biomechanical point of view. 128 screws made of bovine femur bone were employed. Some of them were partially demineralized with 0.6 N HCl, enzymatically digested with collagenase (specific) and pepsin (nonspecific) and then autoclaved. The specimens were subjected to tension, shear and screw torque tests and histologically evaluated. Compared to A1, A2 sterilization method (134 degrees C but higher vacuum and longer time) considerably reduced the mechanical strength of specimens. The enzymatic digestion, expected to reduce antigenicity, did not affect the screw superficial structure and would not modify the bone biomechanical properties per se, but maybe because of the association with autoclaving and partial demineralization.
authors.affiliation: Cátedra B de Anatomía, Facultad de Odontología, Universidad, Nacional de Córdoba, Haya de la Torre s/n, Pabellón Argentina ala izquierda, Ciudad Universitaria, 5000 Córdoba, Argentina. adractis@odo.unc.edu.ar
authors.forename: A B
authors.initials: AB
authors.lastname: Actis
authors.forename: J A
authors.initials: JA
authors.lastname: Obwegeser
authors.forename: P
authors.initials: P
authors.lastname: Bertolotto
mesh_terms: D000818:Animals; D001705:Bioprosthesis; D001842:Bone and Bones; D002417:Cattle; D004798:Enzymes / Q000737:chemistry*; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning
chemical_list: D004798:Enzymes