%0 Journal Article
%T Numerical simulation of in vivo intraosseous torsional failure of a hollow-screw oral implant
%A Murat Cehreli
%A Murat Akkocaoglu
%A Kivanc Akca
%J Head & Face Medicine
%D 2006
%I BioMed Central
%R 10.1186/1746-160x-2-36
%X A £¿ 3.5 mm ¡Á 12 mm ITI£¿ hollow screw dental implant in a patient was subjected to torque failure test using a custom-made strain-gauged manual torque wrench connected to a data acquisition system. The 3-D FE model of the implant and peri-implant circumstances was constructed. The in vivo strain data was converted to torque units (N.cm) to involve in loading definition of FE analysis. Upon processing of the FE analysis, the shear stress of peri-implant bone was evaluated to assume torsional shear stress strength of the bone-implant interface.The in vivo torque failure test yielded 5952 ¦̀strains at custom-made manual torque wrench level and conversion of the strain data resulted in 750 N.cm. FE revealed that highest shear stress value in the trabecular bone, 121 MPa, was located at the first intimate contact with implant. Trabecular bone in contact with external surface of hollow implant body participated shear stress distribution, but not the bone resting inside of the hollow.The torsional strength of hollow-screw implants is basically provided by the marginal bone and the hollow part has negligible effect on interfacial shear strength.Following the introduction of osseointegrated oral implants to rehabilate functional and esthetic consequences related to the loss of teeth and associated hard and soft tissues, a variety of criteria have been placed to evaluate short- and long-term implant success [1-3]. Despite the efforts to optimize implant healing and maintenance of bone-implant interface, early and late implant failures are still reported. At present, commonly cited factors leading to implant failure are biological and biomechanical, but the initiation of marginal bone loss remains essentially unclear.Marginal bone loss to a certain level, particularly within the first year of function, is accepted as a physiologic reaction. Nevertheless, peri-implantitis and functional- or over-loading seem to be role-mates in progressive bone loss beyond the clinically-accepted
%U http://www.head-face-med.com/content/2/1/36