Effect of Abutment Angulation and Material on Stress and Strain Distributions in Premaxillary Bone: A Three-Dimensional Finite Element Analysis

Background and Aim: Dental implants with angled abutments are often inserted in the anterior maxillary region due to the status of the residual ridge and aesthetic considerations. The purpose of this study was to assess stress and strain distributions in the premaxillary bone around dental implants by means of finite element analysis (FEA). Materials and Methods: Four three-dimensional (3D) finite element models were designed by using ANSYS 14.5 software: (1) a straight titanium abutment, (2) a straight zirconia abutment, (3) a 20° angled titanium abutment, and (4) a 20° angled zirconia abutment in the anterior maxilla. Standard Straumann® implants with regular necks (4.8×12 mm) were selected. Premaxillary bone with type 3 bone quality was modelled with a 0.5-mm-thick cortical layer. A 178-N oblique load was applied to the cingulum of the models. Afterwards, stress and strain distributions were measured by using ANSYS 14.5 software. Results: Maximum stress and strain concentrated at the implant-abutment joint at the cervical one-third of crestal bone, mainly in the labial surface. The abutment's material had a less substantial effect on the distribution of stress and strain compared to the angle of the abutment. Stress and strain concentration in angled abutments was higher than that in straight abutments. However, angled abutments transferred lower levels of stress and strain to the bone compared to straight abutments. Conclusion: It can be concluded that an angled abutment might decrease the stress and strain in the anterior maxillary bone in comparison with straight abutments

Investigation on the effects of milling atmosphere on synthesis of barium ferrite/magnetite nanocomposite

In this research, barium ferrite /magnetite nanocomposites synthesized via a mechano-chemical route. Graphite was used in order to reduce hematite content of barium ferrite to magnetite to produce a magnetic nanocomposite. The effects of processing conditions on the powder characteristics were investigated by XRD, VSM, and HRTEM techniques. XRD results revealed that milling under air and argon atmospheres resulted in the appearance of Fe3O4 peaks beside BaFe12O19 peaks after 15 and 20 hrs milling, respectively. The intensity of Fe3O4 peaks in the XRD patterns increased by increasing the milling time. VSM studies revealed that saturation magnetization of the 40-hrs milled samples under air and argon atmospheres was 31.25 and 36.42 emu/g, respectively. This difference might be due to more Fe3O4 content in the latter sample. By annealing of the 40-hrs milled sample in air, saturation magnetization increased to 139.12 emu/g.Nanostructured MaterialsApplied Science