Materials and Methods: A 3D prototype of a mandibular premolar was generated by Digital Imaging and Communications in Medicine (DICOM) images obtained from the cone beam computed tomography and imported to 3D modeling software tool, SpaceClaim. The four distinct load magnitudes of 100, 150, 200, and 250N were applied as a pressure load perpendicular to the lingual plane of the lingual cusp of the occlusal surface (normal load) and at 45° to same (oblique load). The stress distribution patterns and the maximum von Mises stresses were analyzed and compared.
Results: The occlusal stresses were distributed from the force loading point in an approximate actinomorphic pattern, and when the force load was close to the margin, the stress was much greater.
Conclusion: Ovoid cavity showed lesser stress concentration and deformation for each of the tested restorative material.
METHODS: Nanostructured SnO2-Ge multi-layer thin films were fabricated using electron beam evaporation and resistive heating techniques. Alternate layers of SnO2 and Ge were deposited on glass substrate at a substrate temperature of 300 °C in order to obtain uniform and homogeneous deposition. The substrate temperature of 300 °C has been determined to be effective for the deposition of these multi-layer films from our previous studies. The films were characterized by investigating their structural and optical properties. The structural properties of the as-deposited films were characterized by Rutherford Backscattering Spectroscopy (RBS) and Raman spectroscopy and optical properties by Ultra-Violet-Near infrared (UV-VIS-NIR) spectroscopy.
RESULTS: RBS studies confirmed that the layer structure has been effectively formed. Raman spectroscopy results show that the peaks of both Ge and SnO2 shifts towards lower wavenumbers (in comparison with bulk Ge and SnO2, suggesting that the films consist of nanostructures and demonstrate quantum confinement effects. UV-VIS-NIR spectroscopy showed an increase in the band gap energy of Ge and SnO2 and shifting of transmittance curves toward higher wavelength by increasing the number of layers. The band gap lies in the range of 0.9 to 1.2 eV for Ge, while for SnO2, it lies between 1.7 to 2.1 eV.
CONCLUSION: Analysis of results suggests that the nanostructured SnO2-Ge multi-layer thin film can work as heterojunction materials with quantum confinement effects. Accordingly, the present SnO2-Ge multi-layer films may be employed for photovoltaic applications. Few relevant patents to the topic have been reviewed and cited.
METHODS: PubMed and Science Direct were searched for papers published between the years 1974 and 2018. The search was restricted to articles written in English related to modification of glass ionomer cements. Only articles published in peer-reviewed journals were included. The search included literature reviews, in vitro, and in vivo studies. Articles written in other languages, without available abstracts and those related to other field were excluded. About 198 peer-review articles in the English language were reviewed.
CONCLUSION: Based on the finding, most of the modification has improved physical-mechanical properties of glass ionomer cements. Recently, researchers have attempted to improve their antimicrobial properties. However, the attempts were reported to compromise the physical-mechanical properties of modified glass ionomer cements.
CLINICAL SIGNIFICANCE: As the modification of glass ionomer cement with different material improved the physical-mechanical and antimicrobial properties, it could be used as restorative material for wider application in dentistry.