Objectives: Static implant loading caused by non-passive restorations may cause technical complications. As metal-ceramic restorations are most common in implant prosthodontics, the objective of the study was to investigate the effect of static and dynamic loading upon the stability of the ceramic veneer of implant-supported fixed partial dentures (FPDs).
Methods: A total of 10 groups of three-unit implant FPDs with five samples each were investigated in the conditions after fabrication, static loading and dynamic loading (chewing simulator, 20,000 cycles, 100N). The fluorescent penetrant method (FPM) was applied to detect microcracks at the cervical and occlusal aspects of the FPD abutments. Statistical analysis was performed based on the number of microcracks (t-test) and the presence of chipping fractures (Exact Fisher test) with the level of significance set at alpha=0.05.
Results: Static and dynamic loading led to an increase both in number of microcracks and frequency of chipping fractures. After static loading, the screw-retained FPDs cast in one piece revealed significantly lower numbers of cervical microcracks than did the cementable restorations fabricated from repositioning technique impressions (p=0.003). The screw-retained FPDs which were fabricated using premachined gold cylinders showed the highest numbers of cracks and chipping fractures both after static and dynamic loading.
Significance: Static loading may damage the ceramic layer of implant-supported restorations. The use of prefabricated components may cause increased numbers of microcracks due to the lack of bonding oxides.
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http://dx.doi.org/10.1016/j.dental.2007.03.012 | DOI Listing |
Sci Rep
December 2024
Division of Pulmonary and Critical Care, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095-1690, USA.
Electronic cigarettes (e-cigs) fundamentally differ from tobacco cigarettes in their generation of liquid-based aerosols. Investigating how e-cig aerosols behave when inhaled into the dynamic environment of the lung is important for understanding vaping-related exposure and toxicity. A ventilated artificial lung model was developed to replicate the ventilatory and environmental features of the human lung and study their impact on the characteristics of inhaled e-cig aerosols from simulated vaping scenarios.
View Article and Find Full Text PDFNat Commun
December 2024
Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD, USA.
Non-Hermitian models describe the physics of ubiquitous open systems with gain and loss. One intriguing aspect of non-Hermitian models is their inherent topology that can produce intriguing boundary phenomena like resilient higher-order topological insulators (HOTIs) and non-Hermitian skin effects (NHSE). Recently, time-multiplexed lattices in synthetic dimensions have emerged as a versatile platform for the investigation of these effects free of geometric restrictions.
View Article and Find Full Text PDFNat Commun
December 2024
Department of Electronics and Information Convergence Engineering, Kyung Hee University, Yongin-si, Republic of Korea.
Self-assembled configurations are versatile for applications in which liquid-mediated phenomena are employed to ensure that static or mild physical interactions between assembling blocks take advantage of local energy minima. For granular materials, however, a particle's momentum in air leads to random collisions and the formation of disordered phases, eventually producing jammed configurations when densely packed. Therefore, unlike fluidic self-assembly, the self-assembly of dry particles typically lacks programmability based on density and ordering symmetry and has thus been limited in applications.
View Article and Find Full Text PDFStem Cells Transl Med
December 2024
Division of Molecular and Regenerative Prosthodontics, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan.
Mesenchymal stromal/stem cells (MSCs) are promising candidates for regenerative medicine owing to their self-renewal properties, multilineage differentiation, immunomodulatory effects, and angiogenic potential. MSC spheroids fabricated by 3D culture have recently shown enhanced therapeutic potential. MSC spheroids create a specialized niche with tight cell-cell and cell-extracellular matrix interactions, optimizing their cellular function by mimicking the in vivo environment.
View Article and Find Full Text PDFBMC Musculoskelet Disord
December 2024
Sports Medicine Center, West China Hospital, Sichuan University, Chengdu, China.
Background: Traditional examinations of anterior cruciate ligament (ACL) injuries focus primarily on static assessments and lack the ability to evaluate dynamic knee stability. Hence, a dynamic scoring system for knee function is needed in clinical settings. This study aimed to propose a dynamic scoring system based on a large sample of normative six-degree-of-freedom (6-DOF) knee kinematics during gait, and validate its correlation with conventional outcome measurements in assessing ACL-injured knees.
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