This study evaluated the microhardness and polymerization shrinkage of flowable resins that are cured using different light sources. Seven flowable resins and two light sources (diode-pumped solid-state (DPSS) laser (LAS) and Optilux 501 (OP)) were chosen for the study. To evaluate the microhardness, a mold (height: 2 mm, inner diameter: 4 mm) was filled with resin and then light cured. The microhardness was measured at the top and bottom surfaces after aging for 24 h. The level of polymerization shrinkage was evaluated for 130 s (during and after the light curing) by measuring the dimensions of the cylindrical shape resin filling. The light intensity of the LAS and OP was approximately 520 mW/cm(2) and 800 mW/cm(2), respectively. The data for the microhardness and polymerization shrinkage were analyzed statistically. The microhardness (Hv) of the specimens at the top and bottom surface ranged from 25.3 ± 0.6 to 55.3 ± 1.0 and 28.0 ± 2.6 to 63.0 ± 2.3, respectively. Admira flow, Grandio flow, and Filtek Z350 flow showed a slightly higher microhardness at the bottom surface than that at the top surface. The degree of polymerization shrinkage (μm) of the specimens ranged from 30.5 ± 1.3 to 45.9 ± 0.6 for LAS and from 35.1 ± 1.5 to 47.1 ± 1.0 for OP. The values obtained using LAS and OP showed a statistical difference, but in many cases, the difference between the absolute values was minor.
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http://dx.doi.org/10.1007/s10103-011-0964-4 | DOI Listing |
J Occup Environ Hyg
January 2025
Center for Environmental Solutions and Emergency Response, United States Environmental Protection Agency, Cincinnati, Ohio.
Chemical release data are essential for performing chemical risk assessments to understand the potential exposures arising from industrial processes. Often, these data are unknown or unavailable and must be estimated. A case study of volatile organic compound releases during extrusion-based additive manufacturing is used here to explore the viability of various regression methods for predicting chemical releases to inform chemical assessments.
View Article and Find Full Text PDFPolymers (Basel)
December 2024
Department of Chemical Engineering, Kwangwoon University, 20, Kwangwoon-ro, Nowon-gu, Seoul 01897, Republic of Korea.
A novel monomer, 9-bis[4-(2-hydroxyethoxy)phenyl]fluorene di(mercaptopropionate), with a highly refractive index, purity, and excellent UV-curable properties, is synthesized through an optimized Fischer esterification process, reacting 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene with 3-mercaptopropionic acid. The structural characterization of this monomer is performed using Fourier-transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, high-performance liquid chromatography, and liquid chromatography-mass spectrometry. The synthesis conditions are optimized using a design-of-experiments approach.
View Article and Find Full Text PDFPolymers (Basel)
December 2024
Department of Prosthetic Dental Sciences, College of Dentistry, Jazan University, Jazan 45142, Saudi Arabia.
Interocclusal records (IORs) created with bite registration materials (BRMs) accurately reflect the opposing teeth's physiological and anatomical associations in digital and traditional dentistry. This study assessed the linear dimensional accuracy of vinyl polysiloxane-based scannable and transparent BRMs over obligatory clinical time intervals (1, 24, 72, and 168 h/s). A total of 3 scannable [Flexitime Bite, Occlufast CAD, Virtual CADBite] and 3 transparent [Maxill Bite, Charmflex Bite, Defend ClearBite] VPS-based BRMs were divided into 28 subgroups by time interval: 1, 24, 72, and 168 h/s.
View Article and Find Full Text PDFJ Mech Behav Biomed Mater
January 2025
Key Lab for Biomechanical Engineering of Sichuan Province, Sichuan University, Chengdu, China; Sichuan University Yibin Park, Yibin Institute of Industrial Technology, Yibin, China. Electronic address:
Objective: This study aims to investigate adhesive damage caused by the synergistic effects of polymerization shrinkage and occlusal forces via finite element analysis (FEA), based on damage mechanics with the cohesive zone model (CZM). The objective is to obtain the adhesive damage distribution and investigate how the material properties of resin composite impact adhesive damage.
Methods: A 3D reconstruction model of an mandibular first molar was constructed through CBCT imaging, and a Class V cavity was prepared using computer-aided engineering (CAE) software.
BMC Cancer
January 2025
Department of Hepatobiliary Surgery, Guangxi Medical University Cancer Hospital, Nanning, Guangxi Province, 530021, China.
Background And Objective: In clinical practice, CK19 can be an important predictor for the prognosis of HCC. Due to the high incidence and mortality rates of HCC, more effective and practical prognostic prediction models need to be developed urgently.
Methods: A total of 1,168 HCC patients, who underwent radical surgery at the Guangxi Medical University Cancer Hospital, between January 2014 and July 2019, were recruited, and their clinicopathological data were collected.
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