scholarly journals Novel injectable gellan gum hydrogel composites incorporating Zn- and Sr-enriched bioactive glass microparticles: High-resolution X-ray microcomputed tomography, antibacterial and in vitro testing

2018 ◽  
Vol 12 (6) ◽  
pp. 1313-1326 ◽  
Author(s):  
Timothy E.L. Douglas ◽  
Michal Dziadek ◽  
Svetlana Gorodzha ◽  
Jana Lišková ◽  
Gilles Brackman ◽  
...  
2020 ◽  
Vol 190 (1) ◽  
pp. 114-139
Author(s):  
Philippe J R Kok ◽  
Milan A J van der Velden ◽  
D Bruce Means ◽  
Sebastian Ratz ◽  
Iván Josipovic ◽  
...  

Abstract The only study of the osteology of the toad genus Oreophrynella dates back to 1971 and was based on a single species. Here, we use high-resolution X-ray microcomputed tomography to analyse the osteology of all nine described Oreophrynella species, which are compared with representatives of other bufonid lineages. Oreophrynella is unique among bufonids in having opposable digits. Osteological synapomorphies confirmed for the genus are as follows: presence of parietal fontanelles and exposed frontoparietal fontanelle, absence of quadratojugal, five presacral vertebrae, distally enlarged terminal phalanges and urostyle greatly expanded into flanges. Ancestral character reconstruction indicates that arboreal habits in some Oreophrynella species are likely to have evolved after the evolution of opposable digits. Opposable digits, in combination with an extension of the interdigital integument and the relative length/orientation of the digits, are likely to be adaptations to facilitate life on rocky tepui summits and an exaptation to arboreality. Cranial simplification in Oreophrynella, in the form of cranial fontanelles and absence of the quadratojugal, is possibly driven by a reduction of developmental costs, increase in flexibility and reduction of body weight. Cranial simplification combined with the shortening of the vertebral column and the shift towards a partly firmisternal girdle might be adaptations to the peculiar tumbling behaviour displayed by Oreophrynella.


2013 ◽  
Vol 19 (5) ◽  
pp. 327-335 ◽  
Author(s):  
Roman S. Voronov ◽  
Samuel B. VanGordon ◽  
Robert L. Shambaugh ◽  
Dimitrios V. Papavassiliou ◽  
Vassilios I. Sikavitsas

Palaeontology ◽  
2019 ◽  
Vol 63 (1) ◽  
pp. 131-154 ◽  
Author(s):  
Jozef Klembara ◽  
Miroslav Hain ◽  
Marcello Ruta ◽  
David S Berman ◽  
Stephanie E. Pierce ◽  
...  

2019 ◽  
Vol 9 (22) ◽  
pp. 4918 ◽  
Author(s):  
Hyo-Kyung Song ◽  
Kyung-Hyeon Yoo ◽  
Seog-Young Yoon ◽  
Hee Sam Na ◽  
Jin Chung ◽  
...  

White spot lesions (WSL) that occur on teeth after orthodontic appliances have been attached are caused by bacterial demineralization of the enamel surface. This study investigated the anti-demineralization effect of orthodontic resins containing mesoporous bioactive glass nanoparticles (MBN) doped with gallium, which has antibacterial activity, as well as MBN with increased calcium and phosphate contents as these ions can remineralize enamel. Resins (CF, CharmFill Flow, Dentkist, Seoul, South Korea) containing 1%, 3%, and 5% Ga-doped MBN (GaMBN) were characterized using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and isothermal tests, and their physical properties were measured in terms of Vickers microhardness, bracket retention force, and adhesive remnant index (ARI). Cell viability in the resins was confirmed by testing human dental pulp stem cells (hDPSCs), and ion release tests were performed after 1, 7, and 14 days to determine whether the resins released Ga3+, Ca2+, and PO43–. After 14 days, antibacterial activity was determined using Streptococcus mutans (S. mutans)—the bacteria that causes tooth decay—and the chemical remineralization effect was investigated using a cycle of acid–base solutions. The microhardness of the resins increased with GaMBN concentration whereas their bracket retention force, ARI, and cell viability remained unchanged. The bacterial activity of the 5%-GaMBN resin decreased after 24 and 48 h; however, the change in activity was not statistically significant. Anti-demineralization testing demonstrated that the degree of enamel demineralization decreased as the GaMBN concentration increased, which indicates that resins containing 5%-GaMBN may be viable orthodontic adhesives for preventing WSLs.


2010 ◽  
Vol 11 (3) ◽  
pp. 657-665 ◽  
Author(s):  
Rodrigo Oréfice ◽  
Jon West ◽  
Guy LaTorre ◽  
Larry Hench ◽  
Anthony Brennan

2000 ◽  
Vol 662 ◽  
Author(s):  
Sarah E. Efflandt ◽  
Robert F. Cook ◽  
Lorraine F. Francis

AbstractBioactive glass disks from the MgO-CaO-P2O5-SiO2 system were placed in artificial saliva for time periods varying from 1 to 42 days. Surfaces were then analyzed using scanning electron microscopy (SEM) and x-ray diffraction to investigate surface morphologies and crystallinity. SEM examination exhibited dramatic surface changes as early as 2 d. X-ray results showed crystallinity in the form of apatite at 10 d, which became more developed though 42 d. The bioactive glass in water and non-bioactive glass in artificial saliva were used as controls; both exhibited no evidence of apatite formation on their surfaces through the 42 d time period. This study shows that bioactive glass reacts in artificial saliva to form apatite and that the apatite layer becomes better crystallized over an extended time period. These results give a better understanding of the surface changes and mineralization that occur over time and can be used to interpret results from in vitro and in vivo studies done on bioactive glass in the oral environment.


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