Effect of a novel framework design in ceria-stabilized zirconia/alumina nanocomposite (Ce-TZP/A)-based all-ceramic crowns

Purpose: Framework modification is essential to reduce chipping of the veneering porcelain in bilayered all-ceramic restorations. However, conventional modifications are insufficient, because buccal cusps did not correspond to a supporting structure. We manufactured a novel framework design, featuring an anatomical shape with additional two-sided (buccal and lingual) supporting structures, from ceria-stabilized tetragonal zirconia/alumina nanocomposite (Ce-TZP/A), and compared the fracture load and failure mode of all-ceramic crowns with Ce-TZP/A frameworks of different designs. Methods: Four different Ce-TZP/A framework designs were fabricated using CAD/CAM system. The framework designs were as follow; Group 1: anatomical shape; Group 2: with an additional lingual supporting structure; Group 3: with an additional buccal supporting structure; Group 4: with additional buccal and lingual supporting structures. Each framework was veneered with feldspathic ceramic and then cemented to resin tooth analog using self-adhesive resin cement. Fracture load of each crown either without or with mechanical preloading was measured using a universal testing machine. Scanning electron microscopy and stereomicroscopy were performed to classify failure mode as either partial fracture (cracking or chipping of porcelain veneer) or complete fracture (fracture of Ce-TZP/A framework or tooth analog). Results: Three crowns in Group 1 exhibited prefailure by mechanical preloading. Fracture load ranged from 1866–2049 N without mechanical preloading, and from 1828–2374 N with mechanical preloading; fracture load was not significant for any of the framework designs without mechanical preloading. Furthermore, fracture load did not significantly differ between framework designs except Group 1 with mechanical preloading. The most common failure mode was chipping of porcelain veneer without mechanical preloading. Although mechanical preloading promoted failure progression (from partial to complete fracture) in Groups 1–3, failure progression was inhibited in Group 4. Conclusion: This novel Ce-TZP/A framework design has the potential to reduce chipping of the veneering porcelain and improve zirconia based all-ceramic restoration reliability

The Molecular Outflows in the rho Ophiuchi Main Cloud: Implications For Turbulence Generation

We present the results of CO (J=3-2) and CO (J=1-0) mapping observations toward the active cluster forming clump, L1688, in the rho Ophiuchi molecular cloud. From the CO (J=3-2) and CO (J=1-0) data cubes, we identify five outflows, whose driving sources are VLA 1623, EL 32, LFAM 26, EL 29, and IRS 44. Among the identified outflows, the most luminous outflow is the one from the prototypical Class 0 source, VLA 1623. We also discover that the EL 32 outflow located in the Oph B2 region has very extended blueshifted and redshifted lobes with wide opening angles. This outflow is most massive and have the largest momentum among the identified outflows in the CO (J=1-0) map. We estimate the total energy injection rate due to the molecular outflows identified by the present and previous studies to be about 0.2 L_solar, larger than or at least comparable to the turbulence dissipation rate [~(0.03 - 0.1) L_solar]. Therefore, we conclude that the protostellar outflows are likely to play a significant role in replenishing the supersonic turbulence in this clump.Comment: 37 pages, 9 figures, accepted for publication in The Astrophysical Journa

Fretting Corrosion Behavior of Experimental Ti-20Cr Compared to Titanium

Experimental cast titanium alloys containing 20 mass% chromium (Ti-20Cr) show preferable mechanical properties and a good corrosion resistance. This study evaluated the fretting corrosion behavior of Ti-20Cr. Ti-20Cr (n = 4) and commercially pure titanium (CP-Ti, n = 6) disk specimens were used. The fretting corrosion test was performed by electrochemical corrosion at 0.3 V in 0.9% saline solution and mechanical damage using 10 scratching cycles with three different scratching speeds (10–40 mm/s) at 10 N. After testing, the activation peak, repassivation time and surface morphology of each specimen were analyzed. The differences between the results were tested by parametric tests (α = 0.05). The average activation peaks were significantly higher in CP-Ti than in Ti-20Cr (p < 0.01), except at 20 mm/s. In the series of scratching speeds, faster scratching speeds showed higher activation peaks. The maximum activation peaks were also higher in CP-Ti. Slight differences in the repassivation time were observed between the materials at every scratching speed; faster scratching speeds showed shorter repassivation times in both materials (p < 0.05). CP-Ti showed severe damage and significantly higher wear depth than Ti-20Cr (p < 0.05). In conclusion, adding chromium to titanium reduced surface damage and improved the fretting corrosion resistance

Additional ablation effect of low‐speed rotational atherectomy following high‐speed rotational atherectomy on early calcified in‐stent restenosis: A case report

Abstract Optical frequency domain imaging‐guided additional low‐speed rotational atherectomy following sufficient high‐speed rotational atherectomy for early calcified in‐stent restenosis might be a safe and useful option for achieving additional large lumen gains and stent expansion

Fretting Corrosion Behavior of Experimental Ti-20Cr Compared to Titanium

Experimental cast titanium alloys containing 20 mass% chromium (Ti-20Cr) show preferable mechanical properties and a good corrosion resistance. This study evaluated the fretting corrosion behavior of Ti-20Cr. Ti-20Cr (n = 4) and commercially pure titanium (CP-Ti, n = 6) disk specimens were used. The fretting corrosion test was performed by electrochemical corrosion at 0.3 V in 0.9% saline solution and mechanical damage using 10 scratching cycles with three different scratching speeds (10–40 mm/s) at 10 N. After testing, the activation peak, repassivation time and surface morphology of each specimen were analyzed. The differences between the results were tested by parametric tests (α = 0.05). The average activation peaks were significantly higher in CP-Ti than in Ti-20Cr (p < 0.01), except at 20 mm/s. In the series of scratching speeds, faster scratching speeds showed higher activation peaks. The maximum activation peaks were also higher in CP-Ti. Slight differences in the repassivation time were observed between the materials at every scratching speed; faster scratching speeds showed shorter repassivation times in both materials (p < 0.05). CP-Ti showed severe damage and significantly higher wear depth than Ti-20Cr (p < 0.05). In conclusion, adding chromium to titanium reduced surface damage and improved the fretting corrosion resistance

Bone Formation on Murine Cranial Bone by Injectable Cross-Linked Hyaluronic Acid Containing Nano-Hydroxyapatite and Bone Morphogenetic Protein

New injection-type bone-forming materials are desired in dental implantology. In this study, we added nano-hydroxyapatite (nHAp) and bone morphogenetic protein (BMP) to cross-linkable thiol-modified hyaluronic acid (tHyA) and evaluated its usefulness as an osteoinductive injectable material using an animal model. The sol (ux-tHyA) was changed to a gel (x-tHyA) by mixing with a cross-linker. We prepared two sol–gel (SG) material series, that is, x-tHyA + BMP with and without nHAp (SG I) and x-tHyA + nHAp with and without BMP (SG II). SG I materials in the sol stage were injected into the cranial subcutaneous connective tissues of mice, followed by in vivo gelation, while SG II materials gelled in Teflon rings were surgically placed directly on the cranial bones of rats. The animals were sacrificed 8 weeks after implantation, followed by X-ray analysis and histological examination. The results revealed that bone formation occurred at a high rate (>70%), mainly as ectopic bone in the SG I tests in mouse cranial connective tissues, and largely as bone augmentation in rat cranial bones in the SG II experiments when x-tHyA contained both nHAp and BMP. The prepared x-tHyA + nHAp + BMP SG material can be used as an injection-type osteoinductive bone-forming material. Sub-periosteum injection was expected