Fracture Load and Failure Mode of CAD-on Ceramic Structures.

This study evaluated the fracture load (Lf) and the failure mode of CAD-on (Ivoclar Vivadent) ceramic structures, testing the hypotheses that Lf of multilayer structures is governed by the veneering ceramic strength and that chipping is more frequent in multilayer than monolithic structures. Disc-shaped specimens were fabricated as follows: CAD-on- trilayer structure composed of Y-TZP (yttria stabilized tetragonal zirconia polycrystal- IPS e.max ZirCAD) infrastructure, fusion glass-ceramic (IPS e.max CAD Crystall/Connect) and lithium disilicate-based glass-ceramic (IPS e.max CAD); YLD- bilayer structure composed of Y-TZP infrastructure and fluorapatite layering ceramic (IPS e.max Ceram); LDC- monolithic lithium-disilicate glass-ceramic (IPS e.max CAD); and YZW- monolithic Y-TZP (Zenostar Zr Translucent). The specimens were loaded in compression until failure and fracture surfaces were evaluated using fractographic principles. Lf values were statistically analyzed using the Weibull statistics, Kruskal-Wallis and Dunn tests (a= 0.05). YZW (1329 N) and CAD-on (1085 N) showed the greatest Lf median values, followed by YLD (832 N) and LDC (421 N). All monolithic structures (LDC and YZW) fractured catastrophically and all YLD structures failed by chipping. The CAD-on technique seems to be a very promising fabrication process because it showed high Lf, similar to monolithic zirconia, and small chipping rate.

Effects of Intradialytic Neuromuscular Electrical Stimulation on Strength and Muscle Architecture in Patients With Chronic Kidney Failure: Randomized Clinical Trial.

This study aimed to evaluate the effects of neuromuscular electrical stimulation (NMES) on muscle strength and architecture, functional capacity, and endothelial function in patients with chronic kidney failure (CKF) on hemodialysis (HD). Twenty-one patients with CKF on HD were randomized into a control group (CG; n = 10) and neuromuscular electrical stimulation group (NMESG; n = 11) who received NMES in the quadriceps muscle for 8 weeks, 3 times/week (20-34 min) during HD sessions. The muscle strength of the lower limbs was evaluated by dynamometry and sit-and-stand test (SST); muscle architecture through ultrasonography; functional capacity by the distance covered in a 6-min walk test and the endothelial function by flow-mediated dilatation technique of the brachial artery. There was an increase in the strength of the lower limbs in the NMESG compared to the CG (dynamometry: 43.28 ± 16.94 vs. 35.84 ± 16.89, P = 0.006; SST: 16.10 ± 6.51 vs. 12.50 ± 4.7, P = 0.029). There was a significant reduction in pennation angles of the right vastus lateralis (RVL) and left vastus lateralis (LVL) in the CG when compared to the NMESG (RVL: 11.93 [10.70-15.11] vs. 13.57 [11.81-15.96], P = 0.039; LVL: 11.62 [9.00-14.20] vs. 15.52 [12.86-20.02], P = 0.042). There was no change in functional capacity and in the endothelial function for CG and NMESG, respectively. In conclusion, NMES increases muscle strength and has a protective effect against muscle atrophy of the lower limbs of patients with chronic kidney failure on HD.

Reliability and mode of failure of bonded monolithic and multilayer ceramics.

OBJECTIVES: To evaluate the reliability of monolithic and multilayer ceramic structures used in the CAD-on technique (Ivoclar), and the mode of failure produced in ceramic structures bonded to a dentin analog material (NEMA-G10). METHODS: Ceramic specimens were fabricated as follows (n=30): CAD-on- trilayer structure (IPS e.max ZirCAD/IPS e.max Crystall./Connect/IPS e.max CAD); YLD- bilayer structure (IPS e.max ZirCAD/IPS e.max Ceram); LDC- monolithic structure (IPS e.max CAD); and YZW- monolithic structure (Zenostar Zr Translucent). All ceramic specimens were bonded to G10 and subjected to compressive load in 37°C distilled water until the sound of the first crack, monitored acoustically. Failure load (Lf) values were recorded (N) and statistically analyzed using Weibull distribution, Kruskal-Wallis test, and Student-Newman-Keuls test (α=0.05). RESULTS: Lf values of CAD-on and YZW structures were statistically similar (p=0.917), but higher than YLD and LDC (p<0.01). Weibull modulus (m) values were statistically similar for all experimental groups. Monolithic structures (LDC and YZW) failed from radial cracks. Failures in the CAD-on and YLD groups showed, predominantly, both radial and cone cracks. SIGNIFICANCE: Monolithic zirconia (YZW) and CAD-on structures showed similar failure resistance and reliability, but a different fracture behavior.