Aim: Newer zirconia materials may have greater strength degradation under cyclic fatigue with increased yttria and cubic content. The purpose of this study was to evaluate the flexural strength (FS) degradation of newer zirconia materials compared to more traditional tetragonal zirconia materials. Materials and methods: The following materials were tested: two 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) materials (Lava Plus, 3M ESPE; Katana ML, Kuraray), one 4 mol% partially stabilized zirconia (4Y-PSZ) material (Katana STML, Kuraray), two 5 mol% partially stabilized zirconia (5Y-PSZ) materials (Katana STML, Kuraray; Lava Esthetic, 3M ESPE), and one lithium disilicate material (IPS e.max CAD LT, Ivoclar Vivadent). Thirty beams were milled for each ceramic material with final dimensions of 4.0 × 1.3 × 18.0 mm after sintering or crystallization. Each specimen was placed on a 3-point bend test device on a universal testing machine (Instron, Norwood, MA). Flexural strength was determined on 10 beam specimens per group with a central load applied until fracture. Flexural fatigue strength was then measured on the remaining 20 beam specimens per group using the staircase method for 6,000 cycles at 2 Hz. Data were analyzed with one-way ANOVAs/Tukey post hoc tests (α = 0.05). Results: A significant difference was found between groups (p < 0.001) per property. The 3Y-TZP zirconia materials had the greatest flexural and flexural fatigue strength. The cubic containing zirconia materials performed more moderately. The lithium disilicate material had the lowest strength values. The percent degradation in flexural fatigue strength of the 3Y-TZP zirconia materials was less than the 5Y-PSZ, Katana UTML, and the 4Y-PSZ, Katana STML, cubic containing materials, but similar to the 5Y-PSZ cubic containing material, Lava Esthetic. Conclusion: The amount of strength degradation was material dependent, with the 4Y-PSZ or 5Y-PSZ cubic containing zirconia materials demonstrating greater or similar strength degradation compared to the primarily tetragonal 3Y-TZP zirconia materials. Clinical significance: The differences in FS degradation between cubic containing materials and traditional zirconia materials could significantly impact the long-term success of these newer materials. Clinicians should be aware that these cubic containing materials may perform differently long-term than the very strong traditional 3Y-TZP materials and to follow manufacturer instructions on required material thickness and indications for use to prevent premature failure of the restoration.
Aim:The aim of this research was to determine whether sterilization and reutilization of impression copings had an impact on the accuracy of casts made for multiimplant restorations. Materials and methods: Four master casts embedded with five implant analogs were fabricated. Polyvinyl siloxane (PVS) impressions of the master cast with copings attached to the analogs were made and poured in dental stone. The impression copings were subjected to cleaning and sterilization. These processes were repeated 30 cycles for each of the two groups of five impression copings: one without modification and one with modification that included air abrasion and PVS adhesive. A coordinate measuring machine (CMM) was used to measure relative angles and distances between the reference analog and analogs. The relative angles and distances measured on the stone casts were compared to the master resin cast to obtain positional and angular displacements. Results: For impression copings that were not modified, a significant difference was detected for both positional and angular displacements. For impression copings that were modified, a significant change was observed only for positional displacement. The maximum discrepancies measured for positional and angular displacements after 30 cycles of reuse were only 81 μm and 0.46°, respectively, regardless of the modification. Conclusion:Within the limitations of this study, unmodified impression copings that have undergone 30 cycles of cleaning and sterilization appeared to incur more impression inaccuracy than those impression copings that were modified by airborne-particle abrasion and PVS adhesive. Clinical significance: Impression copings used in this study can likely be recycled up to 30 times without reducing the accuracy of the impression to a level that may be considered clinically significant.
Objective We present a novel digital workflow to provide presurgical infant orthopedic (PSIO) treatment for a patient with a unilateral cleft lip/palate utilizing nasoalveolar molding (NAM) and a custom postsurgical nasal stent. Setting Within the US military healthcare system, the Joint Base San Antonio Craniofacial Anomalies Team utilizes dental scanners, predictive 3D modeling software, and 3D printing technology in a digital workflow for NAM appliance fabrication. Workflow Soft tissue facial scanning, peri-oral scanning, and dental putty impressions are used to facilitate fabrication and measure outcomes. Digital modeling software and 3D resin printing are utilized to manufacture the prescribed devices. Main Outcome Measures and Results Extra-oral facial scans and intra-oral impressions are compared between 3 timepoints: pre-treatment, posttreatment with NAM, and postsurgical treatment. Conclusions The ability to share workflows, establish outcome standards, and streamline patient care will continue to advance best practices in digital PSIO.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.