{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T05:49:01Z","timestamp":1790660941170,"version":"4.1.0"},"reference-count":27,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2024,8,16]],"date-time":"2024-08-16T00:00:00Z","timestamp":1723766400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Chang Gung University of Science and Technology Foundation","award":["ZRRPF6N0011"],"award-info":[{"award-number":["ZRRPF6N0011"]}]},{"name":"Chang Gung University of Science and Technology Foundation","award":["112-2314-B-038-118-MY2"],"award-info":[{"award-number":["112-2314-B-038-118-MY2"]}]},{"name":"National Science and Technology Council, Taiwan","award":["ZRRPF6N0011"],"award-info":[{"award-number":["ZRRPF6N0011"]}]},{"name":"National Science and Technology Council, Taiwan","award":["112-2314-B-038-118-MY2"],"award-info":[{"award-number":["112-2314-B-038-118-MY2"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JFB"],"abstract":"<jats:p>Multilayer monolithic zirconia, which incorporates polychromatic layers that mimic natural tooth gradients, offers enhanced aesthetics and functionality while reducing debonding risks and improving fabrication efficiency. However, uncertainties remain regarding the fracture characteristics of multilayer monolithic zirconia crowns under occlusal loading, whether composed of uniform or combined yttria levels. The current study investigated how variations in yttria levels and thicknesses affected the optical properties and fracture loads of multilayer monolithic zirconia. Samples of multilayer monolithic zirconia in the Vita A1 shade were used, while employing 3Y (SZ) and 4Y + 5Y (AZ) yttria levels. The optical properties, including the color difference (\u0394EWS) and translucency parameters (TP00), were measured using a digital colorimeter. The fracture loads were analyzed using a universal testing machine, and fractured surfaces were examined under a stereomicroscope. Statistical analyses assessed the impacts of the yttria levels and sample thicknesses on the optical properties. The \u0394EWS values of SZ ranged 3.6 to 4.0, while for AZ, \u0394EWS at 0.5 mm was 3.9 and &lt;2.6 for other thicknesses. The TP00 values decreased with an increased thickness, with AZ generally exhibiting greater translucency than SZ. In the fracture load investigations, SZ (&gt;1600 N) generally exceeded AZ (&gt;1260 N), with fracture loads notably increasing with thickness, particularly for premolars (SZ &gt; 3270 N, AZ &gt; 2257 N). SZ predominantly exhibited partial and complete fractures, whereas AZ showed fewer non-fracture categorizations. Complete fractures began with dense, irregular cracks that extended outward to reveal smooth surfaces, while premolars subjected to higher loads exhibited concentric ripple-like structures. Partial fractures revealed radial textures indicative of areas of stress concentration. In summary, higher yttria levels were correlated with increased translucency, while variations in the fracture loads primarily stemmed from differences in the tooth position or thickness. Overall, multilayer monolithic zirconia incorporating combined yttria levels of 4Y + 5Y (AZ) offered high translucency, precise color matching, and substantial fracture resistance, rendering it highly suitable for aesthetic and functional dental applications.<\/jats:p>","DOI":"10.3390\/jfb15080228","type":"journal-article","created":{"date-parts":[[2024,8,16]],"date-time":"2024-08-16T06:23:20Z","timestamp":1723789400000},"page":"228","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":12,"title":["Comparison of Optical Properties and Fracture Loads of Multilayer Monolithic Zirconia Crowns with Different Yttria Levels"],"prefix":"10.3390","volume":"15","author":[{"given":"Chien-Ming","family":"Kang","sequence":"first","affiliation":[{"name":"Huayi Dental Laboratory, Taipei 10491, Taiwan"},{"name":"School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei 11031, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7168-9429","authenticated-orcid":false,"given":"Tzu-Yu","family":"Peng","sequence":"additional","affiliation":[{"name":"School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei 11031, Taiwan"},{"name":"Research Center of Digital Oral Science and Technology, College of Oral Medicine, Taipei Medical University, Taipei 11031, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yan-An","family":"Wu","sequence":"additional","affiliation":[{"name":"School of Dental Technology, College of Oral Medicine, Taipei Medical University, Taipei 11031, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chi-Fei","family":"Hsieh","sequence":"additional","affiliation":[{"name":"School of Dental Technology, College of Oral Medicine, Taipei Medical University, Taipei 11031, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Miao-Ching","family":"Chi","sequence":"additional","affiliation":[{"name":"Research Center of Digital Oral Science and Technology, College of Oral Medicine, Taipei Medical University, Taipei 11031, Taiwan"},{"name":"Department of Respiratory Care, Chang Gung University of Science and Technology, Chiayi 61363, Taiwan"},{"name":"Chronic Diseases and Health Promotion Research Center, Chang Gung University of Science and Technology, Chiayi 61363, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hsuan-Yu","family":"Wu","sequence":"additional","affiliation":[{"name":"School of Dental Technology, College of Oral Medicine, Taipei Medical University, Taipei 11031, Taiwan"},{"name":"Division of Integrated Health Sciences, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima 834-8553, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zih-Chan","family":"Lin","sequence":"additional","affiliation":[{"name":"Research Center of Digital Oral Science and Technology, College of Oral Medicine, Taipei Medical University, Taipei 11031, Taiwan"},{"name":"Department of Respiratory Care, Chang Gung University of Science and Technology, Chiayi 61363, Taiwan"},{"name":"Chronic Diseases and Health Promotion Research Center, Chang Gung University of Science and Technology, Chiayi 61363, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2024,8,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"72","DOI":"10.1016\/j.jpor.2016.01.003","article-title":"Advancements in CAD\/CAM technology: Options for practical implementation","volume":"60","author":"Alghazzawi","year":"2016","journal-title":"J. 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