CAD/CAM lithium disilicate ceramic crowns: Effect of occlusal thickness on fracture resistance and fractographic analysis

Abstract

This study uses fracture tests and fractographical analysis to compare computer-aided design and computer-aided manufacturing (CAD/CAM) lithium disilicate molar crowns with the previous occlusal thickness recommendation of 1.5-mm, the new recommendation of 1.0-mm, and a less invasive thickness of 0.8-mm. After fatigue application, fracture tests and fractographic analysis were conducted. The fracture resistance of CAD/CAM lithium disilicate molar crowns was different depending on the occlusal thickness of the restoration, and decreased with lower the thickness. However, the fracture resistance of crowns of all three thicknesses exceeded the reported maximum bite force in the first molar region after the fatigue process, and can be considered acceptable for use in the clinic.

Minimally invasive CAD/CAM lithium disilicate partial‐coverage restorations show superior in‐vitro fatigue performance than single crowns

“…23 Monolithic CAD/CAM fabricated LDS molar crowns were also tested in different ceramic layer thicknesses (0.5-1.5 mm) and various fatigue protocols. 28,34,39,47 Lower and partly unsatisfactory failure load values of 470 N (without fatigue) and 369 N (with fatigue) for 0.5 mm, 801 N (without fatigue) and 889 N (with fatigue) for 1.0 mm, 1107 N (without fatigue) and 980 N (with fatigue) for 1.5 mm LDS molar crowns were observed with a similar aging protocol (1.2 million cycles, 108 N). 47 Yet, the study loaded the specimens in a 30 angle, perpendicular to one cusp and with a higher load during fatigue (108 N) which might explain the lower fracture values.…”

“…39 A study with a prolonged fatigue application (5 million cycles, 275 N) lead to slightly lower failure load values of 980 N (0.8 mm), 1162 N (1.0 mm) and 1540 N (1.5 mm) compared to the obtained results of the present study. 28 Ceramic bulk fractures are still the most common complication for onlays, PCRs, and crowns in clinical observations. 40,41 Failure modes after SLF revealed more bulk fractures with involvement of the fractures without involvement of the tooth for thin restorations.…”

“…25,26 A recent survey by the British Orthodontic Society underlies this: 62% of orthodontists recorded an increase in demand for esthetic treatments during COVID-19. 26 Lithium disilicate glass-ceramics (LDS) offer superior esthetics 27,28 and a reliable clinical long-term survival. [29][30][31] The clinical performance of LDS CAD/CAM crowns is high, with survival rates of 93% after 6 years 32 and 80.1% after 15 years.…”

Traditional versus conservative endodontic access impact on fracture resistance of chairside CAD‐CAM lithium disilicate anterior crowns: An in vitro study

“…Chairside CAD‐CAM lithium disilicate crowns for anterior and posterior teeth have become a widespread option for clinical dentistry 31,32 . In fact, a recent practice‐based study indicated that this ceramic was the second most commonly used material for single restorations 10 .…”

“…Chairside CAD-CAM lithium disilicate crowns for anterior and posterior teeth have become a widespread option for clinical dentistry. 31,32 In fact, a recent practice-based study indicated that this ceramic was the second most commonly used material for single restorations. 10 The purpose of this study was to determine whether crowns without and with different endodontic accesses display different fracture resistance.…”