Effect of Surface Treatment and Cement on Fracture Load of Traditional Zirconia (3Y), Translucent Zirconia (5Y), and Lithium Disilicate Crowns

Abstract

Purpose To determine if surface treatment and cement selection for traditional 3 mol% yttria partially stabilized zirconia (3Y‐PSZ), “translucent” 5 mol% yttria‐stabilized zirconia (5Y‐Z), or lithium disilicate crowns affected their fracture load. Materials and Methods Crowns with 0.8 mm uniform thickness (96, n = 8/group) were milled of 3Y‐PSZ (Lava Plus), 5Y‐Z (Lava Esthetic), or lithium disilicate (e.max CAD) and sintered/crystallized. Half the crowns were either particle‐abraded with 30 µm alumina (zirconias) or etched with 5% hydrofluoric acid (lithium disilicate), and the other half received no surface treatment. Half the crowns from each group were luted with resin‐modified glass ionomer (RMGI, RelyX Luting Plus) and half were luted with a resin cement (RelyX Unicem 2) to resin composite dies. Crowns were load cycled (100,000 cycles, 100 N force, 24°C water) and then loaded with a steel indenter until failure. A three‐way ANOVA examined the effects of material, cement, and surface treatment on fracture load. Post‐hoc comparisons were performed with the Tukey‐Krammer method. Results Fracture load was signficiantly different for materials and cements (p < 0.0001) but not surface treatments (p = 0.77). All lithium disilicate crowns luted with RMGI failed in fatigue loading cycling; 3Y‐PSZ and 5Y‐Z crowns luted with resin showed a higher fracture load compared with RMGI (p < 0.001). With resin cement, there was no signficant difference in fracture load between 5Y‐Z and lithium disiliciate (p = 1) whereas 3Y‐PSZ had a higher fracture load (p < 0.0001). Conclusions Cement type affected fracture load of crowns but surface treatment did not. The 0.8 mm uniform thick crowns tested benefited from using resin cement regardless of type of ceramic material. Crowns fabricated from 5Y‐Z may be particle‐abraded if luted with resin cement.

Are Metal-Free Monolithic Crowns the Present of Prosthesis? Study of Mechanical Behaviour

“…Like other studies such as Camposilvan and Lawson, the present trial found significant differences between tetragonal monolithic zirconia (Group TMZ) and cubic monolithic zirconia (Group CMZ), with higher fracture resistance obtained in Group TMZ [12,13].…”

“…Monolithic zirconia crowns may be stabilized in tetragonal phase, when they present a strength equal to metal-ceramic crowns but with the disadvantage of high opacity [2,3,4,8]. For this reason, zirconia crowns stabilized in cubic phase have been introduced, which offer greater translucency and so better aesthetics, but less strength and hardness [12,13]. Camposilvan analyzed the hardness of zirconia stabilized with different proportions of cubic structure and found that as the percentage of cubic zirconia increased so did its translucency, while strength and hardness decreased [13].…”

“…The load applied was 80 N with vertical displacement of 2 mm and protrusive displacement of 2 mm and 2 Hz frequency. In static load testing, a load cell of 5000 N was used at a crosshead speed of 0.5 mm/min until fracture, a procedure used in many other similar trials [2,3,8,11,12].…”

“…Yttrium-stabilized tetragonal zirconia obtains a fracture resistance similar to metal-ceramic crowns, but its aesthetics are compromised by the high opacity of the blocks the crowns are fabricated from [6,7,8]. In recent years, yttrium-stabilized cubic zirconia has been introduced as it offers more translucency but at the expense of mechanical properties (strength and hardness) [12,13].…”

Fracture Load of Metal, Zirconia and Polyetheretherketone Posterior CAD-CAM Milled Fixed Partial Denture Frameworks

“…However, the conditions of the studies should be established since they can influence the results. Some studies used resin dies because their elasticity modulus is similar to dentin [ 37 , 41 ], while others used metallic dies, as in the present study [ 1 , 6 , 8 , 13 , 22 , 25 , 38 , 42 ], which provide for the standardization of the shape and dimensions of the specimens [ 6 , 42 ], and also avoid possible premature destruction when testing metallic alloys compared to natural or resin teeth [ 43 , 44 ]. In the study, real frameworks were used instead of bar-shaped, cylinder, or disc specimens [ 29 , 45 ], and the thickness was also standardized to simulate clinical conditions [ 37 , 44 , 46 , 47 , 48 ].…”