Clinical Performance and Failure Mechanisms of Zirconia‐Based Toughened Ceramic Crowns

ABSTRACT This review aims to critically analyze the fatigue, aging, wear, and interface‐driven performance of contemporary zirconia crown systems and to establish evidence‐based, indication‐specific guidance for clinical material selection. A comprehensive narrative review was conducted focusing on experimental fatigue studies, hydrothermal aging investigations, wear simulations, bonding durability assessments, and long‐term clinical reports of zirconia crowns. Data were synthesized across zirconia systems with differing yttria contents (3Y‐TZP, 4Y‐PSZ, and 5Y‐PSZ) to identify dominant failure mechanisms, quantify performance limits, and evaluate the influence of surface finishing and cementation strategies under simulated oral service conditions. The analysis demonstrates that the long‐term clinical performance of zirconia crowns is governed primarily by fatigue resistance, surface integrity, and interfacial stability, rather than static strength alone. Tetragonal‐rich 3Y‐TZP exhibits superior fatigue reliability and aging resistance, supporting its use in posterior and high‐load conditions. Increased yttria content enhances translucency but reduces fracture toughness, fatigue thresholds, and tolerance to hydrothermal aging, thereby restricting high‐translucency zirconia to low‐stress indications. Polished surfaces significantly reduce antagonist wear, while MDP‐based adhesive cementation improves retention and fatigue performance, particularly in short or minimally retentive preparations. This review provides a clinically performance‐driven synthesis of zirconia crown behavior, integrating mechanical degradation mechanisms with clinical outcomes.