Background: The wear resistance of modern commercial glass-ceramic materials used in dental prostheses was investigated under cyclic contact conditions that included a rotational component. This loading mode has been largely overlooked in conventional in vitro wear testing, yet may be clinically relevant in patients with parafunctional conditions such as bruxism. Methods: Rotational loading was applied using an all-electric testing machine equipped with a biaxial actuator. Loading cycles combined a normal load (50 N) and a rotation (30°), at a frequency of 1 Hz. Microstructure and damage were characterized using advanced microscopy. Results: Rotational loading induced substantial damage across this class of materials, including the formation of glassy tribolayers with limited protective capability under the low-humidity conditions examined. Significant microstructure-dependent variations in wear volume were observed, with specific wear rates indicating severe wear (SWR above 10⁻⁶ mm³/N·m threshold) in three of the five materials tested. Lithium disilicate glass-ceramics, characterized by a high fraction of elongated reinforcement crystals, exhibited the greatest resistance to damage, whereas leucite-based glass-ceramics showed the lowest. The dominant wear mechanisms were plastic-deformation-induced grooving and fracture-driven chipping. The findings are interpreted within established wear models for brittle materials (Archard and fracture-based) and supported by numerical simulations of stress fields across multiple length scales. Implications: The results provide mechanistic insight into rotational wear damage in glass-ceramic systems, a material class particularly susceptible to such loading, and inform strategies for material selection and microstructural design aimed at improving prosthetic durability.

Motivation: Dental enamel possesses a unique anisotropic, heterogeneous hierarchical structure which enables a combination of high hardness and remarkable durability compared to other natural and synthetic biomaterials. Nevertheless, it undergoes mechanical degradation through fracture from concentrated overloads and/or progressive wear, both of which can compromise tooth function and longevity. Enamel wear is of particular interest to anthropology, as it is ubiquitous and enables researchers to discern the culture, behaviors, and ecologies of the study populations. Studies simulating dental wear in vitro often employ simplified loading configurations based on combinations of axial and lateral forces, which successfully reproduce the “classical” microwear features of pits and scratches, but do not capture the full complexity of in vivo loading conditions. Objectives: To conduct a preliminary in vitro investigation of previously underexplored rotationally induced occlusal mechanical wear in enamel. Methods: Cyclic contact tests combining compression (50 N) and rotation (30°) are applied to human enamel specimens using a testing machine with decoupled biaxial (axial‐torsion) actuators. Damage is characterized by electron and confocal microscopy. Results: Rotational forces produce abrasive wear with distinct microscopic damage patterns, involving transitions from quasi‐plastic to brittle damage modes with an increasing number of contact cycles. After 10 ⁴ cycles, the macrowear volume is 0.0023 mm ³ . Conclusions: Rotational microwear differs from “classical” pits and scratches associated with axial–lateral loading. Findings offer a framework for interpreting curved microscratches and provide a basis for future investigations. More broadly, they contribute to improving models of dental microwear and provide new insights in biomaterials science and anthropology.