Essentials of polishing zirconia dental restorations: a narrative review

Abstract

Objective: This narrative review synthesizes the current literature on the essential elements of polishing procedures for zirconia prosthetic restorations, analyzing biological, mechanical, and clinical aspects to inform clinicians' decision-making.

Method: A non-systematic literature review was conducted using PubMed/MEDLINE and Scopus. The following keywords were used: “zirconia” AND “polishing”; “zirconia” AND “surface roughness”; “zirconia” AND “wear”. Filters applied: from 1 January 2000 to 31 December 2025 (last 25 years). Subject area: Dentistry. This study focused on articles, clinical studies, and in vitro studies concerning polishing methods for zirconia materials used in dental restorations, with particular reference to the biological, mechanical, and clinical consequences of these procedures.

Results and discussion: The introduction of multilayer zirconia materials has broadened the applications of monolithic zirconia restorations, highlighting the critical need for proper polishing techniques. Clinical adjustments are often necessary for zirconia restorations to address issues like occlusal interferences, interproximal spacing, or aesthetic and morphological refinements. However, such modifications can significantly affect surface roughness, potentially impacting critical aspects such as bacterial adhesion, wear resistance, tribological performance, and the overall mechanical integrity of the restoration. These effects may vary depending on the crystallographic phases present in the zirconia composition. To mitigate these effects, adhering to specific polishing protocols after adjustments is highly recommended. Polishing helps minimize surface defects and microcracks while also reducing the depth of phase transformation and the amount of monoclinic phase created during grinding. This process not only restores zirconia’s surface to an acceptable roughness level (Ra) but also enhances its flexural strength, improving its durability and clinical performance.

Conclusion: Chairside adjustments are commonly performed during the delivery of most restorations. Currently, the first choice for clinicians is to apply a zirconia-specific polishing protocol after adjustment. Proper polishing is essential to restore surface quality after grinding, preventing cracks, improving wear resistance, and optimizing durability. Additionally, polishing should aim to achieve Ra values of no more than 0.2 µm to prevent bacterial adhesion. The operating protocols for clinicians include instruments with mandatory sequences according to the manufacturer's instructions. Despite the inherent variability of clinical adjustment procedures, existing polishing protocols have been streamlined and standardized to achieve predictable, less operator-dependent outcomes applicable across all zirconia types. However, advances in zirconia materials and diverse market options call for further research to optimize these procedures.