Comparative Wear of Opposing Natural Enamel by Different Ceramic Materials in Fixed Dental Protheses: A Systematic Review and Meta-Analysis

<b>Background/Objectives</b>: This systematic review aimed to quantify the extent of wear of opposing posterior natural enamel in patients with single-unit ceramic crowns. <b>Methods</b>: A comprehensive search was conducted in PubMed/MEDLINE, Embase, Web of Science, Cochrane Library, and ProQuest through September 2025. A meta-analysis was performed using the inverse variance method. <b>Results</b>: Nine clinical studies (5 randomized controlled trials and 4 prospective studies) involving 203 patients (2015-2025) were included. All studies evaluated monolithic zirconia; two also assessed monolithic lithium disilicate, and three included metal-ceramic restorations with feldspathic veneering. Follow-up ranged from 6 to 24 months. Meta-analysis revealed significant enamel wear from zirconia (<i>p</i> < 0.05; MD: -1.32; 95% CI: -2.06 to -0.57; I² = 94%) and lithium disilicate (<i>p</i> < 0.05; MD: -0.45; 95% CI: -0.71 to -0.19; I² = 2%). Feldspathic ceramics did not show significant enamel wear (<i>p</i> = 0.06; MD: -2.77; 95% CI: -5.66 to 0.13; I² = 96%). <b>Conclusions</b>: Ceramic materials generally cause greater wear on opposing posterior natural enamel than enamel-to-enamel contact. Monolithic zirconia and lithium disilicate crowns produced higher antagonist wear, whereas metal-ceramic restorations with feldspathic veneering appeared more conservative for preserving posterior enamel.