The influence of parafunctional forces on the longevity of ceramic crowns

This study examines the influence of parafunctional forces on the longevity of ceramic crowns, with particular emphasis on the response of different ceramic materials to varying types and intensities of parafunctional activity. A comprehensive review and critical analysis of domestic and international research were conducted, comparing reported survival rates, fracture resistance, and clinical performance of ceramic crowns under parafunctional loading conditions. By synthesizing the available data, this study aims to determine whether certain ceramic materials demonstrate superior durability, and to what extent specific parafunctional habits increase the risk of restoration failure. Additionally, a three-dimensional finite element analysis was performed to evaluate stress distribution and deformation patterns in ceramic crowns subjected to static loading and combined loading forces. This analysis identifies exact locations of possible damages, surface degradation, and structural failure, supplemented by statistical findings from relevant studies and methodological approaches. Results indicate that crown design, internal geometry, and material thickness significantly affect mechanical performance, while material substitution (ceramic vs. zirconia) shows limited improvement under static loading. Based on the combined evidence from the literature and finite element simulations, the study proposes key factors that influence the long-term prognosis of ceramic crowns exposed to parafunctional forces. Clinical implications and recommendations for optimizing crown design in patients with parafunctional habits are discussed. Keywords: parafunctional forces; ceramic crowns; longevity; material fatigue; surface degradation; marginal adaptation; fracture resistance.