Oral Epithelial Remodeling Associated with Long-Term Contact with Conventional Coronal Dental Amalgam Restorations: A...

Background and Objectives: Prolonged contact between oral mucosa and dental amalgam restorations may influence local epithelial homeostasis, but the remodeling profile of clinically non-dysplastic mucosa exposed to long-standing amalgam remains insufficiently characterized. This study aimed to evaluate histopathological changes and CK19, Ki67, and p53 expression in the oral mucosa adjacent to long-term amalgam restorations. Materials and Methods: A retrospective observational analysis was performed on 108 oral mucosal specimens, including 78 samples in direct contact with amalgam restorations and 30 non-exposed controls. Exposed cases were grouped according to contact duration: 5-10 years, 11-20 years, and ≥21 years. Histopathological parameters and immunohistochemical expression of CK19, Ki67, and p53 were semi-quantitatively assessed, and an exploratory Integrated Epithelial Remodeling Score was calculated. Results: Longer amalgam exposure was significantly associated with increased inflammatory infiltrate, basal hyperplasia, acanthosis, fibrosis, suprabasal CK19 redistribution, and higher Ki67 labeling indices. The Integrated Epithelial Remodeling Score differed significantly among exposure groups, with higher values in intermediate- and long-duration exposure categories. p53 expression showed statistically detectable but heterogeneous variation. No epithelial dysplasia was observed. Conclusions: Long-term contact with dental amalgam restorations was associated with a coordinated, non-dysplastic remodeling phenotype of the oral mucosa. Given the age imbalance across exposure duration groups, these findings should be interpreted as exposure-associated patterns rather than evidence of a direct causal effect. Because no comparison group exposed to other restorative materials was included, material-specificity for dental amalgam cannot be inferred. In architecturally preserved mucosa, suprabasal CK19 expression may reflect adaptive epithelial plasticity rather than preneoplastic transformation.