In vitro remineralization effectiveness of eggshell extract on human teeth: a systematic review and meta-analysis

This systematic review and meta-analysis aimed to evaluate the in vitro effectiveness of eggshell extract in remineralizing enamel, focusing on outcomes, such as microhardness, surface roughness, and calcium/phosphate (Ca/P) ratios. A comprehensive literature search was conducted across PubMed, Scopus, Web of Science, Cochrane Library, and Google Scholar for studies published between January 2005 and October 2024. Seventeen eligible in vitro studies involving extracted human or bovine teeth were included. Risk of bias was assessed using the QUIN tool. Meta-analysis using a random-effects model showed that eggshell extract significantly improved enamel microhardness (Cohen's d = 0.45, 95% CI 0.30-0.60, p < 0.05) and reduced surface roughness (Cohen's d = - 0.50, 95% CI - 0.70 to - 0.30, p < 0.01). The Ca/P ratio also improved. Moderate heterogeneity (I² = 45%) was observed, and publication bias appeared minimal. Compared to conventional agents like fluoride varnish and nano-hydroxyapatite, eggshell extract demonstrated comparable remineralization performance. These findings support the potential of eggshell-based materials as cost-effective, biocompatible alternatives in enamel management. Further in vivo studies are warranted to confirm their clinical applicability.Limitations Evidence is in vitro only and eggshell formulations varied across studies.Prospero Registration ID CRD420251015581 & CRD420250619917.