Objective:　The　study　aims　to　enhance　the　anti-caries　performance　of　pit　and　fissure　sealants　through　the　synthesis　of　novel　silver　nanocomposites,　and　to　evaluate　their　mechanical　properties　and　biological　safety　in　vitro　and　in　vivo.　Methods:　The　antibacterial　properties　of　synthetic　eggshell/Ag　were　detected　by　bacterial　inhibition　zone,　minimum　bacteriostatic　concentration,　fluorescence　staining　and　scanning　electron　microscopy.　The　synthetic　products　were　then　combined　with　pit　and　fissure　sealants　to　prepare　specimens,　and　their　effects　on　mechanical　properties,　antibacterial　properties　and　cytotoxicity　were　evaluated.　Furthermore,　an　oral　mucosal　contact　model　of　golden　hamsters　was　established　according　to　the　ISO10933　standard　to　evaluate　local　stimulation　and　systemic　effects.　Results:　The　novel　nanocomposite　eggshell/Ag　was　confirmed　to　exhibit　strong　broad-spectrum　antibacterial　activity,　and　that　the　eggshell/Ag-modified　pit　and　fissure　sealant　had　strong　antibacterial　properties　against　common　dental　caries　bacterial　biofilms,　without　any　significant　change　in　mechanical　properties.　The　gradient　dilution　extract　showed　acceptable　cytotoxicity,　and　in　the　golden　hamster　oral　contact　model,　there　were　no　visible　abnormalities　in　local　mucosal　tissues,　blood　indices,　or　liver　and　kidney　histopathology.　Conclusions:　These　findings　suggest　that　eggshell/Ag　combined　with　pit　and　fissure　sealants　has　strong　antibacterial　activity　and　excellent　biosafety　in　vitro　and　in　vivo,　making　it　a　promising　candidate　for　clinical　applications.　©　2023　Huang　et　al.