Clinical and In Vitro Performance of Bioflx Crowns in Primary Teeth: A Systematic Review

BACKGROUND: Stainless steel crowns (SSCs) are the standard for restoring severely damaged primary teeth, but esthetic concerns and metal hypersensitivity have driven interest in alternatives. Bioflx crowns (BFCs) are flexible, metal-free restorations with uncertain comparative performance. AIM: To evaluate the clinical and in vitro performance of BFCs versus SSCs, zirconia crowns (ZrCs), and other pediatric crown systems (Figaro, PEEK, Edelweiss, and graphene-based). DESIGN: This PRISMA-based systematic review searched PubMed/MEDLINE, Scopus, Web of Science, Cochrane, Embase, and Google Scholar. Comparative clinical and in vitro studies were included. Risk of bias was assessed using Cochrane ROB-2 and modified CONSORT tools. RESULTS: Twenty-six studies (nine clinical and 17 in vitro) were included. BFCs showed variable fracture resistance, favorable stress distribution, and less antagonist enamel wear than ZrCs, but lower, cement-dependent retention compared with SSCs. Clinically, BFCs demonstrated high short-term survival (> 90%), comparable gingival health, and higher parental satisfaction, with an overall low-to-moderate risk of bias. CONCLUSIONS: Bioflx crowns show promising short-term performance as an esthetic prefabricated option for primary teeth. Although SSCs remain superior in retention with conventional cementation, and Hall technique support is not yet validated for BFCs, BFCs offer esthetic, antagonist-preserving, and clinical efficiency advantages. Evidence remains limited, warranting cautious interpretation and long-term RCTs. Trial Registration This systematic review was prospectively registered in PROSPERO (CRD420251083036).