Effects of propolis-modified glass ionomer cement on antimicrobial activity and physico-mechanical properties: a systematic review.

Glass ionomer cement (GIC) is valued in restorative dentistry for its chemical adhesion, fluoride release, and biocompatibility but has limitations in mechanical strength and long-term antibacterial activity. Propolis, a natural resin rich in flavonoids and phenolic acids, has shown antimicrobial, antioxidant, and anti-inflammatory effects, making it a potential bioactive additive to improve GIC performance. This systematic review evaluates the effects of propolis-modified GIC on antimicrobial activity and physico-mechanical properties, while identifying optimal formulations and concentrations for clinical use. Special emphasis is placed on methodological heterogeneity, chemical characterization gaps, and future research needs. Publications up to the end of 2024 were included from the Cochrane Library, Web of Science, PubMed, and Scopus. The review was registered on PROSPERO (CRD42024627498) and conducted according to PRISMA guidelines using the PICO framework. Propolis-modified GIC generally demonstrated enhanced antibacterial activity against Streptococcus mutans, Lactobacillus, and Candida albicans, particularly at concentrations of 25-50%. Mechanical outcomes varied with concentration, with 25% often balancing antimicrobial efficacy and mechanical stability, while higher concentrations improved hardness but sometimes reduced compressive and bond strength. Considerable heterogeneity was observed in GIC brands, propolis sources, extraction techniques, and incorporation methods, limiting direct comparability. Most studies lacked detailed chemical characterization, making it unclear which flavonoids or phenolic compounds drive the observed effects. Yellow discoloration was the main reported esthetic change, with no studies assessing long-term color stability or translucency. Propolis-modified GIC is a promising bioactive restorative material with potential antimicrobial benefits. However, methodological weaknesses, heterogeneity in preparation, and absence of chemical and long-term esthetic evaluation limit the direct clinical applicability of current evidence. Standardized protocols for material preparation, bioactive component identification, and comprehensive testing of mechanical and esthetic properties are recommended to advance this field.