Natural Silica and Plant-Derived Fillers for Dental Composite Resins: A Narrative Review

The ongoing limitations in antibacterial performance, biocompatibility, and environmental sustainability of traditional dental composite resin fillers have caused urgent issues such as secondary caries and marginal microleakage that require immediate attention. The emergence of natural fillers as sustainable options is significant due to their unique bioactive properties and environmental friendliness. This review systematically retrieved and analysed relevant literature published between 2015 and June 2025, focusing on the application mechanisms, performance characteristics, and clinical translation potential of natural silica and plant-derived fillers in dental composite resins. Natural silica derived from agricultural waste, such as rice husks, not only enables high-value utilisation of biomass resources but also improves the mechanical properties of composite resins. Plant-based fillers, like miswak, offer multiple functions, including antibacterial and anti-inflammatory effects, due to their rich bioactive components. However, challenges such as the release behaviour of bioactive components over time, interface bonding stability, and batch consistency remain obstacles to clinical use. While natural fillers show great promise in dental composite resins, further research is clearly necessary. The potential of surface modification techniques, optimisation of composite formulations, and standardised preparation methods is substantial, and detailed studies can help ensure successful translation from the laboratory to clinical practice.