Journal of Dental Medicine

This review article elucidates sol-gel thin films as an engineering tool for the targeted tuning of restorative interphases within the structure-process-property-performance framework. The primary focus is placed on how low-temperature solution routes, through precursor selection, adjustment of deposition parameters, and control of condensation schedules, can lead to network organization, pore distribution, and the formation of surface functionalities; the components that play a decisive role in interfacial adhesion, light transmission, and initial microbial adhesion. In the adhesion domain, siliceous interphases generated via surface infiltration or overlapping thin coatings create silanol-rich surfaces on yttria-stabilized tetragonal zirconia, thereby enabling durable bonding with methacrylate-based systems. Concurrently, the design of zirconia-silica mixed oxides mitigates local incompatibilities and facilitates uniform primer spreading. In the optical domain, refractive index engineering is pursued through the incorporation of porous silica or nanoscale organic-inorganic networks, strategies that target antireflective behavior, preservation of surface gloss, and increased tolerance to layer thickness variations via gradient structures. In biofilm control, visible-light-responsive titania coatings exhibit effective performance under clinical illumination conditions. In contrast, the siliceous matrices or ion-doped organic-inorganic systems provide localized release of silver or zinc ions and light-independent antibacterial effects. Key challenges reported for these approaches include balancing refractive index reduction and hardness retention, improving hydrolytic stability to mitigate the risk of embrittlement, and preventing undesirable photocatalytic effects on surface color and gloss. From a clinical translation perspective, reproducibility remains dependent on defining narrow processing windows, precise monitoring of layer thickness and surface roughness, alignment with common airborne-particle abrasion and silanization workflows, and judicious adjustment of light dose. Overall, sol-gel nanolayers provide a modular engineering toolbox for selective interphase reinforcement, optical tuning, and surface bioactivation, provided that layer structure and quality control are considered as central design variables.

This narrative review provides a comprehensive overview of the potential of plant-derived polyphenols in restorative and preventive dentistry. As natural bioactive compounds such as polyphenols reshape the oral microbial ecology by attenuating virulence, inhibiting quorum-sensing communication, disrupting extracellular polymeric substance (EPS) formation, and reducing acidogenicity within dental biofilms. Beyond their antimicrobial effects, polyphenols can protect host tissues, namely, enamel, dentin, and gingiva, by cross-linking collagen fibrils, suppressing matrix metalloproteinase (MMP) activity, and modulating inflammatory pathways. Experimental, in situ, and clinical evidence consistently demonstrated improved bond durability at the dentin–resin interface. The most compelling data support the use of primers containing proanthocyanidins, quercetin, epigallocatechin gallate (EGCG), and resveratrol. In preventive applications, catechin-based varnishes have demonstrated remineralization effects comparable to those of fluoride varnishes. Conversely, pomegranate extract–enriched mouthrinses, in the presence of fluoride, could enhance both anti-demineralization and antibiofilm activity. In the context of implants and dental prostheses, the polyphenol-functionalized coatings, particularly those based on tannic or caffeic acid, would reduce biofilm formation and provide corrosion resistance for metallic surfaces. Nevertheless, several formulation challenges remain, including rapid oxidation, limited solubility, and discoloration, all of which require careful management. Strategies such as dose optimization, solvent selection, covalent stabilization, and microencapsulation are recommended to overcome these limitations. For broader and more effective clinical translation, standardization of multispecies laboratory models and harmonization of clinical endpoints are essential. Furthermore, future longitudinal trials are needed to bridge the gap between laboratory findings and clinical performance. Ultimately, with the design of innovative delivery systems and long-term monitoring of parameters such as restoration survival, secondary caries, periodontal health, and color stability, polyphenols hold promise to define a new generation of antibacterial, biocompatible, and aesthetically stable dental materials.