Preparation and evaluation of (R)-(-)-carvone-doped polymeric resins as potential antibacterial dental materials.

OBJECTIVES: This study aimed to develop and evaluate resin-based antibacterial materials incorporating carvone for restorative dentistry. The objectives included assessing antimicrobial activity, conversion degree, mechanical properties, hydrolytic and hygroscopic behavior, cytotoxicity, among others. METHODOLOGY: Carvone was incorporated into resin-based materials following established protocols. Antimicrobial activity was evaluated against S. Aureus. Conversion degree, polimerization kinetics, mechanical properties, hydrolytic and hygroscopic behavior, cytotoxicity, and other properties were assessed using standardized tests and methodologies. RESULTS: Carvone-incorporated materials demonstrated significant antimicrobial activity, minimal changes in conversion degree, comparable mechanical properties, improved hydrolytic and hygroscopic behavior, and lack of cytotoxicity. Antimicrobial resins were obtained due to the hydrophobic nature of carvone and its ability to diffuse through the cell walls of microorganisms, causing membrane damage. The polymerization process yielded successful conversion, ensuring adequate material performance. SIGNIFICANCE: This study showcases that incorporating carvone into methacrylate-based resins can confer antimicrobial properties while preserving key material attributes. Antimicrobial activity against S. aureus is achieved without cytotoxicity in human fibroblasts. While flexural properties are affected only at carvone concentrations exceeding 9%, conversion degree and polymerization kinetics remain stable, except for a specific experimental formulation. These findings highlight the balanced integration of carvone. However, further work, including assessing antimicrobial performance against specific strains like S. Mutans and/or C. Albicans, and evaluating long-term effectiveness, is essential to establish the potential of these materials for dental restorations.

Fully Bio-Based Elastomer Nanocomposites Comprising Polyfarnesene Reinforced with Plasma-Modified Cellulose Nanocrystals.

This article proposes a process to prepare fully bio-based elastomer nanocomposites based on polyfarnesene and cellulose nanocrystals (CNC). To improve the compatibility of cellulose with the hydrophobic matrix of polyfarnesene, the surface of CNC was modified via plasma-induced polymerization, at different powers of the plasma generator, using a trans-ß-farnesene monomer in the plasma reactor. The characteristic features of plasma surface-modified CNC have been corroborated by spectroscopic (XPS) and microscopic (AFM) analyses. Moreover, the cellulose nanocrystals modified at 150 W have been selected to reinforce polyfarnesene-based nanocomposites, synthesized via an in-situ coordination polymerization using a neodymium-based catalytic system. The effect of the different loading content of nanocrystals on the polymerization behavior, as well as on the rheological aspects, was evaluated. The increase in the storage modulus with the incorporation of superficially modified nanocrystals was demonstrated by rheological measurements and these materials exhibited better properties than those containing pristine cellulose nanocrystals. Moreover, we elucidate that the viscoelastic moduli of the elastomer nanocomposites are aligned with power-law model systems with characteristic relaxation time scales similar to commercial nanocomposites, also implying tunable mechanical properties. In this foreground, our findings have important implications in the development of fully bio-based nanocomposites in close competition with the commercial stock, thereby producing alternatives in favor of sustainable materials.