Dental composite resins with low polymerization stress based on a new allyl carbonate monomer

Characterization of dental light-curing resin composites incorporating multiple modified low-shrink monomers

OBJECTIVE

Polymerization shrinkage poses a significant challenge in dental resin composites. The objective of this study is to introduce spiroorthocarbonate monomer 3,9-dimethylene-1,3,5,7-tetraoxa-spiro[5,5]undecane (BMSOC) and epoxy resin monomer 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate (ECHM-ECHC) into bisphenol-S-bis(3-methacrylato-2-hydroxy propyl)ether (BisS-GMA) based resin composites to develop composites with reduced shrinkage properties.

METHODS

BMSOC and BisS-GMA were synthesized and thoroughly mixed with ECHM-ECHC, followed by inorganic fillers and photoinitiators. Based on the composition of the resin matrix, five groups of experimental composites were prepared, with traditional bisphenol A-dimethacrylate glycidyl ester (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA) based composite serving as the control. The polymerization properties, including degree of conversion (DC) and polymerization shrinkage (PS), as well as marginal microleakage, wettability, flexural strength (FS), flexural modulus (FM), and biocompatibility were evaluated.

RESULTS

The results demonstrated that compared with the control group, the PS of BisS-GMA based composites containing BMSOC and ECHM-ECHC were significantly reduced (P < 0.05), and the lowest PS (0.96 ± 0.08 %) was observed when the ratio of BisS-GMA: (Epoxy + BMSOC) was 4:6. Additionally, the experimental composites also exhibited improved DC, minimal microleakage, low hydrophilicity, enhanced mechanical properties, qualified in vivo biocompatibility, and slight/moderate in vitro biocompatibility.

SIGNIFICANCE

The resin composites incorporating multiple modified low-shrink monomers are promising for dental applications to prevent various clinical problems caused by PS and extend restoration longevity.

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.

Evaluation of a biobased polycarbonate interpenetrated network in a dental resin composite

Silanization of filler particles in a dental resin composite is achieved by the formation of Si-O-Si bonds, however, these bonds are especially vulnerable to hydrolysis because this covalent bond has a significant ionic character due to the electronegativity differences between the atoms. The objective of this study was to evaluate the use of an interpenetrated network (IPN) as alternative of silanization reaction and to assess its effect in selected properties of experimental photopolymerizable resin composites. The interpenetrate network was obtained during the photopolymerization reaction of organic matrix (BisGMA/TEGDMA) with a biobased polycarbonate. Its characterization was performed via FTIR, flexural strength, flexural modulus, depth of cure, sorption water and solubility. A resin composite formulated with non-silanized filler particles was used as control. The IPN with a biobased polycarbonate was successfully synthesized. The results showed that the IPN based resin composite had higher values of flexural strength, flexural modulus, and degree of double bond conversion than the control (p < 0.05). Polymerization shrinkage, water sorption and solubility were statistically significantly lower than the control resin (p < 0.05). Finally, this study shows there were no statistically significant differences for the biocompatibility outcomes (p > 0.05). The biobased IPN replaces the silanization reaction in resin composites, improving physical and chemical properties. Therefore, IPN with a biobased polycarbonate could be potentially useful in the formulation of dental resin composites.

Surface Modifications of High-Performance Polymer Polyetheretherketone (PEEK) to Improve Its Biological Performance in Dentistry

This comprehensive review focuses on polyetheretherketone (PEEK), a synthetic thermoplastic polymer, for applications in dentistry. As a high-performance polymer, PEEK is intrinsically robust yet biocompatible, making it an ideal substitute for titanium-the current gold standard in dentistry. PEEK, however, is also inert due to its low surface energy and brings challenges when employed in dentistry. Inert PEEK often falls short of achieving a few critical requirements of clinical dental materials, such as adhesiveness, osseoconductivity, antibacterial properties, and resistance to tribocorrosion. This study aims to review these properties and explore the various surface modification strategies that enhance the performance of PEEK. Literatures searches were conducted on Google Scholar, Research Gate, and PubMed databases using PEEK, polyetheretherketone, osseointegration of PEEK, PEEK in dentistry, tribology of PEEK, surface modifications, dental applications, bonding strength, surface topography, adhesive in dentistry, and dental implant as keywords. Literature on the topics of surface modification to increase adhesiveness, tribology, and osseointegration of PEEK were included in the review. The unavailability of full texts was considered when excluding literature. Surface modifications via chemical strategies (such as sulfonation, plasma treatment, UV treatment, surface coating, surface polymerization, etc.) and/or physical approaches (such as sandblasting, laser treatment, accelerated neutral atom beam, layer-by-layer assembly, particle leaching, etc.) discussed in the literature are summarized and compared. Further, approaches such as the incorporation of bioactive materials, e.g., osteogenic agents, antibacterial agents, etc., to enhance the abovementioned desired properties are explored. This review presents surface modification as a critical and essential approach to enhance the biological performance of PEEK in dentistry by retaining its mechanical robustness.

Resin-Based Composites for Direct and Indirect Restorations: Clinical Applications, Recent Advances, and Future Trends

Continuous advancements in resin-based composites can make selection of the appropriate system a daunting task for the clinician. This review aims to simplify this process and clarify some new or controversial topics. Various types of composites for direct and indirect applications are discussed, including microfilled and microhybrid composites, nanocomposites, single shade, bulk fill, fiber-reinforced, high temperature/high pressure processed, CAD/CAM, and three-dimensional printable composites. Recent material advancements that lead to improved seal and toughness, degradation resistance, antimicrobial and self-healing capabilities are presented. Future directions are highlighted, such as the development of "smart" materials that are able to interact with the host environment.