Preparation of Silica Aerogel/Resin Composites and Their Application in Dental Restorative Materials

Direct Ink Writing Additive Manufacturing of Silica Aerogels

Silica aerogels (SAs) have garnered significant attention due to their high porosity, low density, hydrophobic properties, low thermal conductivity, and optical transparency. The traditional method for producing SAs, known as "sol-gel" technology, involves precursor preparation, aging, and drying processes. However, aerogels produced through this method often exhibit drawbacks such as poor processability and low precision, which prevent them from fully leveraging their potential properties, including catalysis, adsorption, insulation, and sensing. In contrast, direct ink writing (DIW) technology offers a promising avenue for creating functional structures from SAs. This technique enables the production of inks with shear-thinning behavior, facilitating the high-precision printing of complex SA structures. This review summarizes the advancements in DIW additive manufacturing (AM) of SAs and the challenges currently faced in this field. Briefly, we first introduce the ink preparation, 3D printing process, drying and heat treatment suitable for DIW 3D printing of silica aerogels, followed by the discussion of the current state of research and key challenges of DIW 3D printing SAs.

Efficacy of digital guide-assisted implant restoration in anterior teeth aesthetics and its impact on labial bone mass

OBJECTIVE

To analyze the efficacy of digital guide-assisted implant restoration technique in enhancing the anterior teeth aesthetics and its impact on labial bone mass.

METHODS

We retrospectively analyzed clinical data from 90 patients who underwent maxillary anterior teeth implant restoration at The First People's Hospital of Fuyang, Hangzhou, from January 2021 to September 2023. The patients were divided into two groups: a conventional group (n=45, 45 implants, standard implant restoration) and a digital group (n=45, 45 implants, digital guide-assisted implant). We compared implant positional deviations, changes in dental plaque index (PLI), aesthetic effect scores, labial bone mass differences, and the occurrence of adverse reactions post-treatment between the two groups.

RESULTS

The digital group exhibited significantly less deviation in root position in the buccolingual and vertical directions, less neck deviation in the buccolingual and vertical directions, and less apical deviation than the conventional group (P=0.021, P=0.005, P=0.016, P=0.008, P=0.026, respectively). Three months postoperatively, the digital group demonstrated a significantly lower mean PLI (P<0.001), higher white and pink aesthetic scores (P=0.021, P=0.005), and increased alveolar ridge height and coronal and middle labial bone mass (P=0.006, P=0.015, P=0.008). Additionally, this group experienced lower incidence of adverse reactions (4.44% vs. 17.78%) compared with the conventional group (P=0.044).

CONCLUSION

The digital guide-assisted implant restoration significantly enhances implant accuracy, reduces bone resorption, improves aesthetic outcomes, and ensures higher safety.

An Updated Overview of Silica Aerogel-Based Nanomaterials

Silica aerogels have gained much interest due to their unique properties, such as being the lightest solid material, having small pore sizes, high porosity, and ultralow thermal conductivity. Also, the advancements in synthesis methods have enabled the creation of silica aerogel-based composites in combination with different materials, for example, polymers, metals, and carbon-based structures. These new silica-based materials combine the properties of silica with the other materials to create a new and reinforced architecture with significantly valuable uses in different fields. Therefore, the importance of silica aerogels has been emphasized by presenting their properties, synthesis process, composites, and numerous applications, offering an updated background for further research in this interdisciplinary domain.

Bioactive Dental Resin Composites with MgO Nanoparticles

Photoactivating dental resin composites have been the most prevailing material for repairing dental defects in various clinical scenarios due to their multiple advantages. However, compared to other restorative materials, the surface of resin-based composites is more susceptible to plaque biofilm accumulation, which can lead to secondary caries and restoration failure. This study introduced different weight fractions (1, 2, 5, 10, and 15%) of magnesium oxide nanoparticles (MgONPs) as antibacterial fillers into dental resin composites. Multifarious properties of the material were investigated, including antibacterial activity against a human salivary plaque-derived biofilm, cytotoxicity on human gingival fibroblasts, mechanical and physicochemical properties as well as the performance when subjected to thermocycling aging treatment. Results showed that the incorporation of MgONPs significantly improved the composites' anti-biofilm capability even at a low amount of 2 wt % without compromising the mechanical, physicochemical, and biocompatibility performances. The results of the thermocycling test suggested certain of aging resistance. Moreover, a small amount of MgONPs possibly made a difference in enhancing photoactivated polymerization and increasing the curing depth of experimental resin composites. Overall, this study highlights the potential of MgONPs as an effective strategy for developing antibacterial resin composites, which may help mitigating cariogenic biofilm-associated secondary caries.

Antibacterial and physical properties of resin cements containing MgO nanoparticles

Cariogenic bacteria and dental plaque biofilm at prosthesis margins are considered a primary risk factor for failed restorations. Resin cement containing antibacterial agents can be beneficial in controlling bacteria and biofilm. This work aimed to evaluate the impact of incorporating magnesium oxide nanoparticles (MgONPs) as an antibacterial filler into dual-cure resin cement on bacteriostatic activity and physical properties, including mechanical, bonding, and physicochemical properties, as well as performance when subjected to a 5000-times thermocycling regimen. Experimental resin cements containing MgONPs of different mass fractions (0, 2.5%, 5%, 7.5% and 10%) were developed. Results suggested that the inclusion of MgONPs markedly improved the materials' bacteriostatic effect against Streptococcus mutans without compromising the physical properties when its addition reached 7.5 wt%. The mechanical properties of the specimens did not significantly decline after undergoing aging treatment, except for the flexural properties. In addition, the cements displayed good bonding performance and the material itself was not prone to cohesive fracture in the failure mode analysis. Furthermore, MgONPs possibly have played a role in decelerating material aging during thermocycling and enhancing bonding fastness in the early stage of cementation, which requires further investigation. Overall, developing MgONPs-doped resin cements can be a promising strategy to improve the material's performance in inhibiting cariogenic bacteria at restoration margins, in order to achieve a reduction in biofilm-associated secondary caries and a prolonged restoration lifespan.

Emerging Trends in Nanotechnology: Aerogel-Based Materials for Biomedical Applications

At present, aerogel is one of the most interesting materials globally. The network of aerogel consists of pores with nanometer widths, which leads to a variety of functional properties and broad applications. Aerogel is categorized as inorganic, organic, carbon, and biopolymers, and can be modified by the addition of advanced materials and nanofillers. Herein, this review critically discusses the basic preparation of aerogel from the sol-gel reaction with derivation and modification of a standard method to produce various aerogels for diverse functionalities. In addition, the biocompatibility of various types of aerogels were elaborated. Then, biomedical applications of aerogel were focused on this review as a drug delivery carrier, wound healing agent, antioxidant, anti-toxicity, bone regenerative, cartilage tissue activities and in dental fields. The clinical status of aerogel in the biomedical sector is shown to be similarly far from adequate. Moreover, due to their remarkable properties, aerogels are found to be preferably used as tissue scaffolds and drug delivery systems. The advanced studies in areas including self-healing, additive manufacturing (AM) technology, toxicity, and fluorescent-based aerogel are crucially important and are further addressed.