A paper recently published in the journal Materials discusses the recent developments in the use of advanced materials in dentistry, evaluating multiple studies within this field of research.
Study: Advanced Materials for Oral Application. Image Credit: Serhii Bobyk/Shutterstock.com
Background
The replacement of diseased dental tissues with prostheses where they cannot regenerate is the primary objective of dental treatment. The introduction of new prototyping and manufacturing tools, processing software, digital devices, and aesthetic materials has substantially transformed the dental profession.
Bioactive dental materials that release specific ions play a crucial role in restorative and preventative dentistry, in the regenerative process, and in maxillofacial or endodontics surgery by exerting antimicrobial actions, promoting the formation of hard tissue, and inducing cell stimulation and differentiation.
Smart materials can induce reparative processes and react to pH changes in the oral environment. In this paper, researchers discussed several advanced dental materials that allow dental technicians and dentists to select the most effective therapeutic solution for each dental patient.
Application of Advanced Dental Materials in Dental Treatment
In endodontic treatment, the ultimate goal is to obtain a three-dimensional (3D) tight canal seal. Tricalcium-silicate-based sealers were considered for improving the canal filling quality, owing to their high biocompatibility and low cytotoxicity.
In a recent study, calcium-silicate-based root canal sealers demonstrated a good overall performance compared to conventional sealers. However, the specificities of calcium silicate-based root canal sealers must be considered by practitioners due to significant differences in various formulations before selecting the appropriate material for clinical usage.
3D cleaning and shaping of the root canal system are necessary for proper obturation. Innovative manufacturing technologies such as active cutting regions or reciprocating files that do not experience fatigue can be used for this purpose.
The shaping ability of continuous rotation instrumentation movement and adaptive reciprocation kinematics was evaluated and compared using an ex-vivo model. The results showed that both rotary systems could produce canal preparations with sufficient geometrical changes. However, none of them touched all the canal walls.
The materials utilized in restorative dentistry are continuously improving, both in terms of aesthetic appearance and physical properties. Direct composite materials are often preferred when aesthetics is the primary objective.
Although an extensive range of materials is currently available, the match between the tooth structures and the appearance of the restoration depends on the color and fundamental optical properties, such as fluorescence and translucency of materials, which are essential for clinical shade-matching.
The fluorescence of nine composite resins was investigated in the study. The findings showed that the fluorescence intensity of the studied restorative materials differed significantly compared to dental enamel. Moreover, the fluorescence values of all composite resins were reduced after six months.
Base materials are typically used in dental treatment to enable uniform distribution of the load and tension and replace lost dentin to prevent tooth fracture. A study was performed to compare the fracture resistance of teeth with medium-sized mesial–occlusal–distal cavities that were restored with a light-cured composite resin using various base materials, including resin-modified glass ionomer cement, flow composite, zinc polycarboxylate cement, and glass ionomer cement.
The findings demonstrated that flow composite as a base material possesses the highest fracture resistance, followed by resin-modified glass ionomer cement, glass ionomer cement, and zinc polycarboxylate cement, due to its better compatibility with light-cured restoration material.
Computer-aided manufacturing and computer-aided design (CAM/CAD) are the most performant and recent technologies used in the prosthetic industry that enable additive or subtractive fabrication of different types of dental appliances and prostheses.
A study was performed to compare the fracture resistance of additive manufactured and milled interim three-unit fixed dental prostheses (FDPs) and bar-shaped specimens. A light-curing resin was used for additive manufacturing, while polymethylmethacrylate was used for subtractive manufacturing.
The subtractive manufactured prostheses and bars demonstrated the highest strength, which indicated that the manufacturing technique and printing orientation significantly affects the fracture resistance.
Recent advances in CAM/CAD technologies have also allowed the fabrication of various materials for the CAM/CAD milling process. Polymer infiltrated ceramic network (PICN) composites have gained attention as CAM/CAD restorative materials owing to their mechanical biocompatibility with human enamel.
In a study, a novel PICN composite CAM/CAD block material composed of infiltrated urethane dimethacrylate (UDMA)-based resin and silica skeleton was synthesized and evaluated. The findings displayed that the synthesized PICN nanocomposite possesses a similar flexural modulus to dentin and Vickers hardness to enamel and exceptional bond properties with resin cement.
Lithium disilicate glass-ceramic, a ceramic-based CAM/CAD block, has gained prominence in prosthodontics due to its translucency and multifunctional use. A study was performed to assess the effect of various cement layer thicknesses on aged and immediate microtensile bond strength between dentin and lithium disilicate.
The results indicated that the cement layer thickness has no impact on the immediate bond strength in lithium disilicate restorations. However, thicker cement layers induce higher residual stress in the long term, which weakens the bond strength. Thus, a thinner cement layer is suitable for improving the bond durability.
Dental zirconia, another popular ceramic-based CAM/CAD block, has received attention owing to its high strength and acceptable aesthetics. The latest generations of 3-yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) zirconia possess wider indications and improved properties for veneered and monolithic restorations.
In a study, the masking ability of one mm thick veneered and monolithic zirconia crowns was evaluated on various discolored substrates. Although the color coordinates of veneered and monolithic crowns were considerably different on all substrates, none of the zirconia crowns demonstrated sufficient masking ability on severely or moderately colored substrates.
In addition to CAM/CAD-associated digital impression procedures, conventional impressions are also used extensively in daily dental practice. A study investigated the cross-contamination risk while using dental tray adhesives with reusable brush systems.
Specifically, the risk of Candida albicans, Streptococcus oralis, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus transmission was assessed for four dental tray adhesives with various disinfectant components.
The findings demonstrated that ethyl acetate and isopropanol were the most effective disinfectants, while acetone and hydrogen chloride were the least effective. However, all four adhesives displayed sufficient fungicidal and bactericidal properties.
Currently, the repair or reconstruction of maxillofacial and oral aesthetics and functionalities is a priority for dental patients. Tissue reconstruction is the most crucial part of maxillofacial and oral surgery, endodontics, orthodontics, and periodontics.
Tissue reconstruction involves several techniques, ranging from traditional tissue grafts to novel regenerative techniques, such as tissue engineering. In the future, tissue engineering can be used to achieve regeneration of the entire tooth, as the procedure has a high rate of success.
Advanced platelet-rich fibrin is used extensively to stimulate soft and bone tissue regeneration as it has high concentrations of growth factors. Currently, advanced platelet-rich fibrin is completely autologous and prepared without using any separators or anticoagulants.
The findings of another study showed that the release of components required during the healing processes, such as transforming growth factor-beta 1 and 2, vascular endothelial growth factor, and fibroblast growth factor, increase when advanced platelet-rich fibrin is combined with autogenous fibroblasts. Thus, advanced platelet-rich fibrin with autogenous fibroblasts can effectively serve as a substitute for connective tissue in keratinized gingiva augmentation and significantly enhance surgical wound healing.
Recently, anorganic equine bone (AEB) was introduced as a substitute for bone grafting used in oral surgery. In a study, the structural and physicochemical properties of AEB and it's in vivo performance in mandibular bony defects were evaluated.
The study findings demonstrated that both physicochemical and structural properties of AEB matched with the typical features of heat-treated xenogeneic bone substitutes, and the use of AEB as a grafting material resulted in bone formation without any presence of inflammatory cell infiltrate.
In another study, polydimethylsiloxane with silver nanoparticles (PDMS/AgNPs) was utilized for surgical reconstruction of the esophagus with templates, and in vitro testing was performed to assess its antifungal properties. The findings displayed that the inclusion of AgNPs as bacteriostatic agents decreased fatigue strength, increased flexibility, and offered optimum local protection against fungal development.
To summarize, durable, novel, and highly aesthetic dental materials have demonstrated significant potential in dental treatment and can be used to improve the quality of life for dental patients.
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Source:
Rusu, L.-C., Ardelean, L.C. Advanced Materials for Oral Application. Materials 2022. https://www.mdpi.com/1996-1944/15/14/4749