Researchers discuss the use of advanced materials in dentistry

A recent article published in the journal Materials discusses recent developments in the use of advanced materials in dentistry, evaluating several studies in this area 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 goal of dental treatment. The introduction of new prototyping and manufacturing tools, processing software, digital devices and aesthetic materials has dramatically transformed the dental profession.

Bioactive dental materials that release specific ions play a crucial role in restorative and preventive dentistry, in the regeneration process and in maxillofacial or endodontic surgery by exerting antimicrobial actions, promoting hard tissue formation and inducing stimulation and cell differentiation.

Smart materials can induce repair processes and respond to pH changes in the oral environment. In this article, researchers have 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 achieve a three-dimensional (3D) seal of the canal. Tricalcium silicate sealants have been considered to improve the quality of root canal filling, due to their high biocompatibility and low cytotoxicity.

In a recent study, calcium silicate-based root canal sealers demonstrated good overall performance compared to conventional sealants. However, the specifics of calcium silicate root canal sealants should be considered by practitioners due to significant differences in different formulations before selecting the appropriate material for clinical use.

Cleaning and 3D shaping of the root canal system is necessary for a good obturation. Innovative manufacturing technologies such as active cutting zones or fatigue-free reciprocating files can be used for this purpose.

The shapeability of continuously rotating instrumentation motion and adaptive reciprocating kinematics were assessed and compared using an ex-vivo model. The results showed that both rotary systems could produce root canal preparations with sufficient geometric changes. However, none of them hit all the channel walls.

The materials used in restorative dentistry are continually improving, both in terms of aesthetic appearance and physical properties. Direct composite materials are often preferred when aesthetics are the primary objective.

Although a wide range of materials are currently available, the match between tooth structures and the appearance of the restoration depends on the color and fundamental optical properties, such as fluorescence and translucency of the materials, which are essential for clinical shade matching.

The fluorescence of nine composite resins was investigated in the study. The results showed that the fluorescence intensity of the restorative materials studied differed significantly from that of dental enamel. Additionally, the fluorescence values ​​of all composite resins were reduced after six months.

Base materials are typically used in dental treatment to provide even load and stress distribution and to replace lost dentin to prevent tooth fractures. A study was performed to compare the fracture resistance of teeth with medium-sized mesio-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 results demonstrated that flowable composite as the base material has the highest fracture toughness, followed by resin-modified glass ionomer cement, glass ionomer cement, and zinc polycarboxylate cement, due to its better compatibility with light-cured restorative material.

Computer Aided Manufacturing and Computer Aided Design (CAM/CAD) are the most advanced and latest technologies used in the prosthetics industry that enable the additive or subtractive manufacturing of different types of dental appliances and prostheses.

A study was performed to compare the fracture toughness of additive fabricated and milled temporary three-unit fixed dental prostheses (FDPs) and bar specimens. A light-cured resin was used for additive manufacturing, while polymethyl methacrylate was used for subtractive manufacturing.

Dentures and bars fabricated by subtraction demonstrated the highest strength, indicating that fabrication technique and impression orientation significantly affect fracture toughness.

Recent advancements in CAM/CAD technologies have also enabled the fabrication of various materials for the CAM/CAD milling process. Polymer-infiltrated ceramic network composites (PICN) have attracted attention as CAM/CAD restorative materials due to their mechanical biocompatibility with human enamel.

In a study, a new PICN composite CAM/CAD block material composed of an infiltrated urethane dimethacrylate (UDMA) resin and a silica backbone was synthesized and evaluated. The results showed that the synthesized PICN nanocomposite has a similar flexural modulus to dentin and Vickers hardness to enamel and exceptional bonding 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 evaluate the effect of various cement layer thicknesses on the bond strength in aged and immediate microtensile bonding between dentin and lithium disilicate.

The results indicated that cement layer thickness has no impact on immediate bond strength in lithium disilicate restorations. However, thicker cement layers induce higher long-term residual stresses, which weaken bond strength. Thus, a thinner layer of cement is appropriate to improve the durability of the bond.

Dental zirconia, another popular ceramic-based CAM/CAD block, has gained attention due to its high strength and acceptable aesthetics. The latest generations of 3-yttria-stabilized tetragonal zirconia (3Y-TZP) polycrystalline zirconia have broader indications and improved properties for layered and monolithic restorations.

In one study, the masking ability of veneered and monolithic zirconia crowns one mm thick was evaluated on various discolored substrates. Although the color coordinates of the veneered and monolithic crowns were significantly different on all substrates, none of the zirconia crowns demonstrated sufficient masking ability on severely or moderately colored substrates.

Besides digital impression procedures associated with CAM/CAD, conventional impressions are also widely used in daily dental practice. A study investigated the risk of cross-contamination when using dental impression tray adhesives with reusable brush systems.

More specifically, the risk of Candida albicans, oral streptococcus, Pseudomonas aeruginosa, Escherichia coliand Staphylococcus aureus transmission was evaluated for four dental impression tray adhesives containing various disinfectant components.

The results showed that ethyl acetate and isopropanol were the most effective disinfectants, while acetone and hydrogen chloride were the least effective. However, all four adhesives showed sufficient fungicidal and bactericidal properties.

Currently, the repair or reconstruction of esthetics and maxillofacial and oral functionality 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 new regeneration techniques, such as tissue engineering. In the future, tissue engineering may be used to achieve whole tooth regeneration, as the procedure has a high success rate.

Advanced Platelet Rich Fibrin is widely used to stimulate soft tissue and bone regeneration as it contains high concentrations of growth factors. Currently, Advanced Platelet-Rich Fibrin is completely autologous and prepared without the use of separators or anticoagulants.

The results of another study showed that the release of components necessary during healing processes, such as transforming growth factor beta 1 and 2, vascular endothelial growth factor and fibroblast growth factor , increases when advanced platelet-rich fibrin is associated with autogenous fibroblasts. . Thus, advanced platelet-rich fibrin with autogenous fibroblasts can effectively serve as a substitute for connective tissue in augmenting keratinized gingiva and significantly improve surgical wound healing.

Recently, anorganic equine bone (AEB) has been introduced as a substitute for bone graft used in oral surgery. In one study, the structural and physicochemical properties of AEB and its in vivo performance in mandibular bone defects were evaluated.

The results of the study demonstrated that the physicochemical and structural properties of AEB matched the typical characteristics of heat-treated xenogeneic bone substitutes, and the use of AEB as a graft material resulted in bone formation without any presence of inflammatory cell infiltrate.

In another study, polydimethylsiloxane with silver nanoparticles (PDMS/AgNPs) was used for surgical reconstruction of the esophagus with models, and in vitro tests were performed to evaluate its antifungal properties. The results showed that the inclusion of AgNPs as bacteriostatic agents decreased fatigue resistance, increased flexibility and offered optimal local protection against fungal development.

In summary, durable, novel and highly esthetic dental materials have demonstrated significant potential in dental treatment and can be used to improve the quality of life of dental patients.

Source

Rusu, L.-C., Ardelean, LC Advanced materials for oral application. Materials 2022. https://www.mdpi.com/1996-1944/15/14/4749

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