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Biomedical Materials (Bristol, England) May 2022The aim of this study was to evaluate the application prospect of a tantalum (Ta) and zirconium (Zr) alloy as a dental implant material. The Ta-20Zr (wt.%) alloy was...
The aim of this study was to evaluate the application prospect of a tantalum (Ta) and zirconium (Zr) alloy as a dental implant material. The Ta-20Zr (wt.%) alloy was prepared by powder metallurgy, and its microstructure and mechanical properties were analyzed by standard techniques. The effect of Ta-20Zr alloy on inflammation, bone remodeling and osseointegration was analyzed in rat and rabbit models by biochemical, histological and imaging tests. The Ta-20Zr alloy showed excellent mechanical compatibility with the bone tissue on account of similar elastic modulus (49.2 GPa), thereby avoiding the 'stress shielding effect'. Furthermore, Ta-20Zr alloy enhanced the inflammatory response by promoting secretion of interleukin-6 (IL-6) and IL-10, and facilitated the balance between the M1/M2 macrophage phenotypes. Finally, Ta-20Zr also showed excellent osseointegration and osteogenic ability without any systemic side effects, making it an ideal dental implant material.
Topics: Alloys; Animals; Dental Implants; Dental Materials; Osseointegration; Rabbits; Rats; Tantalum; Titanium
PubMed: 35477054
DOI: 10.1088/1748-605X/ac6b05 -
The Journal of Adhesive Dentistry Jul 2021Different kinds of interactions between the restorative material and mineralized dental tissues result in secondary caries around dental composites. Of these, the... (Review)
Review
Different kinds of interactions between the restorative material and mineralized dental tissues result in secondary caries around dental composites. Of these, the mechanical interactions have to be carefully investigated. Due to the elastic mismatch between dental tissues and the composite restoration, complex stresses and strains develop at their interface. This complex mechanical environment disturbs the demineralization-remineralization equilibrium of dental hard tissues. The fluid flow both over and within enamel and dentin, associated with their complex ultrastructure and mechanical behavior, is a key factor. It is known that external mechanical loading can indirectly promote the dissolution of enamel and dentin through a pumping action of cariogenic fluids in and out of microgaps at the interface between mineralized tissues and composite. Mechanical loading can also directly influence the physicochemical behavior of dental hard tissues by inducing complex strain and stress fields on the crystal scale. It is important to consider both the direct and indirect paths by which mechanical loading can influence the apatite dissolution kinetics. Therefore, a systematic approach should be used to investigate the mechanism of secondary caries formation considering the tooth-composite interface as a unique complex in which each element has an influence on the other.
Topics: Composite Resins; Dental Caries; Dental Caries Susceptibility; Dental Enamel; Dental Materials; Dental Restoration, Permanent; Dentin; Humans
PubMed: 34269540
DOI: 10.3290/j.jad.b1649941 -
International Dental Journal Feb 2023The term bioactivity is being increasingly used in medicine and dentistry. Due to its positive connotation, it is frequently utilised for advertising dental restorative... (Review)
Review
The term bioactivity is being increasingly used in medicine and dentistry. Due to its positive connotation, it is frequently utilised for advertising dental restorative materials. However, there is confusion about what the term means, and concerns have been raised about its potential overuse. Therefore, FDI decided to publish a Policy Statement about the bioactivity of dental restorative materials to clarify the term and provide some caveats for its use in advertising. Background information for this Policy Statement was taken from the current literature, mainly from the PubMed database and the internet. Bioactive restorative materials should have beneficial/desired effects. These effects should be local, intended, and nontoxic and should not interfere with a material's principal purpose, namely dental tissue replacement. Three mechanisms for the bioactivity of such materials have been identified: purely biological, mixed biological/chemical, or strictly chemical. Therefore, when the term bioactivity is used in an advertisement or in a description of a dental restorative material, scientific evidence (in vitro or in situ, and preferably in clinical studies) should be provided describing the mechanism of action, the duration of the effect (especially for materials releasing antibacterial substances), and the lack of significant adverse biological side effects (including the development and spread of antimicrobial resistance). Finally, it should be documented that the prime purpose, for instance, to be used to rebuild the form and function of lost tooth substance or lost teeth, is not impaired, as demonstrated by data from in vitro and clinical studies. The use of the term bioactive dental restorative material in material advertisement/information should be restricted to materials that fulfil all the requirements as described in the FDI Policy Statement.
Topics: Humans; Dental Restoration, Permanent; Dental Caries; Policy; Dental Materials; Composite Resins
PubMed: 36577639
DOI: 10.1016/j.identj.2022.11.012 -
Journal of Dentistry Jul 2024To give a comprehensive review of advancement in dental ceramics, fabrication methods, and the challenges associated with clinical application. (Review)
Review
OBJECTIVES
To give a comprehensive review of advancement in dental ceramics, fabrication methods, and the challenges associated with clinical application.
DATA, SOURCES AND STUDY SELECTION
Researches on chemical composition, biomechanical behaviors, optical properties, bonding strategies and fabrication methods were included. The search of articles was independently conducted by two authors in the PubMed, Scopus, Medline and Web of Science.
CONCLUSIONS
Dental ceramics have shown significant advancements in terms of esthetics and function. However, improving fracture toughness without compromising optical properties remains a challenge. Repairing fractured zirconia or glass-matrix ceramic prostheses with the same material is difficult due to the sintering process. Developing innovative bonding techniques that provide strong and long-lasting bonding strength between ceramics and tooth structures poses a recurring obstacle.
CLINICAL SIGNIFICANCE
Despite the emergence of dental ceramics and fabrication techniques, certain limitations such as susceptibility to brittleness and fracture still exist. Therefore, the current review provided valuable information around the advanced dental ceramics in tooth repair. The laboratory test data and the clinical outcome are also presented in details, aiming to guide clinicians in making informed decisions regarding ceramic restorations.
Topics: Humans; Ceramics; Zirconium; Dental Materials; Dental Bonding; Dental Porcelain; Esthetics, Dental; Materials Testing; Dental Prosthesis Design
PubMed: 38729288
DOI: 10.1016/j.jdent.2024.105053 -
Operative Dentistry Jan 2022Resin-based materials used in restorative dentistry are introduced at a fast pace with limited knowledge about their properties. Comparing properties of these materials...
OBJECTIVE
Resin-based materials used in restorative dentistry are introduced at a fast pace with limited knowledge about their properties. Comparing properties of these materials from different restorative categories is lacking but can help the clinician in material selection. This study aimed to compare mechanical properties and wear resistance of bis-acryl-, composite-, and ceramic-resin restorative materials.
METHODS AND MATERIALS
Bisacryl-resin (Bis-R, LuxaCrown, DMG), composite-resin (Com-R, Filtek Supreme Ultra, 3M Oral Care), and ceramic-resin (Cer-R, Enamic, VITA Zahnfabrik) specimens were prepared for mechanical tests: fracture toughness (FT) with and without initial thermomechanical loading using a mastication simulator, flexural strength (FS), and flexural modulus (FM), compressive strength (CS), and volumetric wear loss measurement. The datasets for FT and wear resistance were each analyzed using two-way ANOVA followed by pairwise comparisons or Tukey testing as appropriate. The datasets for FS, FM, and CS were analyzed using one-way ANOVA followed by the Tukey test.
RESULTS
Analysis of FS, FM, and CS showed significant differences between materials, with all pairwise comparisons between materials showing significance. Analysis of FT resulted in a significant interaction between the material and treatment, with analysis of wear loss showing a significant interaction between the material and the number of cycles.
CONCLUSIONS
Cer-R demonstrated superior FT, CS, and wear resistance compared to Bis-R and Comp-R materials. Fracture toughness of Bis-R increased after thermomechanical loading.
Topics: Ceramics; Composite Resins; Dental Materials; Flexural Strength; Materials Testing; Surface Properties
PubMed: 35029680
DOI: 10.2341/20-191-L -
The Journal of Prosthetic Dentistry Jan 2022How the loading rate might affect the mechanical properties of interim materials and interim fixed dental prostheses is unclear.
STATEMENT OF PROBLEM
How the loading rate might affect the mechanical properties of interim materials and interim fixed dental prostheses is unclear.
PURPOSE
The purpose of this in vitro study was to compare the material stiffness, material strength, and structural strength of interim 3-unit fixed dental prostheses fabricated from 3 interim materials when stressed at different loading rates.
MATERIAL AND METHODS
Bar-shaped specimens and anatomically correct interim 3-unit fixed dental prostheses with a modified-ridge lap pontic were fabricated from polyethyl methacrylate resin (Trim) and 2 bis-acrylic composite resins (TempSmart; Integrity) (n=10). Flexural modulus and strength of the bar specimens, representing material stiffness and strength, were determined with a 4-point bend test in a universal testing machine. The structural strength of the prosthesis was assessed from the failure load from a vertical force applied on the occlusal surface of the pontic. Three loading rates, 0.5, 5, or 10 mm/min, were evaluated. Results were statistically analyzed with 2-way analysis of variance and multiple comparisons (α=.05).
RESULTS
Loading rate and material significantly affected flexural modulus, flexural strength, and structural strength (P<.05). Increasing loading rate significantly increased the flexural modulus of all materials (P<.05), but the effect of loading rate on the flexural strength of bis-acrylic composite resins was mostly insignificant. Polyethyl methacrylate specimens did not fracture when loaded at 0.5 or 5 mm/min, and the interim fixed dental prostheses made from polyethyl methacrylate did not fracture at the 0.5 mm/min loading rate. Dual-polymerizing bis-acrylic composite resin had significantly higher flexural modulus and strengths than autopolymerizing bis-acrylic composite resin.
CONCLUSIONS
Polyethyl methacrylate resin had the lowest stiffness among the interim materials tested and did not fracture but excessively deformed at the low loading rate. Dual-polymerizing bis-acrylic composite resin consistently had higher stiffness and material strength and provided higher structural strength than the autopolymerizing bis-acrylic composite resin. Loading rate significantly affected the mechanical properties of polyethyl methacrylate resin (P<.05), but the effect was indistinct for the bis-acrylic materials.
Topics: Composite Resins; Dental Materials; Dental Stress Analysis; Denture, Partial, Temporary; Materials Testing; Pliability; Stress, Mechanical; Surface Properties
PubMed: 33218745
DOI: 10.1016/j.prosdent.2020.10.008 -
Dental Materials : Official Publication... May 2024The objective was to discuss the research on zirconia published in the past 15 years to help the dental materials community understand the key properties of the types of... (Review)
Review
OBJECTIVES
The objective was to discuss the research on zirconia published in the past 15 years to help the dental materials community understand the key properties of the types of zirconia and their clinical applications.
METHODS
A literature search was performed in May/2023 using Web of Science Core Collection with the term "dental zirconia". The search returned 5102 articles, which were categorized into 31 groups according to the research topic.
RESULTS
The current approach to improving the translucency of zirconia is to decrease the alumina content while increasing the yttria content. The resulting materials (4Y-, 5Y-, and above 5 mol% PSZs) may contain more than 50% of cubic phase, with a decrease in mechanical properties. The market trend for zirconia is the production of CAD/CAM disks containing more fracture resistant 3Y-TZP at the bottom layers and more translucent 5Y-PSZ at the top. Although flaws located between layers in multilayered blocks might represent a problem, newer generations of zirconia layered blocks appear to have solved this problem with novel powder compaction technology. Significant advancements in zirconia processing technologies have been made, but there is still plenty of room for improvement, especially in the fields of high-speed sintering and additive manufacturing.
SIGNIFICANCE
The wide range of zirconia materials currently available in the market may cause confusion in materials selection. It is therefore imperative for dental clinicians and laboratory technicians to get the needed knowledge on zirconia material science, to follow manufacturers' instructions, and to optimize the design of the prosthetic restoration with a good understanding where to reinforce the structure with a tough and strong zirconia.
Topics: Zirconium; Dental Materials; Computer-Aided Design; Surface Properties; Yttrium; Materials Testing
PubMed: 38521694
DOI: 10.1016/j.dental.2024.02.026 -
Dental Materials : Official Publication... Jan 2023Different types of direct-placement dental materials are used for the restoration of structure, function and aesthetics of teeth. The aim of this research investigation...
OBJECTIVES
Different types of direct-placement dental materials are used for the restoration of structure, function and aesthetics of teeth. The aim of this research investigation is to determine, through a comparative cradle-to-gate life cycle assessment, the environmental impacts of three direct-placement dental restorative materials (DRMs) and their associated packaging.
METHODS
Three direct-placement dental materials; dental amalgam, resin-based composite (RBC) and glass polyalkenoate cements (GIC) are assessed using primary data from a manufacturer (SDI Limited, Australia). The functional unit consisted of 'one dental restoration' of each restorative system under investigation: 1.14 g of dental amalgam; 0.25 g of RBC (plus the adhesive = 0.10 g); and 0.54 g of GIC. The system boundary per restoration included the raw materials and their associated packaging materials for each DRM together with the processing steps for both the materials and packaging. The environmental impacts were assessed using an Egalitarian approach under the ReCiPe method using Umberto software and the Ecoinvent database. Nine different impact categories were used to compare the environmental performance of these materials.
RESULTS
Dental amalgam had the highest impact across most of the categories, but RBC had the highest Global Warming Potential. The highest sources of the environmental impacts for each restorative material were: Amalgam, derived from material use; RBC, derived from energy use in processing material and packaging material; GIC, derived from material and energy use for packaging.
SIGNIFICANCE
Less intensive energy sources or more sustainable packaging materials can potentially reduce the impacts associated with RBC and GIC thus making them suitable alternatives to dental amalgam.
Topics: Animals; Dental Restoration, Permanent; Dental Amalgam; Dental Materials; Glass Ionomer Cements; Life Cycle Stages; Composite Resins
PubMed: 36428112
DOI: 10.1016/j.dental.2022.11.007 -
The Journal of Prosthetic Dentistry May 2024The increasing use of computer-aided design and computer-aided manufacturing (CAD-CAM) systems has led to the development of resin-ceramic materials that meet the... (Review)
Review
STATEMENT OF PROBLEM
The increasing use of computer-aided design and computer-aided manufacturing (CAD-CAM) systems has led to the development of resin-ceramic materials that meet the requirements of minimally invasive dentistry, including the resin nanoceramic (RNC) and polymer-infiltrated ceramic network (PICN). The wear characteristics of these materials are unclear.
PURPOSE
The purpose of this systematic review was to compare the wear resistance of resin-ceramic materials when compared with one another or with lithium disilicate glass-ceramics.
MATERIAL AND METHODS
The PubMed, Scopus, and DOSS search engines were used to identify articles published between 2013 and 2021. Two independent researchers conducted the systematic review by following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines and by following a combination of keywords.
RESULTS
Of a total of 310 articles, 26 were selected, including only 1 clinical study. Among these, 15 compared resin-ceramic materials with each other, while 11 compared resin-ceramic materials with lithium disilicate ceramics. Two types of wear were used to compare the materials: attrition and abrasion. The most commonly studied materials were 2 RNCs (Lava Ultimate and Cerasmart), 1 PICN (Vita Enamic), and 1 ceramic (IPS e.max CAD). Among the resin-ceramic materials, the PICN (Vita Enamic) showed less wear than the RNCs. Of the RNCs, Cerasmart had less attrition wear and less wear of the opposing teeth.
CONCLUSIONS
Lithium disilicate glass-ceramics have a higher wear resistance than resin-ceramic materials, but they cause more wear of the opposing teeth.
Topics: Computer-Aided Design; Ceramics; Humans; Dental Porcelain; Dental Restoration Wear; Dental Materials; Resins, Synthetic
PubMed: 35459543
DOI: 10.1016/j.prosdent.2022.01.027 -
Brazilian Dental Journal Jun 2020The objective of this work was to evaluate the effects of in vitro and in situ biodegradation on the surface characteristics of two resin cements and a hybrid ceramic...
The objective of this work was to evaluate the effects of in vitro and in situ biodegradation on the surface characteristics of two resin cements and a hybrid ceramic system. One hundred and eighty specimens (4X1.5mm) of each material (Maxcem Elite, NX3 Nexus and Vita Enamic) were made and randomly distributed in twelve groups (n=15) according to the material and biodegradation method. The specimens were then submitted to the following challenges: storage in distilled water 37 ºC for 24 h or 7 days, storage for 7 days, at 37 ºC, in stimulated saliva or in situ. The in situ stage corresponded to the preparation of 15 intraoral palatal devices, used for 7 days. Each device presented 3 niches, where a sample of each materials was accommodated. Specimens from both saliva and in situ groups suffered a cariogenic challenge, corresponding to the application of a solution of 20% of sucrose, 10 times throughout each day. After each biodegradation method, the surface roughness (Ra), Vickers hardness (VHN) and scanning electron microscopy (SEM) analyzes were performed. The data collected were evaluated by Levene test, two-way ANOVA and Tukey`s test (α=5%). The in situ challenge promoted the greater biodegradation, regardless of the material. Regarding the materials, the Vita Enamic VHN was negatively affected by all biodegradation methods and the Nexus NX3 presented better performance than the self-adhesive cement tested. Therefore, within the conditions of this work, it was concluded that in situ biodegradation can affect negatively the surface characteristics of indirect restorative materials.
Topics: Ceramics; Dental Materials; Hardness; Materials Testing; Resin Cements; Surface Properties
PubMed: 32667515
DOI: 10.1590/0103-6440202002982