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Surface characterization of indirect restorative materials submitted to different etching protocols.Journal of Dentistry Dec 2022This in vitro study aimed to evaluate the effect of different times and concentrations of hydrofluoric acid etching on the surface of indirect restorative materials...
OBJECTIVES
This in vitro study aimed to evaluate the effect of different times and concentrations of hydrofluoric acid etching on the surface of indirect restorative materials obtained from blocks used in CAD-CAM technology.
METHODS
Specimens (4 mm × 4 mm × 0.8 mm) were obtained for each indirect restorative material: zirconia-reinforced lithium monosilicate ceramic (Celtra Duo), nanoceramic resin (Lava Ultimate), and polymer-infiltrated ceramic network material (Vita Enamic). The materials were submitted to etching with 5% or 10% hydrofluoric acid for 20, 40, 60, or 90 s. A control group for each material was evaluated without any surface treatment, totaling nine experimental groups for each material (n = 10). The specimens were evaluated for surface roughness (R and R), confocal optical microscopy, the contact angle (θ), surface free energy (γs), total free interaction energy (∆G) using a goniometer, and microshear bond strength to resin cement. Specimen images were obtained using scanning electron microscopy, confocal optical microscopy, and atomic force microscopy. Data on the surface roughness, the contact angle, surface free energy, total free interaction energy, and bond strength were subjected to two-way ANOVA and Tukey´s test (α=0.05).
RESULTS
In general, Celtra Duo showed better results after etching with 10% hydrofluoric acid for 40 or 60 s. Lava Ultimate showed better performance after etching with 10% hydrofluoric acid for 20 or 40 s, whereas Vita Enamic showed better results after etching with 5% hydrofluoric acid for 90 s.
CONCLUSION
Each material showed different characteristics after etching with hydrofluoric acid. Knowledge of the proper protocol for each material is essential to ensure improvements in the adhesion process and durability of indirect restorations. In general, Celtra Duo presented mechanical properties superior to those of Lava Ultimate and Vita Enamic.
CLINICAL SIGNIFICANCE
Specific etching protocols must be recommended for each indirect material because longer exposure to hydrofluoric acid can jeopardize the surface, thus affecting the mechanical and bond strength properties.
Topics: Hydrofluoric Acid; Dental Bonding; Dental Porcelain; Materials Testing; Surface Properties; Dental Materials; Resin Cements; Ceramics; Computer-Aided Design
PubMed: 36280006
DOI: 10.1016/j.jdent.2022.104348 -
Influence of inorganic nanoparticles on dental materials' mechanical properties. A narrative review.BMC Oral Health Nov 2023Inorganic nanoparticles have been widely incorporated in conventional dental materials to help in improving their properties. The literature has shown that incorporating... (Review)
Review
Inorganic nanoparticles have been widely incorporated in conventional dental materials to help in improving their properties. The literature has shown that incorporating nanoparticles in dental materials in different specialties could have a positive effect on reinforcing the mechanical properties of those materials; however, there was no consensus on the effectiveness of using nanoparticles in enhancing the mechanical properties of dental materials, due to the variety of the properties of nanoparticles itself and their effect on the mechanical properties. This article attempted to analytically review all the studies that assessed the effect of different types of inorganic nanoparticles on the most commonly used dental materials in dental specialties such as polymethyl methacrylate, glass ionomer cement, resin composite, resin adhesive, orthodontic adhesive, and endodontic sealer. The results had shown that those inorganic nanoparticles demonstrated positive potential in improving those mechanical properties in most of the dental materials studied. That potential was attributed to the ultra-small sizes and unique physical and chemical qualities that those inorganic nanoparticles possess, together with the significant surface area to volume ratio. It was concluded from this comprehensive analysis that while a definitive recommendation cannot be provided due to the variety of nanoparticle types, shapes, and incorporated dental material, the consensus suggests using nanoparticles in low concentrations less than 1% by weight along with a silane coupling agent to minimize agglomeration issues and benefit from their properties.
Topics: Humans; Dental Cements; Dental Bonding; Resin Cements; Composite Resins; Glass Ionomer Cements; Nanoparticles; Materials Testing; Surface Properties; Stress, Mechanical; Dental Materials
PubMed: 37990196
DOI: 10.1186/s12903-023-03652-1 -
Acta Biomaterialia Sep 2022Dental caries is a biofilm-mediated, diet-modulated, multifactorial and dynamic disease that affects more than 90% of adults in Western countries. The current treatment... (Review)
Review
Dental caries is a biofilm-mediated, diet-modulated, multifactorial and dynamic disease that affects more than 90% of adults in Western countries. The current treatment for decayed tissue is based on using materials to replace the lost enamel or dentin. More than 500 million dental restorations are placed annually worldwide, and materials used for these purposes either directly or indirectly interact with dentin and pulp tissues. The development and understanding of the effects of restorative dental materials are based on different in-vitro and in-vivo tests, which have been evolving with time. In this review, we first discuss the characteristics of the tooth and the dentin-pulp interface that are unique for materials testing. Subsequently, we discuss frequently used in-vitro tests to evaluate the biocompatibility of dental materials commonly used for restorative procedures. Finally, we present our perspective on the future directions for biological research on dental materials using tissue engineering and organs on-a-chip approaches. STATEMENT OF SIGNIFICANCE: Dental caries is still the most prevalent infectious disease globally, requiring more than 500 million restorations to be placed every year. Regrettably, the failure rates of such restorations are still high. Those rates are partially based on the fact that current platforms to test dental materials are somewhat inaccurate in reproducing critical components of the complex oral microenvironment. Thus, there is a collective effort to develop new materials while evolving the platforms to test them. In this context, the present review critically discusses in-vitro models used to evaluate the biocompatibility of restorative dental materials and brings a perspective on future directions for tissue-engineered and organs-on-a-chip platforms for testing new dental materials.
Topics: Adult; Composite Resins; Dental Caries; Dental Materials; Dental Restoration, Permanent; Dentin; Humans; Lab-On-A-Chip Devices; Materials Testing
PubMed: 35933103
DOI: 10.1016/j.actbio.2022.07.060 -
International Journal of Molecular... Dec 2023The dental material industry is rapidly developing resin-based composites (RBCs), which find widespread use in a variety of clinical settings. As such, their... (Review)
Review
The dental material industry is rapidly developing resin-based composites (RBCs), which find widespread use in a variety of clinical settings. As such, their biocompatibility has gained increasing interest. This literature review presents a summary of research into the cytotoxicity of methacrylate-based composites published from 2017 to 2023. Subject to analysis were 14 in vitro studies on human and murine cell lines. Cytotoxicity in the included studies was measured via MTT assay, LDH assay, and WST-1 assay. The QUIN Risk of Bias Tool was performed to validate the included studies. Included studies (based entirely on the results of in vitro studies) provide evidence of dose- and time-dependent cytotoxicity of dental resin-based composites. Oxidative stress and the depletion of cellular glutathione (GSH) were suggested as reasons for cytotoxicity. Induction of apoptosis by RBCs was indicated. While composites remain the golden standard of dental restorative materials, their potential cytotoxicity cannot be ignored due to direct long-term exposure. Further in vitro investigations and clinical trials are required to understand the molecular mechanism of cytotoxicity and produce novel materials with improved safety profiles.
Topics: Humans; Animals; Mice; Apoptosis; Biological Assay; Cell Line; Dental Materials; Glutathione
PubMed: 38203323
DOI: 10.3390/ijms25010152 -
The Journal of Prosthetic Dentistry Jan 2021Information on the mechanical properties of the materials used for manufacturing computer-engineered complete dentures is scarce.
STATEMENT OF PROBLEM
Information on the mechanical properties of the materials used for manufacturing computer-engineered complete dentures is scarce.
PURPOSE
The purpose of this in vitro study was to evaluate the mechanical properties of 3 prepolymerized polymethyl methacrylate (PMMA) resins used in the fabrication of computer-aided design and computer-aided manufacturing (CAD-CAM) milled complete dentures (CDs), as well as 2 denture base polymers used for conventionally fabricated CDs.
MATERIAL AND METHODS
Three CAD-CAM materials were evaluated: Degos Dental L-Temp, IvoBase CAD, and Zirkonzahn Temp Basic Tissue. Two materials used for conventionally manufactured dentures were also included as controls (Palapress and Paladon 65). Each material type was sectioned into bars for flexural strength, nanohardness, elastic modulus, and surface microhardness evaluation (n=8/material). Half of the specimens were stored in water for 30 days, while the other half was dry-stored. A 2-way ANOVA was conducted to detect the effect of material and storage on the evaluated properties (α=.05). Linear contrasts were conducted to compare the differences among the 3 types of CAD-CAM material and the conventional ones.
RESULTS
Material type and storage had a significant influence on the flexural strength, nanohardness, elastic modulus, and surface hardness of the materials investigated (P<.001). The post hoc Scheffé test for flexural strength revealed a nonsignificant difference in the interaction between Degos L-Temp and Paladon (P=1.000). In terms of nanohardness, no difference was found when comparing Palapress with Paladon, as well as IvoBase CAD with Zirkonzahn Temp Basic (P=1.000). A nonsignificant interaction in terms of surface hardness was also found between IvoBase CAD and Palapress (P=.575).
CONCLUSIONS
The tested materials showed variation in their mechanical properties, with satisfactory behavior of the CAD-CAM materials. However, the results obtained when testing the materials used for the conventional fabrication of complete dentures suggest that their use might still be advisable.
Topics: Computer-Aided Design; Dental Materials; Denture, Complete; Materials Testing; Polymers; Polymethyl Methacrylate; Surface Properties
PubMed: 32063383
DOI: 10.1016/j.prosdent.2019.12.008 -
BioMed Research International 2023Considering the unique properties of magnesium and its alloy, it has a vast demand in biomedical applications, particularly the implant material in tissue engineering...
Considering the unique properties of magnesium and its alloy, it has a vast demand in biomedical applications, particularly the implant material in tissue engineering due to its biodegradability. But the fixing spares must hold such implants till the end of the biodegradation of implant material. The composite technology will offer the added benefits of altering the material properties to match the requirements of the desired applications. Hence, this experimental investigation is aimed at developing a composite material for manufacturing fixing spares like a screw for implants in biomedical applications. The matrix of AZ63 magnesium alloy is reinforced with nanoparticles of zirconium (Zr) and titanium (Ti) through the stir casting-type synthesis method. The samples were prepared with equal contributions of zirconium (Zr) and titanium (Ti) nanoparticles in the total reinforcement percentage (3%, 6%, 9%, and 12%). The corrosive and tribological studies were done. In the corrosive study, the process parameters like NaCl concentration, pH value, and exposure time were varied at three levels. In the wear study, the applied Load, speed of sliding, and the distance of the slide were considered at four levels. Taguchi analysis was employed in this investigation to optimize the reinforcement and independent factors to minimize the wear and corrosive losses. The minimum wear rate was achieved in the 12% reinforced sample with the input factor levels of 60 N of load on the pin, 1 m/s of disc speed at a sliding distance was 1500 m, and the 12% reinforce samples also recorded a minimum corrosive rate of 0.0076 mm/year at the operating environment of 5% NaCl-concentrated solution with the pH value of 9 for 24 hrs of exposure. The prediction model was developed based on the experimental results.
Topics: Titanium; Zirconium; Caustics; Magnesium; Sodium Chloride; Dental Materials; Alloys
PubMed: 37187465
DOI: 10.1155/2023/6297372 -
Journal of the Mechanical Behavior of... Oct 2021The aim of this study was to investigate whether there is a relation between impact strength and flexural strength of different composite and ceramic materials used in...
AIM
The aim of this study was to investigate whether there is a relation between impact strength and flexural strength of different composite and ceramic materials used in dental restorations.
MATERIALS AND METHODS
The three-point-bending test was used to determine the flexural strength and flexural modulus, and the Dynstat impact test was used to determine the impact strength of different composite and ceramic dental materials. The relation between the flexural strength and impact strength was mathematically investigated and a three-dimensional finite element analysis model of the impact test set-up was created to verify these results.
RESULTS
We found a relation between the impact strength, a, the flexural strength, σ, and the flexural modulus, E, which can be represented by the formula: a=λ(σ⁄E), where λ is a constant dependent on the test set-up.
CONCLUSION
The obtained impact strength of materials is specific to the test set-up and dependent on the geometric configuration of the test set-up and the specimen thickness. The clinical significance of this investigation is that roughness and fatigue have far more influence on the impact strength than the flexure strength.
Topics: Ceramics; Dental Materials; Dental Porcelain; Flexural Strength; Humans; Materials Testing; Pliability; Surface Properties
PubMed: 34214922
DOI: 10.1016/j.jmbbm.2021.104658 -
Dental Materials : Official Publication... Jan 2023This study aimed to evaluate the influence of new resin-based CAD-CAM implant-supported materials on posterior crown restoration stress and strain concentrations.
OBJECTIVE
This study aimed to evaluate the influence of new resin-based CAD-CAM implant-supported materials on posterior crown restoration stress and strain concentrations.
METHODS
A previous 3D implant model was edited to receive a cement-retained posterior crown manufactured with different CAD/CAM materials (Estelite P Block, Estelite Block II or Estelite Layered Block). Each solid model was exported to the computer-aided engineering software and submitted to the finite element analysis of stress and strain. Material properties were assigned to each solid with isotropic and homogeneous behavior according to the manufacturer information. A vertical load of 600 N was applied in the occlusal region of the crown, via a simulated food bolus, and stress was calculated in Von Misses (σVM) for the implant, abutment and screw, Maximum (σMAX) Principal Stresses for the crown and microstrain for the bone.
RESULTS
All simulated materials showed acceptable stresses levels with a similar stress pattern among the models. At the crown intaglio region and cement layer, however, differences were observed: Estelite P Block showed a lower tensile and shear stresses magnitude when compared to other resin-based materials with lower elastic modulus.
SIGNIFICANCE
The stress effect of different resin-based CAD-CAM implant-supported crowns is predominant in the crown and cement layer, with Estelite P Block showing 7.4 % versus 9.3 % and 9.2 % for Estelite Block II and Estelite Layered Block of crown failure risk.
Topics: Dental Porcelain; Dental Implants; Crowns; Dental Materials; Dental Cements; Computer-Aided Design; Dental Stress Analysis; Dental Prosthesis, Implant-Supported; Finite Element Analysis; Materials Testing; Dental Prosthesis Design
PubMed: 36566152
DOI: 10.1016/j.dental.2022.12.001 -
British Dental Journal May 2022Restorative dental materials are among the most important medical devices in terms of the numbers of patients who benefit and the technical sophistication of the...
Restorative dental materials are among the most important medical devices in terms of the numbers of patients who benefit and the technical sophistication of the products. Many though contain toxic or noxious substances, including potentially sensitising resin monomers, photoinitiators, acidic polymers and glass or ceramic filler particles. Despite this, dental materials are among the safest medical devices in use today, with very few reports of adverse reactions or injuries among both patients or the dental team. This paper considers the potential for adverse reactions to dental materials, current evidence for harm and finally examines the reasons why in real-world clinical use the likelihood of an adverse event is extremely low. Medical devices regulations, responsible manufacture and clinical vigilance all appear to play important roles in ensuring that dental materials do not cause or present a risk to patients. While this excellent in-practice safety record is welcome, there is now increasing interest in the 'macro' scale biocompatibility of dental materials and their packaging in the environment, subjects that have been relatively neglected until recently. It was concluded that this should be a priority for future research and development and support is needed from governments alongside the manufacturing industry and the profession.
Topics: Ceramics; Composite Resins; Dental Materials; Dental Restoration, Permanent; Esthetics, Dental; Humans
PubMed: 35562452
DOI: 10.1038/s41415-022-4198-6 -
Clinical Oral Investigations Jan 2021This study aimed to survey dentists in Germany to identify their favored materials for the fabrication of tooth-supported single crowns (SCs) depending on the location...
OBJECTIVES
This study aimed to survey dentists in Germany to identify their favored materials for the fabrication of tooth-supported single crowns (SCs) depending on the location of the abutment teeth and the preparation margin.
MATERIALS AND METHODS
The survey included questions regarding demographic characteristics of dentists/their dental practice and preferred restorative materials for the fabrication of SCs for abutment teeth 16, 11, 34, and 36 with either supra- or subgingival preparation margins.
RESULTS
Between August 2019 and February 2020, 721 dentists participated in the survey; responses from 33 dentists were excluded from data analysis because the dentists did not work in Germany or provided less than one fixed dental prosthesis/month. Dentists favored ceramic materials independent of the location of the abutment tooth and preparation margin (56.6-92.2%). CAD/CAM resin composites or full metals were preferred by only a few participants. A significantly higher proportion of dentists recommended porcelain fused to metal for subgingival preparation margins than for supragingival margins (p < 0.001). Characteristics of dentists/dental practices influenced a single scenario (11 subgingival) that was dependent on the dentist's time since graduation. When asked to specify the ceramic materials, numerous participants wrote a free response (5.7-7.8%) or did not answer (0.7-4.8%).
CONCLUSIONS
Dentists in Germany selected restorative materials for SCs depending on the clinical scenario. Since numerous dentists did not specify the ceramic materials, postgraduate information and education might help to extend expertise.
CLINICAL RELEVANCE
The results of this survey provide insight into the favored materials of dentists for the fabrication of tooth-supported SCs.
Topics: Crowns; Dental Porcelain; Dental Prosthesis Design; Dentists; Germany; Humans; Surveys and Questionnaires
PubMed: 32556660
DOI: 10.1007/s00784-020-03363-9