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The Journal of Prosthetic Dentistry Oct 2022Selective laser melting (SLM) additive manufacturing (AM) technologies provide an alternative to conventional casting and milling procedures in fabricating metal-ceramic... (Meta-Analysis)
Meta-Analysis Review
Adhesion of veneering porcelain to cobalt-chromium dental alloys processed with casting, milling, and additive manufacturing methods: A systematic review and meta-analysis.
STATEMENT OF PROBLEM
Selective laser melting (SLM) additive manufacturing (AM) technologies provide an alternative to conventional casting and milling procedures in fabricating metal-ceramic dental prostheses. However, the quality of porcelain bond strength to the SLM AM cobalt-chromium (Co-Cr) metal framework of a dental restoration is unclear.
PURPOSE
The purpose of this systematic review and meta-analysis was to identify in vitro studies that reported the porcelain bond strength to SLM AM Co-Cr dental metal alloys and compare the porcelain bond strength values to cast, milled, and additively manufactured Co-Cr dental alloys.
MATERIAL AND METHODS
An electronic systematic review was performed in different databases: MEDLINE/PubMed, EMBASE, World of Science, Cochrane, and Scopus. A manual search was also conducted. Studies that reported the porcelain bond strength to SLM Co-Cr metal alloys and in the English language were included. Two investigators evaluated the quality assessment of the studies by applying the JBI critical appraisal checklist for quasi-experimental studies (nonrandomized experimental studies). A third investigator was consulted to resolve lack of consensus. Two subgroups were created based on the test used, 3-point bend and shear bond strength tests. The porcelain bond strength of cast, milled, and AM Co-Cr dental alloys were compared. The I2 statistic and its associated P value were used to assess the heterogeneity between studies. The Eger test was used for determining significance of the funnel pots.
RESULTS
A total of 216 studies were collected from the electronic and manual searches. After independently evaluating the titles and abstracts by the reviewers, 26 articles were identified. Three of these were excluded after full-text revision. The porcelain bond strength comparison between the cast and AM alloys for the 3-point bend subgroup revealed a significant result for overall effect (P<.001) favoring the SLM method with considerable heterogeneity (I2=83%, P<.001). Furthermore, the porcelain bond strength comparison between cast and milled alloys for the shear bond strength subgroup revealed a significant test for overall effect (P=.04) favoring milled procedures with a nonsignificant unimportant heterogeneity (I2= 0%, P<.47) and for the 3-point bend subgroup (P<.001) favoring milled specimens with a significant considerable heterogeneity (I2=79%, P<.001).
CONCLUSIONS
The metal manufacturing method had no effect on the porcelain bond strength to Co-Cr dental metal alloys.
Topics: Dental Porcelain; Chromium Alloys; Metal Ceramic Alloys; Dental Bonding; Materials Testing; Surface Properties; Cobalt; Chromium; Dental Alloys
PubMed: 34294418
DOI: 10.1016/j.prosdent.2021.01.001 -
Journal of Nanoscience and... Jul 2021In the context of biology and medicine, nanotechnology encompasses the materials, devices, and systems whose structure and function are relevant for small length scales,...
In the context of biology and medicine, nanotechnology encompasses the materials, devices, and systems whose structure and function are relevant for small length scales, from nanometers through microns. The purpose of this study was to compare the microstructures and resultant biocompatibility of three commercially available soft milled cobalt-chromium (Co-Cr) alloys (Ceramill Sintron, CS; Sintermetall, SML; and Soft Metal, SM). Disc-shaped specimens were prepared by milling the soft blanks and subsequent post-sintering. The crystal and microstructures of the three different alloys were studied using optical microscopy, X-ray diffractometry (XRD), energy dispersive X-ray spectroscopy, and electron backscatter diffraction. The amounts of Co, Cr, and molybdenum (Mo) ions released from the alloys were evaluated using inductively coupled plasma-mass spectroscopy. The effect of ion release on the viability of L929 mouse fibroblasts was evaluated by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The SML alloy showed a finer grain size (approx. 5 and a larger pore size (approx. 5 than the CS and SM alloys, and its XRD pattern exhibited a slightly higher ε phase peak intensity than that of the phase. In the CS and SML alloys, the average crystallite sizes of the nano-sized CrC carbide were 21.6 and 19.3 nm, respectively. The SML alloy showed higher concentrations of Cr and Mo in the grain boundaries than the other two alloys. The SML alloy showed significantly higher Co and Mo ion releases (p < 0.001) and significantly lower cell viability (p < 0.05) than the CS and SM alloys. The combined results of this study suggest that the three soft milled Co-Cr alloys had different crystal and microstructures and, as a result, different levels of biocompatibility.
Topics: Alloys; Animals; Chromium; Chromium Alloys; Cobalt; Dental Alloys; Materials Testing; Mice; Molybdenum; Spectrometry, X-Ray Emission
PubMed: 33715723
DOI: 10.1166/jnn.2021.19170 -
Journal of the Mechanical Behavior of... Oct 2023The present work describes green-mediated copper oxide nanoparticles as a potential corrosion inhibitor for the dental alloy Ti-6Al-4V. The salt of copper was reduced to...
The present work describes green-mediated copper oxide nanoparticles as a potential corrosion inhibitor for the dental alloy Ti-6Al-4V. The salt of copper was reduced to metal nanoparticles using Murraya koenigii leaves, which helps with the agglomeration and nanocluster formation through a reduction mechanism. The current synthesis is a single-step process and is cost-effective. The synthesized nanoparticle was characterized using UV, FTIR, XRD, Zeta potential and Particle size analyzer, SEM, and EDX. The particles were then electrodeposited on Ti-6Al-4V alloy, and the corrosion resistivity in the dental medium was analyzed using Electrochemical parameters such as Corrosion current, Corrosion potential, and anodic and cathodic intercepts through the Tafel and Nyquist plots. The synthesized nanoparticles showed characteristic absorbance at 359 nm. FTIR peaks confirm the phytochemical constituents present in the Murraya koenigii that accounts for the formation of nanoparticles. The XRD predicts the crystalline nature, which is further studied using SEM and EDX. The Zeta potential and Particle size analyzer confirms the negative-negative interactive nature of the synthesized CuO NPs. The NPs showed explicit corrosion inhibition properties with an overall inhibition efficiency of 58.15% and 25.6%, respectively. The study confirms the advantage of using Copper Oxide nanoparticles as a potential coating agent in dental implant alloys in increasing its corrosion efficiency.
Topics: Corrosion; Copper; Murraya; Metal Nanoparticles; Alloys; Dental Alloys; Oxides
PubMed: 37643540
DOI: 10.1016/j.jmbbm.2023.106080 -
Journal of Oral Science 2022This study investigated whether additive manufactured (AM) surfaces inhibit accumulation of bacterial biofilm on the surfaces of Ti-6Al-4V alloy dental implants....
PURPOSE
This study investigated whether additive manufactured (AM) surfaces inhibit accumulation of bacterial biofilm on the surfaces of Ti-6Al-4V alloy dental implants. Bacterial biofilms are thought to cause peri-implant disease, which develops in mucosa surrounding titanium (Ti) and Ti alloy dental implants and can lead to bone loss and implant failure.
METHODS
Accumulation of a Streptococcus mutans (ATCC 25175) biofilm on Ti-6Al-4V alloy was compared in relation to fabrication method, ie, AM using electron beam melting (EBM) or laser beam melting (LBM). Conventional lost-wax casting was used as positive control, and Teflon was used as negative control. Biofilm accumulation on the alloys and negative control (each n = 10) was conducted at 37°C under anaerobic conditions. After 4 h, the number of metabolically active S. mutans bacteria adhering to the alloy was determined with a bioluminescence assay.
RESULTS
The quantitative roughness values of the specimens, before exposure to bacteria, ranked EBM > LBM > cast > Teflon.
CONCLUSION
The amount of biofilm accumulation on the investigated AM metals and cast metal controls did not significantly differ.
Topics: Alloys; Biofilms; Dental Alloys; Titanium
PubMed: 35370181
DOI: 10.2334/josnusd.21-0521 -
Bundesgesundheitsblatt,... Jul 2021Dental amalgam has been successfully used for the restoration of carious lesions for more than 180 years. It is clinically characterized by high longevity and low... (Review)
Review
Dental amalgam has been successfully used for the restoration of carious lesions for more than 180 years. It is clinically characterized by high longevity and low technique sensitivity. For decades, dental amalgam has been discussed in the public, especially due to its roughly 50% mercury content. Since the Minamata Convention was published in 2013 with the primary goal of reducing the anthropogenic mercury release into the environment, the previously muted amalgam discussion has received fresh impetus. Another considerable disadvantage of amalgam is its silver/greyish color, which simply no longer matches patients' esthetic demands.The present paper describes the basic problems with amalgam against the background of multiple biological, clinical, and health policy factors. Possible consequences of the Minamata Convention concerning legal regulations as well as the use of dental biomaterials and therefore also relating to the future national healthcare system are discussed. Finally, possible amalgam alternatives and the urgent need for biomedical research towards restorative dentistry are presented, embedded into the crucial question of whether we are actually conducting the correct debate.
Topics: Dental Amalgam; Germany; Health Policy; Humans; Mercury
PubMed: 34143251
DOI: 10.1007/s00103-021-03355-4 -
The Journal of Prosthetic Dentistry May 2022The marginal and internal adaptation of a fixed dental prosthesis depends on a variety of factors, finish line designs being one of them. A clear consensus as to which... (Meta-Analysis)
Meta-Analysis Review
Effect of different finish line preparations on the marginal and internal adaptation of cobalt-chromium metal alloy copings fabricated by using CAD-CAM technology: A systematic review and meta-analysis.
STATEMENT OF PROBLEM
The marginal and internal adaptation of a fixed dental prosthesis depends on a variety of factors, finish line designs being one of them. A clear consensus as to which finish line design can provide a better marginal and internal adaptation with respect to cobalt-chromium metal alloy copings fabricated by using computer-aided design and computer-aided manufacturing (CAD-CAM) technology is lacking.
PURPOSE
The purpose of this systematic review and meta-analysis was to evaluate the effect of different finish line preparations on the marginal and internal adaptation of cobalt-chromium metal alloy copings fabricated by using CAD-CAM technology.
MATERIAL AND METHODS
Electronic (PubMed, Cochrane, EBSCOhost, and Google Scholar) and manual searches were conducted for articles published from January 2010 to December 2020 to identify relevant studies evaluating the effect of different finish line preparations (chamfer, deep chamfer, shoulder, rounded shoulder) on the marginal and internal adaptation of cobalt-chromium metal alloy copings fabricated by using CAD-CAM technology.
RESULTS
A total of 573 articles were obtained via electronic search, and 10 articles were obtained through manual search, of which 24 in vitro studies were selected after title, abstract, and full-text screening and were included for both qualitative and quantitative analyses. The marginal adaptation was evaluated under the parameters of marginal gap, absolute marginal discrepancy, and vertical marginal discrepancy, whereas internal adaptation was evaluated under the parameters of internal gap, cervical discrepancy, axial discrepancy, and occlusal discrepancy. The methods of CAD-CAM fabrication (direct metal laser sintering, hard milling, and soft milling) were considered under the subgroup analysis.
CONCLUSIONS
An overall better marginal and internal adaptation was observed with shoulder and rounded shoulder finish line designs when CAD-CAM methods were used for coping fabrication. Marginal and internal adaptation in chamfer and deep chamfer finish line designs showed better results with soft milling and direct metal laser sintering methods, whereas shoulder finish line showed better results with hard milling.
Topics: Adaptation, Psychological; Chromium; Chromium Alloys; Cobalt; Computer-Aided Design; Crowns; Dental Marginal Adaptation; Dental Prosthesis Design
PubMed: 34716012
DOI: 10.1016/j.prosdent.2021.06.030 -
The cytotoxic and oxidative effects of restorative materials in cultured human gingival fibroblasts.Drug and Chemical Toxicology Sep 2021The aim of this study was to evaluate the cytotoxic and oxidative effects of the most commonly used dental restorative materials on human gingival fibroblast cells... (Comparative Study)
Comparative Study
The aim of this study was to evaluate the cytotoxic and oxidative effects of the most commonly used dental restorative materials on human gingival fibroblast cells (HGFCs). HGFCs were obtained from healthy individuals. The tested restorative materials were a microhybrid resin based composite, a compomer resin, a glass ionomer cement, and an amalgam alloy. One hundred eight cylindirical samples, 10 mm in diameter and 2 mm in height, were prepared according to ISO 10993-12:2002 specifications ( = 9 in the tested subgroups). Freshly prepared and aged samples in artificial saliva at 37 °C (7 and 21 d) were placed into well plates and incubated. Wells without dental materials were constituted as the control group. After 72 h incubation period, cytotoxicity was determined using the neutral red (NR) assay. Oxidative alterations were assessed using total antioxidant capacity (TAC) and total oxidant status (TOS) assay kits. Data were analyzed using the ANOVA and LSD post hoc tests. All tested materials led to significant decreases in the cell viability rates (33-73%) compared to the control group. Glass ionomer and resin composite were found to be more cytotoxic than amalgam alloy and compomer. The highest TAC level was observed in glass ionomer after seven-day aging and these changes prevented an increase in TOS levels. Increases in TAC levels after seven-day aging in all groups exhibited significant differences with freshly prepared samples ( < 0.05). In all material groups, TOS levels of freshly prepared samples differed statistically and significantly from samples aged for 7 and 21 d ( < 0.05). The data obtained suggested that all the tested materials exhibited cytotoxic and pro-oxidant features. Freshly prepared samples caused higher TOS levels. However, oxidant status induced by materials decreased over time.
Topics: Cells, Cultured; Compomers; Composite Resins; Dental Alloys; Dental Amalgam; Dental Cements; Fibroblasts; Gingiva; Glass Ionomer Cements; Humans; Materials Testing; Oxidative Stress; Saliva; Time Factors
PubMed: 31146597
DOI: 10.1080/01480545.2019.1620265 -
International Endodontic Journal Apr 2023To compare design, metallurgy and mechanical performance of the ProTaper (PT) Ultimate system with instruments of similar dimensions from the ProGlider, PT Gold and PT...
AIM
To compare design, metallurgy and mechanical performance of the ProTaper (PT) Ultimate system with instruments of similar dimensions from the ProGlider, PT Gold and PT Universal systems.
METHODOLOGY
New PT Ultimate instruments (n = 248) were compared with instruments of similar dimensions from ProGlider (n = 31), PT Gold (n = 155) and PT Universal (n = 155) systems regarding their number of spirals, helical angle, blade symmetry, tip geometry, surface finishing, nickel/titanium ratio, phase transformation temperatures and mechanical performance. One-way anova and nonparametric Mood's median tests were used for statistical comparison (α = 5%).
RESULTS
All instruments had symmetrical blades without radial lands or flat sides, similar surface finishing and an almost equiatomic nickel/titanium ratio, whilst the number of spirals, helical angles and the tip geometry were different. PT Ultimate instruments showed 3 distinct heat treatments that matched with the colour of their metal wire. Slider and ProGlider instruments had similar R-phase start (Rs) and R-phase finish (Rf) temperatures. SX, F1, F2, F3 and Shaper instruments showed equivalent heat treatments (Rs ~45.6°C and Rf ~28.3°C) that were similar to their PT Gold counterparts (Rs ~47.9°C and Rf ~28.2°C), but completely distinct to the PT Universal ones (Rs ~16.2°C and Rf ~-18.2°C). Amongst the PT Ultimate instruments, the lowest maximum torques were observed in the SX (0.44 N cm), Slider (0.45 N cm) and Shaper (0.60 N cm) instruments, whilst the highest was noted in the FXL (4.90 N cm). PT Ultimate Slider and ProGlider had similar torsional (~0.40 N cm) and bending loads (~145.0 gf) (p = 1.000), whilst the other PT Ultimate instruments showed statistically significantly lower maximum torque, higher angle of rotation and lower bending load (higher flexibility) than their counterparts of the PT Universal and PT Gold systems.
CONCLUSIONS
The PT Ultimate system comprises instruments with 3 distinct heat treatments that showed similar phase transformation temperatures to their heat-treated analogues. PT Ultimate instruments presented lower torsional strength and superior flexibility than their counterparts, whilst maximum torque, angle of rotation and bending loads progressively increased with their sizes.
Topics: Titanium; Nickel; Hot Temperature; Equipment Failure; Materials Testing; Dental Alloys; Root Canal Preparation; Equipment Design; Torsion, Mechanical
PubMed: 36508297
DOI: 10.1111/iej.13880 -
Dental Materials Journal Jun 2020The aim of this study was to construct a Ti-Nb-Cu ternary phase diagram that plays the role of a map for developing new titanium alloys with excellent machinability and...
The aim of this study was to construct a Ti-Nb-Cu ternary phase diagram that plays the role of a map for developing new titanium alloys with excellent machinability and mechanical properties. Fifteen experimental Ti-Nb-Cu ternary alloys composed of Ti-5-30%Nb-2-20%Cu were designed, and ingots made using Ar-arc melting furnace before casting to generate specimen. The alloy castings were evaluated in terms of their microstructures and alloy phases. A Ti-Nb-TiCu pseudo-ternary phase diagram was constructed using X-ray diffractmetry results. Three alloy phases (α-Ti, β-Ti and TiCu) were established within the specimen. Furthermore, the prescence of two-phase coexistence regions (α+TiCu, α+β and β+TiCu), and three-phase coexistence region (α+β+TiCu) was noted. The findings obtained through microstructural observation corresponded well with the constructed phase diagram.
Topics: Alloys; Dental Alloys; Titanium; X-Ray Diffraction
PubMed: 31969544
DOI: 10.4012/dmj.2018-394 -
Journal of Prosthodontics : Official... Feb 2023To evaluate and compare the shear bond strength (SBS) of composite veneering material to polyetherketoneketone (PEKK), polyetheretherketone (PEEK), zirconia (YZ), and...
PURPOSE
To evaluate and compare the shear bond strength (SBS) of composite veneering material to polyetherketoneketone (PEKK), polyetheretherketone (PEEK), zirconia (YZ), and nickel-chromium alloy (NiCr) substructure restorative materials.
MATERIALS AND METHODS
Forty samples (12 × 2 mm) were prepared from four materials: PEKK, PEEK, zirconia, and NiCr alloy (n = 10). The Vickers hardness was evaluated before preparing the surface for bonding by shot-blasting using 110 μm Al O particles. The surface roughness (Ra) of each sample was determined using a noncontact optical profilometer. The veneering resin was bonded onto each sample following primer application. The prepared samples were then subjected to an SBS test using a universal testing machine at 0.5 mm/min crosshead speed. Failure modes and surface topography following debonding were assessed. The data were statistically analyzed using ANOVA and Tukey's post-hoc comparison test (p < 0.05). RESULTS: The highest and lowest mean surface roughness was observed in PEEK (3.45 ±0.13 μm) and NiCr (1.87 ±0.07 μm) materials, respectively. A significant difference in roughness values was observed between the materials except for NiCr and YZ (p = 0.547). Concerning SBS, PEEK and NiCr exhibited the highest (16.23 ±0.96 MPa) and lowest (10.1 ±0.63 MPa) values. The mean difference in SBS indicated a statistically significant difference between the material groups (p < 0.01).
CONCLUSIONS
PEKK materials demonstrated significantly lower SBS than PEEK and significantly higher SBS values than conventional zirconia and alloy materials. A positive and significant correlation between mean roughness and SBS was observed, but the causality could be either intrinsic to the material or the roughness.
Topics: Composite Resins; Dental Bonding; Resin Cements; Dental Materials; Chromium Alloys; Polyethylene Glycols; Ketones; Materials Testing; Surface Properties; Shear Strength; Dental Stress Analysis
PubMed: 35340086
DOI: 10.1111/jopr.13511