Porcelain Firing Research Articles

Was bone used in the glaze of the ancient Qiong kilns for the production of tang dynasty opaque glaze celadon?

Being an important source of primary celadon in ancient China, the Qiong kiln is one of the few kilns that can skillfully produce opaque glaze celadon, which is of great significance in the history of Chinese ceramics. In this study, the chemical composition, microstructure, and crystalline phase of sixteen pieces of opaque glaze celadon excavated from the site of Qiong kiln Shifangtang dated at the Tang Dynasty were investigated by using ultra depth of field microscopy, scanning electron microscopy, energy spectrometry, and micro confocal Raman spectrometry. The findings indicate that Fe is the predominant coloring element in the ceramic glaze, and Cu is sometimes a secondary coloring element. During porcelain firing, washed plant ash was used to increase the phosphorus content of the glaze, while some wares incorporated animal ashes as a flux to improve glaze emulsification.

Energy-exergy analysis of tunnel type glaze kiln used in porcelain firing

Energy-exergy analysis of tunnel type glaze kiln used in porcelain firing

Determination and interpretation of firing temperature in ancient porcelain utilizing thermal expansion analysis

This study utilizes a multidisciplinary approach, combining simulation experiments, thermal expansion analysis, XRD, SEM, and physical property assessments to investigate the firing temperature in illitic-kaolinitic porcelain. Our findings indicate that the accuracy of the thermal expansion method depends on both the actual firing temperature and dwell time. When dwell time is uncertain, the method provides a range of possible actual firing temperatures, differing by approximately 100 °C. Remarkably, as the porcelain body nears full vitrification, the determined firing temperature tends to be notably higher. A critical analysis of previous research suggests potential overestimation of ancient kiln temperatures. Additionally, our study highlights the usefulness of bulk density, water absorption, porosity, and mullite content in determining dwell time. Overall, our research offers new insights into ancient porcelain firing processes.

Influence of various fabrication techniques and porcelain firing on the accuracy of metal-ceramic crowns

BackgroundThe fit of a metal-ceramic restoration is essential to its long-term durability. Regarding marginal and internal fit, there is not enough information about the technologies used in the production of metal-ceramic restorations. The aim of this in vitro study is to compare, both before and after porcelain firing, the marginal, axial, axio-occlusal, and occlusal fit of metal-ceramic restorations manufactured using casting, additive or subtractive computer-aided design, and computer-aided manufacturing techniques (CAD/CAM).MethodsCAD/CAM were used to create 50 prepared maxillary first molar-shaped Co-Cr die models, which were randomly divided into 5 groups (n = 10). Cobalt-chrome copings were produced by casting (C), hard metal milling (HM), soft metal milling (SM), selective laser melting (SLM), and selective laser sintering (SLS) techniques. Before and after porcelain firing, discrepancies of the copings were measured using the silicone replica technique. The data obtained by measurements with a stereomicroscope at x80 magnification were analyzed statistically in the SPSS program. The ROBUST three-way analysis of variance (ANOVA) method was used to compare the discrepancy values.ResultsThere were statistically significant differences among fabrication methods (P < .001). The HM method showed the highest discrepancy (90.1 μm), and the C (63 μm) method showed the lowest discrepancy in terms of the die model- crown fit. The C, SLS, and SM methods (63 μm; 61.6 μm; 67.7 μm) were statistically similar (P > .001). The highest discrepancy was observed on the occlusal area (87.1 μm), and the lowest discrepancy was observed on the axial area (47.7 μm) of the coping. Porcelain firing had a decrease in the discrepancy values (P = .001).ConclusionAll CAD/CAM techniques are appropriate for clinical use; selective laser sintering and soft milling can be the more recommended methods for the compatibility of metal-porcelain restorations, as they have lower discrepancy values than the SLM and HM methods.

Ni–Cr dental alloys - porcelain firing impact on corrosion properties and surface characteristics

Biocompatibility is a critical aspect of the use of materials in the human body. The use of base metal alloys in dentistry is primarily regulated by health and safety standards set by regulatory authorities in various countries. The porcelain-fused-to-metal (PFM) process applied to Ni-Cr dental alloys can alter their properties, particularly in terms of corrosion and surface characteristics. This study aimed to assess the effect of the heat processing used for dental porcelain firing on these properties. The two casted alloys: Ceramic N and Ivoclar Vivadent 4all, used in the study were characterized by analyzing the microstructure by scanning electron microscopy (SEM), composition with energy dispersive x-ray spectroscopy (EDS), hardness, surface profile and electrochemical corrosion resistance (Ecorr, jcorr, polarization curve, Ebr and electrochemical impedance spectroscopy (EIS) results), as well as ions release before and after the simulated porcelain firing. Based on the conducted research the following conclusions can be drawn: Analyzes of the material characteristics before and after the simulation showed that the discussed process, although it does not cause the formation of chemical impurities on the surface of the alloys, results in changes in the chemical composition and structure of surface oxides, increases roughness and reduces hardness. The results of the corrosion examinations showed a deterioration in anti-corrosion properties after the simulation. The statistically significant decrease in corrosion resistance may result from the increased heterogeneity of the surface oxide layers and partial changes in their composition.

Impact of Porcelain Firing Cycling on the Microstructure and Mechanical Properties of Selective Laser-Melted Co-Cr-Mo-W Dental Alloys

Impact of Porcelain Firing Cycling on the Microstructure and Mechanical Properties of Selective Laser-Melted Co-Cr-Mo-W Dental Alloys

Marginal fit of 3-unit implant-supported fixed partial dentures: Influence of pattern fabrication method and repeated porcelain firings.

Marginal fit significantly impacts the long-term success of dental restorations. Different pattern fabrication methods, including hand-waxing, milling, or 3D printing, may affect restorations accuracy. The effect of porcelain firing cycles on the marginal fit of metal-ceramic restorations remains controversial, with conflicting findings across studies. The aim was to evaluate the potential effects of multiple porcelain firings (3, 5, 7 cycles) as well as pattern fabrication method (conventional hand-waxing, milling, and 3D printing) on the marginal adaptation of 3-unit implant-supported metal-ceramic fixed partial dentures. It was hypothesized that neither the wax pattern fabrication method nor repeated ceramic firings would significantly affect the marginal adaptation of metal-ceramic crowns. In this in-vitro study, 30 Cobalt-Chromium alloy frameworks were fabricated based on pattern made through three techniques: conventional hand-waxing, CAD-CAM milling, and CAD-CAM 3D printing (n = 10 per group). Sixteen locations were marked on each abutment to measure the vertical marginal gap at four stages: before porcelain veneering and after 3, 5, and 7 firing cycles. The vertical marginal gap was measured using direct microscopic technique at ×80 magnification. Mean vertical marginal gap values were calculated and two-way ANOVA and Tukey's post hoc tests were used for inter-group comparisons (α = 0.05). The 3D printing group showed significantly lower (P<0.001) mean vertical marginal gaps (60-76 μm) compared to the milling (77-115 μm) and conventional hand-waxing (102-110 μm) groups. The milling group exhibited a significant vertical gap increase after 3 firing cycles (P<0.001); while the conventional (P = 0.429) and 3D printing groups (P = 0.501) showed no significant changes after 7 firing cycles. Notably, the vertical marginal gap in all groups remained below the clinically acceptable threshold of 120 μm. CAD-CAM 3D printing provided superior marginal fit compared to CAD-CAM milling and conventional hand-wax pattern fabrication methods. The impact of porcelain firing on the mean marginal gap was significant only in the milling group. All three fabrication techniques yielded clinically acceptable vertical marginal adaptation after repeated firings. Additive manufacturing holds promise to produce precise implant-supported prostheses.

SINTERING PROCESSES, PHASE AND STRUCTURE FORMATION AND PROPERTIES OF ELECTRICAL PORCELAIN WITH THE USE OF MARSHALLIT AND WOLLASTONITE ADDITIVES

The effect of marshallite upon its complete replacement of quartz and wollastonite additions (2.0 wt.%) on the sintering and phase formation processes, as well as the structure and properties of insulation porcelain was studied. The object of study is insulation porcelain of typical component composition (kaolin, soft clay, feldspar, quartz sand). It has been established that the processes of melting and sintering at firing of the investigated porcelain compositions are not equilibrial. The formation of ternary eutectics fusions of the R2O-Al2O3-SiO2 systems at temperatures of 985 and 1050 °C in amounts of 45–60% does not occur. The formation of a fusion during firing of ceramics occurs due to partial binary eutectics “white feldspar-earth silicon” and “orthoclase feldspar-earth silicon” during the interaction of feldspar with silica-containing components (990–1060 °C). This is due to the fact that primary mullite is formed at temperatures of its stable state above 1200 °C. The actual processes of fusion formation during porcelain firing are not equilibrium. Recrystallization of mullite occurs due to the dissolution of primary mullite in the fusion, followed by crystallization of acicular mullite. Replacing of quartz sand with marshallite leads to a decrease in the temperatures of earth silicon with feldspar interaction and the formation of a primary fusion, which results in a decrease in the ceramics firing temperature by 70° from 1340 to 1270 °C. The addition of wollastonite – CaSiO3 (2 %wt.) intensifies the process of primary mullite dissolution and crystallization of acicular mullite. The length of the mullite needles increases from 2–3 μm up to 7–10 μm, the mullite needles form aggregates, which provides an increase in the bending strength of porcelain by 36% up to 80 MPa. For citation: Vereshchagin V.I., Kurbanbayev M.Ye., Yessimov B.O., Root L.O., Mogilevskaya N.V. Sintering processes, phase and structure formation and properties of electrical porcelain with the use of marshallit and wollastonite additives. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 5. P. 87-98. DOI: 10.6060/ivkkt.20246705.6960.

The effect of repeated porcelain firings on the marginal fit of millable and conventional casting alloys.

The durability of dental restorations is highly determined by an accurate marginal fit, which is in turn affected by the high temperature of porcelain firing. Information is inadequate about the marginal adaptation of metal-ceramic restorations fabricated by soft metal milling technologies after repeated firings. This study aimed to compare the effect of repeated ceramic firings on the marginal fit of copings fabricated from cobalt-chromium through soft metal milling and a conventional nickel-chromium casting alloy. A single standard brass die was designed, machined, and scanned, based on which, 20 frameworks were designed and fabricated through either soft metal milling or conventional casting (n = 10 per group) and porcelain veneered. The vertical marginal fit of the metal copings was measured after 3, 5, and 7 firing cycles by using a digital microscope on 16 points around the finish line of the metal die at ×80 magnification. The data were analyzed through repeated measures ANOVA and independent t-test (α = 0.05). The marginal fit of neither metal group was significantly affected by the number of firing cycles (P = 0.747). However, the marginal discrepancy was statistically lower in the soft metal milling group than that in the casting group (P<0.001). Repeated porcelain firings did not significantly affect the marginal fit of either alloy and remained within the clinically acceptable range after firings. However, the milled alloy had superior marginal fit regardless of the number of firing cycles.

Simulating porcelain firing effect on the structure, corrosion and mechanical properties of Co–Cr–Mo dental alloy fabricated by soft milling

This study aims at evaluating the effect of simulating porcelain firing on the microstructure, corrosion behavior and mechanical properties of a Co–Cr–Mo alloy fabricated by Metal Soft Milling (MSM). Two groups of Co-28Cr-5Mo specimens (25 × 20 × 3 mm) were prepared by MSM: The as-sintered (AS) specimens and the post-fired (PF) specimens that were subjected to 5 simulating porcelain firing cycles without applying the ceramic mass onto their surface. Phase identification by X-ray Diffraction (XRD), microstructure examination by optical microscopy and Scanning Electron Microscopy combined with Energy-Dispersive X-ray Spectroscopy (SEM/EDX), corrosion testing by cyclic polarization and chronoamperometry in simulated body fluid (SBF), the latter test accompanied by Cr3+ and Cr6+ detection in the electrolyte through the 1.5-diphenylcarbazide (DPC) method and UV/visible spectrophotometry, and mechanical testing by micro-/nano-indentation were conducted to evaluate the effect of the post-firing cycles on the properties of Co–Cr–Mo. The results were statistically analyzed by the t test (p < 0.05: statistically significant). All specimens had a mixed γ-fcc and ε-hcp cobalt-based microstructure with a dispersion of pores filled with SiO2 and a fine M23C6 intergranular presence. PF led to an increase in the ε-Co content and slight grain coarsening. Both AS and PF alloys showed high resistance to general and localized corrosion, whereas neither Cr6+ nor Cr3+ were detected during the passivity-breakdown stage. PF improved the mechanical properties of the AS-alloy, especially the indentation modulus and true hardness (statistically significant differences: p = 0.0009 and 0.006, respectively). MSM and MSM/simulating-porcelain firing have been proven trustworthy fabrication methods of Co–Cr–Mo substrates for metal-ceramic prostheses. Moreover, the post-firing cycles improve the mechanical behavior of Co–Cr–Mo, which is vital under the dynamically changing loads in the oral cavity, whereas they do not degrade the corrosion performance.

Development of Cordierite Based Carrier Refractory Sagar Bodies for Bone Porcelain Firing Process

During the firing process of porcelain tableware; Biscuit firing takes place at low temperatures (980-1000°C), while glazed firing takes place at high temperatures (1250-1280°C for soft porcelain, 1350-1380°C for hard porcelain). Biscuit firing in bone porcelain products, which is in the soft porcelain class, is done at higher temperatures than glazed firings. Due to the presence of bone ash in the Bone China recipe formulation, it causes the bodies to undergo vitrification in a narrow range and thus the final product to deform during sintering. Bone porcelain products are fired on carrier refractories called sagar so that they do not deform during sintering. Sagars are designed to support that model for each product model and do not shrink or deform during firing thanks to its low thermal expansion coefficient. In this study, a refractory body with a porous structure with the code of "PS1-Std" was developed by performing the characterization analyzes of refractory products with different technical properties supplied from different companies. In order to improve the mechanical properties by changing the ratios of talc, alumina, quartz and zircon in the recipe composition; A refractory product containing 8.47% zircon in its recipe composition and containing indialite, corundum, mullite, quartz and zircon phases after sintering has been developed. The microstructure images of the developed refractory product were examined with the support of SEM analysis. It has been observed that refractory products obtained as a result of recipe development studies offer a 10% longer service life than equivalent refractory products.

Fundamental Properties and Clinical Application of 3D-Printed Bioglass Porcelain Fused to Metal Dental Restoration.

The purpose of this study is to evaluate the mechanical properties and clinical fitness of 3D-printed bioglass porcelain fused to metal (PFM) dental crowns. To evaluate the mechanical properties, tensile strength, Vickers microhardness, shear bond strength, and surface roughness tests of the SLM printed Co-Cr alloy was conducted. A right mandibular 1st molar tooth was prepared for a single dental crown (n = 10). For a three-unit metal crown and bridge, the right mandibular first premolar and first molar were prepared. Bioglass porcelain was fired to fabricate PFM dental restorations. A clinical gap was observed and measured during each of the four times porcelain was fired. A statistical analysis was conducted. The SLM technique showed the largest statistically significant tensile strength and a 0.2% yield strength value. The milling technique had the lowest statistically significant compressive strength value. The shear bond strength and surface roughness showed no statistically significant difference between the fabricated method. There was a statistically significant change in marginal discrepancy according to the porcelain firing step. The casting technique showed the greatest statistically significant margin discrepancy value. The SLM method showed better fitness than the traditional casting method and showed better mechanical properties as a dental material.

Effects of repetitive firings on mechanical, optical, and phase formation changes of ceramic materials

Statement of problemStudies are sparse on how rapid heating and cooling negatively affect optical properties, including color and transparency, and mechanical properties, including hardness and durability, that affect esthetics and shorten the clinical usage period of the ceramics. PurposeThe purpose of this in vitro study was to determine the effects of repeated firing on the color difference, mechanical properties, and phase formation of different ceramic materials. Material and methodsA total of 160 disks (12×1.35 mm) were produced from 4 different ceramic materials: lithium disilicate glass-ceramic, zirconia-reinforced lithium silicate ceramic, zirconia core, and monolithic zirconia. Specimens from all groups were divided into 4 groups (n=10) with a different number of veneer porcelain firings (1 to 4) by simple randomization. After the firings, color measurement, X-ray diffraction analysis, environmental scanning electron micrograph analysis, surface roughness evaluation, Vickers hardness evaluation, and biaxial flexural strength tests were performed. Data were analyzed with analysis of variance (2-way ANOVA) (α=.05). ResultsRepeated firing did not affect the flexural strength of the specimens in any of the groups (P>.05), while the color, surface roughness, and surface hardness were significantly affected (P<.05). The specimens fired 4 times showed the highest mean Vickers hardness and ΔE00 values but the lowest mean surface roughness values. Zirconia core specimens showed the highest mean ΔE00 and flexural strength values, and lithium disilicate glass-ceramic specimens had the highest mean Vickers hardness values. ConclusionsThe increase in the number of firings affected the color, mechanical properties, and phase formation of the specimens; this change differed according to the ceramic tested.

Effects of posttreatment on the metal-ceramic bond properties of selective-laser-melted Co-Cr dental alloy—Part 2: Heat treatment after porcelain firing

Statement of problemThe selective laser melting (SLM) technique has been a promising method of fabricating Co-Cr metal-ceramic restorations; however, the lower metal-ceramic bond properties of SLM Co-Cr restorations have become a major issue in clinical use. PurposeThe purpose of this in vitro study was to propose and verify a method of improving the metal-ceramic bond properties of SLM Co-Cr alloy with heat treatment after porcelain firing (PH). Material and methodsForty-eight (25×3×0.5 mm) Co-Cr specimens, divided into 6 groups (Control group [CG]; 550 °C; 650 °C; 750 °C; 850 °C; 950 °C) according to PH temperatures, were prepared by using SLM techniques. The 3-point bend tests were performed to evaluate the metal-ceramic bond strengths; subsequently, the fracture feature was assessed by using a digital camera and scanning electron microscope (SEM) coupled with an energy-dispersive X-ray spectroscopy (EDS) detector, to determine the area fraction of adherence porcelain (AFAP). The interface morphologies and element distribution were determined with SEM/EDS detectors. Phase identification and quantification were examined with an X-ray diffractometer (XRD). A 1-way ANOVA and the Tukey honestly significant difference tests were used to analyze bond strengths and AFAP values (α=.05). ResultsThe bond strengths were 35.33 ±1.25 MPa for the CG group, 34.53 ±3.20 MPa for the 550 °C group, 38.20 ±2.60 MPa for the 650 °C group, 42.85 ±2.31 MPa for the 750 °C group, 33.28 ±3.85 MPa for the 850 °C group, and 29.09 ±2.86 MPa for the 950 °C group. Significant differences were not observed among the CG, 550 °C, and 850 °C groups (P>.05) but were found among the other groups (P<.05). Fracture and AFAP results displayed a mixed fracture mode of adhesive and cohesive fracture. The thicknesses of native oxide films across the 6 groups were relatively close as the temperature increased, but the thickness of the diffusion layer increased as well. Excessive oxidation and massive phase transformation caused holes and microcracks to appear in the 850 °C and 950 °C groups, reducing bond strengths. XRD analysis evidenced that the phase transformation of γ→ε occurred at the interface during PH treating. ConclusionsPH treatment significantly affected the metal-ceramic bond properties of SLM Co-Cr porcelain specimens. The 750 °C-PH-treated specimens displayed higher mean bond strengths and improved fracture characteristics among the 6 groups.

INVESTIGATION OF HARDNESS AND ELASTIC MODULUS OF MILLED AND SLM Ti6Al4V ALLOY

The aim of the present paper is to investigate the hardness and elastic modulus of Ti6Al4V alloy produced by CAD/CAM milling and selective laser melting. The Vickers micro-hardness is measured, while the modulus of elasticity is determined by new developed methodology consisting of bending test and finite element analysis. It was established that the manufacturing methodlead to differences in the micro-hardness and elastic modulus of the milled and SLM samples. The measured micro-hardness of the Ti6Al4V alloy was higher for the SLM samples (396 HV) compared to the milled ones (347 HV). The values of the modulus of elasticity of Ti6Al4V alloy are 180 GPa for the milled and 120 GPa for the SLM fabricated samples. They are higher than the data given in the literature or by the manufacturers. Subsequent heat treatment with porcelain firing modes slightly decreased the micro-hardness to 322 HV for the milled and 388 HV for the SLM produced samples and had almost no effect on the modulus of elasticity for both groups.

Margin Adaptation of Zirconia and Sintron Copings before and after Firing with Two Different Types of Porcelain

Introduction: Given the surge in the restoration of infrastructures with zirconia and sintron and the use of different porcelain on them and the lack studies on marginal adaptation in different situations, this study aimed to evaluate the marginal gap before and after porcelain firing.&#x0D; Materials &amp; Methods: This cross sectional experimental laboratory research was performed in 2019 in the Transgenesis research center, Isfahan (Khorasgan) Branch, Islamic Azad University, where 40 abutments were divided into two groups of 20 with two types of substructures (zirconia and soft presintered chrome-cobalt alloy (Syntron) AmannGirrbach, Koblach, Austria)) then ,each group was subdivided into two porcelain subgroup of ten (noritake and creation).Marginal gap was evaluated by stereomicroscope before and after porcelain firing .Data was gathered and analyzed by means of one way and two-way ANOVA (α = 0.05).&#x0D; Results: The difference observed between marginal gap in studied groups was statistically significant (p value &lt; 0.05). But marginal gap in respect to the type of porcelain did not show a significant difference between the groups (p value = 0.214). The lowest amount of change after firing with porcelain was related to the Syntron substructure group with Noritake porcelain, which was significantly different from the two zirconia frame groups (p value = 0.045), (p value = 0.006).&#x0D; Conclusion: In this research after porcelain firing, sintron showed better results compared to zirconia regardless of porcelain type.

Characterisation of heat-treated cobalt–chromium alloy fabricated by selective laser melting

The present work focuses on the stress-relief annealing (SRA) modification and porcelain firing (PF) treatment effect in biomedical Cobalt–Chromium (Co–Cr) components for dental applications components produced by the SLM process. The specimens’ phase transformation was examined by X-ray diffraction, optical microscopy, scanning and transmission electron microscopy, combined with energy dispersive X-ray spectroscopy. The corresponding mechanical properties were assessed by compression tests and Vickers hardness measurements. The matrix microstructure consisted mainly of the FCC γ phase with a small amount of the HCP-structured ϵ phase. SRA at 750°C and 950°C, followed by PF at the 930°C treatment, increased the percentage of the ϵ phase and caused the precipitation of fine carbides and intermetallic precipitates, thus improving the final mechanical properties.

Effect of firing procedures and layering thickness of porcelain on internal adaptation of zirconia cantilever resin-bonded fixed dental prostheses.

This study evaluated the influence of firing procedures and layering thickness of porcelain on internal adaptation of maxillary anterior cantilever zirconia resin-bonded fixed dental prostheses (RBFDPs). The maxillary right central incisor on a model was prepared for a single-retainer zirconia RBFDP. A total of 36 frameworks of cantilever zirconia RBFDPs were classified into three groups (CB0.5, CB1.0, and CB2.0 groups) based on the thickness of the cut-back on the facial surface (0.5 mm, 1.0 mm, and 2.0 mm, respectively). Feldspathic porcelain was layered onto the facial surface of the zirconia RBFDP frameworks. Internal space widths between the abutment tooth and the framework were measured before and after porcelain firing by a replica technique. The internal space values before and after porcelain firings were compared using the paired t-test within the same group (α = 0.05). Differences in internal space values (distortion) between before and after porcelain firing were compared using one-way analysis of variance and Tukey multiple comparison tests. For all framework designs, internal space values after porcelain firing were significantly higher than those before firing. Among all groups, the CB0.5 group showed the lowest internal distortion values for the whole measured area. The CB2.0 group showed higher distortion values than the CB1.0 group. Porcelain firing procedures negatively impacted the internal space in cantilever zirconia RBFDPs. In addition, the increased volume of layering porcelain had a negative effect on the internal distortion of maxillary anterior cantilever zirconia RBFDPs.

50 - Different Mechanical Properties of Sand Blasting on Co-Cr Alloys

The purpose of this in study was to determine the influence of the sand blasting on the microstructure and the mechanical properties of cobalt chromium alloys. Thirty Co-Cr metal substrates were fabricated according to ISO 9693-1, by Direct Melting Laser Sintering fabricating technique. One group of ten were sandblasted with 50μm Zinc oxide nanopowder, another group of ten were sandblasted with 250μm and one more group group of ten substrates were left as received without sandblasting at all. On the two fist groups a feldspathic porcelain was placed. Then the specimens were tested for metal-ceramic bond strength with 3-point bend test. The fractured specimens were observed with an optical and scanning electron microscopy in order to define the mode of failure. Also, X-ray diffraction spectroscopy was conducted to determine changes in crystalline phases after fabrication and the 3-point bend test. The first group of the 250μm gave more plasticity to the substrates and observed as more eslastic than th other two groups. The groups with the ceramic coating revealed cohesive bond strength. The metallographic analysis of the after porcelain firing, the after 3-point bend test specimens and the as-received revealed changes in microstructure. Regarding the crystallographic microstructure, the patterns had minor changes among the groups. The profilometry also indicated that the bigger the gridblasting particles made the surface of the substrates smother. The adhesion between the metal substrate and the ceramic layer is not affected by the sandblasting. All of the techniques showed similar results and the modulus of elasticity revealed that the bigger the particle of the sandblasting is the higher the mechanical properties are.

Effect of firing temperature on the interface between 3Y-TZP zirconia and porcelain.

The purpose of this study is to clarify the porcelain firing temperature conditions that give strongest bonding strength of porcelain to zirconia to manufacture all-ceramic fixed dental prostheses (FDPs) with excellent long-term stability. Opaque porcelain samples (8.0 × 3.0 × 1.2 mm) were placed in the center of zirconia plates (25.0 × 3.0 × 0.5 mm) and fired at temperatures of 950°C, 1,050°C, 1,100°C, and 1,150°C. Schwickerath crack initiation tests, elemental analyses, and morphological changes of the samples were compared. There was no difference in the bonding strength among all the groups of porcelain fired at different temperatures. Elemental analysis of Si and O2 at the interface between the zirconia and porcelain were observed in the 950°C, 1,050°C, and 1,100°C groups. No silicon was found in the 1,150°C group by elemental analysis, and the zirconia plate where the porcelain sample was placed had irregular shape changes. It is suggested that silicon is also involved in chemical bonds due to firing at high temperatures.