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Journal of Oral Science Apr 2022The purpose of this study is to clarify the porcelain firing temperature conditions that give strongest bonding strength of porcelain to zirconia to manufacture...
PURPOSE
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.
METHODS
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.
RESULTS
There was no difference in the bonding strength among all the groups of porcelain fired at different temperatures. Elemental analysis of Si and O 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.
CONCLUSION
It is suggested that silicon is also involved in chemical bonds due to firing at high temperatures.
Topics: Dental Bonding; Dental Porcelain; Dental Stress Analysis; Dental Veneers; Materials Testing; Surface Properties; Temperature; Zirconium
PubMed: 35197417
DOI: 10.2334/josnusd.21-0431 -
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 -
British Dental Journal Feb 2021
Topics: Ceramics; Dental Porcelain; Dental Veneers
PubMed: 33574519
DOI: 10.1038/s41415-021-2683-y -
Dental Materials : Official Publication... Jun 2023Feasibility investigation of natural teeth shades replication on dental prosthetics fabricated via functionally graded additive manufacturing (FGAM) using combination of...
OBJECTIVE
Feasibility investigation of natural teeth shades replication on dental prosthetics fabricated via functionally graded additive manufacturing (FGAM) using combination of feldspathic porcelain (FP) and yttrium aluminum garnet cerium (YAlOCe, YAG:Ce) as a promising esthetic restoration option.
METHODS
Color-graded feldspathic crown fabrication parameter through FGAM method was comprehensively examined from the slurry rheology, cure depth, debinding to sintering temperature. Effect of light absorbent also checked towards overcuring reaction during UV exposure by the shape comparison. Lastly, the flexural bending strength measured following ISO 6872:2015 to assure the applicability. Applying the studied parameter, natural teeth shades then imitated and investigated by alteration of FP and FP + 0.1 wt% YAG:Ce (Y-FP). Generated color across the structure captured through mobile camera, interpreted through the CIELAB coordinate and the gradation confirmed by the color differences (ΔE) calculated using CIEDE2000 formula.
RESULT
Parameter study indicated that 70 wt% of FP slurry with 3 wt% dispersant and 0.2 wt% light absorbent is favored. It produces excellent flowability in our FGAM system with less overcuring justified by edge margin reduction from 95.65° to 90.00° after UV exposure on rectangle shapes masking. The obtain structure also offers adequate flexural bending strength of 106.26 MPa (FP) and 101.36 MPa (Y-FP) after sintering at 780 °C. This validated the materials as class 2 dental prosthetics citing ISO 6872:2015. Color gradation was verified by the yellow b* value reduction (14.8 to -3.33) as it shifted from cervical to incisal area while ΔE further affirmed the differences from each segment in comparison with the FP and Y-FP.
SIGNIFICANCE
Color gradation was successfully replicated by FP and YAG:Ce composition shift via FGAM technique. This result highlights the potential of FGAM as an alternative for fabricating dental prosthetics with high efficiency and improved esthetic appeal.
Topics: Materials Testing; Esthetics, Dental; Dental Porcelain; Crowns; Temperature; Color; Ceramics
PubMed: 37088587
DOI: 10.1016/j.dental.2023.03.021 -
Journal of the Mechanical Behavior of... Dec 2021Zirconia-based dental materials are extensively used in clinical practice due to their tooth-like appearance, biofunctionality, biocompatibility, and affordability.... (Review)
Review
Zirconia-based dental materials are extensively used in clinical practice due to their tooth-like appearance, biofunctionality, biocompatibility, and affordability. However, premature clinical failures of veneering porcelains raise a concern about their integrity. Extensive studies have been performed over a decade to resolve this issue, but it is challenging to reference all information effectively. A single source identifying the significance of potential parameters on material performance has not previously been available. An evidence-based meta-narrative review technique was used to review the characteristic parameters that can affect the overall behaviour of zirconia-based materials. Keywords were chosen to assess manuscripts based on scientific coherence with this paper's research objective. Online keyword searches were carried out on ScienceDirect, PubMed, and SAGE databases for relevant published manuscripts from year 1985-2020.261 out of 3170 identified manuscripts were included. A total of 10 parameters were identified and classified into the material, manufacturing, and geometric aspects. The effect of every parameter was reviewed on the performance of the material. A discrepancy in findings was observed and is attributed to the fact that there is no standard methodology. This review acts as a single source that summarizes various parameters' contribution to zirconia-based dental materials' performance. This review facilitates manufacturing improvements by accounting for every parameter's effect on overall performance.
Topics: Dental Porcelain; Dental Veneers; Zirconium
PubMed: 34600431
DOI: 10.1016/j.jmbbm.2021.104861 -
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 -
Journal of Esthetic and Restorative... Jan 2022To review the ultrastructural characteristics of novel lithium disilicate based glass ceramics (LDC), how their manufacturing process influences their structure and... (Review)
Review
OBJECTIVE
To review the ultrastructural characteristics of novel lithium disilicate based glass ceramics (LDC), how their manufacturing process influences their structure and their clinical use.
OVERVIEW
Lithium disilicate based glass ceramic has been successfully used for indirect restorations ranging from partial tooth coverage up to tooth replacement for over 20 years. It combines esthetic and mechanical properties, unlike any other indirect material which makes it an indispensable part of esthetic and restorative dentistry. Recently, novel LDCs have been introduced to the market. Parameters for their use and their microstructure are still not been widely known. This article will review these materials and highlight with high-resolution scanning electron microscopic images their structural aspects and their resulting clinical relevance.
CONCLUSION
Restorations made from LDCs are reliable and can be predictably used only when proper guidelines and protocols during manufacturing and clinical use are followed. For novel LDCs manufacturing and long-term bonding protocols still must be established. Moreover, novel LDCs machinable blocks should be crystallized or heat-treated after milling for superior performance.
CLINICAL SIGNIFICANCE
With more and newer etchable LDC materials entering the market, clinicians and technicians need to be aware of the differences in manufacturing and the resulting microstructure to ensure a successful treatment outcome that will last.
Topics: Ceramics; Computer-Aided Design; Dental Porcelain; Materials Testing; Surface Properties
PubMed: 34995008
DOI: 10.1111/jerd.12864 -
Clinical and Experimental Dental... Dec 2020Creating a tooth-like appearance by use of dental ceramics is still a challenge. Opalescence is a unique property of dental enamel, attempted to be mimicked by dental...
OBJECTIVES
Creating a tooth-like appearance by use of dental ceramics is still a challenge. Opalescence is a unique property of dental enamel, attempted to be mimicked by dental restorative materials. This study aimed to assess the effect of ceramic thickness on opalescence.
MATERIALS AND METHODS
Twenty-four discs were fabricated of feldspathic ceramic, IPS e.max, zirconia and Enamic ceramics with 10 mm diameter and 0.5 and 1 mm thicknesses (n = 12). The opalescence of ceramic specimens was calculated by measuring the difference in yellow-blue axis (CIE ∆b*) and red-green axis (CIE ∆a*) between the transmitted and reflected spectra. One-way ANOVA was applied to compare the opalescence of different ceramic specimens with variable thicknesses at .05 level of significance.
RESULTS
The opalescence of feldspathic, IPS e.max, zirconia and Enamic ceramic specimens with 0.5 mm thickness was 1.06 ± 0.15, 3.39 ± 0.15, 1.98 ± 0.15 and 1.44 ± 0.15, respectively. By increasing the thickness to 1 mm, the opalescence of feldspathic, IPS e.max, zirconia and Enamic ceramics changed to 1.12 ± 0.15, 1.47 ± 0.15, 3.85 ± 0.15 and 2.00 ± 0.15, respectively. In all groups except for IPS e.max, the mean opalescence of 1-mm-thick specimens was higher than that of 0.5-mm-thick specimens.
CONCLUSION
Type and thickness of ceramic affect its opalescence. The opalescence of all ceramic specimens tested in this study with 0.5 and 1 mm thicknesses was lower than that of the enamel.
Topics: Ceramics; Dental Enamel; Dental Porcelain; Dental Restoration, Permanent; Humans; Iridescence; Materials Testing; Surface Properties; Zirconium
PubMed: 32902165
DOI: 10.1002/cre2.325 -
Journal of Prosthodontics : Official... Aug 2022To evaluate and compare the mechanical properties and ceramic bond of additively manufactured and milled dental zirconia materials.
PURPOSE
To evaluate and compare the mechanical properties and ceramic bond of additively manufactured and milled dental zirconia materials.
MATERIALS AND METHODS
Disc (r = 10 mm, h = 2 mm) and bar (25 4 × 1. 2 mm) shaped milled (M group) (Nacera Pearl; Doceram) and additively manufactured (AM group) (NanoParticle Jetting; XJet, Carmel 1400) zirconia specimens were prepared for 2 experimental groups. Ceramic was applied to the disc specimens (h = 4 mm, r = 6 mm) (n = 9) and their shear bond strength (SBS) was measured. The surface morphology of disc specimens was analyzed with a scanning electron microscope (SEM). The Vickers microhardness (Vh), surface roughness (Ra), and three-point flexural strength (FS) of bar specimens (n = 9) were measured. Results were statistically analyzed with Mann-Whitney U-test (α = 0.05).
RESULTS
Significant differences were found in FS and Vh values of the M and AM groups. M group (1501.4 ± 60.1 HV1) showed a significantly higher Vh value than the AM group (1169.2 ± 48.4 HV1) (p < 0.001). FS of the M group (1287.5 ± 115.2 MPa) exhibited significantly high value than the AM (1030.0 ± 29.2 Mpa) group (p < 0.001). Statistically, no significant differences were seen in SBS and Ra values of the M and AM groups.
CONCLUSION
Within the limitations of this in vitro study, the manufacturing technique affected the mechanical properties of the zirconia materials. AM zirconia material showed lower Vh and FS values than M zirconia. Additionally AM zirconia demonstrated adequate bond strength with dental ceramic.
Topics: Ceramics; Dental Bonding; Dental Porcelain; Dental Stress Analysis; Materials Testing; Pilot Projects; Shear Strength; Surface Properties; Zirconium
PubMed: 34940979
DOI: 10.1111/jopr.13472 -
Journal of Dentistry Dec 2020To establish the thresholds of chromatic perception and clinical acceptability of gingival colour according to professional category and in accordance with the...
OBJECTIVE
To establish the thresholds of chromatic perception and clinical acceptability of gingival colour according to professional category and in accordance with the perceptibility/acceptability threshold of 50:50 (colour differences that can be perceived/accepted by 50 % of the observers).
METHODS
A total of 21 different coloured samples made of pink gingiva Heraceram porcelain were used. Dentists (n = 54), dental assistants (n = 56), dental students (n = 126) and participants unrelated to dentistry (n = 116) were asked to identify pairs of samples that appeared identical. In addition, they were asked to indicate the pairs of samples whose colour they considered to be acceptable for use in a dental rehabilitation. A least squares regression was adjusted using an S-shaped curve of the equation y = exp (B0 + B1/x). The adjusted model was used to predict a colour difference value for an acceptability percentage of 50 %.
RESULTS
The threshold value for the perception of colour changes in human gingiva varies from ΔEab* 2.3 ± 0.38 units and CIEDE2000 (ΔE00) 1.5 ± 0.28units (dental students) to ΔEab* 2.7 ± 0.43 units and ΔE00 1.8 ± 0.30 units (participants unrelated to dentistry). The threshold of gingival acceptability varies from ΔEab* 2.9 ± 0.43 units and ΔE00 2.0 ± 0.31 units (dental assistants) to ΔEab* 3.6 ± 0.54 units and ΔE00 2.5 ± 0.41 units (dental students).
CONCLUSION
From the total number of samples, the average threshold of perception for the gingival chromatic space is 3.1 units for ΔEab* and 2.1 units for ΔE00. Moreover, the mean gingival acceptance threshold is 4.1 units for ΔEab* and 2.9 units for ΔE00. These thresholds are similar for all professional categories studied.
CLINICAL SIGNIFICANCE
The determination of the perception and acceptability thresholds in the gingival chromatic space are of special relevance for designing the physical shade tabs used in gingival colour guides. The results from this work will aid in selecting optimal gingival colour for patients.
Topics: Color; Color Perception; Dental Porcelain; Gingiva; Humans
PubMed: 33069771
DOI: 10.1016/j.jdent.2020.103502