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van Leeuwen CMC, Papazoglou E, van Eersel JHW, Stolwijk-Swüste JM, Post MWM. Associations between personality traits and depressive and anxiety symptoms among persons with spinal cord injury in first inpatient rehabilitation. Spinal Cord 2024; 62:178-182. [PMID: 38388760 DOI: 10.1038/s41393-024-00964-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 01/12/2024] [Accepted: 02/02/2024] [Indexed: 02/24/2024]
Abstract
STUDY DESIGN Retrospective analysis of medical records. OBJECTIVE To assess personality traits in persons with spinal cord injury (SCI) and compare these with the general population group. Moreover, to explore associations between personality traits and depressive and anxiety symptoms among persons with SCI in first inpatient rehabilitation. SETTING Specialized rehabilitation center in The Netherlands. METHODS Data were used from a routine psychological screening, administered in the first weeks of admission (N = 67). Measures included the Hospital Anxiety and Depression Scale and the Dutch Personality Questionnaire, which includes subscales measuring neuroticism, social inadequacy, rigidity, hostility, egoism, dominance, and self-esteem. Correlational and regression analyses were conducted. RESULTS Mean age of the participants was 58 (SD 17) years. The majority (63%) were male, and had a low lesion (57%). The participants scored significantly higher on dominance and lower on social inadequacy, hostility, and egoism in comparison with the general population. In the bivariate regression analyses, high neuroticism (β = 0.42 and β = 0.53) and low self-esteem (β = -0.25 and β = -0.29) were significantly associated with increased depressive and anxiety symptoms. In the hierarchical regression analyses, only high neuroticism was significantly associated with increased depressive (β = 0.42, p < 0.05) and anxiety (β = 0.55, p < 0.001) symptoms. CONCLUSIONS Personality traits are not the same between the SCI population and the general population. Assessment of personality traits early in inpatient rehabilitation can help to identify individuals at risk of mood problems and, thereby, facilitate interventions. Future research with a larger, representative SCI sample, is required to confirm these findings.
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Affiliation(s)
- Christel M C van Leeuwen
- Center of Excellence for Rehabilitation Medicine, UMC Brain Center, University Medical Centre Utrecht, Utrecht University and De Hoogstraat Rehabilitation, Utrecht, The Netherlands.
- Department of Spinal Cord Injury and Orthopedics, De Hoogstraat Rehabilitation, Utrecht, The Netherlands.
| | - Erika Papazoglou
- Center of Excellence for Rehabilitation Medicine, UMC Brain Center, University Medical Centre Utrecht, Utrecht University and De Hoogstraat Rehabilitation, Utrecht, The Netherlands
- Department of Clinical Psychology, Utrecht University, Utrecht, The Netherlands
| | | | - Janneke M Stolwijk-Swüste
- Center of Excellence for Rehabilitation Medicine, UMC Brain Center, University Medical Centre Utrecht, Utrecht University and De Hoogstraat Rehabilitation, Utrecht, The Netherlands
- Department of Spinal Cord Injury and Orthopedics, De Hoogstraat Rehabilitation, Utrecht, The Netherlands
| | - Marcel W M Post
- Center of Excellence for Rehabilitation Medicine, UMC Brain Center, University Medical Centre Utrecht, Utrecht University and De Hoogstraat Rehabilitation, Utrecht, The Netherlands
- University of Groningen, University Medical Centre Groningen, Centre for Rehabilitation, Groningen, The Netherlands
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Ntovas P, Gogolas N, Gogolas G, Mougiou E, Papazoglou E. Tooth Splinting: Implementing a 3D-printed Guide with Pre-defined Composite Resin Reservoirs: A Digital Workflow. Oper Dent 2024; 49:5-10. [PMID: 38058017 DOI: 10.2341/23-069-t] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/18/2023] [Indexed: 12/08/2023]
Abstract
The integration of digital technologies in dentistry has led to the development of various techniques to facilitate tooth splinting. In the present digital workflow, the advantages of the virtual treatment plan were combined with the versatility of the commercially available tooth splinting materials. An intraoral scanner was utilized to digitize both arches along with the patient's occlusion, eliminating the need for models from physical impressions. A template based on the virtual design of the splint was 3D-printed and served as a guide to individualize a twisted wire. The bent wire was transferred and bonded, using a 3D-printed template with pre-defined reservoirs for the composite resin. Digital technology has been implemented for tooth splinting, by fabricating a splint after its virtual design. However, the digital fabrication of the metal splints is available for limited splinting materials and the service is only provided by specific centers around the world.
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Affiliation(s)
- P Ntovas
- *Panagiotis Ntovas, DDS, MSc, scientific associate, Department of Operative Dentistry, National and Kapodistrian, University of Athens, Greece
| | - N Gogolas
- Nikolaos Gogolas, DDS, private practice, Athens, Greece
| | - G Gogolas
- George Gogolas, DDS, private practice, Athens, Greece
| | - E Mougiou
- Eleni Mougiou, DDS, private practice, Athens, Greece
| | - E Papazoglou
- Efstatios Papazoglou, DDS, MSc, PhD, Department of Operative Dentistry, National and Kapodistrian, University of Athens, Greece
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O'Leary L, Tildy B, Papazoglou E, Adcock I, Chung K, Perry M. S50 Airway Smooth Muscle Inflammation Is Controlled By Microrna-145 Targeting Of Smad3 In Copd. Thorax 2014. [DOI: 10.1136/thoraxjnl-2014-206260.56] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Kampouropoulos D, Gaintantzopoulou M, Papazoglou E, Kakaboura A. Colour matching of composite resin cements with their corresponding try-in pastes. Eur J Prosthodont Restor Dent 2014; 22:84-88. [PMID: 25134367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Two shades of four resin cements (Calibra, Clearfil Esthetic, Insure, Variolink II), in light- and dual-curing modes, were tested for colour matching with their corresponding try-in pastes, immediately after photopolymerization and after 24-hour dry and dark storage. Colour measurements were performed for 0.8 mm-thick specimens through a 0.8mm-thick ceramic plate. For each resin cement, colour differences (deltaE) were calculated between the two curing modes, and between the corresponding try-in paste, at baseline and after 24h. deltaE>0 values were detected between all resin cements and their try-in pastes, which were brand/shade/curing mode depended. The try-in pastes of the Variolink II system demonstrated the best colour matching (deltaE<2). Try-in pastes of Calibra and Insure, at both curing modes, did not match at an acceptable value, the shade of their corresponding resin cements (deltaE>3.3). Calibra presented the highest colour differences. deltaE values of the Clearfil Esthetic system immediately after photo-activation ranged between 2 and 3 units. A ceramic restoration may fail aesthetically as a result of not acceptable colour match (deltaE>3.3) between the shade of certain resin cements and their relevant try-in pastes.
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Abstract
BACKGROUND Ultraviolet (UV) irradiation is the main cause of skin photodamage; the resulting modulation of matrix metalloproteinases (MMPs) leads to collagen degradation. There is no easily accessible molecular indicator of early skin UV damage. OBJECTIVES In this study, we investigated the effects of Syk kinase on MMP expression and evaluated the sensitivity and usefulness of Syk as an early indicator of skin UV damage. METHODS Human dermal fibroblasts (HDFs) were transfected with Syk cDNA to overexpress Syk. MMP-1 expression and Syk activity were determined by Western blot after UV exposure. The effect of Syk on MMP-1 expression in HDFs was further explored by either Syk siRNA or a selective Syk inhibitor. Possible downstream molecules of Syk were also evaluated in HDFs upon UV exposure. The relationship between Syk and collagenase was further explored in vivo (MMP-13, hairless mice). RESULTS Our studies in HDFs demonstrated that both a Syk inhibitor and Syk siRNA were able to inhibit MMP-1 expression in HDFs exposed to UV and that overexpression of Syk increased MMP-1 expression and the activity of JNK kinase, but not p38 or Erk1/2 MAP kinase. UV exposure enhanced both expression and activity of Syk in HDFs. Experiments with hairless mice suggested that Syk expression is an earlier indicator of UV exposure than MMP-13 expression. CONCLUSIONS Our results demonstrate that Syk expression correlates well with increase of MMPs (MMP-1 in humans and MMP-13 in mice) in response to UV exposure. The findings suggest that Syk may be a novel target for the prevention and treatment of skin photodamage by modulating MMPs.
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Affiliation(s)
- E Papazoglou
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA 19104, USA.
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Kriete A, Papazoglou E, Edrissi B, Pais H, Pourrezaei K. Automated quantification of quantum-dot-labelled epidermal growth factor receptor internalization via multiscale image segmentation. J Microsc 2006; 222:22-7. [PMID: 16734710 DOI: 10.1111/j.1365-2818.2006.01564.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The ability to monitor epidermal growth factor receptor (EGFr) internalization specifically, and cellular protein concentrations and activation states in general, has been recently improved by the use of appropriately functionalized quantum dots (QDs), as a result of the long-lasting fluorescence, brightness and multicolour of these nanoparticles. However, important quantitative information about locational proteomics is based on the analysis of the properties of many cells and cell cultures on a per-cell basis, rather than tracking individual events within one cell. Moreover, relative positional information is often gained from traditional staining protocols of distinct cellular compartments that are prone to noise, fading and low contrast. We apply a novel multiscale image segmentation based on region growing to classify automatically objects in fixed cell preparations and to define regional zones in all cells prior to QD concentration measures. This allows rapid quantitative description of EGFr internalization as it changes with incubation time. The capabilities realizable by simultaneous application of confocal imaging and functionalized QDs in conjunction with advanced image analysis are a prerequisite for automated and multiplexed cytomics assays.
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Affiliation(s)
- A Kriete
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA 19104, USA.
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Abstract
Objective. The purpose of this study was to employ transmission electron microscopy (TEM) to investigate the microstructures of Pd-Cu-Ga and Pd-Ga dental alloys that had been permanently deformed, in order to obtain information about the deformation behavior of individual phases and changes in microstructure brought about by that deformation.Methods. Heavily deformed regions taken from fractured tensile test bars of the two alloys in the as-cast condition were prepared for TEM analysis, using mechanical grinding and polishing, ion milling, and plasma cleaning. The specimens were examined in the TEM using bright-field and dark-field diffraction contrast imaging. Selected-area and convergent-beam electron diffraction patterns were employed to analyze the structures of the phases, and standardless energy-dispersive X-ray spectrometry was used to determine their mean compositions.Results. For both alloys, tweed structures underwent permanent deformation by twinning, whereas dislocation movement occurred in the face-centered cubic (fcc) palladium solid solution matrix. A body-centered cubic (bcc) phase, previously unreported in our TEM studies and containing a high density of dislocations, was identified in the Pd-Cu-Ga alloy, while fine-scale, stress-induced precipitates were found in some regions of the fcc matrix in the Pd-Ga alloy.Significance. The present results have provided novel information about the mechanical deformation behavior of high-palladium alloys. The stress-induced precipitation in the Pd-Ga dental alloy studied may be a critical component of strengthening mechanisms.
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Affiliation(s)
- W H Guo
- Section of Restorative Dentistry, Prosthodontics and Endodontics, College of Dentistry, The Ohio State University, 305 West 12th Avenue, Mailbox #191, PO Box 182357, Columbus, OH 43210-2357, USA
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Li D, Brantley WA, Mitchell JC, Daehn GS, Monaghan P, Papazoglou E. Fatigue studies of high-palladium dental casting alloys: Part I. Fatigue limits and fracture characteristics. J Mater Sci Mater Med 2002; 13:361-367. [PMID: 15348610 DOI: 10.1023/a:1014332416832] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The fatigue limits and fracture characteristics for a Pd-Cu-Ga alloy and a Pd-Ga alloy were studied. The alloys were cast into tensile test bars with gauge diameter of 3 mm and gauge length of 15 mm, and the surfaces of the castings were neither air-abraded nor polished after removal from the investment. Specimens were prepared from all-new metal (not previously melted), a combination of 50% new metal and 50% old metal (previously melted one time) and 100% old metal. The cast bars were subjected to heat treatment simulating the complete firing cycles for dental porcelain, and fatigued in air at room temperature under uniaxial tension-compression stress at 10 Hz and a ratio of tensile stress amplitude to compressive stress amplitude (R-ratio) of -1. The alloy microstructures and fracture surfaces were examined with a scanning electron microscope (SEM). Results showed that the fatigue limits at 2 x 10(6)cycles of the Pd-Cu-Ga and Pd-Ga alloys were approximately 0.20 and 0.15 of their 0.1% yield strength (YS) in tension, respectively. The fatigue resistance for specimens from both alloys containing 50% old metal and 50% new metal was comparable to that of specimens containing all-new metal, although this decreased dramatically for Pd-Cu-Ga alloy specimens containing all-old metal. The fatigue resistance of the Pd-Cu-Ga alloy subjected to heat treatment simulating the porcelain firing cycles was not adversely affected by remnants of the original as-cast dendritic microstructure that remained in the relatively large test specimens. A longer heat treatment than recommended by the manufacturer for the porcelain firing cycles is needed to completely eliminate the as-cast dendritic structure in these specimens. The Pd-Cu-Ga alloy exhibited superior fatigue resistance to the Pd-Ga alloy, which has an equiaxed-grain microstructure and lower yield strength.
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Affiliation(s)
- D Li
- Section of Restorative Dentistry, Prosthodontics and Endodontics, College of Dentistry, The Ohio State University, Columbus, OH 43218-2357, USA
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Abstract
STATEMENT OF PROBLEM Crown fit is a prerequisite for long-term clinical success; however, crown distortion may occur during porcelain firing. The dimensional stability of some high-palladium alloys at high temperatures has been questioned. PURPOSE The purpose of this study was to use a new method to measure the distortion of copings for metal-ceramic single units of selected high-palladium alloys with compositions representative of commercial alloys. MATERIAL AND METHODS Four high-palladium alloys containing copper and 3 containing no copper were tested. A palladium-silver alloy was included for comparison, and a gold-palladium alloy served as the control. By using reference points scribed on the margin, the mesiodistal and buccolingual margin diameters of identical copings were measured with a traveling microscope at 4 stages: as-cast, oxidized, after 2 simulated opaque porcelain firings, and after 2 simulated dentin porcelain firings. The margin distortions for the various specimen groups representing combinations of alloys, stages, and measurement diameters were compared with the use of 1-way analysis of variance and a multiple range test. RESULTS Most of the high-palladium alloys had high-temperature distortions that were not significantly different from those of the control alloy. The distortions occurred principally during the oxidation cycle. The effect of mesiodistal groove reinforcement on preventing distortion was not the same for all alloys. CONCLUSION The results suggest that small observed distortions of these alloys will not produce clinical problems. Several laboratory techniques are available to counteract the distortions.
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Affiliation(s)
- E Papazoglou
- Section of Restorative Dentistry, Prosthodontics, and Endodontics, College of Dentistry, The Ohio State University, Columbus, Ohio, USA.
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Papazoglou E, Wu Q, Brantley WA, Mitchell JC, Meyrick G. Comparison of mechanical properties for equiaxed fine-grained and dendritic high-palladium alloys. J Mater Sci Mater Med 2000; 11:601-608. [PMID: 15348083 DOI: 10.1023/a:1008940510856] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Two Pd-Cu-Ga alloys and a Pd-Ga alloy were selected for study. Bars of each alloy were tested in tension for the as-cast and simulated porcelain-firing conditions, and values of mechanical properties were measured. Fracture surfaces and microstructures of axially sectioned fracture specimens were observed with the SEM. The two Pd-Cu-Ga alloys exhibited similar mechanical properties. The Pd-Ga alloy had lower strength and higher percentage elongation. Heat treatment simulating porcelain firing cycles decreased the strength of both Pd-Cu-Ga alloys and increased their ductility. However, this heat treatment did not significantly affect the mechanical properties of the Pd-Ga alloy. All three high-palladium alloys had the same modulus of elasticity. The amount of overall porosity was relatively minimal (< 1%) and not significantly different among the three alloys. However, porosity was a significant factor for UTS of one Pd-Cu-Ga alloy and the Pd-Ga alloy.
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Affiliation(s)
- E Papazoglou
- College of Dentistry, The Ohio State University, Columbus, OH, USA.
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11
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Abstract
PURPOSE The purpose of this study was to assess the effect of different high-palladium alloys on the resulting color of opaque porcelain. Three Pd-Cu-Ga alloys, Spartan Plus (S; Williams Dental Co/Division of Ivoclar North America, Amhest, NY), Liberty (B; J.F. Jelenko & Co, Armonk, NY), and Freedom Plus (F; J.F. Jelenko & Co); 4 Pd-Ga alloys, Legacy (L; J.F. Jelenko & Co), IS 85 (I; Williams Dental Co), Protocol (P; Williams Dental Co), and Legacy XT (X; J.F. Jelenko & Co); and a Pd-Ag alloy, Super Star (T; J.F. Jelenko & Co), were examined. The Au-Pd alloy Olympia (O; J.F. Jelenko & Co) served as the control. MATERIALS AND METHODS Three cast 16-mm discs, 1-mm thick, were prepared from each of the alloys. After metallurgically polishing and air-abrading, the specimens were oxidized following the manufacturer's recommendations. Shade B1 opaque porcelain (Vita-Omega; Vident, Baldwin Park, CA) was applied at a final thickness of 0.1 mm using a mold. After 2 opaque porcelain firing cycles, the surfaces were air-abraded. The colors of the specimens were measured using a colorimeter and expressed in Commission International de l'Eclairage (CIE) L*a*b* coordinates. Color differences (delta E) were determined between the control and each experimental group. Analysis of Variance and Tukey-Kramer tests were performed on the delta E data. RESULTS The 3 Pd-Cu-Ga alloys showed significantly greater (p < .01) delta E values (S = 2.8 +/- 1.1, B = 3.0 +/- 0.6, and F = 2.1 +/- 0.2) than the remaining 5 experimental groups (L = 0.7 +/- 0.5, I = 0.7 +/- 0.4, P = 0.7 +/- 0.2, X = 0.7 +/- 0.4, and T = 0.7 +/- 0.5). The directions of the significant color changes were relatively equally distributed along the L*, a*, and b* axes, and all delta L*, delta a*, and delta b* values were negative (lower value, more green and blue relative to control O). CONCLUSIONS This work suggests that a 0.1-mm-thick layer of opaque porcelain in the Pd-Cu-Ga alloys studied, did not reliably reproduce the color of porcelain.
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Affiliation(s)
- M M Stavridakis
- Ohio State University College of Dentistry, Columbus, OH, USA.
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12
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Abstract
Statement of problem. Composite has been used to modify acrylic resin denture teeth. Purpose. This in vitro investigation examined the shear bond strengths between composite and autopolymerized acrylic resin bonded to acrylic resin denture teeth. Material and methods. The surface treatments used for the denture teeth included wetting with methyl methacrylate (MMA), vinylethyl methacrylate monomer (VEMA), unfilled liquid resin, composite bonding agent, and composite color modifier. Nonhydrated and hydrated denture tooth groups were included. A commercial composite was bonded to the denture teeth. The control group consisted of autopolymerized PMMA resin bonded to the acrylic resin denture teeth, and another group consisted of polyvinylethyl methacrylate bonded to acrylic resin denture teeth. The samples were thermocycled and tested in shear. Results. Acrylic resin denture teeth prewetted with MMA and treated with unfilled resin or a bonding agent had bond strength values comparable to the control group. VEMA was not as effective in promoting the bond. Composite color modifier did not produce a significantly weaker bond between the acrylic resin teeth and added composite. No prewetting of the teeth with MMA resulted in the lowest bond strength. Mean shear bond strengths for corresponding hydrated and non-hydrated groups were not significantly different. Conclusion. Bond strength of composite-to-acrylic resin denture teeth was comparable to the bond strength of autopolymerized acrylic resin.
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Affiliation(s)
- E Papazoglou
- College of Dentistry, The Ohio State University, Columbus 43210-1241, USA.
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Abstract
PURPOSE The aim of this study was to assess distortion inherent in casting, soldering, and simulated porcelain firings of screw-retained, implant-supported three-unit fixed partial dentures (FPDs). MATERIALS AND METHODS Ten wax patterns were fabricated on a die-stone cast containing two implants, 20 mm apart from center to center. Five specimens were cast in a high-palladium alloy, exposed to simulated porcelain firings, sectioned, and then soldered with low-fusing solder. Five specimens were cast, sectioned, soldered with high-fusing solder, and then exposed to simulated porcelain firings. For each specimen, two horizontal and six vertical distances between appropriately scribed reference points were measured with a traveling microscope. Comparisons were made among the various measurements taken after wax-pattern fabrication, casting, high- and low-fusing soldering, and each porcelain firing. Data were analyzed using a repeated-measures factorial ANOVA (alpha = 0.05). RESULTS Significant difference was detected in the amount of horizontal distortion during casting (53 +/- 24 microns) and high-fusing soldering (-49 +/- 50 microns), as well as in the amount of horizontal distortion during high-fusing soldering (-49 +/- 50 microns) and low-fusing soldering (17 +/- 26 microns). However, no clinically significant difference was found in the amount of horizontal distortion during casting, low-fusing, and high-fusing soldering. The greatest amount of distortion during the simulated porcelain firings took place during the oxidizing cycle. CONCLUSIONS Soldering did not improve the casting misfit of a three-unit implant-retained FPD model. Metal-ceramic implant frameworks should be oxidized before intraoral fit evaluation.
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Affiliation(s)
- P J Zervas
- Ohio State University, College of Dentistry, Columbus 43210-1241, USA
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Abstract
STATEMENT OF PROBLEM Little information is available on the optimum technique for soldering high-palladium alloys, which have gained considerable popularity for prosthodontic applications. PURPOSE The objective of this study was to compare the flexural stress at the proportional limit of four noble dental alloy specimens soldered with torch, oven, and infrared-techniques. MATERIALS AND METHODS The high-palladium alloys studied were Legacy XT (Jelenko), Freedom Plus (Jelenko), and IS 85 (Williams/Ivoclar). A gold-palladium alloy, Olympia (Jelenko), served as the control. Thirty round bars, 18 x 3 mm, were cast from each alloy, cut in half, aligned, and joined using Olympia Pre solder (Jelenko) for the gas-oxygen torch and the infrared technique and Alboro LF solder (Jelenko) for the oven technique. Each soldered bar was subjected to three-point bending, and the maximum elastic stress or strength of the solder joint was calculated at the proportional limit. Data were analyzed by two-way ANOVA and the Ryan-Einot-Gabriel-Welsch (REGW) multiple range test at the 0.05 level of significance. RESULTS There was no significant difference between torch and oven-soldering, but both were significantly different from the infrared technique. ANOVA showed a significant difference between alloys, but this difference could not be detected with the REGW test. SEM examination of the fracture surfaces revealed grooves associated with the path of crack propagation. X-ray energy-dispersive spectroscopic analysis failed to detect copper in the solders, and there were no significant changes in the solder compositions after the melting procedures. CONCLUSIONS All three techniques can yield satisfactory solder joints in high-palladium alloys. These joints should be well-polished to achieve optimal strength.
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Affiliation(s)
- M Chaves
- College of Dentistry, Ohio State University, Columbus, USA
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Papazoglou E, Brantley WA, Johnston WM, Carr AB. Effects of dental laboratory processing variables and in vitro testing medium on the porcelain adherence of high-palladium casting alloys. J Prosthet Dent 1998; 79:514-9. [PMID: 9597603 DOI: 10.1016/s0022-3913(98)70171-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE This study assessed the effects of dental laboratory processing variables and testing medium on porcelain adherence of representative high-palladium alloys. MATERIAL AND METHODS The processing variables were recasting two and three times, porcelain stripping with hydrofluoric acid and rebuilding, and changing the recommended oxidation procedures. The testing medium was air for these four groups and the nontreatment group. In the last group, the specimens were stored and tested in artificial saliva. The metal ceramic specimens were fractured with biaxial flexure in constant strain. The area fraction of adherent porcelain (%) was calculated with a standardized spectrometric technique. A gold-palladium alloy served as the control. RESULTS Recasting without adding new alloy negatively affected some high-palladium alloys. Porcelain stripping did not cause a decrease in adherence of the tested alloys. The alternate oxidation treatment reduced significantly the porcelain adherence of the Au-Pd and one Pd-Cu-Ga alloy. Storage and testing in artificial saliva did not significantly affect the porcelain adherence of the alloys. The Au-Pd alloy exhibited the highest porcelain adherence.
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Affiliation(s)
- E Papazoglou
- Section of Restorative Dentistry, Prosthodontics and Endodontics, College of Dentistry, Ohio State University, Columbus 43210-1241, USA
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Abstract
OBJECTIVES The purpose of this study was to characterize the metal-ceramic bond of four commercial Pd-Ga alloys by two separate tests: porcelain adherence and bond failure force. A Pd-Ag alloy was the control. A secondary goal was to investigate a possible correlation between the percent porcelain retained and bond failure forces. METHODS For adherence testing, five cast plates of each alloy were air abraded and oxidized. The porcelain was applied on a circular area in the center of each plate and fractured using constant-strain flexure. The area fraction of adherent porcelain (%) was calculated via a standardized spectrometric technique. Bond failure forces were measured in three-point bending using bar specimens. The modulus of elasticity of the five alloys was also measured. No attempt was made to calculate bond strength since the residual thermal stresses at the interfacial region were unknown. Data were compared via ANOVA and the Tukey multiple range test (p < 0.05). RESULTS All failures occurred at the porcelain termination sites with no tensile fracture of the porcelain. Two Pd-Ga alloys exhibited porcelain adherence comparable with previously studied Pd-Cu-Ga alloys. There was no correlation between the porcelain adherence and the force to failure (r2 = 0.0159). Additionally, no statistically significant differences were found among the moduli of elasticity of the five alloys. SIGNIFICANCE The new Pd-Ga alloys have been commercially introduced with little information on the quality of the bond with porcelain. The use of two different means for assessing the metal-ceramic bond provides information on the relationship of data using different experimental techniques.
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Affiliation(s)
- E Papazoglou
- Section of Restorative Dentistry, Prosthodontics and Endodontics, College of Dentistry, Ohio State University, Columbus, USA
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Abstract
OBJECTIVE The purpose of this study was to use x-ray diffraction (XRD) to obtain new information about the oxide layers on four representative oxidized high-palladium alloys. METHODS Cast specimens of two Pd-Cu-Ga alloys and two Pd-Ga alloys, with both polished and etched surfaces and air-abraded surfaces, were subjected to oxidation procedures recommended by the manufacturers. The specimens were analyzed by x-ray diffraction using CuK alpha radiation, and the peaks were compared to appropriate Joint Committee on Powder Diffraction Standards (JCPDS). RESULTS The surface preparation procedure had a profound effect on the phases present in the oxide layers. For the specimens that had been polished and etched, CuGa2O4 and beta-Ga2O3 were detected on the 79Pd-10Cu-9Ga-2Au alloy, whereas SnO2 and CuGa2O4 were detected on the 76Pd-10Cu-5.5Ga-6Sn-2Au alloy. The oxide layers on both Pd-Cu-Ga alloys contained Cu2O1 and the oxide layer on the 76Pd-10Cu-5.5Ga-6Sn-2Au alloy may contain beta-Ga2O3. The principal phase in the oxide layers on both Pd-Ga alloys that had been polished and etched was ln2O3, which exhibited extreme preferred orientation. No other phase was detected in the oxide layer on the 85Pd-10Ga-2Au-1Ag-1 ln alloy, whereas beta-Ga2O3 was found in the oxide layer on the 75Pd-6Ga-6Au-6Ag-6.5ln alloy. For the air-abraded specimens, beta-Ga2O2 was not present in the oxide layers on the Pd-Cu-Ga alloys, and beta-Ga2O3 was the major phase in the oxide layers on the Pd-Ga alloys. Palladium oxide(s) in varying amounts were detected for both surface preparations of the Pd-Cu-Ga alloys and for the air-abraded Pd-Ga alloys. Except for the 76Pd-10Cu-5.5Ga-6Sn-2Au alloy, the oxide layer caused minimal change in the lattice parameter of the palladium solid solution compared to that for the as-cast alloy. SIGNIFICANCE Knowledge of the phases found in the oxide layers on these high-palladium alloys is of fundamental importance for interpreting differences in the adherence of dental porcelain to the metal substrates under static and dynamic conditions, and may provide guidance in the development of new high-palladium alloys with improved metal-ceramic bonding.
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Affiliation(s)
- W A Brantley
- Section of Restorative Dentistry, Prosthodontics and Endodontics, College of Dentistry, Ohio State University, Columbus, USA
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Papazoglou E, Brantley WA, Mitchell JC, Cai Z, Carr AB. New high-palladium casting alloys: studies of the interface with porcelain. INT J PROSTHODONT 1996; 9:315-22. [PMID: 8957869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
This investigation studied the metal ceramic interface for two representative high-palladium alloys each of the Pd-Cu-Ga and Pd-Ga systems, using scanning electron microscopy and x-ray energy dispersive spectroscopy. The Pd-Cu-Ga alloys produced complex subsurface oxidation regions with thickness ranging from 15 to 20 microns for one alloy and 5 to 10 microns for the other alloy. Ga, In, and Sn accumulated at the interfaces, and Ga-rich deposits were found in the subsurface scale. One Pd-Ga alloy presented a surface oxidation region which dissolved in the ceramic, producing "islands" rich in Pd and Ga with a width that ranged from 1 to 2 microns. These islands were separated from the alloy by a band rich in Ga and Si which was 1 to 2.5 microns thick. While the other Pd-Ga alloy presented similar interfacial microstructures, the "islands" formed for this alloy were relatively sparse. The Pd-Cu-Ga alloys had a more favorable interface for metal ceramic bonding, which agrees with previous characterization of bond failures between these alloys and dental porcelain.
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Affiliation(s)
- E Papazoglou
- Ohio State University College of Dentistry, Section of Restorative Dentistry, Prosthodontics, and Endodontics, Columbus 43210-1241, USA
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Clelland NL, Papazoglou E, Carr AB. Comparison of strains transferred to a bone simulant among implant overdenture bars with various levels of misfit. IMPLANT DENT 1996. [DOI: 10.1097/00008505-199600530-00027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Clelland NL, Papazoglou E, Carr AB, Gilat A. Comparison of strains transferred to a bone simulant among implant overdenture bars with various levels of misfit. J Prosthodont 1995; 4:243-50. [PMID: 8601182 DOI: 10.1111/j.1532-849x.1995.tb00350.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
PURPOSE To measure and compare strains transferred to a bone simulant by screw-fastening implant overdenture bars with various levels of fit or misfit. MATERIALS AND METHODS Photoelastic resin was cast directly to two 3.75 X 13-mm Branemark fixtures (Nobelpharma USA Inc, Chicago, IL) situated 20 mm apart in a silicone mold of an edentulous mandible. Two strain-gauge rosettes were also incorporated in the resin to allow precise determination of principal stresses at two locations. Four groups of three overdenture bars with 0-, 180-, 360-, and 500-micrometer vertical gaps were fabricated. These bars were sequentially secured to the abutments with gold slot screws tightened to 10 N-cm. Strain indicator readings were recorded at a standardized time following the initial fastening of each bar. The test was repeated three times for each overdenture bar. RESULTS Mean principal stresses and strains at the location of the rosettes were determined. The magnitude of these stresses and strains increased significantly with each increase in gap size. Strains were several times larger mesial to the fixture than they were distal. CONCLUSIONS Strains are transferred to the bone when misfitting prostheses were secured. Some of the strains mesial to the fixture appeared to be unfavorable for regions of lower bone density when the groups with designed gaps were secured. These data will be compared with those in ongoing animal studies regarding the cellular response to prosthesis misfit.
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Affiliation(s)
- N L Clelland
- College of Dentistry, Ohio State University, Columbus 43210-1241, USA
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Abstract
OBJECTIVES The purpose of this study was to use x-ray diffraction (XRD) to investigate four representative high-palladium alloys in the as-cast condition and obtain new information about the metallurgical phases. METHODS Two Pd-Cu-Ga alloys and two Pd-Ga alloys were cast into plate-shaped specimens (20 mm x 1.5 mm) which were bench-cooled. Polished and etched specimens were analyzed using two different x-ray diffractometers and CuKa radiation. RESULTS All four alloys exhibited strong XRD peaks for the face-centered cubic (fcc) palladium solid solution matrix, and variations in the lattice parameter were consistent with alloy compositions. Comparison of the relative peak intensities for the alloys and the pure palladium powder standard indicated that the as-cast microstructures had preferred crystallographic orientation. Because the two Pd-Cu-Ga alloys contained appreciable amounts of near-surface lamellar interdendritic or eutectic constituents, it was possible to determine previously unreported XRD peaks for the Pd2Ga phase in these alloys. Low-intensity peaks in the Pd-Ga alloys were attributed to small amounts of secondary phases observed in the microstructures. SIGNIFICANCE Knowledge of the metallurgical structures of these high-palladium alloys can be important for interpretation of microstructural observations, mechanical properties, corrosion behavior and clinical performance.
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Affiliation(s)
- W A Brantley
- Section of Restorative and Prosthetic Dentistry, The Ohio State University, Columbus, Ohio, USA
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Carr AB, Larsen PE, Papazoglou E, McGlumphy E. Reverse torque failure of screw-shaped implants in baboons: baseline data for abutment torque application. Int J Oral Maxillofac Implants 1995; 10:167-74. [PMID: 7744435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Torque failure for endosseous implants has been used as a biomechanical measure of anchorage, though the significance of such data is not known. A practical understanding of the resistance to torque failure of implant-tissue interfaces at stage 2 surgery would help in assigning torque levels for implant abutment-screw fastening. The purpose of this study was to measure torque failure levels of commercially pure (CP) titanium, Ti-6Al-4V, hydroxyapatite-coated (HA-coated) screw-shaped implants placed into the maxillae and mandibles of baboons. Implants identical in size were placed into the edentulous posterior maxillae and mandibles of six female baboons (n = 37 each group) using a standardized surgical protocol. Reverse-torque data were collected at postinsertion time intervals ranging from 3 to 4 months using a counterclockwise torque driver and the data were analyzed (repeated measures ANOVA) for torque differences related to time, biomaterial, and jaw. The HA-coated implants exhibited significantly greater torque-removal values compared to both metallic implants (HA: 186.0 Ncm [50.1]; Ti-6Al-4V: 78.6 Ncm [18.1]; CP Ti 74.0 Ncm [24.4]). Analysis of torque interactions with jaw showed no significant difference; however, the mandible was found to be greater than the maxilla in torque resistance for all groups tested. Understanding the risks in inferring animal data to human application, the clinical implications of these data suggest that the recommended torque level of 35 Ncm for abutment fastening may provide a margin of safety for most implants of similar design and material as used in this study.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- A B Carr
- Section of Restorative and Prosthetic Dentistry, Ohio State University College of Dentistry, Columbus 43210-1241, USA
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Carr AB, Papazoglou E, Larsen PE. The relationship of Periotest values, biomaterial, and torque to failure in adult baboons. INT J PROSTHODONT 1995; 8:15-20. [PMID: 7710620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
A quantitative measure of implant stability would be beneficial to decision-making regarding the status of the bone anchorage around an implant. The Periotest device has been reported to provide such a measure, but the in vivo data are incomplete and inconclusive in support of this claim. The purpose of this study was to determine in an in vivo model the relationship between Periotest values (PTV), three different implant biomaterials, and torque to failure. A total of 79 screw-shape implants made of commericially pure titanium, titanium alloy, and HA-coated alloy were evaluated in the posterior maxillary and mandibular quadrants of six female baboons following healing for 3 to 4 months. At uncovering, the implants were tested with the Periotest device and torqued to failure using an electronic torque driver. Analysis of the PTV-biomaterial relationship revealed no significant difference among the implants based on the biomaterial (P = .7453). Analysis of PTV-torque revealed a significant relationship (P = .0117), however, the association between PTV and torque was not strong and does not explain 92% of the variation between the parameters (Pearson correlation .2823, R2 = .08).
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Affiliation(s)
- A B Carr
- Department of Restorative and Prosthetic Dentistry, College of Dentistry, Ohio State University, Columbus 43210-1241, USA
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Abstract
The adherence of porcelain to four representative high-palladium alloys of the first generation (Pd-Cu-Ga) and second generation (Pd-Ga) was measured by use of a gold-palladium alloy as a control. The area fraction of adherent porcelain after metal-ceramic specimens were debonded in biaxial flexure at constant strain was calculated from the characteristic Si x-ray intensity with a standardized scanning electron microscope/energy-dispersive spectroscopy technique (SEM/EDS). The gold-palladium alloy exhibited the highest percentage of cohesive fracture through the porcelain, the two first-generation alloys were intermediate, and the two second-generation alloys exhibited the lowest area fractions. This study demonstrated that conventional visual (naked eye) or microscopic examination of the fractured metal-ceramic specimens at moderate magnification and the use of standard quantitative metallographic techniques were inadequate to provide accurate measurements of the area fraction covered with porcelain.
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Affiliation(s)
- E Papazoglou
- Section of Restorative and Prosthetic Dentistry, College of Dentistry, Ohio State University, Columbus
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McGlumphy EA, Papazoglou E, Riley RL. The combination implant crown: a cement- and screw-retained restoration. Compendium 1992; 13:34, 36, 38 passim. [PMID: 1521259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- E A McGlumphy
- Ohio State University, College of Dentistry, Columbus
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