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Reimann L, Brytan Z, Jania G. Influence of Filler Metal on Electrochemical Characteristics of a Laser-Welded CoCrMoW Alloy Used in Prosthodontics. MATERIALS (BASEL, SWITZERLAND) 2022; 15:5721. [PMID: 36013855 PMCID: PMC9412628 DOI: 10.3390/ma15165721] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/06/2022] [Accepted: 08/12/2022] [Indexed: 06/15/2023]
Abstract
This paper sought to determine corrosion resistance changes in the artificial saliva of a CoCrMoW-based alloy used for dental prostheses under Nd:YAG laser welding with CoCr alloy and stainless steel wire filler metals. The paper presents the corrosion characteristics of such joints, including the next stage of porcelain-fused-to-metal (PFM) firing. Corrosion tests were performed by electrochemical methods registering anodic polarization curves and electrochemical impedance spectroscopy (EIS). The microstructures were assessed by scanning microscopy (SEM) and chemical composition analysis (EDS) at the connection and heat-affected zones. Welding CoCrMoW alloy with and without a filler material increased the open circuit potential of the samples by 40-100 mV compared to unwelded base alloy. At the same time, a potentiodynamic test showed a polarization resistance Rpol reduction in welded samples, both for CoCr and stainless steel wires, as compared to the base CoCrMoW material. On the other hand, when comparing the current density and polarization resistance between materials welded with two different filler metals, better results were obtained for samples welded with stainless steel wire. The polarization resistance Rpol for the base alloy was 402 kΩ·cm2, for the CoCr wire weld it was 436 kΩ·cm2, and the value was 452 kΩ·cm2 for stainless steel wire welds. Comparing polarization resistance Rpol from the Tafel analysis and the total charge transfer resistance from Rp(EIS) from EIS, the CoCrMoW alloy welded with a stainless steel wire after heat treatment equaled or even slightly exceeded the corrosion resistance of the base alloy and alloy welded with dedicated CoCr wire after heat treatment. These results indicated the possibility of using stainless steel wire for the laser welding of CoCrMoW alloys dental prostheses, including the next stage of PFM, without sacrificing the corrosion resistance of such connections, and this was confirmed by most electrochemical parameters.
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Affiliation(s)
- Lukasz Reimann
- Materials Research Laboratory, Faculty of Mechanical Engineering, Silesian University of Technology, Konarskiego St. 18a, 44-100 Gliwice, Poland
| | - Zbigniew Brytan
- Department of Engineering Materials and Biomaterials, Faculty of Mechanical Engineering, Silesian, University of Technology, 44-100 Gliwice, Poland
| | - Grzegorz Jania
- Dental Engineering Laboratory Grzegorz Jania, 48-200 Prudnik, Poland
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Perveen A, Molardi C, Fornaini C. Applications of Laser Welding in Dentistry: A State-of-the-Art Review. MICROMACHINES 2018; 9:E209. [PMID: 30424142 PMCID: PMC6187655 DOI: 10.3390/mi9050209] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 04/23/2018] [Accepted: 04/25/2018] [Indexed: 12/13/2022]
Abstract
The dental industry without lasers is inconceivable right now. This captivating technology has outlasted other possible alternative technologies applied in dentistry in the past due to its precision, accuracy, minimal invasive effect as well as faster operating time. Other alternatives such as soldering, resistance (spot) welding, plasma (torch) welding, and single pulse tungsten inert gas welding have their pros and cons; nevertheless, laser welding remains the most suitable option so far for dental application. This paper attempts to give an insight into the laser principle and types of lasers used for dental purposes, types of dental alloys used by the dentist, and effect of laser parameters on prosthesis/implants. It is apparent from the literature review that laser assisted dental welding will continue to grow and will become an unparalleled technology for dental arena.
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Affiliation(s)
- Asma Perveen
- Mechanical Engineering, Nazarbayev University, Astana 010000, Kazakhstan.
| | - Carlo Molardi
- Electrical & Electronics Engineering, Nazarbayev University, Astana 010000, Kazakhstan; .
| | - Carlo Fornaini
- Department of Engineering and Architecture, University of Parma, Parma, I-43124, Italy.
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Jamjoom FZ, Lee DJ. Modification of clinically short Locator abutments using laser welding. J Prosthet Dent 2018; 120:13-16. [PMID: 29429841 DOI: 10.1016/j.prosdent.2017.11.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2017] [Revised: 11/06/2017] [Accepted: 11/06/2017] [Indexed: 11/30/2022]
Abstract
As dental implants continue to survive longer, managing and maintaining implant prostheses can be complicated by the lack of compatible parts or the discontinuation of implant systems. This report describes a laser welding procedure for the management of clinically short Locator abutments (Zest Anchors Inc) that lacked a commercially available, compatible alternative.
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Affiliation(s)
- Faris Z Jamjoom
- Graduate student, Advanced Graduate Program in Implant Dentistry, Harvard School of Dental Medicine, Boston, Mass.
| | - Damian J Lee
- Program Director and Assistant Professor, Advanced Education in Prosthodontics Program, Division of Restorative Sciences and Prosthodontics, The Ohio State University College of Dentistry, Columbus, Ohio
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Venkat G, Krishnan M, Srinivasan S, Balasubramanian M. Evaluation of Bond Strength between Grooved Titanium Alloy Implant Abutments and Provisional Veneering Materials after Surface Treatment of the Abutments: An In vitro Study. Contemp Clin Dent 2017; 8:395-399. [PMID: 29042724 PMCID: PMC5643996 DOI: 10.4103/ccd.ccd_118_17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Introduction: Titanium has become the material of choice with greater applications in dental implants. The success of the dental implant does not only depend on the integration of the implant to the bone but also on the function and longevity of the superstructure. The clinical condition that demands long-term interim prosthesis is challenging owing to the decreased bond between the abutment and the veneering material. Hence, various surface treatments are done on the abutments to increase the bond strength. Aim: This study aimed to evaluate the bond strength between the abutment and the provisional veneering materials by surface treatments such as acid etching, laser etching, and sand blasting of the abutment. Materials and Methods: Forty titanium alloy abutments of 3 mm diameter and 11 mm height were grouped into four groups with ten samples. Groups A, B, C, and D are untreated abutments, sand blasted with 110 μm aluminum particles, etched with 1% hydrofluoric acid and 30% nitric acid, and laser etched with Nd: YAG laser, respectively. Provisional crowns were fabricated with bis-acrylic resin and cemented with noneugenol temporary luting cement. The shear bond strength was measured in universal testing machine using modified Shell–Nielsen shear test after the cemented samples were stored in water at 25°C for 24 h. Load was applied at a constant cross head speed of 5 mm/min until a sudden decrease in resistance indicative of bond failure was observed. The corresponding force values were recorded, and statistical analysis was done using one-way ANOVA and Newman–Keuls post hoc test. Results: The laser-etched samples showed higher bond strength. Conclusion: Among the three surface treatments, laser etching showed the highest bond strength between titanium alloy implant abutment and provisional restorations. The sand-blasted surfaces demonstrated a significant difference in bond strength compared to laser-etched surfaces. The results of this study confirmed that a combination of surface treatments and bond agents enhances the bond strength.
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Affiliation(s)
- Gowtham Venkat
- Department of Prosthodontics, SRM Dental College, Chennai, Tamil Nadu, India
| | - Murugesan Krishnan
- Department of Prosthodontics, SRM Dental College, Chennai, Tamil Nadu, India
| | - Suganya Srinivasan
- Department of Prosthodontics, SRM Dental College, Chennai, Tamil Nadu, India
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Influence of stress corrosion on the mechanical properties of laser-welded titanium. J Prosthet Dent 2015; 115:356-62. [PMID: 26548870 DOI: 10.1016/j.prosdent.2015.09.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2014] [Revised: 09/10/2015] [Accepted: 09/16/2015] [Indexed: 11/21/2022]
Abstract
STATEMENT OF PROBLEM Whether laser-welded (LW) titanium can resist the stress corrosion produced by the combination of fluoride ions and stress in the oral environment is unknown. PURPOSE The purpose of this in vitro study was to investigate the influence of stress corrosion on the mechanical properties of LW titanium. MATERIAL AND METHODS Twenty-seven titanium bars (25×2 mm) with a circular cross-section were cut in half and laser-welded, while another 27 nonwelded (NW) bars were used as the control. Thirty bars were submitted to a flexural load of 480 N at 1 Hz and immersed in artificial saliva at pH 6 (S1) or in 1000 ppm fluoride-containing saliva at pH 6.0 (S2) or 2.0 (S3) at room temperature for up to 4000 cycles. After the stress corrosion simulation, the tensile strength and Vickers microhardness were determined (n=5). Twelve LW and NW bars were submitted to the corrosion immersion test media for 51 days (n=2) to determine polarization curves (n=2) in an artificial saliva media. The corroded surface was examined with scanning electron microscopy (SEM). RESULTS The combination of fluoride and low pH significantly decreased the tensile strength of LW (P<.05). Stress corrosion did not affect the hardness of LW or NW (P>.05). NW bars immersed in S3 exhibited progressive surface dissolution, while LW bars spontaneously fractured at the welded area after 25 days of immersion in the same medium. SEM images demonstrated pitting corrosion without the presence of cracks in both groups immersed in S3. CONCLUSIONS Stress corrosion caused by acidic fluoride-containing saliva and flexural load cycling decreased the tensile strength and hardness of LW titanium bars.
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Castro MG, Araújo CA, Menegaz GL, Silva JPL, Nóbilo MAA, Simamoto Júnior PC. Laser and plasma dental soldering techniques applied to Ti-6Al-4V alloy: Ultimate tensile strength and finite element analysis. J Prosthet Dent 2015; 113:460-6. [DOI: 10.1016/j.prosdent.2014.10.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 10/21/2014] [Accepted: 10/22/2014] [Indexed: 10/23/2022]
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Simamoto Júnior PC, Resende Novais V, Rodrigues Machado A, Soares CJ, Araújo Raposo LH. Effect of joint design and welding type on the flexural strength and weld penetration of Ti-6Al-4V alloy bars. J Prosthet Dent 2015; 113:467-74. [PMID: 25749091 DOI: 10.1016/j.prosdent.2014.10.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 10/08/2014] [Accepted: 10/08/2014] [Indexed: 10/23/2022]
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Bock JJ, Bailly J, Fuhrmann RA. Effects of different brazing and welding methods on the fracture load of various orthodontic joining configurations. J Orthod 2014; 36:78-84. [PMID: 19487737 DOI: 10.1179/14653120722986] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Affiliation(s)
- Jens J Bock
- Martin Luther University of Halle Wittenberg, Halle, Germany.
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Mechanical properties of thin films of laser-welded titanium and their associated welding defects. Lasers Med Sci 2014; 29:1799-805. [PMID: 23636297 DOI: 10.1007/s10103-013-1334-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 04/18/2013] [Indexed: 10/26/2022]
Abstract
The aim of this study was to evaluate the mechanical properties of thin films of laser-welded cast titanium using an interference strain/displacement gauge (ISDG) and to analyze factors that affect laser welding. Dog-bone-shaped small specimens of cast titanium were prepared by wire cutting after they were laser-welded. The specimens were divided into three groups according to the gap distance of the laser weld; the control was non-welded titanium. Small specimens without cast defects detected by X-ray screening were measured by a tensile test machine using ISDG, and stress-strain curves were drawn. Finally, the fracture texture was analyzed. The ultimate tensile strengths (UTSs) of specimens with a gap distance of 0.00, 0.25, and 0.50 mm were 492.16 ± 33.19, 488.09 ± 43.18, and 558.45 ± 10.80 MPa, respectively. There were no significant differences in UTS between the test groups and the control group (p > 0.05). However, the plastic deformation and the percent elongation increased as the gap distance increased. Incomplete penetration defects appeared in groups that had small gap distances, which may have affected the properties of the laser-welded titanium. However, the welding material was still pure titanium. These results suggest that an appropriate gap distance should be maintained to improve the application of dental laser welding.
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Bertrand C, Poulon-Quintin A. Temporal pulse shaping: a key parameter for the laser welding of dental alloys. Lasers Med Sci 2014; 30:1457-64. [PMID: 24913424 DOI: 10.1007/s10103-014-1606-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 05/28/2014] [Indexed: 11/26/2022]
Abstract
This study aims to describe the effect of pulse shaping on the prevention of internal defects during laser welding for two dental alloys mainly used in prosthetic dentistry. Single spot, weld beads, and welds with 80 % overlapping were performed on Co-Cr-Mo and Pd-Ag-Sn cast plates with a pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) laser. A specific welding procedure using adapted parameters to each alloy was completed. All the possibilities for pulse shaping were tested: (1) the square pulse shape as a default setting, (2) a rising edge slope for gradual heating, (3) a falling edge slope to slow the cooling process, and (4) a combination of rising and falling edges. The optimization of the pulse shape is supposed to produce defect-free welds (crack, pores, voids). Cross-section SEM observations and Vickers microhardness measurements were made. Pd-Ag-Sn was highly sensitive to hot cracking, and Co-Cr-Mo was more sensitive to voids and small porosities (sometimes combined with cracks). Using a slow cooling ramp allowed a better control on the solidification process for those two alloys always preventing internal defects. A rapid slope should be preferred for Co-Cr-Mo alloys due to its low-laser beam reflectivity. On the opposite, for Pd-Ag-Sn alloy, a slow rising slope should be preferred because this alloy has a high-laser beam reflectivity.
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Affiliation(s)
- Caroline Bertrand
- Institut de la Chimie de la Matière Condensée de Bordeaux (ICMCB), C.N.R.S., UPR9048, Université Bordeaux, 87 Avenue du Dr. Albert Schweitzer, 33608, Pessac, France,
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Ghadhanfari HA, Khajah HM, Monaco EA, Kim H. Effects of soldering methods on tensile strength of a gold-palladium metal ceramic alloy. J Prosthet Dent 2014; 112:994-1000. [PMID: 24840906 DOI: 10.1016/j.prosdent.2014.02.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 02/10/2014] [Accepted: 02/10/2014] [Indexed: 11/28/2022]
Abstract
STATEMENT OF PROBLEM The tensile strength obtained by conventional postceramic application soldering and laser postceramic welding may require more energy than microwave postceramic soldering, which could provide similar tensile strength values. PURPOSE The purpose of the study was to compare the tensile strength obtained by microwave postceramic soldering, conventional postceramic soldering, and laser postceramic welding. MATERIAL AND METHODS A gold-palladium metal ceramic alloy and gold-based solder were used in this study. Twenty-seven wax specimens were cast in gold-palladium noble metal and divided into 4 groups: laser welding with a specific postfiller noble metal, microwave soldering with a postceramic solder, conventional soldering with the same postceramic solder used in the microwave soldering group, and a nonsectioned control group. All the specimens were heat treated to simulate a normal porcelain sintering sequence. An Instron Universal Testing Machine was used to measure the tensile strength for the 4 groups. The means were analyzed statistically with 1-way ANOVA. The surface and fracture sites of the specimens were subjectively evaluated for fracture type and porosities by using a scanning electron microscope. RESULTS The mean (standard deviation) ultimate tensile strength values were as follows: nonsectioned control 818 ±30 MPa, microwave 516 ±34 MPa, conventional 454 ±37 MPa, and laser weld 191 ±39 MPa. A 1-way ANOVA showed a significant difference in ultimate tensile strength among the groups (F3,23=334.5; P<.001). Follow-up multiple comparisons showed a significant difference among all the groups. Microwave soldering resulted in a higher tensile strength for gold and palladium noble metals than either conventional soldering or laser welding. CONCLUSION Conventional soldering resulted in a higher tensile strength than laser welding. Under the experimental conditions described, either microwave or conventional postceramic soldering would appear to satisfy clinical requirements related to tensile strength.
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Affiliation(s)
| | - Hasan M Khajah
- Consultant, Fixed Prosthodontics, Al-Amiri Dental Center, Kuwait City, Kuwait.
| | - Edward A Monaco
- Assistant Professor and Director, Postgraduate Prosthodontics, Department of Restorative Dentistry, School of Dental Medicine, State University of New York at Buffalo, Buffalo, NY
| | - Hyeongil Kim
- Assistant Professor, Postgraduate Prosthodontics, Department of Restorative Dentistry School of Dental Medicine, State University of New York at Buffalo, Buffalo, NY
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Al Jabbari YS, Koutsoukis T, Barmpagadaki X, El-Danaf EA, Fournelle RA, Zinelis S. Effect of Nd:YAG laser parameters on the penetration depth of a representative Ni-Cr dental casting alloy. Lasers Med Sci 2013; 30:909-14. [PMID: 24326743 DOI: 10.1007/s10103-013-1502-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 11/25/2013] [Indexed: 11/26/2022]
Abstract
The effects of voltage and laser beam (spot) diameter on the penetration depth during laser beam welding in a representative nickel-chromium (Ni-Cr) dental alloy were the subject of this study. The cast alloy specimens were butted against each other and laser welded at their interface using various voltages (160-390 V) and spot diameters (0.2-1.8 mm) and a constant pulse duration of 10 ms. After welding, the laser beam penetration depths in the alloy were measured. The results were plotted and were statistically analyzed with a two-way ANOVA, employing voltage and spot diameter as the discriminating variables and using Holm-Sidak post hoc method (a = 0.05). The maximum penetration depth was 4.7 mm. The penetration depth increased as the spot diameter decreased at a fixed voltage and increased as the voltage increased at a fixed spot diameter. Varying the parameters of voltage and laser spot diameter significantly affected the depth of penetration of the dental cast Ni-Cr alloy. The penetration depth of laser-welded Ni-Cr dental alloys can be accurately adjusted based on the aforementioned results, leading to successfully joined/repaired dental restorations, saving manufacturing time, reducing final cost, and enhancing the longevity of dental prostheses.
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Affiliation(s)
- Youssef S Al Jabbari
- Dental Biomaterials Research and Development Chair, College of Dentistry, King Saud University, P.O. Box 60169, Riyadh, 11545, Saudi Arabia,
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Atoui JA, Felipucci DNB, Pagnano VO, Orsi IA, Nobilo MADA, Bezzon OL. Tensile and Flexural Strength of Commercially Pure Titanium Submitted to Laser and Tungsten Inert Gas Welds. Braz Dent J 2013; 24:630-4. [DOI: 10.1590/0103-6440201302241] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 09/02/2013] [Indexed: 11/21/2022] Open
Abstract
This study evaluated the tensile and flexural strength of tungsten inert gas (TIG) welds in specimens made of commercially pure titanium (CP Ti) compared with laser welds. Sixty cylindrical specimens (2 mm diameter x 55 mm thick) were randomly assigned to 3 groups for each test (n=10): no welding (control), TIG welding (10 V, 36 A, 8 s) and Nd:YAG laser welding (380 V, 8 ms). The specimens were radiographed and subjected to tensile and flexural strength tests at a crosshead speed of 1.0 mm/min using a load cell of 500 kgf applied on the welded interface or at the middle point of the non-welded specimens. Tensile strength data were analyzed by ANOVA and Tukey's test, and flexural strength data by the Kruskal-Wallis test (α=0.05). Non-welded specimens presented significantly higher tensile strength (control=605.84±19.83) (p=0.015) and flexural strength (control=1908.75) (p=0.000) than TIG- and laser-welded ones. There were no significant differences (p>0.05) between the welding types for neither the tensile strength test (TIG=514.90±37.76; laser=515.85±62.07) nor the flexural strength test (TIG=1559.66; laser=1621.64). As far as tensile and flexural strengths are concerned, TIG was similar to laser and could be suitable to replace laser welding in implant-supported rehabilitations.
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Piveta ACG, Ricci WA, Montandon AAB, Nagle MM. Análise metalográfica do titânio puro submetido à soldagem laser Nd: YAG e TIG. REVISTA DE ODONTOLOGIA DA UNESP 2013. [DOI: 10.1590/s1807-25772013000100001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
INTRODUÇÃO: Os métodos de soldagem mais utilizados em Odontologia não podem ser aplicados ao titânio puro e às suas ligas em função da alta reatividade do titânio com elementos atmosféricos; dessa forma, o mesmo não deve ser soldado por processo comum. OBJETIVO: O objetivo deste trabalho foi avaliar a característica metalúrgica do titânio comercialmente puro sem solda e submetido aos processos de soldagem a laser e TIG. MATERIAL E MÉTODO: Foram confeccionados 15 corpos de prova em titânio comercialmente puro, cinco para cada condição, na forma de hastes cilíndricas, obtidas por fundição odontológica, sob atmosfera de gás argônio e vácuo, com calor produzido por um arco voltaico, com a injeção do titânio sob vácuo-pressão. Três grupos foram formados I: soldagem a laser; II: soldagem TIG, e III: sem solda. Os corpos de prova do grupo I e II foram seccionados ao meio e soldados por TIG e por laser, respectivamente; o grupo III foi mantido sem corte e sem solda, como controle. A análise metalográfica foi realizada sob aumentos de 50×, 100× e 200×, em microscópio. RESULTADO: Pelos resultados obtidos nas micrografias, o titânio comercialmente puro apresentou uma morfologia de grãos equiaxiais da fase α, o cordão de solda a laser apresentou estrutura martensítica e, na TIG, microestrutura Widmanstätten. CONCLUSÃO: A microestrutura martensítica é condizente com a alta taxa de resfriamento proveniente do processo de soldagem a laser. As estruturas martensítica e Widmansttäten são mais refinadas quando comparadas à microestrutura do metal base.
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Lyra e Silva JP, Fernandes Neto AJ, Raposo LHA, Novais VR, de Araujo CA, Cavalcante LDAL, Simamoto Júnior PC. Effect of plasma welding parameters on the flexural strength of Ti-6Al-4V alloy. Braz Dent J 2013; 23:686-91. [PMID: 23338261 DOI: 10.1590/s0103-64402012000600010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 11/30/2012] [Indexed: 11/22/2022] Open
Abstract
The aim of this study was to assess the effect of different plasma arc welding parameters on the flexural strength of titanium alloy beams (Ti-6Al-4V). Forty Ti-6Al-4V and 10 NiCr alloy beam specimens (40 mm long and 3.18 mm diameter) were prepared and divided into 5 groups (n=10). The titanium alloy beams for the control group were not sectioned or subjected to welding. Groups PL10, PL12, and PL14 contained titanium beams sectioned and welded at current 3 A for 10, 12 or 14 ms, respectively. Group NCB consisted of NiCr alloy beams welded using conventional torch brazing. After, the beams were subjected to a three-point bending test and the values obtained were analyzed to assess the flexural strength (MPa). Statistical analysis was carried out by one-way ANOVA and Tukey's HSD test at 0.05 confidence level. Significant difference was verified among the evaluated groups (p<0.001), with higher flexural strength for the control group (p<0.05). No significant differences was observed among the plasma welded groups (p>0.05). The NCB group showed the lowest flexural strength, although it was statistically similar to the PL 14 group (p>0.05). The weld depth penetration was not significantly different among the plasma welded groups (p=0.05). Three representative specimens were randomly selected to be evaluated under scanning electron microcopy. The composition of the welded regions was analyzed by energy dispersive X-ray spectroscopy. This study provides an initial set of parameters supporting the use of plasma welding during fabrication of titanium alloy dental frameworks.
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Affiliation(s)
- João Paulo Lyra e Silva
- Department of Occlusion, Fixed Prosthodontics and Dental Materials, Dental School, UFU - Universidade Federal de Uberlândia, Uberlândia, MG, Brazil.
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Poulon-Quintin A, Watanabe I, Watanabe E, Bertrand C. Microstructure and mechanical properties of surface treated cast titanium with Nd:YAG laser. Dent Mater 2012; 28:945-51. [PMID: 22578991 DOI: 10.1016/j.dental.2012.04.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 12/02/2011] [Accepted: 04/16/2012] [Indexed: 11/24/2022]
Abstract
OBJECTIVE To investigate the effect of laser surface treatment of cast titanium alloy on microstructure and mechanical properties. METHODS Dumbbell- and plate-shaped cast titanium specimens were prepared for mechanical testing and microstructure analysis. After the cast surfaces of each specimen were laser-treated using a dental Nd:YAG laser machine at 240 V and 300 V with and without argon gas shielding, tensile testing and microstructure analysis were conducted. Hardness depth profiles were also made from the cross-section of laser-treated cast specimens. Microstructural and chemical analysis were performed by means of the SEM, XRD, AES and WDS. RESULTS The results of tensile testing and Vickers hardness depth profiling showed that laser treatment improved the mechanical properties. Bulk microstructure of as-cast titanium was mainly composed of α-grains with acicular and widmanstatten patterns. The laser melted zone was characterized by columnar beta grains. When the emission voltage of laser increased to 300V, a larger grain size was promoted. The XRD analysis indicated that the beta phase formation was clearly noticeable after laser surface treatment. Supplementary marked peaks of the TiO, TiO(2) and Ti(2)N were detected without argon gas shielding. When argon shielding gas was used, the presence of titanium oxide was significantly reduced and the peaks of titanium nitride disappeared. SIGNIFICANCE Laser treatment on cast titanium surfaces showed significant enhancement of mechanical properties and modification of microstructures, and therefore could produce reliable titanium metal frameworks for dental prostheses.
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TAKAYAMA Y, NOMOTO R, NAKAJIMA H, OHKUBO C. Effects of argon gas flow rate on laser-welding. Dent Mater J 2012; 31:316-26. [PMID: 22447067 DOI: 10.4012/dmj.2011-158] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Yasuko TAKAYAMA
- Department of Removable Prosthodontics, Tsurumi University School of Dental Medicine
| | - Rie NOMOTO
- Department of Dental Engineering, Tsurumi University School of Dental Medicine
| | | | - Chikahiro OHKUBO
- Department of Removable Prosthodontics, Tsurumi University School of Dental Medicine
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Nuñez-Pantoja JMC, Vaz LG, Nóbilo MADA, Mesquita MF. Fatigue performance of joints executed in pure titanium structures with several diameters. Dent Mater J 2011; 30:887-93. [PMID: 22123013 DOI: 10.4012/dmj.2011-112] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This study evaluated fatigue strength of CP-Ti laser-welded joints. Sixty (20/diameter) CP-Ti casted dumbbell rods with diameters of 1.5, 2.0, and 3.5 mm were sectioned and welded using two joint openings (0.0 (00) and 0.6 mm (06)). Six groups were formed, amounting to a total of 9 (n=10) with inclusion of intact groups. Welding was executed using 360 V/8 ms (1.5 and 2.0 mm) and 380 V/9 ms (3.5 mm). Joints were finished, polished, and submitted to radiographic examination to visually analyze presence of porosity (PP). Specimens were submitted to cyclic tests, and the number of cycles until failure (NC) was recorded. Fractured surfaces were examined by SEM. Kruskal-Wallis and Dunn (α=0.05) tests demonstrated that NC was lower for all diameters with 06, and for 3.5 mm/00. NC and PP were found to have a negative correlation (Spearman Coefficient). For CP-Ti frameworks with thin diameters, laser welding is better when structures are juxtaposed.
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Nuñez Pantoja JM, Farina AP, Vaz LG, Consani RL, de Arruda Nóbilo MA, Mesquita MF. Fatigue strength: effect of welding type and joint design executed in Ti-6Al-4V structures. Gerodontology 2011; 29:e1005-10. [DOI: 10.1111/j.1741-2358.2011.00598.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Augusta Orsi I, Raimundo LB, Luiz Bezzon O, Antonio de Arruda Nóbilo M, Kuri SE, Rovere CAD, Oliveira Pagnano V. Evaluation of Anodic Behavior of Commercially Pure Titanium in Tungsten Inert Gas and Laser Welds. J Prosthodont 2011; 20:628-31. [DOI: 10.1111/j.1532-849x.2011.00771.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Nuñez-Pantoja JMC, Takahashi JMFK, Nóbilo MADA, Consani RLX, Mesquita MF. Radiographic inspection of porosity in Ti-6Al-4V laser-welded joints. Braz Oral Res 2011; 25:103-8. [DOI: 10.1590/s1806-83242011005000005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Accepted: 12/06/2010] [Indexed: 11/21/2022] Open
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NUÑEZ-PANTOJA JMC, VAZ LG, NÓBILO MAA, HENRIQUES GEP, MESQUITA MF. Effects of laser-weld joint opening size on fatigue strength of Ti-6Al-4V structures with several diameters. J Oral Rehabil 2011; 38:196-201. [DOI: 10.1111/j.1365-2842.2010.02140.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Nomoto R, Takayama Y, Tsuchida F, Nakajima H. Non-destructive three-dimensional evaluation of pores at different welded joints and their effects on joints strength. Dent Mater 2010; 26:e246-52. [PMID: 20828805 DOI: 10.1016/j.dental.2010.08.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2009] [Revised: 03/12/2010] [Accepted: 08/09/2010] [Indexed: 10/19/2022]
Abstract
OBJECTIVES The purpose of this study was to measure the porosity in different laser welded cast alloys non-destructively using X-ray micro-focus computerized tomography (micro-CT) and to evaluate the effect of porosity on the tensile strength of the welded joints. MATERIALS AND METHODS The welding procedure was conducted in rectangular cast metals, CoCr, Ti and platinum added gold alloy (AuPt). The metal plates were butted CoCr to CoCr (CoCr/CoCr) or Ti to Ti (Ti/Ti) for welding of similar metals and Ti to AuPt (Ti/AuPt) for welding of dissimilar metals. Specimens were welded under several laser-welding conditions; with groove (normal), without groove (no groove), spatter, crack, or no overlapped welding (no overlap) (n=5). Porosity in the welded area was evaluated using a micro-CT. Tensile strength of the welded specimens was measured at a crosshead speed of 1mm/min. Multiple comparisons of the group means were performed using ANOVA and Fisher's multiple comparisons test (α=.05). The relationship between the porosity and the tensile strength was investigated with a regression analysis. RESULTS Three-dimensional images of Ti/AuPt could not be obtained due to metal artifacts and the tensile specimens of Ti/AuPt were debonded prior to the tensile test. All other welded specimens had porosity in the welded area and the porosities ranged from 0.01% to 0.17%. The fractures of most of the CoCr/CoCr and Ti/Ti specimens occurred in the parent metals. Joint strength had no relationship with the porosity in the welded area (R(2)=0.148 for CoCr/CoCr, R(2)=0.088 for Ti/Ti, respectively). SIGNIFICANCE The small amount of porosity caused by the laser-welding procedures did not affect the joint strength. The joint strength of Ti/AuPt was too weak to be used clinically.
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Affiliation(s)
- Rie Nomoto
- Department of Dental Engineering, Tsurumi University School of Dental Medicine, 2-1-3 Tsurumi, Tsurumi-ku, Yokohama 230-8501, Japan.
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Bertrand C, Poulon-Quintin A. Proposals for optimization of laser welding in prosthetic dentistry. J Prosthodont 2009; 19:69-76. [PMID: 19780906 DOI: 10.1111/j.1532-849x.2009.00523.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
This paper points out each key parameter involved in laser welding and discusses the parameters' effects on weld microstructure and defects detected inside the weld. Solutions are proposed to adjust the parameters to provide an optimal dental assembly. Metallurgical effects as well as defects are briefly discussed. A welding procedure adapted to different compositions of dental alloys is proposed.
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Affiliation(s)
- Caroline Bertrand
- Department of Prosthodontics, TELEO, University of Nice Sophia-Antipolis, Nice, France.
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da Silveira-Júnior CD, Neves FD, Fernandes-Neto AJ, Prado CJ, Simamoto-Júnior PC. Influence of Different Tightening Forces Before Laser Welding to the Implant/Framework Fit. J Prosthodont 2009; 18:337-41. [DOI: 10.1111/j.1532-849x.2008.00418.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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Watanabe I, McBride M, Newton P, Kurtz KS. Laser surface treatment to improve mechanical properties of cast titanium. Dent Mater 2009; 25:629-33. [DOI: 10.1016/j.dental.2008.11.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2008] [Accepted: 11/14/2008] [Indexed: 11/27/2022]
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Bock JJ, Bailly J, Gernhardt CR, Fuhrmann RAW. Fracture strength of different soldered and welded orthodontic joining configurations with and without filling material. J Appl Oral Sci 2009; 16:328-35. [PMID: 19089229 PMCID: PMC4327598 DOI: 10.1590/s1678-77572008000500005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2008] [Accepted: 04/18/2008] [Indexed: 11/22/2022] Open
Abstract
The aim of this study was to compare the mechanical strength of different joints made by conventional brazing, TIG and laser welding with and without filling material. Five standardized joining configurations of orthodontic wire in spring hard quality were used: round, cross, 3 mm length, 9 mm length and 7 mm to orthodontic band. The joints were made by five different methods: brazing, tungsten inert gas (TIG) and laser welding with and without filling material. For the original orthodontic wire and for each kind of joint configuration or connecting method 10 specimens were carefully produced, totalizing 240. The fracture strengths were measured with a universal testing machine (Zwick 005). Data were analyzed by ANOVA (p=0.05) and Bonferroni post hoc test (p=0.05). In all cases, brazing joints were ruptured on a low level of fracture strength (186-407 N). Significant differences between brazing and TIG or laser welding (p<0.05, Bonferroni post hoc test) were found in each joint configuration. The highest fracture strength means were observed for laser welding with filling material and 3 mm joint length (998 N). Using filling materials, there was a clear tendency to higher mean values of fracture strength in TIG and laser welding. However, statistically significant differences were found only in the 9-mm long joints (p<0.05, Bonferroni post hoc test). In conclusion, the fracture strength of welded joints was positively influenced by the additional use of filling material. TIG welding was comparable to laser welding except for the impossibility of joining orthodontic wire with orthodontic band.
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Affiliation(s)
- Jens Johannes Bock
- Department of Orthodontics, Martin-Luther-University Halle, Wittenberg, Germany
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Liu H, Ni J, Wu L, He G. Diffusion bonding of mismatch dental alloys. J Biomed Mater Res B Appl Biomater 2009; 93:39-50. [DOI: 10.1002/jbm.b.31556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Watanabe I, Wallace C. Bond strength of gold alloys laser welded to cobalt-chromium alloy. Open Dent J 2008; 2:109-13. [PMID: 19088892 PMCID: PMC2596600 DOI: 10.2174/1874210600802010109] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2008] [Revised: 07/14/2008] [Accepted: 09/01/2008] [Indexed: 11/22/2022] Open
Abstract
The objective of this study was to investigate the joint properties between cast gold alloys and Co-Cr alloy laser-welded by Nd:YAG laser. Cast plates were fabricated from three types of gold alloys (Type IV, Type II and low-gold) and a Co-Cr alloy. Each gold alloy was laser-welded to Co-Cr using a dental laser-welding machine. Homogeneously-welded and non-welded control specimens were also prepared. Tensile testing was conducted and data were statistically analyzed using ANOVA. The homogeneously-welded groups showed inferior fracture load compared to corresponding control groups, except for Co-Cr. In the specimens welded heterogeneously to Co-Cr, Type IV was the greatest, followed by low-gold and Type II. There was no statistical difference (P<0.05) in fracture load between Type II control and that welded to Co-Cr. Higher elongations were obtained for Type II in all conditions, whereas the lowest elongation occurred for low-gold welded to Co-Cr. This study indicated that, of the three gold alloys tested, the Type IV gold alloy was the most suitable alloy for laser-welding to Co-Cr.
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Affiliation(s)
- Ikuya Watanabe
- Department of Biomaterials Science, Baylor College of Dentistry, Texas A&M Health Science Center, Dallas, TX, 75246 USA
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Bock JJ, Fraenzel W, Bailly J, Gernhardt CR, Fuhrmann RAW. Influence of different brazing and welding methods on tensile strength and microhardness of orthodontic stainless steel wire. Eur J Orthod 2008; 30:396-400. [PMID: 18617503 DOI: 10.1093/ejo/cjn022] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Jens Johannes Bock
- Department of Orthodontics, University School of Dental Medicine, Martin-Luther-University Halle-Wittenberg, Halle/Saale, Germany.
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Srimaneepong V, Yoneyama T, Kobayashi E, Doi H, Hanawa T. Comparative study on torsional strength, ductility and fracture characteristics of laser-welded α+β Ti–6Al–7Nb alloy, CP Titanium and Co–Cr alloy dental castings. Dent Mater 2008; 24:839-45. [DOI: 10.1016/j.dental.2007.10.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Revised: 09/24/2007] [Accepted: 10/09/2007] [Indexed: 11/17/2022]
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Lin MC, Lin SC, Wang YT, Hu SW, Lee TH, Chen LK, Huang HH. Fracture resistance of Nd:YAG laser-welded cast titanium joints with various clinical thicknesses and welding pulse energies. Dent Mater J 2007; 26:367-72. [PMID: 17694746 DOI: 10.4012/dmj.26.367] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The purpose of this study was to evaluate the fracture resistance of Nd:YAG laser-welded cast titanium (Ti) joints with various clinical thicknesses and welding pulse energies. A four-point bending test was used to assess the effects of various specimen thicknesses (1-3 mm) and welding pulse energies (11-24 J) on the fracture resistance of Nd:YAG laser-welded Ti dental joints. Fracture resistance was evaluated in terms of the ratio of the number of fractured specimens to the number of tested specimens. As for the fracture frequencies, they were compared using the Cochran-Mantel-Haenszel test. Morphology of the fractured Ti joints was observed using a scanning electron microscope. Results showed that decreasing the specimen thickness and/or increasing the welding pulse energy, i.e., increasing the welded area percentage, resulted in an increase in the fracture resistance of the Ti joint. Where fracture occurred, the fracture site would be at the center of the weld metal.
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Affiliation(s)
- Mau-Chin Lin
- Department of Dental Laboratory Technology, Central Taiwan University of Science and Technology, Taichung 406, Taiwan
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Watanabe I, Chang J, Chiu Y. Dimensional change of laser-welded gold alloy induced by heat treatment. J Prosthodont 2007; 16:365-9. [PMID: 17559532 DOI: 10.1111/j.1532-849x.2007.00210.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
PURPOSE This study examined the effects of laser welding and heat treatment on the dimensional change of cast gold alloy frameworks. MATERIALS AND METHODS Pairs of cast gold alloy plates were matched, fixed in a jig, and welded in a laser-welding machine at constant welding parameters. The specimens were welded unilaterally (on one surface) or bilaterally (on two surfaces) with five spots as follows: two ends fixed/unilaterally welded (A); two ends fixed/bilaterally welded (AA); one end fixed/unilaterally welded (B); two ends fixed/welded on one surface and then one end fixed/welded on the opposite surface (AB); or one end fixed/bilaterally welded (BB). The dimensional change was determined by measuring the gap between the jig base and one end of the specimen after each welding application. Dimensional change was also measured after two different heat treatments (softening and hardening). The results were analyzed using a two-way ANOVA and Duncan's test (p < 0.05). RESULTS The dimensional change of the specimens fixed at only one end on either surface (AB, B, and BB) was higher compared with the two ends-fixed specimens (A and AA) after laser welding. The heat treatments also increased the dimensional change in all groups except for the B group. The dimensional change was similar for each fixing method between the two types of heat treatment. CONCLUSIONS The method of fixing the specimens in the jig significantly affected the amount of dimensional change of the gold alloys. The heat treatments of the laser-welded specimens increased the dimensional change by releasing the residual stress.
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Affiliation(s)
- Ikuya Watanabe
- Department of Biomaterials Science, Baylor College of Dentistry, Texas A&M University System Health Science Center, Dallas, TX 75246, USA.
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Bertrand C, Laplanche O, Rocca JP, Le Petitcorps Y, Nammour S. Effect of the combination of different welding parameters on melting characteristics of grade 1 titanium with a pulsed Nd-Yag laser. Lasers Med Sci 2007; 22:237-44. [PMID: 17308957 DOI: 10.1007/s10103-006-0438-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2006] [Accepted: 12/18/2006] [Indexed: 10/23/2022]
Abstract
The laser is a very attractive tool for joining dental metallic alloys. However, the choice of the setting parameters can hardly influence the welding performances. The aim of this research was to evaluate the impact of several parameters (pulse shaping, pulse frequency, focal spot size...) on the quality of the microstructure. Grade 1 titanium plates have been welded with a pulsed Nd-Yag laser. Suitable power, pulse duration, focal spot size, and flow of argon gas were fixed by the operator. Five different pulse shapes and three pulse frequencies were investigated. Two pulse shapes available on this laser unit were eliminated because they considerably hardened the metal. As the pulse frequency rose, the metal was more and more ejected, and a plasma on the surface of the metal increased the oxygen contamination in the welded area. Frequencies of 1 or 2 Hz are optimum for a dental use. Three pulse shapes can be used for titanium but the rectangular shape gives better results.
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Affiliation(s)
- C Bertrand
- Department of Restorative Dentistry and Endodontics (Nice Sophia-Antipolis, France), Laboratoire LASIO, 06357, Nice Cedex, France.
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Huang HH, Lin MC, Lin CC, Lin SC, Hsu CC, Chen FL, Lee SY, Hung CC. Effects of welding pulse energy and fluoride ion on the cracking susceptibility and fatigue behavior of Nd:YAG laser-welded cast titanium joints. Dent Mater J 2007; 25:632-40. [PMID: 17076339 DOI: 10.4012/dmj.25.632] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In this study, the cracking susceptibility and fatigue behavior of Nd:YAG laser-welded cast Ti joints (welding pulse energy: 11, 15, and 18 J) in fluoride-containing (0 and 0.5% NaF) artificial saliva were evaluated using constant elongation rate test (CERT) and fatigue test (FT), respectively. Both CERT and FT were also carried out in open air as controls. Results showed that increasing the welding energy increased the elongation and fatigue life, but decreased the tensile strength, of cast Ti joints in open-air environment. With a welding energy of 11 J, the fluoride ions in the artificial saliva increased the cracking susceptibility and decreased the fatigue life of Ti joints. When the welding energy exceeded 15 J, the presence of fluoride ions still increased the cracking susceptibility, but did not reduce the fatigue life of Ti joints. Rupture of Ti joints--if it occurred--occurred only at the welded metal (versus the non-welded part).
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Affiliation(s)
- Her-Hsiung Huang
- Faculty of Dentistry, School of Dentistry, National Yang-Ming University, Taipei, Taiwan
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Zupancic R, Legat A, Funduk N. Tensile strength and corrosion resistance of brazed and laser-welded cobalt-chromium alloy joints. J Prosthet Dent 2006; 96:273-82. [PMID: 17052472 DOI: 10.1016/j.prosdent.2006.08.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
STATEMENT OF PROBLEM The longevity of prosthodontic restorations is often limited due to the mechanical or corrosive failure occurring at the sites where segments of a metal framework are joined together. PURPOSE The purpose of this study was to determine which joining method offers the best properties to cobalt-chromium alloy frameworks. Brazed and 2 types of laser-welded joints were compared for their mechanical and corrosion characteristics. MATERIAL AND METHODS Sixty-eight cylindrical cobalt-chromium dental alloy specimens, 35 mm long and 2 mm in diameter, were cast. Sixteen specimens were selected for electrochemical measurements in an artificial saliva solution and divided into 4 groups (n=4). In the intact group, the specimens were left as cast. The specimens of the remaining 3 groups were sectioned at the center, perpendicular to the long-axis, and were subsequently rejoined by brazing (brazing group) or laser welding using an X- or I-shaped joint design (X laser and I laser groups, respectively). Another 16 specimens were selected for electrochemical measurements in a more acidic artificial saliva solution. These specimens were also divided into 4 groups (n=4) as described above. Electrochemical impedance spectroscopy and potentiodynamic polarization were used to assess corrosion potentials, breakdown potentials, corrosion current densities, total impedances at lowest frequency, and polarization charge-transfer resistances. The remaining 36 specimens were used for tensile testing. They were divided into 3 groups in which specimen pairs (n=6) were joined by brazing or laser welding to form 70-mm-long cylindrical rods. The tensile strength (MPa) was measured using a universal testing machine. Differences between groups were analyzed using 1-way analysis of variance (alpha=.05). The fracture surfaces and corrosion defects were examined with a scanning electron microscope. RESULTS The average tensile strength of brazed joints was 792 MPa and was significantly greater (P<.05) than the tensile strength of both types of laser-welded joints (404 MPa and 405 MPa). When laser welding was used, successful joining was limited to the peripheral aspects of the weld. The welding technique did not significantly affect the joint tensile strength. Electrochemical measurements indicated that the corrosion resistance of the laser-welded joints was better than of the brazed ones, primarily due to differences in passivation ability. CONCLUSION Laser welding provides excellent corrosion resistance to cobalt-chromium alloy joints, but strength is limited due to the shallow weld penetration. Brazed joints are less resistant to corrosion but have higher tensile strength than laser welds.
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Affiliation(s)
- Rok Zupancic
- Department of Prosthodontics, University of Ljubljana, Faculty of Medicine, Division of Dental Medicine, Slovenia.
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Abstract
PURPOSE This study investigated the effect of argon gas shielding on the strengths of laser-welded cast Ti and Ti-6Al-7Nb and compared the results to those of two dental casting alloys. MATERIALS AND METHODS Cast plates of Ti, Ti-6Al-7Nb, gold, and Co-Cr alloy were prepared. After polishing the surfaces to be welded, two plates were abutted and welded using Nd:YAG laser at a pulse duration of 10 ms, spot diameter of 1 mm, and voltage of 200 V. Five specimens were prepared for each metal by bilaterally welding them with three or five spots either with or without argon shielding. The failure load and percent elongation were measured at a crosshead speed of 1.0 mm/min. RESULTS The factor of argon shielding significantly affected the failure load and elongation of the laser-welded specimens. The failure loads of argon-shielded laser-welded CP Ti and Ti-6Al-7Nb were greater compared with the failure loads of specimens welded without argon shielding for both three- and five-spot welding. Regardless of argon shielding, the failure loads of the laser-welded gold alloy were approximately half that of the control specimens. In contrast, the failure loads of the nonshielded laser-welded Co-Cr alloy were greater. The percent elongations positively correlated with the failure loads. CONCLUSIONS The use of argon shielding is necessary for effective laser-welding of CP Ti and Ti-6Al-7Nb but not for gold and Co-Cr alloy.
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Affiliation(s)
- Ikuya Watanabe
- Department of Biomaterials Science, Baylor College of Dentistry, Texas A&M University System Health Science Center, Dallas, 75246, USA.
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Baba N, Watanabe I. Penetration depth into dental casting alloys by Nd:YAG laser. J Biomed Mater Res B Appl Biomater 2005; 72:64-8. [PMID: 15389499 DOI: 10.1002/jbm.b.30117] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
This study investigated the effect of laser-beam welding conditions [voltage (V) and spot diameter (mm)] on the penetration depth into dental casting alloys. Castings (3.0 mm x 8.0 mm x 50 mm) were prepared from the metals used in this study: commercially pure titanium (CP Ti), Ti-6Al-4V, Ti-6Al-7Nb, cobalt-chromium alloy (Co-Cr) and Type IV gold alloy. Two cast blocks of each metal were butted against one another at the 8.0 x 50-mm surfaces. They were then welded at their interface under the following conditions: voltage of 160-340 V, spot diameter of 0.4-1.6 mm, and pulse duration of 10 ms. After laser welding, the blocks were separated, and the penetration depth into each alloy was measured. The data were analyzed with the use of ANOVA at the p < 0.05 level of significance. The penetration depths were as follows: CP Ti (0.29-6.45 mm), Ti-6Al-4V (0.32-5.24 mm), Ti-6Al-7Nb (0.34-5.65 mm), Co-Cr (0.24-6.15 mm), and Type IV gold alloy (0.12-5.22 mm). The voltage and spot diameter affected the penetration depth into the metals tested. When the voltage increased and the spot diameter decreased, the penetration depth increased for each metal. Selecting suitable conditions for laser welding to obtain sufficient penetration depth for the optimal thickness of the metal is important when welding prostheses.
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Affiliation(s)
- N Baba
- Department of Developmental and Reconstructive Medicine, Division of Fixed Prosthodontics and Oral Rehabilitation, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
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Maalhagh-Fard A, Wagner WC. Repair of fractured framework: scanning electron microscopy and energy dispersive X-ray spectroscopy. IMPLANT DENT 2004; 13:197-201. [PMID: 15359153 DOI: 10.1097/01.id.0000135915.21010.e3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Fractured metal prostheses can be analyzed for possible causes of failure using scanning electron microscopy (SEM). In this study, fractography is used to determine the cause of the failure and whether repair is practical. Energy-dispersive x-ray spectroscopy (EDS) is used to determine composition of the fractured prosthesis so that a repair process can be recommended. The technique is presented for the repair of a titanium framework for an implant-supported overdenture based on the analysis data.
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Affiliation(s)
- Ahmad Maalhagh-Fard
- Department of Prosthodontics, University of Detroit, Mercy School of Dentistry, Detroit, Michigan 48219-0900, USA.
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Costa EMVD, Neisser MP, Bottino MA. Multiple-unit implant frames: one-piece casting vs. laser welding and brazing. J Appl Oral Sci 2004; 12:227-31. [PMID: 21049258 DOI: 10.1590/s1678-77572004000300013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2004] [Accepted: 05/27/2004] [Indexed: 11/22/2022] Open
Abstract
The linear distortion of prostheses over implants, one-piece casting and cast in sections followed by laser welding by laser and brazing was evaluated in an edentulous mandibular model with five parallel abutments, with a distance of 10mm from center to center. Seventy five gold cylinders were tightened with screws on the abutments with 10Ncm torque. The cylinder/analogue assemblies were measured by microscopic examination (0.001mm accuracy) and the obtained results were compared with the GC (control group). Fifteen metal frames were waxed and cast in a gold alloy (Stabilor, Degussa Hulls, Brazil) and divided into three groups with five elements each, as followed: GM (one-piece casting), GB (section and brazing) and GL (section and laser welding). In all groups, measurements were taken at the right, left, buccal and lingual sides of the cylinder/analogue interface and the results were submitted to analysis of variance (ANOVA) and to the Tukey test (5%). The smallest amount of distortion was seen in the laser group (GL with a mean value of 13.58), followed by the brazing group (GB with a mean value of 24.33) and one-piece (GM with a mean value of 40.00). The greatest distortion was found in the one-piece group (GM).
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Affiliation(s)
- Elza Maria Valadares da Costa
- Department of Prosthodontics and Dental Materials, Dental School, Universidade Estadual Paulista, São José dos Campos, São Paulo, Brazil
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Bertrand C, le Petitcorps Y, Albingre L, Dupuis V. Optimization of operator and physical parameters for laser welding of dental materials. Br Dent J 2004; 196:413-8; discussion 407. [PMID: 15071534 DOI: 10.1038/sj.bdj.4811138] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2002] [Accepted: 09/23/2002] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Interactions between lasers and materials are very complex phenomena. The success of laser welding procedures in dental metals depends on the operator's control of many parameters. The aims of this study were to evaluate factors relating to the operator's dexterity and the choice of the welding parameters (power, pulse duration and therefore energy), which are recognized determinants of weld quality. DESIGN In vitro laboratory study. MATERIALS AND METHODS FeNiCr dental drawn wires were chosen for these experiments because their properties are well known. Different diameters of wires were laser welded, then tested in tension and compared to the control material as extruded, in order to evaluate the quality of the welding. Scanning electron microscopy of the fractured zone and micrograph observations perpendicular and parallel to the wire axis were also conducted in order to analyse the depth penetration and the quality of the microstructure. Additionally, the micro-hardness (Vickers type) was measured both in the welded and the heat-affected zones and then compared to the non-welded alloy. RESULTS Adequate combination of energy and pulse duration with the power set in the range between 0.8 to 1 kW appears to improve penetration depth of the laser beam and success of the welding procedure. Operator skill is also an important variable. CONCLUSION The variation in laser weld quality in dental FeNiCr wires attributable to operator skill can be minimized by optimization of the physical welding parameters.
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Affiliation(s)
- C Bertrand
- Dental School, Laboratoire 'surface- interface', Université de Nice, Sophia-Antipolis, 24, avenue des diables bleus, 06357 Nice Cedex 04, France.
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Abstract
OBJECTIVE The objective of this study was to examine the joint strength of titanium laser-welding using several levels of laser output energy [current (A)]. METHODS Cast titanium plates (0.5 x 3.0 x 40 and 1.0 x 3.0 x 40 mm(3)) were prepared and perpendicularly cut at the center of the plate. After the cut halves were fixed in a jig, they were laser-welded using a Nd: YAG laser at several levels of output energy in increments of 30A from 180 to 300A. The penetration depths of laser to titanium were measured under various conditions for output energy, pulse duration, and spot diameter to determine the appropriate conditions for these parameters. Based on the correlation between the results obtained for penetration depth and the size of the specimens (thickness: 0.5 and 1.0 mm, width: 3.0 mm), the pulse duration and spot diameter employed in this study were 10 ms and 1.0 mm, respectively. Three laser pulses (spot diameter: 1.0 mm) were applied from one side to weld the entire joint width (3.0 mm) of the specimens. Uncut specimens served as the non-welded control specimens. Tensile testing was conducted at a crosshead speed of 2 mm/min and a gage length of 10 mm. The breaking force (N) was recorded, and the data (n=5) were statistically analyzed. RESULTS For the 0.5 mm thick specimens, the breaking force of the specimens laser-welded at currents of 240, 270, and 300A were not statistically (P>0.05) different from the non-welded control specimens. There were no significant differences in breaking force among the 1.0mm thick specimens laser-welded at currents of 270 and 300A, and the non-welded control specimens. SIGNIFICANCE Under appropriate conditions, joint strengths similar to the strength of the non-welded parent metal were achieved.
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Affiliation(s)
- J Liu
- Department of Fixed Prosthodontics, School of Dentistry, Nagasaki University, 1-7-1 Sakamoto, Nagasaki 852-8588, Japan
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Watanabe I, Liu J, Atsuta M. Effects of heat treatments on mechanical strength of laser-welded equi-atomic AuCu-6at%Ga alloy. J Dent Res 2001; 80:1813-7. [PMID: 11926239 DOI: 10.1177/00220345010800090801] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
There is little information available on the mechanical strengthening of laser-welded gold alloys to achieve reliable dental prostheses. This study examined the hypothesis that heat treatments increase the mechanical strength of a laser-welded equi-atomic AuCu-6at%Ga alloy with age "hardenability" at intra-oral temperature. Cut cast gold alloy plates were laser-welded. The specimens were given one of three heat treatments: (1) solution treatment, (2) high-temperature aging after solution treatment, and (3) simulated intra-oral aging after solution treatment. As-cast and uncut specimens were also prepared. Tensile testing was conducted, and the breaking stress and yield strength were recorded. The yield strength values of all the heat-treated specimens nearly reached the values of the corresponding heat-treated control specimens. The results of this study indicated that, for high mechanical strength to be achieved, the laser-welded alloy tested should be aged at a high temperature or be intraorally aged after being laser-welded.
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Affiliation(s)
- I Watanabe
- Department of Fixed Prosthodontics, Nagasaki University, School of Dentistry, Sakamoto, Japan.
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