26
|
Degidi M, Gehrke P, Spanel A, Piattelli A. Syncrystallization: A Technique for Temporization of Immediately Loaded Implants with Metal-Reinforced Acrylic Resin Restorations. Clin Implant Dent Relat Res 2006; 8:123-34. [PMID: 16919020 DOI: 10.1111/j.1708-8208.2006.00011.x] [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: 11/29/2022]
Abstract
BACKGROUND Rigid temporization has been recognized to have a significant impact on the peri-implant tissue response in immediate implant loading since it reduces the mechanical stress exerted on each implant. PURPOSE A successful protocol for immediate loading of multiple implants depends on an adequate fixation and immobility of the implants to prevent the risk of micromovements in relation to the surrounding bone. The objective of this article was to evaluate a prosthetic concept for an accelerated rigid splinting of multiple implants for same-day immediate loading with metal-reinforced provisional restorations using a technique of welding temporary implant abutments with a prefabricated titanium bar directly in the oral cavity (syncrystallization). MATERIALS AND METHODS Between June 2004 and January 2005, immediate loading of threaded implants with a metal- reinforced acrylic resin provisional restoration at stage 1 surgery was evaluated in 40 consecutive patients. A total of 192 implants were placed in selected edentulous or partially edentulous patients using the syncrystallization technique. Once the titanium bar was welded intraorally to the abutments, opaque was applied and the provisional restoration was relined and screw-retained the same day. In addition, a comparison of deformations and stress distributions in implant-supported, metal-reinforced and nonmetal-reinforced resin provisional restorations was analyzed in the edentulous mandible by a three-dimensional finite element model (FEM). RESULTS All of the 192 rigidly temporized immediately loaded implants osseointegrated. An implant success rate of 100% was achieved over a period of 6 months postplacement. No fracture or luting cement failure of the provisional restoration occurred during the observation time. Compared to mere acrylic superstructures, a significant reduction of deformation and strain within metal-reinforced provisional restorations was detected by FEM analysis. CONCLUSION The results of this study indicate that the syncrystallization technique allows an expedite and adequate rigid splinting of multiple immediately loaded implants. The advantages of the technique are: (1) reduction of treatment time for immediate temporization at stage 1 surgery; (2) predictable fixation and immobility of implants in the early stages of bone healing; and (3) less time for repairing provisional restorations as a result of no or rare fracture.
Collapse
MESH Headings
- Acrylic Resins/chemistry
- Computer Simulation
- Crystallization
- Dental Abutments
- Dental Alloys/chemistry
- Dental Implantation, Endosseous/methods
- Dental Implants
- Dental Prosthesis, Implant-Supported
- Dental Restoration, Temporary
- Dental Soldering/methods
- Denture Design
- Finite Element Analysis
- Humans
- Imaging, Three-Dimensional
- Jaw, Edentulous/rehabilitation
- Jaw, Edentulous/surgery
- Jaw, Edentulous, Partially/rehabilitation
- Jaw, Edentulous, Partially/surgery
- Mandible/physiopathology
- Osseointegration/physiology
- Splints
- Stress, Mechanical
- Titanium
- Treatment Outcome
Collapse
|
27
|
Huang QF, Zhang JZ, Jiang WD, Li Q, Yu JX. [The effects of different welding wires on the mechanical properties of laser welding joints]. SHANGHAI KOU QIANG YI XUE = SHANGHAI JOURNAL OF STOMATOLOGY 2006; 15:427-30. [PMID: 16955174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
PURPOSE To evaluate the mechanical properties and microstructure of laser-welded joints with different welding wires for clinical use of welding wire. METHODS The standard tensile test and three-point bending test rods were made from Co-Cr and Ni-Cr alloy, and were laser-welded with different welding wire (commercially welding wire and casting wire). Then the tensile rods were tested for the ultimate tensile strength (UTS), and the bending rods for the ultimate bending strength (UBS). The results was analyzed by one-way ANOVA. The tensile fracture surface were examined by scanning electron microscopy (SEM). Metallurgical analysis were also performed on polished longitudinal sectioned samples. RESULTS For Co-Cr alloy, the UTS of casting wire group and commercially welding wire group was respectively (606.40+/-82.53)MPa and (693.61+/-47.68)MPa; the UBS was respectively (997.95+/-88.89)MPa and (1160.76+/-91.59)MPa. ANOVA showed a significant difference of UTS and UBS between the two groups at the 0.05 level (P<0.05). For Ni-Cr alloy, the UTS of casting wire group and commercially welding wire group was respectively (558.14+/-46.75)MPa and (582.32+/-35.43)MPa; the UBS was respectively (1084.75+/-46.02)MPa and (1078.29+/-36.25)MPa. There was no significant difference between the two groups (P>0.05). SEM and metallurgical examination showed the welded zone exhibiting more cracks in the casting wire group than in the commercially welding wire group. CONCLUSION It would be advisable to work with commercially welding wire for the joints that need better strength.
Collapse
|
28
|
Hart CN, Wilson PR. Evaluation of welded titanium joints used with cantilevered implant-supported prostheses. J Prosthet Dent 2006; 96:25-32. [PMID: 16872927 DOI: 10.1016/j.prosdent.2006.05.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
STATEMENT OF PROBLEM Early failure of laser-welded titanium implant frameworks in clinical practice has prompted an investigation of the strength and durability of welded cantilevered titanium sections. PURPOSE The purpose of this study was to determine the effect that the use of filler wire in laser welding of titanium cantilever frameworks had on the flexural strength and fatigue resistance of the welded joints. MATERIAL AND METHODS Sixty titanium implant-supported frameworks with 12-mm cantilevers were fabricated in 4 groups (n=15), using 3 different laser welding protocols with 0, 1, and 2 weld passes with filler wire, and 1 conventional tungsten inert gas welding method. The volume of filler wire used (mean volumes 0, 1.7, 3.4, and 8.3 mm(3)) was determined by measurement of the length of wire before and after welding each joint. Ten frameworks from each group were tested for ultimate flexural strength by loading the cantilevers 10 mm from the abutment. The remaining 5 frameworks from each group were similarly tested under a simulated masticatory load of 200 N until failure, or to 1 million cycles. A 2-way analysis of variance was used to examine the flexural strengths, and log-rank statistics were applied to cyclic test data (alpha=.05). RESULTS There were significant differences between the 4 groups for ultimate flexural strength (P<.001) and resistance to cyclic loading (P=.002). The volume of filler wire added was a significant predictor of ultimate flexural strength (P=.03), and was a borderline determinant of the number of cycles to failure at 200 N (P=.05). Each laser weld pass with filler wire roughly doubled the ultimate flexural strength and fatigue resistance of the joint relative to the previous weld. Tungsten inert gas welding with efficient argon shielding deposited the most filler wire and produced the strongest and most fatigue-resistant joints. CONCLUSION The ultimate flexural strength and fatigue resistance of cantilevered joints in laser-welded titanium prostheses are improved by the use of filler wire. Tungsten inert gas welding with efficient argon shielding can be used in situations when a high-strength joint is required.
Collapse
|
29
|
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.
Collapse
|
30
|
Jackson BJ. The use of laser-welded titanium framework technology: a case report for the totally edentulous patient. J ORAL IMPLANTOL 2006; 31:294-300. [PMID: 16447902 DOI: 10.1563/779.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Laser-welded technology has become a viable alternative to the conventional lost wax-casting technique in the field of implant dentistry. Studies have demonstrated the predictable nature of laser-welded titanium frameworks for endosseous implants in the partial and totally edentulous patient. A standardized impression and fabrication procedure is required for an accurate and predictable superstructure. More long-term studies are needed for more widespread acceptance and usage by dental practitioners.
Collapse
|
31
|
Rubenstein JE, Lowry MB. A comparison of two solder registration materials: A three-dimensional analysis. J Prosthet Dent 2006; 95:379-91. [PMID: 16679133 DOI: 10.1016/j.prosdent.2006.02.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
STATEMENT OF PROBLEM Use of a segmental indexing/soldering approach for assembly of complete arch implant frameworks has been advocated by some clinicians to achieve a passively fitting framework. To the authors' knowledge, a mathematical assessment using a 3-dimensional (3-D) distortion analysis has not been performed comparing segmental framework assembly to reassembly of 1-piece complete arch frameworks that required sectioning, indexing, and soldering. PURPOSE The present study compared the use of 2 indexing materials, autopolymerizing acrylic resin and light-polymerized composite resin, for use in solder registration of complete-arch implant frameworks using 3 framework/indexing material combinations: gold/light-polymerized composite resin, silver palladium/autopolymerizing acrylic resin, and silver palladium/light-polymerized composite resin. MATERIAL AND METHODS Five frameworks for each alloy/index combination were fabricated, for a total of 15 frameworks. Each framework was fitted to 5 implant abutments. Measurements were made of the initial gold cylinder/abutment positions for each of the 5 sites for the 15 frameworks. The 3-D spatial orientation of each gold cylinder/abutment was calculated prior to the gold cylinders being incorporated into the framework casting and served as the control against which all measurements were compared. After the indexing/soldering procedures, the 3-D spatial orientations of the cylinders were measured, first as 2- and 3-unit solder assembled framework segments and, finally, for complete-arch frameworks. These measurements were recorded in micrometers for linear distortions and degrees for angular distortions using a coordinate measurement machine (CMM). These data were compared and statistically assessed using a 1-way analysis of variance (ANOVA). A Student-Newman-Keuls test was used to determine significance between cylinders within each indexing combination. A repeated-measures ANOVA and a Student-Newman-Keuls test were used to determine significance between alloy/index group and cylinders for each of the measurement variables with statistical significance at alpha=.05 for all statistical analyses. RESULTS Mean differences and SDs of total linear change for all groups found dR (total linear change) to be 33.56 +/- 27.70 mum for gold/light-polymerized composite resin, 34.87 +/- 27.99 mum for silver palladium/autopolymerizing acrylic resin, and 31.56 +/- 24.37 mum for silver palladium/light-polymerized composite resin. Total angular change, dtheta(R), was calculated to be 0.47 +/- 0.13 degrees for gold/light-polymerized composite resin, 0.46 +/- 0.17 degrees for silver palladium/autopolymerizing acrylic resin, and 0.52 +/- 0.15 degrees for silver palladium/light-polymerizing composite resin. CONCLUSIONS No significant differences were found between alloy/index combinations, except for the measured variable dtheta(y), angular change about the Y axis.
Collapse
|
32
|
Michalakis KX, Kang K, Hirayama H. Repositioning implant replicas after soldering a fixed complete denture framework. J Prosthet Dent 2006; 95:331-2. [PMID: 16616133 DOI: 10.1016/j.prosdent.2006.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
33
|
Zhu JF, He HM, Gao B, Wang ZY. [Effects of laser welding on bond of porcelain fused cast pure titanium]. ZHONGHUA KOU QIANG YI XUE ZA ZHI = ZHONGHUA KOUQIANG YIXUE ZAZHI = CHINESE JOURNAL OF STOMATOLOGY 2006; 41:236-9. [PMID: 16784592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
OBJECTIVE To investigate the influence of the laser welding on bond of porcelain fused to cast pure titanium. METHODS Twenty cast titanium plates were divided into two groups: laser welded group and control group. The low-fusing porcelain was fused to the laser welded cast pure titanium plates at fusion zone. The bond strength of the porcelain to laser welded cast pure titanium was measured by the three-point bending test. The interface of titanium and porcelain was investigated by scanning electron microscopy (SEM) and energy depressive X-ray detector (EDX). The non-welded titanium plates were used as comparison. RESULTS No significant difference of the bond strength was found between laser-welded samples [(46.85 +/- 0.76) MPa] and the controls [(41.71 +/- 0.55) MPa] (P > 0.05). The SEM displayed the interface presented similar irregularities with a predominance. The titanium diffused to low-fusing porcelain, while silicon and aluminum diffused to titanium basement. CONCLUSIONS Laser welding does not affect low-fusing porcelain fused to pure titanium.
Collapse
|
34
|
Gehrke P. The syncrystallization technique: expediting rigid splinting of immediately loaded implants. DENTAL IMPLANTOLOGY UPDATE 2006; 17:17-23. [PMID: 16524254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
|
35
|
Shin C, Miura H, Okada D, Yamazaki A. Accuracy of Temporary Laser Welding of FPDs by Nd:YAG Laser in the Oral Cavity. Dent Mater J 2006; 25:604-10. [PMID: 17076334 DOI: 10.4012/dmj.25.604] [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: 11/23/2022]
Abstract
The purpose of this study was to investigate the accuracy of temporary fixation with laser welding for fixed partial dentures (FPDs). Five kinds of experimental FPD with different welding/soldering gaps were fabricated (0, 20, 50 microm for welding; 300 microm for soldering). Then, FPDs were temporary-fixed by laser welding or with a self-curing resin. Fixation accuracy was evaluated by the change in distance and the angular deformation between two retainers. The change in distance and the angular deformation between two retainers of the FPD without welding/soldering gap were significantly larger than the other FPDs (p<0.05). With due consideration to the displacement of teeth or implants especially in the mesiodistal direction, and by taking into account the inevitable errors of the indirect method, it seemed reasonable to provide a welding space of approximately 20 microm.
Collapse
|
36
|
Rocha R, Pinheiro ALB, Villaverde AB. Flexural strength of pure Ti, Ni-Cr and Co-Cr alloys submitted to Nd:YAG laser or TIG welding. Braz Dent J 2006; 17:20-3. [PMID: 16721459 DOI: 10.1590/s0103-64402006000100005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Welding of metals and alloys is important to Dentistry for fabrication of dental prostheses. Several methods of soldering metals and alloys are currently used. The purpose of this study was to assess, using the flexural strength testing, the efficacy of two processes Nd:YAG laser and TIG (tungsten inert gas) for welding of pure Ti, Co-Cr and Ni-Cr alloys. Sixty cylindrical specimens were prepared (20 of each material), bisected and welded using different techniques. Four groups were formed (n=15). I: Nd:YAG laser welding; II- Nd:YAG laser welding using a filling material; III- TIG welding and IV (control): no welding (intact specimens). The specimens were tested in flexural strength and the results were analyzed statistically by one-way ANOVA. There was significant differences (p<0.001) among the non-welded materials, the Co-Cr alloy being the most resistant to deflection. Comparing the welding processes, significant differences (p<0.001) where found between TIG and laser welding and also between laser alone and laser plus filling material. In conclusion, TIG welding yielded higher flexural strength means than Nd:YAG laser welding for the tested Ti, Co-Cr and Ni-Cr alloys.
Collapse
|
37
|
Abstract
A technique to create an individually modified implant prosthetic abutment is described. An overcasting is waxed onto a machined titanium abutment, cast in titanium, and joined to it with laser welding. With the proposed technique, a custom-made titanium implant prosthetic abutment is created with adequate volume and contour of metal to support a screw-retained, metal-ceramic implant-supported crown.
Collapse
|
38
|
Watanabe I, Benson AP, Nguyen K. Effect of Heat Treatment on Joint Properties of Laser-Welded Ag-Au-Cu-Pd and Co-Cr Alloys. J Prosthodont 2005; 14:170-4. [PMID: 16336234 DOI: 10.1111/j.1532-849x.2005.04040.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
PURPOSE This study investigated the effect of heat treatment on the strengths of laser-welded cast Ag-Au-Cu-Pd and Co-Cr alloys. MATERIALS AND METHODS Cast plates of Ag-Au-Cu-Pd (Ag) and Co-Cr (Co) alloys were prepared. After polishing the surfaces to be welded, the plates were matched and butted Ag to Ag (Ag/Ag), Co to Co (Co/Co), and Ag to Co (Ag/Co) 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 experimental condition by bilaterally welding them with five spots. The Ag/Ag, Ag/Co, and control Ag underwent two heat treatments-softening (ST) and hardening (AH). A group of as-cast specimens serving as controls was not given either heat treatment. The failure load and percent elongation were measured at a crosshead speed of 1.0 mm/min. RESULTS The fracture resistance of Co/Co was similar to that of the control Co, while the fracture resistance of Co/Ag was significantly lower than that of both like alloy pairings for all heat-treating conditions. The control Ag had greater fracture resistance after AH and lower fracture resistance after ST. The AH treatment increased the fracture resistance, and the ST treatment decreased the fracture resistance of both Ag/Ag and Co/Ag, although not significantly. The percentage of elongation appeared to positively correlate with the fracture resistance results. CONCLUSIONS The results obtained in this study indicated that the age-hardening heat treatment increased the weld strength between the paired Au-Ag-Cu-Pd alloys and between the Au-Ag-Cu-Pd and Co-Cr alloys.
Collapse
|
39
|
Chao Y, Du L, Yang L. Comparative study of the surface characteristics, microstructure, and magnetic retentive forces of laser-welded dowel-keepers and cast dowel-keepers for use with magnetic attachments. J Prosthet Dent 2005; 93:473-7. [PMID: 15867758 DOI: 10.1016/j.prosdent.2005.02.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
STATEMENT OF PROBLEM Information regarding the merits and problems associated with connecting a keeper to a dowel and coping using a laser welding technique has not been explored extensively in the dental literature. PURPOSE This in vitro study compared the surface characteristics, microstructure, and magnetic retentive forces for a dowel and coping-keeper mechanism fabricated using a laser welding process and a cast-to casting technique. MATERIAL AND METHODS Five cast-to and 6 laser-welded dowel and coping-keeper specimens were tested. Using 5 freestanding keepers as the control group, the surface characteristics and microstructures of the specimens were examined by means of stereomicroscopy, metallographic microscopy, and scanning electron microscopy (SEM). Energy-dispersive spectroscopic (EDS) microanalysis with SEM provided elemental concentration information for the test specimens. The vertical magnetic retentive forces (N) of the 3 groups were measured using a universal testing machine. The results were statistically compared using 1-way analysis of variance and the Newman-Keuls multiple range test (alpha =.05). RESULTS The laser-welded dowel-keeper generally maintained its original surface smoothness as well as the original microstructure. Elements diffused readily through the fusion zone. The surface of the cast dowel-keeper became rough with the formation of an oxide layer, the microstructure changed, and there was only limited elemental diffusion in the fusion zone. The average vertical magnetic retentive force of the laser-welded group, the cast group, and the control group were 4.2 +/- 0.2 N, 3.8 +/- 0.3 N, and 5.6 +/- 0.3 N, respectively. Statistically significant differences in vertical magnetic retentive force were found between the control group and both the laser-welded and cast groups (P <.01). Compared with the cast dowel-keepers, the average vertical magnetic retentive force of the laser-welded dowel-keepers was significantly higher (P <.05). CONCLUSION The laser welding technique had less influence on the surface characteristics, the microstructure, and the magnetic retentive forces of keepers relative to techniques that incorporate a keeper at the time of cast dowel and coping fabrication.
Collapse
|
40
|
Uysal H, Kurtoglu C, Gurbuz R, Tutuncu N. Structure and mechanical properties of Cresco-Ti laser-welded joints and stress analyses using finite element models of fixed distal extension and fixed partial prosthetic designs. J Prosthet Dent 2005; 93:235-44. [PMID: 15775924 DOI: 10.1016/j.prosdent.2004.11.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
STATEMENT OF PROBLEM The Cresco-Ti System uses a laser-welded process that provides an efficient technique to achieve passive fit frameworks. However, mechanical behavior of the laser-welded joint under biomechanical stress factors has not been demonstrated. PURPOSE This study describes the effect of Cresco-Ti laser-welding conditions on the material properties of the welded specimen and analyzes stresses on the weld joint through 3-dimensional finite element models (3-D FEM) of implant-supported fixed dentures with cantilever extensions and fixed partial denture designs. MATERIAL AND METHODS Twenty Grade III (ASTM B348) commercially pure titanium specimens were machine-milled to the dimensions described in the EN10002-1 tensile test standard and divided into test (n = 10) and control (n = 10) groups. The test specimens were sectioned and laser-welded. All specimens were subjected to tensile testing to determine yield strength (YS), ultimate tensile strength (UTS), and percent elongation (PE). The Knoop micro-indentation test was performed to determine the hardness of all specimens. On welded specimens, the hardness test was performed at the welded surface. Data were analyzed with the Mann-Whitney U test and Student's t test (alpha=.05). Fracture surfaces were examined by scanning electron microscopy to characterize the mode of fracture and identify defects due to welding. Three-dimensional FEMs were created that simulated a fixed denture with cantilever extensions supported by 5 implants (M1) and a fixed partial denture supported by 2 implants (M2), 1 of which was angled 30 degrees mesio-axially. An oblique load of 400 N with 15 degrees lingual-axial inclinations was applied to both models at various locations. RESULTS Test specimens fractured between the weld and the parent material. No porosities were observed on the fractured surfaces. Mean values for YS, UTS, PE, and Knoop hardness were 428 +/- 88 MPa, 574 +/- 113 MPa, 11.2 +/- 0.4%, 270 +/- 17 KHN, respectively, for the control group and 642 +/- 2 MPa, 772 +/- 72 MPa, 4.8 +/- 0.7%, 353 +/- 23 KHN, respectively, for the test group. The differences between the groups were significant for all mechanical properties ( P <.05). For both models, the FEA revealed that maximum principal stresses were concentrated at the framework-weld junction but did not exceed the UTS of the weld joint. CONCLUSION Within the constraints of the finite element models, mechanical failure of the welded joint between the support and the framework may not be expected under biomechanical conditions simulated in this study.
Collapse
|
41
|
Shehab AH, Pappas M, Burns DR, Douglas H, Moon PC. Comparative tensile strengths of preceramic and postceramic solder connectors using high-palladium alloy. J Prosthet Dent 2005; 93:148-52. [PMID: 15674225 DOI: 10.1016/j.prosdent.2004.11.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
STATEMENT OF PROBLEM It is not known whether different high-palladium alloys of similar composition possess comparable tensile strength properties associated with connector soldering. PURPOSE The purpose of this study was to evaluate the tensile strength properties of 2 high-palladium alloys on soldered connectors under simulated pre-ceramic and post-ceramic soldering conditions. MATERIAL AND METHODS Eighty cylindrical castings were fabricated (Rx Naturelle Plus alloy and Option alloy). The 40 castings for each alloy were subdivided into 2 groups of 20 each. In the first group, castings for each alloy were randomly paired and soldered with presolder (SMG2) to produce 10 preceramic test connector specimens for each alloy. In the second group, castings were similarly paired and soldered with postsolder (490 fine) to produce 10 postceramic test connector specimens for each alloy. Each soldered connector was subjected to tensile force until failure in a universal testing machine. Statistical analysis using a Wilcoxon rank sums test was performed (alpha=.05) RESULTS No significant difference was found between the mean tensile failure stress for Rx Naturelle Plus preceramic solder (344.7 +/- 77.6 MPa) compared to Option preceramic solder (411.5 +/- 112.8 MPa) (P =.1202). However, the mean tensile failure stress for Rx Naturelle Plus postceramic solder (260.8 +/- 223.7 MPa) was significantly lower than the Option postceramic solder (312.6 +/- 120.8 MPa) (P =.0407). Not only did Rx Naturelle Plus postceramic solder connectors show evidence of lower strength, but also an increased variation among specimens. CONCLUSIONS Rx Naturelle Plus solder connectors provided better strength with the preceramic as opposed with the postceramic connectors. For postsolder connectors, Rx Naturelle Plus alloy had less acceptable strength and a wider variation, suggesting it is more technique sensitive than Option alloy connectors.
Collapse
|
42
|
Huang QF, Zhang JZ, Situ JL, Li Q, Yu JX. [Effect of irradiation power on the mechanical properties of laser-welded titanium joints.]. SHANGHAI KOU QIANG YI XUE = SHANGHAI JOURNAL OF STOMATOLOGY 2004; 13:408-11. [PMID: 15514868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
PURPOSE To make an clinical implication for the use of laser welding pure titanium,this study investigate the effect of irradiation power on the mechanical properties of laser-welded joints. METHODS The pure titanium tensile test and three-point bending test rods were laser-welded with different irradiation power. Then the tensile rods were tested for the ultimate tensile strength (UTS), and the bending rods for the ultimate bending strength (UBS). The tensile fracture surface was examined by scanning electron microscopy (SEM). Metallurgical analysis was also performed on polished longitudinal sectioned samples. RESULTS A small portion of the central area in group 1.4 kW was not joined. ANOVA showed no significant difference of OTS and VBS between group 1.6 kW and group 1.8 kW at the 0.05 level. SEM examination and metallurgical analysis showed that there were defects such as pores and cracks in the welding zone; and as the irradiation power increased, there were more pores and cracks. CONCLUSION The increase in laser irradiation power cannot increase melting depth significantly.
Collapse
|
43
|
Huang QF, Zhang JZ, Jiang WD, Li Q, Yu JX. [An experimental study on laser-welded dissimilar alloys in dentistry.]. SHANGHAI KOU QIANG YI XUE = SHANGHAI JOURNAL OF STOMATOLOGY 2004; 13:412-5. [PMID: 15514869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
PURPOSE This study evaluated the mechanical properties and microstructure of the joints of laser-welded dissimilar alloys usually used in clinical nowadays. METHODS The dissimilar alloys for Co-Cr alloy,Ni-Cr alloy and pure titanium were laser-welded. The joints were tested for the ultimate tensile strength (UTS) and the ultimate bending strength (UBS). The tensile fracture surfaces were examined by scanning electron microscopy (SEM). Metallurgical analysis was also performed on polished longitudinal sectioned samples. RESULTS Laser-welded dissimilar alloys between Co-Cr and Ni-Cr alloy can yield satisfactory mechanical properties, and there was no significant difference of UTS and UBS between Co-Cr welding wire group and Ni-Cr welding wire group (P>0.05). The laser-welded joints for dissimilar metal of pure titanium and Co-Cr,pure titanium and Ni-Cr, showed more brittle characteristics and severe defects (pores and cracks). CONCLUSIONS With Co-Cr or Ni-Cr welding wire, the laser-welded dissimilar alloys of Co-Cr alloy and Ni-Cr alloy can yield satisfactory joints. But pure titanium and Co-Cr alloy, pure titanium and Ni-Cr alloy cannot be directly melted together.
Collapse
|
44
|
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.
Collapse
|
45
|
Watanabe I, Liu J, Baba N, Atsuta M, Okabe T. Optimizing mechanical properties of laser-welded gold alloy through heat treatment. Dent Mater 2004; 20:630-4. [PMID: 15236937 DOI: 10.1016/j.dental.2003.08.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2003] [Revised: 07/03/2003] [Accepted: 08/12/2003] [Indexed: 11/24/2022]
Abstract
OBJECTIVE The goal of this work was to improve the mechanical strength of laser-welded gold alloy with age-hardenability at intraoral temperature. METHODS The gold alloy was cast conventionally in plate patterns (0.5 mm x 3.0 mm x 20 mm). After bench-cooling the mold to room temperature (as-cast state), transverse sections of the plate were made at mid-span. They were butted against one another and welded using Nd:YAG laser (current: 320 A; time: 10 ms; spot diameter: 1 mm). Three laser pulses were applied from both sides to cover the joint width (3.0 mm) of the specimens before or after solution heat treatment at 700 degrees C/5 min. Uncut control specimens (non-welded) were also prepared. After solution treatment, two different heat treatments were given the laser-welded specimens: high-temperature aging at 250 degrees C/15 min, or intraoral aging at 37 degrees C/3 days. Control specimens underwent all of the heat treatments after solution treatment. Tensile testing was conducted at a crosshead speed of 2 mm/min and a gauge length of 10 mm. RESULTS Solution treatment of the gold alloy before laser-welding did not improve the mechanical strength of laser-welded gold alloy after high-temperature aging or intraoral aging. The joint strengths of laser-welded gold alloy were improved only by solution heat treatments after laser-welding and subsequent aging treatment at high or intraoral temperatures. SIGNIFICANCE The results of this study indicated that laser-welded cast gold alloy prostheses aged at high or intraoral temperatures produce high strength when they are solution-treated after laser-welding.
Collapse
|
46
|
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.
Collapse
|
47
|
Du L, Yang L, Xu C. [A study on microstructures and heat reaction zone of laser-melted and cast post-keepers]. HUA XI KOU QIANG YI XUE ZA ZHI = HUAXI KOUQIANG YIXUE ZAZHI = WEST CHINA JOURNAL OF STOMATOLOGY 2003; 21:383-5. [PMID: 14650997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
OBJECTIVE In order to introduce the laser welding technology into root-cap making, this study compared the surface characters and internal structures of laser-melted and cast post-keeper to provide experimental data for clinical application of the technique. METHODS Using untreated keeper as the control group, the surface characters and metallographic structures of the keepers were examined by stereomicroscope, metallographic microscope and SEM, and element analysis were conducted with EPMA. RESULTS The laser-melted post-keeper basically kept the original smooth and the internal structure of the keeper, the heat reaction zone was extremely small and elements diffused mutually around the fusion zone obviously. While in the cast post-keeper, the surface was rough and had an oxide-layer. The internal structure changed and a fusion band formed between the base alloy and the keeper, but element diffusion was limited to the fusion zone. CONCLUSION Compared with casting, laser welding technique demonstrated less influence on the surface and internal structure of the keepers.
Collapse
|
48
|
Yang L, Du L, Lin Y. [The measurement of retentive force of laser-melted and cast post-keepers of Magfit magnetic attachments]. HUA XI KOU QIANG YI XUE ZA ZHI = HUAXI KOUQIANG YIXUE ZAZHI = WEST CHINA JOURNAL OF STOMATOLOGY 2003; 21:386-8. [PMID: 14650998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
OBJECTIVE In order to compare the influence of casting and laser welding on magnetic retentive force, the magnetic retentive forces of laser-melted and cast post-keepers of the magnetic attachments were measured in vitro. METHODS 5 cast and 6 laser-melted post-keeper specimens (Magfit MD800) were formed, respectively. Using untreated keeper as control group, the vertical magnetic retentive forces were measured by a universal testing machine. RESULTS The average vertical magnetic retentive force of the laser-melted post-keeper group and the cast post-keeper group in vitro were (4.223 +/- 0.217,0)N, (3.792,9 +/- 0.296,4)N, respectively. Compared with the cast post-keeper group, the average vertical magnetic retentive force of the laser-melted post-keeper groups was much higher in vitro (P < 0.05). CONCLUSION Laser welding had less influence on the magnetic retentive force of the magnetic attachments than casting.
Collapse
|
49
|
Watanabe I, Liu J, Atsuta M, Okabe T. Effect of welding method on joint strength of laser-welded gold alloy. AMERICAN JOURNAL OF DENTISTRY 2003; 16:231-4. [PMID: 14579875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
PURPOSE To examine the effect of welding method and heat treatment on the strength of laser-welded gold alloy with age-hardenability at intraoral temperature. METHODS Cast gold alloy plates (0.5 x 3.0 x 20 mm3) were prepared and cut perpendicular to the 3.0 mm surface of the plate. After the cut halves were fixed in a jig, they were laser-welded using a Nd: YAG laser. Three laser pulses were applied from one side (single-welded) or both sides (double-welded) to weld the entire joint width of the specimens. Three different heat treatments were given the specimens: solution treatment at 700 degrees C for 5 minute (ST), aging at 250 degrees C for 15 minute after ST (HA), and aging at 37 degrees C for 3 day after ST (IA). As-cast specimens were also reserved. Uncut specimens served as non-welded control specimens. Tensile testing was conducted at a crosshead speed of 2 mm/minute and a gauge length of 10 mm. The breaking stress (Bs: MPa) was recorded, and the data (n = 5 per group) were statistically analyzed. RESULTS In the control groups, the Bs values of the IA were not significantly different (P > 0.05) from those of the HA specimens. The laser-welded IA specimens showed significantly greater (P < 0.05) Bs values compared to the solution-treated and as-cast specimens. The double-welded specimens showed significantly greater Bs values compared to the single-welded specimens after any heat treatment.
Collapse
|
50
|
Fujioka S, Kakimoto K, Inoue T, Okazaki J, Komasa Y. Metallurgical Effects on Titanium by Laser Welding on Dental Stone. Dent Mater J 2003; 22:581-91. [PMID: 15005234 DOI: 10.4012/dmj.22.581] [Citation(s) in RCA: 9] [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
It is not known for certain that dental stone components influence titanium welding. In this study, we investigated metallurgical problems caused by laser welding on dental stones using wrought commercial pure (CP) titanium. A pulsed Nd:YAG laser irradiated a number of specimens' surfaces which were fixed on either a dental hard stone or a titanium plate. The metallurgical properties of the weld were evaluated using the Vickers hardness test, microstructure observation, fractured surface observation and quantitative analysis of oxygen and hydrogen. In the weld formed on the dental stone there was an increase in hardness, the existence of an acicular structure and a brittle fractured surface, and an increase in the oxygen and hydrogen concentrations compared with base metal. In the weld formed on the titanium plate, these changes were not observed. Therefore, it was demonstrated that laser welding on dental stones made the welds brittle.
Collapse
|