Abstract
Statement of problem
The literature provides limited information regarding the performance of Ti-6Al-4V
laser and plasma joints welded in prefabricated bars in dental applications.
Purpose
The purpose of this study was to evaluate the mechanical strength of different diameters
of Ti-6Al-4V alloy welded with laser and plasma techniques.
Material and methods
Forty-five dumbbell-shaped rods were created from Ti-6Al-4V and divided into 9 groups
(n=5): a control group with 3-mm and intact bars; groups PL2.5, PL3, PL4, and PL5
(specimens with 2.5-, 3-, 4-, and 5-mm diameters welded with plasma); and groups L2.5,
L3, L4, and L5 (specimens with 2.5-, 3-, 4-, and 5-mm diameters welded with laser).
The specimens were tested for ultimate tensile strength (UTS), and elongation percentages
(EP) were obtained. Fractured specimens were analyzed by stereomicroscopy, and welded
area percentages (WAP) were calculated. Images were made with scanning electron microscopy.
In the initial analysis, the data were analyzed with a 2-way ANOVA (2×4) and the Tukey
Honestly Significant Difference (HSD) test. In the second analysis, the UTS and EP
data were analyzed with 1-way ANOVA, and the Dunnett test was used to compare the
4 experimental groups with the control group (α=.05). The Pearson and Spearman correlation
coefficient tests were applied to correlate the study factors. Finite element models
were developed in a workbench environment with boundary conditions simulating those
of a tensile test.
Results
The 2-way ANOVA showed that the factors welding type and diameter were significant
for the UTS and WAP values. However, the interaction between them was not significant.
The 1-way ANOVA showed statistically significant differences among the groups for
UTS, WAP, and EP values. The Dunnett test showed that all the tested groups had lower
UTS and EP values than the control group. The 2.5- and 3-mm diameter groups showed
higher values for UTS and WAP than the other test groups. A positive correlation was
found between welded area percentage and UTS and a negative correlation between these
parameters and the diameters of the specimens. No statistically significant difference
was found between the weld techniques.
Conclusions
Under the experimental conditions described, diameters of 2.5 and 3 mm resulted in
higher UTS and WAP for both laser and plasma welding and appear to be the best option
for joining prefabricated rods in this kind of union.
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Article info
Publication history
Published online: March 04, 2015
Footnotes
This study is supported by the National Council for Scientific and Technological Development (CNPQ) (07/2010 PIBIC/CNPq/UFU) and the Foundation for Research of the State of Minas Gerais (FAPEMIG) (SAU19/20009).
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© 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.
