Fracture strength of different soldered and welded orthodontic joining configurations with and without filling material

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.

Fracture Strength of Soldered and Laser Welded Orthodontic Bands and Wires With and Without Filling Material: A Preliminary Report

“…There are studies 9,13-18-26 combination, but few study 9,13 is about orthodontic band-wire combination. Band-wire combinations are commonly used during fabricating the active or anchorage orthodontic appliances so that the mechanical behavior researches of this combination are necessary and important.…”

“…There are different results in the literature based on the influence of brazing or welding on tensile strength. When band to wire joints were evaluated; Bock et al 9 demonstrated that the mean values of fracture strength did not differ significantly between laser welding with filling material (441.3 N) and brazing (406.7 N), but a slight tendency to lower means in laser welding without filling material (328.8 N). In a different study, Bock et al 22 showed no significant differences between the mean fracture loads for the band-to-wire joints between laser welding (354.4 N) and brazing (406.6 N), although there was less variability with the laser welding.…”

“…5 In conventional dental brazing -defined as soldering over a temperature of 450°C -the parent metals are joined with different types of metals, which may reduce corrosion resistance because of galvanic corrosion between metals. [6][7][8] The high corrosion rates can influence the biocompatibility [9][10][11] and mechanical strength. 9 Laser welding using a pulsed Nd:YAG (neodymium-doped yttrium aluminium garnet; Nd:Y3Al5O12) laser is a current technology and has been developed for joining purposes in the dental laboratory and offers clear-cut advantages compared to the various soldering methods.…”

“…[6][7][8] The high corrosion rates can influence the biocompatibility [9][10][11] and mechanical strength. 9 Laser welding using a pulsed Nd:YAG (neodymium-doped yttrium aluminium garnet; Nd:Y3Al5O12) laser is a current technology and has been developed for joining purposes in the dental laboratory and offers clear-cut advantages compared to the various soldering methods. 7 Laser welding can weld metals without solder or with material consisting of the same parent metal; hence, the corrosion resistance and biocompatibility may be increased.…”

Mechanical Properties of Welded Orthodontic Metal Appliances

“…The advantages of laser welding systems can be summarized as follows: no solder and thus no galvanic corrosion at the joint. Some phenomena can be blurred by using protection inert gases in the area of the joint(Jens Johannes Bock, 2008;Szuhanek, 2006). The application of laser welding technology allows titanium to be welded predictably and precisely in order to achieve an accurate fit of a milled framework.…”