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Synergistic effect of wire bending and salivary pH on surface properties and mechanical properties of orthodontic stainless steel archwires.

Hobbelink MG, He Y, Xu J, Xie H, Stoll R, Ye Q - Prog Orthod (2015)

Bottom Line: A significant effect was found between Ra-values regarding the main effect of pH, ignoring the influence of shape.Bigger surface irregularities were seen on SEM images of straight wires immersed in artificial saliva at pH 5.6 compared to artificial saliva at other pH values.Ra showed a comparable result of surface roughness to Ra-value measured by the profilometer.

View Article: PubMed Central - PubMed

Affiliation: Orthodontic Department, College of Medicine and Dentistry, James Cook University, Cairns, Australia.

ABSTRACT

Background: The aim of this study was to investigate the corrosive behaviour of stainless steel archwires in a more clinically relevant way by bending and exposing to various pH.

Methods: One hundred and twenty pieces of rectangular stainless steel wires (0.43 × 0.64 mm) were randomly assigned into four groups. In each group, there were 15 pieces of bent wires and 15 straight ones. Prior to measurements of the wires, as individual experimental groups (group 1, 2, and 3), the wires were exposed to artificial saliva for 4 weeks at pH 5.6, 6.6, and 7.6, respectively. A control group of wires (group 4) remained in air for the same period of time before sent for measurements. Surface roughness (Ra-value) was measured by a profilometer. Young's modulus and maximum force were determined by a four-point flexural test apparatus. Scanning electron microscopy was used to observe the surface morphology of straight wire. Differences between groups were examined using a two-way analysis of variance (ANOVA).

Results: Mean surface roughness values, flexural Young's moduli, and maximum force values of bent wires are significantly different from those of the straight wires, which was the main effect of wire bending, ignoring the influence of pH. A significant effect was found between Ra-values regarding the main effect of pH, ignoring the influence of shape. There was a significant interaction effect of bending and pH on flexural Young's moduli of stainless steel archwires, while pH did not show much impact on the maximum force values of those stainless steel wires. Bigger surface irregularities were seen on SEM images of straight wires immersed in artificial saliva at pH 5.6 compared to artificial saliva at other pH values. Surface depth (Rz) was more sensitive than Ra in revealing surface roughness, both measured from 3D reconstructed SEM images. Ra showed a comparable result of surface roughness to Ra-value measured by the profilometer.

Conclusions: Bending has a significant influence on surface roughness and mechanical properties of rectangular SS archwires. pH plays a synergistic effect on the change of mechanical properties of stainless steel (SS) wires along with wire bending.

No MeSH data available.


Related in: MedlinePlus

Typical force-deflection curves of an elastic material. The flexural Young’s modulus and maximum force value are indicated as brown circles. The flexural Young’s modulus is calculated as the slope of the linear portion of the curve by taking into account the dimensions of the wire. The maximum force is the maximum amount of force a material can withstand before it starts to fail. Curve a represents a stiffer material than curve b
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Fig1: Typical force-deflection curves of an elastic material. The flexural Young’s modulus and maximum force value are indicated as brown circles. The flexural Young’s modulus is calculated as the slope of the linear portion of the curve by taking into account the dimensions of the wire. The maximum force is the maximum amount of force a material can withstand before it starts to fail. Curve a represents a stiffer material than curve b

Mentions: An important parameter is the flexural Young’s modulus (Fig. 1). It represents the flexibility of an archwire and can be calculated as the slope of a force-deflection curve. Researchers have been reporting a flexural Young’s modulus of ~120–217 GPa [2] for as-received stainless steel archwires. Another important parameter is the maximum force. This is defined as the maximum amount of force the wire can withstand before it starts to fail [3].Fig. 1


Synergistic effect of wire bending and salivary pH on surface properties and mechanical properties of orthodontic stainless steel archwires.

Hobbelink MG, He Y, Xu J, Xie H, Stoll R, Ye Q - Prog Orthod (2015)

Typical force-deflection curves of an elastic material. The flexural Young’s modulus and maximum force value are indicated as brown circles. The flexural Young’s modulus is calculated as the slope of the linear portion of the curve by taking into account the dimensions of the wire. The maximum force is the maximum amount of force a material can withstand before it starts to fail. Curve a represents a stiffer material than curve b
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4621974&req=5

Fig1: Typical force-deflection curves of an elastic material. The flexural Young’s modulus and maximum force value are indicated as brown circles. The flexural Young’s modulus is calculated as the slope of the linear portion of the curve by taking into account the dimensions of the wire. The maximum force is the maximum amount of force a material can withstand before it starts to fail. Curve a represents a stiffer material than curve b
Mentions: An important parameter is the flexural Young’s modulus (Fig. 1). It represents the flexibility of an archwire and can be calculated as the slope of a force-deflection curve. Researchers have been reporting a flexural Young’s modulus of ~120–217 GPa [2] for as-received stainless steel archwires. Another important parameter is the maximum force. This is defined as the maximum amount of force the wire can withstand before it starts to fail [3].Fig. 1

Bottom Line: A significant effect was found between Ra-values regarding the main effect of pH, ignoring the influence of shape.Bigger surface irregularities were seen on SEM images of straight wires immersed in artificial saliva at pH 5.6 compared to artificial saliva at other pH values.Ra showed a comparable result of surface roughness to Ra-value measured by the profilometer.

View Article: PubMed Central - PubMed

Affiliation: Orthodontic Department, College of Medicine and Dentistry, James Cook University, Cairns, Australia.

ABSTRACT

Background: The aim of this study was to investigate the corrosive behaviour of stainless steel archwires in a more clinically relevant way by bending and exposing to various pH.

Methods: One hundred and twenty pieces of rectangular stainless steel wires (0.43 × 0.64 mm) were randomly assigned into four groups. In each group, there were 15 pieces of bent wires and 15 straight ones. Prior to measurements of the wires, as individual experimental groups (group 1, 2, and 3), the wires were exposed to artificial saliva for 4 weeks at pH 5.6, 6.6, and 7.6, respectively. A control group of wires (group 4) remained in air for the same period of time before sent for measurements. Surface roughness (Ra-value) was measured by a profilometer. Young's modulus and maximum force were determined by a four-point flexural test apparatus. Scanning electron microscopy was used to observe the surface morphology of straight wire. Differences between groups were examined using a two-way analysis of variance (ANOVA).

Results: Mean surface roughness values, flexural Young's moduli, and maximum force values of bent wires are significantly different from those of the straight wires, which was the main effect of wire bending, ignoring the influence of pH. A significant effect was found between Ra-values regarding the main effect of pH, ignoring the influence of shape. There was a significant interaction effect of bending and pH on flexural Young's moduli of stainless steel archwires, while pH did not show much impact on the maximum force values of those stainless steel wires. Bigger surface irregularities were seen on SEM images of straight wires immersed in artificial saliva at pH 5.6 compared to artificial saliva at other pH values. Surface depth (Rz) was more sensitive than Ra in revealing surface roughness, both measured from 3D reconstructed SEM images. Ra showed a comparable result of surface roughness to Ra-value measured by the profilometer.

Conclusions: Bending has a significant influence on surface roughness and mechanical properties of rectangular SS archwires. pH plays a synergistic effect on the change of mechanical properties of stainless steel (SS) wires along with wire bending.

No MeSH data available.


Related in: MedlinePlus