Physical and Mechanical Properties of
Commercial Orthodontic Elastomeric Ligatures
Authors :
- Tool Sriamporn D.D.S.
- Niyom Thamrongananskul D.D.S., Ph.D.
- Nushanad Na Ranong Ph.D.
- Somporn Swasdison D.D.S., Ph.D.
Abstract :
Objective To study the mechanical and physical properties of commercially available orthodontic
elastomeric ligatures.
Materials and methods For the mechanical test, the elastomeric ligatures were divided into seven
groups (n=20 for each group) according to commercial companies. The initial tensile force and the
force after immersion in distilled water for 1, 7 and 28 days of specimens were measured by Lloyd
Universal Testing Machine with the method modified form ISO 21606. For the surface hardness test,
10 specimens from each group were measured for the initial surface hardness by Durometer Shore A.
They were then immersed in distilled water for 1, 7, and 28 days and measured for the surface
hardness again at each time period. In the case of color staining resistance test, the specimens
were immersed in tea or coffee solution for 1 hour and 1 day and the different color value (ΔE) was
measured by spectrophotometer at each time interval. One way ANOVA and Bonferroni multiple
comparisons were used to analyze the data from the tensile force and the surface hardness tests.
Results The results showed that the tensile force of elastomeric ligatures of all groups after immersion
in distilled water for 1, 7, and 28 days was significantly lower than the initial force (p < 0.05). The force
was 40-60% decreased after 1 day of water immersion. The tensile force was not significantly different
(p > 0.05) when compared among the specimens immersed in the distilled water at different time
periods. The surface hardness Shore A of all groups was not significantly different (p > 0.05) at every
immersion time. For the color staining resistance, the specimens showed the difference color value
(ΔE) higher than 3.3 after 1 hour of immersion in tea or coffee solution.
Conclusion The tensile force of the elastomeric ligature was decreased after 1 day of immersion in
distilled water and the surface hardness of specimens was not altered at every immersion time. In addition,
the specimens demonstrated the color change after 1 hour of immersion in tea or coffee solution.
(CU Dent J. 2009;32:11-22)
Keywords :
color staining resistance; elastomeric ligature; surface hardness Shore A; tensile force
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