Residual Force of Orthodontic Elastomeric Ligature

Abstract

Objectives:The study aimed to compare the residual forceoflocally produced Thai orthodontic elastomeric ligatureswith 2 commercial brands.Materials and Methods: The study compared Thai clear and blue orthodontic elastomeric ligatures with clear and blue commercial brands[Unitek (USA) and W&H (China)]. The dimensional characteristics of the ligatures (i.e., inner diameter, outer diameter and cross-section thickness) were measured. Then initial extension force was measured. After that, the residual force was determined at day 1and repeated on day 2,3,4,5,6,7,14,21, and 28 andthe percentage of residual force wascalculatedaccording to ISO 21606:2007. The data were analyzed with Two-way ANOVA and multiple linear regression (p<0.05). Results: Thai ligatures had significantly greater inner diameter(clear 1.22 mm, blue 1.21 mm) and cross-section thickness (clear 0.78 mm, blue 0.79 mm) in both colors when compared with Unitek and W&H brands. Thai ligatures had no significant difference in cross-section thickness between clear and blue.Thai clear ligatures hadthe highest initial extension force(2.30 N). Thai ligatures showed similar force decay patterns as other brands, rapidly decreasing the first day, gradually decreasing over 7 days and remaining nearly constant until 28 days.However, both clear and blue Thai elastomeric ligatures had significantly less outer diameters (clear 3.12 mm, blue 3.15mm). Thai blue ligatures had the lowest initial extension force (1.96 N).TheThai clear and blue demonstrated less percentage of residual force in the first day (clear 53.00%, blue 50.66%) and28 days (clear, 37.69%, blue, 37.00%) butthey were clinically acceptable. In general, clear ligatures exhibited a greater percentage of residual force than blue ligatureamong the 3 brands. Conclusion:Thai orthodontic elastomeric ligature properties are comparable to commercially available brands and acceptable for clinical application.