Thai orthodontic elastomeric ligatures

Abstract

Objective: To compare the in vitro properties of locally produced Thai orthodontic elastomeric ligatures (Thai Ligature) with the imported brands (Dynaflex, Unitek, Ormco and W&H). Materials and Methods: Five brands of orthodontic elastomeric ligatures, four commercially available and one locally made, were chosen in this study. Three experiments were designed to measure and compare the dimension, initial extension force, relaxation force and cytotoxicity according to ISO 21606:2007 and ISO 10993-5:1999, the international standard of elastomeric auxiliaries for use in orthodontics and cytotoxic evaluation of dental materials. Property comparison among the five brands of orthodontic elastomeric ligatures was done through the One-way ANOVA test (P<0.05). Results: The results showed that the properties of Thai ligatures met the standards. They had a significantly greater cross-section thickness and inner diameter. The mean initial extension force measured at three times of inner diameter was 2.004, 2.304, 2.535, 2.371 and 2.309 N for Dynaflex, Unitek, Ormco, W&H and Thai ligature, respectively. Thai ligature and Unitek were not significantly different in mean initial extension force. To measure relaxation force, the percentage of force loss was determined. After 24 hours, the mean percentage of force loss was 27.38, 41.49, 48.35, 46.62 and 36.18 for Dynaflex, Unitek, Ormco, W&H and Thai ligature, respectively. Regarding the percentage of force loss, the Thai produced ligatures were the second best among all brands. Cytotoxic evaluation by MTT assay showed that W&H had mild toxicity while the other four brands had no toxicity. Conclusion: This study showed that the Thai ligature can be a suitable alternative orthodontic elastomeric ligature and presents opportunities for further development.