Strength decay of orthodontic elastomeric ligatures.

AIM

To evaluate, over a 12-week period, the tensile strength (TS) and extension to TS of elastomeric ligatures (both clear and coloured) obtained from two companies.

SETTING

Ex vivo study.

METHOD

Seven replicates of five ligatures from two orthodontic companies were tested using an ex vivo assembly which simulated a clinical situation.

RESULTS

The ligatures tested had a similar TS decay pattern, with the TS gradually decreasing over the duration of the study. The Unitek ligatures exhibited a greater TS than their respective Ormco ligatures. Generally, all of the ligatures tested experienced an increase in the extension to TS over time. The pre-stretching procedure used in this study did not produce any long-term detrimental effects on the TS and extension to TS of the ligatures tested.

CONCLUSIONS

The results of this study confirm there are differences in TS, and extension to TS between clear and coloured elastomeric ligatures, and that some significant differences also exist between different brands of elastomeric ligatures.