Effect on Mechanical Properties of Orthodontic Elastomeric Ligatures on Immersion in Disinfecting Solutions - an in vitro Study

Background and Objectives: Cold water disinfection can damage the elastomeric material, cross contamination in handling elastomeric ligatures is a serious concern in the orthodontic office. In addition, elastomeric strips with enough ligatures for both arches of a single patient are produced by most manufacturers. Thus, cross -contamination can occur in remaining ligatures if an entire strip is not used at once.

In this investigation effect on tensile strength on short to medium exposure of elastomeric ligatures to disinfection solution and in turn its effect on force delivery is studied.

Aims and Objectives: Effect of extended exposure to disinfection solutions on tensile load at failure of different orthodontic elastomeric ligatures is assessed.

Materials and Methods: Orthodontic elastomeric ligatures were obtained from 5 manufacturers;

3M Unitek, Ormco, Ortho organizer, GAC, T P Orthodontics.

3 Disinfectant solutions used were

Glutarex-3M Unitek, Cidex-Johnson and Johnson and Cidex OPA- Johnson and Johnson.

From each manufacturer, ten orthodontic elastomeric ligatures will be exposed to each disinfectant solution with exposure times of 30 minutes, 1 hour, 12 hour and 24 hours. Ten unexposed elastomeric ligatures from each manufacturer will also be tested which will act as control group.

Ligatures were stretched in custom made jig of a universal testing machine (INSTRON) until they fractured to determine the tensile load failure. Maximum tensile load were recorded. The tensile load at failure was used as an analog to the clinical situation of the ligature breakage during tie-in.

Results and Conclusions: Three-way ANOVA showed significant differences (P < .0001) not only within manufacturer and time of exposure but also between disinfectants (P < .001). Significant interactions (P < .0001) were observed between manufacturer and time and between disinfectant and time. Greater significant changes were seen in tensile load at failure for all 5 manufactures ligatures in Cidex solution whereas changes were less significant in Glutarex and Cidex OPA solution. The ligatures from all companies showed significantly different failure loads from each other, with the ligatures from 3M exhibiting the greatest tensile load at failure and those from Ortho Organizer, the least.

Elastomeric Ligatures Tensile Load at Failure Followed the Pattern: 3M Unitek _ GAC _ Ormco _ T P Orthodontics _ Ortho organizer. Tensile load to failure of elastomeric ligatures, compared to unexposed specimens changed when exposed to disinfectant solution for as little as 30 minutes.