Force decay of latex and non-latex intermaxillary elastics: a clinical study.

Objective: To evaluate force decay between intermaxillary orthodontic elastics with and without latex in the oral medium at different time intervals.

Materials And Methods: Intermaxillary orthodontic elastics with and without latex [1/8″ (3.2mm), 1/4″ (6.35mm), and 5/16″ (7.94mm) in diameter] were evaluated 'clinically'. For this purpose, 26 patients served as hosts for the elastics during the evaluation period. Initially, 52 thermoplasticized plates 1mm thick were made according to the patients' mould. Then, the orthodontic accessories were bonded to the plates, which kept the elastics distended throughout the experimental period. The force released by the elastics at this distance was evaluated at 0, 12, and 24 hours. Statistical analyses were performed using the Friedman, Wilcoxon, and Mann-Whitney tests (significance set at 5 per cent).

Results: Elastics with and without latex presented with permanent deformation and increasing internal diameter throughout the entire period. Elastics with latex, 1/8″ (3.2mm) in diameter, sustained higher levels of force than those without latex. Elastics measuring 1/4″ (6.35mm) and 5/16″ (7.94mm) in diameter without latex sustained higher levels of force at 0 and 12 hours compared to those with latex. At the end of the experiment (24 hours), no significant difference was observed between the elastics (P > 0.05).

Limitations: This study only evaluated three time intervals: 0, 12, and 24 hours. If the behaviour was evaluated at different time intervals, different behaviours of these materials might be revealed.

Conclusion: Elastics with latex 1/8″ in diameter sustained a higher level of final force than the corresponding type without latex. The 1/4 and 5/16 elastics with and without latex were not different at the end of the evaluation period.