Abstract:
Objective: The objective of this study was to compare the strength degradation force
of intermaxillary elastic used for different periods of time. Material and Methods: The
sample included intermaxillary elastics used for 20 adult patients with bilateral Class
II or III malocclusion in orthodontic treatment with fixed appliances, with mean age of
27.25 years. Latex orthodontic elastics with 3/16" of diameter were used, with an
average stretching of 3 times its diameter. The elastic were used in the same patient
bilaterally for different time periods, with each pair of elastics used for 1, 12, 24 and
48 hours. Thus, the sample consisted of 200 elastics, 40 being used in each time
period (one pair used by each patient) and 40 new elastics without use tested as
control. Elastics were tested in a Universal Testing Machine, stretched with velocity
of 30mm per minute and the force was evaluated in stretches of 15mm, 20mm,
25mm and 30mm. The degradation force was compared in the four different times of
use and control by one-way ANOVA and Tukey tests. Results: There were significant
differences among the groups in all evaluated stretches (15, 20, 25 and 30mm). The
control elastics presented higher average forces numerically and statistically
significant for all tested times, except for the elastic used for 1 hour. The elastics
used for 1, 12 and 24 hours had similar forces among them, with a significant
difference to the elastics used for 48 hours. Conclusion: It is recommended to
change the intermaxillary elastics after 24 hours of use.
