COMPARAÇÃO DA FORÇA LIBERADA POR ELÁSTICOS INTERMAXILARES UTILIZADOS POR DIFERENTES PERÍODOS DE TEMPO

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.