Table of Contents
ISRN Dentistry
Volume 2011, Article ID 536089, 5 pages
Research Article

Force Relaxation Characteristics of Medium Force Orthodontic Latex Elastics: A Pilot Study

1Department of Orthodontics, State University of Rio de Janeiro, 20551-030 Rio de Janeiro, Brazil
2Department of Material Sciences, Military Institute of Engineering, 22290-270 Rio de Janeiro, Brazil

Received 30 April 2011; Accepted 15 May 2011

Academic Editors: C. P. Lin and A. Vissink

Copyright © 2011 Daniel J. Fernandes et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


To evaluate force extension relaxation of different brands and diameters of latex elastics subjected to static tensile testing under an apparatus designed to simulate oral environments, sample sizes of 5 elastics from American Orthodontics (AO), Tp, and Morelli Orthodontics (Mo) of equivalent medium force, (3/16, 1/4, and 5/16 inch size) were tested. The forces were read after 1-, 3-, 6-, 12- and 24-hour periods in Emic testing machine with 30 mm/min cross-head speed and load cell of 20 N. Two-way ANOVA and Bonferroni tests were used to identify statistical significance. There were statistically differences among different manufacturers at all observation intervals ( 𝑃 < 0 . 0 0 0 1 ). The relationships among loads at 24-hour time period were as follows: Morelli>AO>Tp for 3/16, 1/4, and 5/16 elastics. The force decay pattern showed a notable drop-off of forces until 3 hours, a slight increase in some groups from 3–6 hours and a more homogeneous force pattern over 6–24 hours.