title: Force relaxation characteristics of medium force orthodontic latex elastics: a pilot study.
abstract: 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 < 0.0001). 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.
authors: Department of Orthodontics, State University of Rio de Janeiro, 20551-030 Rio de Janeiro, Brazil.
authors: Daniel J
authors: DJ
authors: Fernandes
authors: Gisele M
authors: GM
authors: Abrahão
authors: Carlos N
authors: CN
authors: Elias
authors: Alvaro M
authors: AM
authors: Mendes