In vitro comparison of the force degradation of orthodontic intraoral elastics from different compositions

Resumo

The synthetic intermaxillary elastic emerged as an
alternative for clinical use in patients with latex sensitivity. However,
there are disagreements about this elastic protocol use according
to the force degradation. Objective: The aim of this study was to
evaluate, in vitro, the forces generated by latex and synthetic elastics
over time. Material and methods: Sample size of 840 elastics were
used (420 latex and 420 synthetic), delivering medium strength (Dental
Morelli®) with internal diameter of 1/8”, 3/16”, 1/4” and 5/16”. The
elastics were randomly divided into 6 groups according to the time
of the force measuring and immersed into distilled water at 37°C.
To measure the force in each group, the elastics were stretched in
six progressive increases of 100% of its internal diameter with the
aid of a testing machine Emic and measured up to 72 hours. Data
were analyzed with SPSS 16.0, using one-way analysis of variance
(ANOVA). Results: Immediate force level of synthetic elastics was
statistically higher than latex elastics in all strains, for the same
size. However, the latex elastics mean force slightly decreased over time, while the synthetic elastics presented an abrupt decrease.
Conclusion: The synthetic elastic presented high force degradation,
decreasing the cost-benefit ratio due to the high frequency of exchange
of elastic. The latex elastic showed better mechanical performance
in comparison to synthetic ones.