RESUMO
BACKGROUND: Elastomeric chains promote controlled movements and are widely used in orthodontics. OBJECTIVES: The aim of the study was to evaluate the force decay and elongation of orthodontic chains exposed to low-pH saliva (pH = 4) and different beverages common in the diet. MATERIAL AND METHODS: Force decay and elongation were determined in vitro at 6 time intervals over 21 days for 2 commercial elastomeric chains - Ormco (group A) and Borgatta (group B). The samples were immersed in artificial saliva (AS) at pH 4, Coca-Cola®, coffee, or beer for 15 min every day, or in AS (the control group). For the remaining time, the chains were placed into AS at 37°C. In addition, microscopic qualitative changes were recorded by means of scanning electron microscopy (SEM). RESULTS: The group B chains showed higher force decay and elongation at the end of the follow-up as compared to the group A chains. Exposure to beer had a greater impact on the force decay and elongation of the chains as compared to other liquids, but it was not statistically significant. The group A chains showed a more irregular surface than the group B chains, in particular, those exposed to coffee. CONCLUSIONS: Elastomeric chains suffer force decay and elongation as a function of time, mainly in the first 24 h. At the end of the follow-up, the group A chains exhibited less force decay in comparison with the group B chains. The qualitative observations showed that the chains in group A had a more irregular surface than the chains in group B.
