Effect of citric acid on force decay of orthodontic elastomeric chains

This study aimed to assess the effect of citric acid, as a weak acid commonly used in food industry, on elastomeric chain force decay.

In this in vitro, experimental study, sixty elastomeric chains from two commercial brands of American Orthodontics and Ortho Technology (n = 30) were cut into five-piece segments. Elastomeric chains of each brand were randomly divided into two groups of control (artificial saliva) and citric acid. All elastomeric chains were incubated in artificial saliva at 37°C. Experimental samples were immersed in 10 mL of citric acid for 90 s daily and were then transferred back to the artificial saliva. The elastomeric chain force was measured at baseline (before the experiment), 1 day, 1 week, 2 weeks, and 3 weeks using an electromechanical universal testing machine. Data were analyzed using t-test, Kruskal-Wallis test, and Mann-Whitney U-test at 0.05 level of significance.

The elastomeric chain force gradually degraded over time. The difference in this respect was not significant at 2 and 3 weeks in any group (P > 0.05). On initiation of the experiment, the force in the citric acid group experienced a greater decay than that in the control group; the difference between the citric acid and control groups in both the brands was significant at all time points until the end of the 3^rd week (P < 0.05). The difference between the American Orthodontics and Ortho Technology brands in the control and citric acid groups was significant at all time points (P < 0.001).

Elastomeric chains in both the citric acid and artificial saliva groups experienced force decay over time. Force decay was greater in the citric acid group. Thus, citric acid can effectively decrease the elastomeric chain force. The Ortho Technology chain force was higher than that of American Orthodontics in both the groups at all time points.