Effects of e-cigarette aerosol on the force degradation of elastomeric chain: An in vitro study

This study aimed to evaluate the effects of e-cigarette aerosol on force degradation of the orthodontic elastomeric chain.

A total of 300 Rocky Mountain Orthodontics (RMO) elastomeric chains consisting of 5 links with a half link at each end were divided into 3 test groups. An additional 20 samples were used for initial force testing on the Instron (Instron, Norwood, Mass) electromechanical testing machine. Group 1 was a control group exposed to ambient air on a benchtop (BT) at room temperature; group 2 was a control group exposed to a simulated oral environment (SOE); and group 3 was an experimental group exposed to 5% JUUL menthol e-cigarette aerosol and the SOE (SOE + e-cigarette). The degradation of elastic chains was tested in 6-time intervals: baseline, 1 day, 1 week, 2 weeks, 3 weeks, and 4 weeks. All chains were stretched and held at 32.8 mm on elastomeric jigs. E-cigarette aerosol exposure occurred 5 days a week and continued every day until the JUUL pod was emptied of e-liquid. An exposure device consisting of an aerosol trap, exposure chamber, flow meter, and particle sensor was used to expose the elastomeric chains. After the aerosol exposure, the elastomeric chain was placed back into the SOE. At every time interval, 20 samples were removed and placed on an Instron machine for force testing.

Significant force degradation was found among the 6-time intervals for all 3 tested groups, especially between baseline and day 1. After 1 day of exposure, the degradation force decreased by 670.0 + 0.1 g to 292.5 ± 16.7 g in the BT group, whereas the SOE and SOE + e-cigarette groups decreased to 249.0 ± 9.7 g and 237.3 ± 10.6 g, respectively. The average force delivered by the end of the fourth-week interval decreased to 265.5 ± 13.9 g, 234.6 ± 14.7 g, and 234.0 ± 13.2 g for the BT, SOE, and SOE + e-cigarette groups, respectively. The average difference in force between the BT and the SOE + e-cigarette group for the fourth-week interval was 31.5 g (P <0.0001). The average difference in force between the SOE and SOE + e-cigarette group for the 4-week interval samples was 0.61 g (P = 0.89).

There is a 50% decrease in elastic force for the RMO Energy Chain in the first 24 hours when exposed to the SOE and after exposure to the SOE together with the JUUL menthol 5% e-cigarette aerosol. There is no added increase in force degradation when exposed to JUUL menthol 5% e-cigarette aerosol and an SOE vs the SOE over the next 4 weeks. Clinically, if the RMO Energy Chain was stretched 30 mm in length, even though losing 50% of its elastic force for the initial 24 hours, 240 g of force remains ideal for retracting a maxillary canine.