# Force of Intermaximillary Late Elastics from Different Suppliers: A Comparative In Vitro Study
## 4 Discussion
As the value of generated force can be influenced by the age and storage of elastics, all elastics used in the present study were within their use-by date, delivered by the manufacturer no later than two weeks prior to the measurement, manufactured no later than two months prior to the measurement, and stored in dark plastic containers in a dry and cool environment. Twenty elastics from five different production batches from each manufacturer were measured; the reason for this was to reduce the incidence of bias in case a manufacturing problem occurred within a specific batch, or if it was heated during transport. Clinically, not only is the initial force important, but also the force degradation while wearing the elastics; however, the degradation rates are not reported by any manufacturer. According to our results, on average, a force degradation of 25.43% was found for all five manufacturers at 24 h, with the greatest force degradation occurring within the first two hours (10.05-18.76%), followed by a more gradual decrease. In most other studies, the greatest rate of force degradation was also noted in the first measured interval. [PERSON] et al. [9] reported 15.26-20.7% for the American Orthodontics 3/16\" elastics stretched to 30 mm during the first two hours, similar to our findings. [PERSON] et al. [10] measured a force degradation rate of 7.92% in the 3/16\" Medium elastics from the 3M brand stretched to 24.6 mm during the first hour, and [PERSON] et al. [18] reported a force degradation of 14.6% in the same time interval and using the same manufacturer. By contrast, [PERSON] et al. [6] reported a greater force degradation by 26.3 \(\pm\) 8.6% in the 3/16\" Medium elastics from the 3M brand when stretched to 24.1 mm. Other studies also demonstrated a greater rate of force degradation within the first two hours, being between 25% and 40% [9; 10; 11]. Some studies found an even greater rate of force degradation during the first hour [14; 18; 19; 20; 21; 22; 23], in the first half hour [7; 14], and in the first three hours [24]. [PERSON] and [PERSON] [25] showed that after one day, the force degradation was approximately 23% to 28%. Similar to our findings, there have been studies reporting that, as time progressed, the force degradation became slower with continued stretching for longer periods [9; 11; 21; 26]. In a study by [PERSON] et al. [5], where forces were measured continuously, the rate of degradation in the first hours of testing was not reported, but it was stated that the greatest rate of force degradation occurred between 3 and 5 h. In our research, continuous data were not collected, and force was recorded periodically at 0, 2, 8, 24, and 48 h in accordance with most studies; however, using noncontinuous data to construct force relaxation curves may have induced some unavoidable approximation. Force degradation over time differed among individual manufacturers in the present study, as did the values of initial force. The greatest rate of force degradation occurred in the elastics from American Orthodontics, which had 72.3 g of force at 48 h. By contrast, the elastics from Ortho Organizers, whose initial force was highest, exhibited a force after 48 h of 124.5 g, i.e., a value close to the declared initial force. This supports the findings of the study of [PERSON] and [PERSON], in which the authors reported that initial force had no relationship with the amount of force degradation [27]. By contrast, two older studies by [PERSON] [28] and [PERSON] et al. [29] suggested that the greater the initial force of the rubber band, the greater the amount of force degradation. Despite the extensive use of intermaximillary elastics in orthodontics, the force released during their clinical application and force degradation in vivo remains unclear.