Mechanical properties intermaxillary latex and latex-free elastics

BackgroundHypersensitivity to latex is frequently observed in patients undergoing orthodontic treatment. In the search for new alternatives to meet the needs of these patients, latex-free intermaxillary elastics were developed in the 1920s. Although the use of latex-free elastics in dentistry is not new, studies evaluating the mechanical properties of these devices in the literature are scarce.ObjectiveThe aim of this study was to evaluate the mechanical properties of latex and synthetic latex-free intermaxillary elastics.MethodsLatex and latex-free orthodontic elastics, both of 5/16 diameter, were preselected with regard to uniformity of diameter and thickness and were evaluated (n = 17 per group). Initially, the elastics were weighed, and their external diameters at rest were measured. After this, they were taken to a digital dynamometer mounted on a device suitable for measuring initial force. The elastics were kept distended (10 cm) and were immersed into artificial saliva at 37°C. A series of evaluations of force were performed at 2, 6, 8, 12, and 24 hours, and weight and diameter evaluations were repeated at 24 hours. The values for the amount of force released and weight and diameter were analyzed using ANOVA and the Tukey test.ResultsThe latex elastics released statistically greater force than did the latex-free elastics at each time point (all, P < 0.05). The weight of the latex-free elastics did not increase from 0 to 24 hours, whereas the weight of the latex elastics presented a statistical difference (P < 0.05). All of the elastics evaluated had an increase in internal diameter showing permanent deformation (P < 0.05).ConclusionThe intermaxillary latex elastics released greater force and underwent greater degradation than did the latex-free type.