In vitro study of force decay of latex and non-latex orthodontic elastics

• Published in: European journal of orthodontics 2012-04, Vol.34 (2), p.202-207
• Main Authors: López, Noelia, Vicente, Ascensión, Bravo, Luis A, Calvo Guirado, José L, Canteras, Manuel
• Format: Article
• Language: English
• Subjects: Dental Materials - chemistry; Dentistry; Elasticity; Humans; Latex - chemistry; Materials Testing; Orthodontic Appliances; Stress, Mechanical; Temperature; Time Factors; Water - chemistry
• ISSN: 0141-5387; 1460-2210
• DOI: 10.1093/ejo/cjq188

The aim of this study was to evaluate the force decay of two brands of orthodontic elastics, both offering latex and non-latex products. Samples were subjected to continuous stretching, measuring force at 5 seconds, 8 hours, and 24 hours in both dry and wet conditions. Five hundred samples were used, GAC® and Lancer® 0.25 inch and 4 oz, divided into testing sample sizes of n = 25 per group. For the dry test, elastics were kept stretched to three times their internal diameter for 5 seconds (initial force), 8 hours, and 24 hours; for the wet test, they were stretched for 8 and 24 hours. Both brands showed initial forces significantly greater than those specified by the manufacturers (P < 0.05). Comparing wet/dry conditions, there was a greater force loss in the wet medium than the dry. As for elastic composition (latex or non-latex), the only significant difference found was between Lancer elastics with and without latex in dry conditions, force loss being greater for latex-free elastics. Comparing brands, there was greater force loss with GAC than with Lancer. Comparing elastic force at the eight-hour mark and the twenty-four hour mark to the initial force (only in wet conditions), GAC latex and non-latex and Lancer latex elastics showed significantly less force at eight and twenty four hours than initially. On the other hand, Lancer non-latex was the only type of elastics that did not show a significant decrease in its initial elastic characteristics at eight hours in wet conditions. Nevertheless, Lancer non-latex did show significantly less force in wet conditions at twenty four-hours than the forces observed initially and at eight-hours.