Authors' response

Abstract

elastomeric chains reduce by 50% to 70% in the first 24 hours. Although the results were significant, we would like to put forth our queries regarding the methodology. Proffit et al 1 stated that the anchorage value of each tooth differs, which affects the amount of orthodontic tooth movement to the applied force. The authors measured the amount of space closure when canine retractions, reciprocal molar to premolar, and en-masse retraction were being carried out. Thus, the amount of force required would vary, and the space closure measured would be substantially different. The authors did not discuss any difference in the amount of space closure with regard to the type of tooth movement. Any difference in the rates of retraction in the maxillary and mandibular arches would validate the study further. 2 With regard to the results in Table I, would it be prudent to compare mean space closure accomplished with a reference value of zero? Regarding results mentioned in Table II, "When 2 sites from the same patient are positively correlated," which were the 2 sites correlated here? The details of the study with respect to these queries would help us to understand better.

Mechanical Strength Variety of Orthodontic Polymeric Chains In vitro assessment and mathematical model

“…So, in other words, orthodontic elastomeric chains are polyurethanes, thermosetting polymer products of a step-reaction polymerization process, possessing a -(NH)-(C=O)-O-unit [4,5]. The various time-dependent force loss of the orthodontic elastomeric chains available at this time on the market are the result of different manufacturing processes and chemical composition, variation of manufacturing techniques and morphology and dimensional characteristics [6,7]. Based on the manufacturing technique, the orthodontic elastomeric chains can be thermoplastic or thermoset.…”