Analysis of Class II Intermaxillary Elastics Applied Forces: An in-vitro Study

Abstract

ObjectivesThe aims of this study were: (1) to assess the average inter-arch distances characterizing Class II malocclusions, (2) to analyze the applied forces at those distances by different elastics, and (3) to compare measured forces with those declared by manufacturers, both in dry and wet environments.Materials and MethodsSettings and sample population: Class II models of 167 adult subjects (96 women and 71 men, age: 28 ± 3 years) referred to the Orthodontic Department of the University of Turin, Turin, Italy, between January 2018 and January 2020, were collected. Distances between facial axes (FA) points of upper canines and lower first molars (A), upper first premolar and lower first molar (B), upper second premolar and lower first molar (C), upper canine and lower first premolar (D), and upper canine and lower second premolar (E), were measured using 3Shape Ortho® Viewer program. Different elastics' diameters and forces were tested at those distances. The MTS Insight® Electromechanical Testing System was used to measure the tensile forces of elastics. The applied forces were measured in dry (T0) and wet conditions, after 1 (T1), 6 (T2), and 12 h (T3).ResultsAverage distances were calculated: A = 24.64 mm (SD 2.10), B = 16.3 mm (SD 1.94), C = 9.78 mm (SD 1.77), D = 9.8 mm (SD 1.88), and E = 15.99 mm (SD 2.06). Significant differences (p < 0.05) were highlighted between the measured force and the force declared by manufacturers, and all elastics had a significant force decay (p < 0.05).ConclusionThe results showed that 3/16" 4.5 oz are the most reliable elastics in terms of applied force with respect to the declared one and in terms of force degradation.

Design and Utilization of a 3D printed Tooth-Borne Orthodontic Molar Distalizer Library

“…Before light curing excessive remnants were being removed. The activation of the molar distalizers was done with class II elastics, during testing from beginning until the end with 1/4 inch (6.35mm), 6 oz (170 g) and 3/16 inch (4.76mm), 8 oz (230 g) elastics were connected from the canine pad to a button on teeth 46 or 47 and 36 or 37 [68][69][70][71].…”

Design and Utilization of a 3D printed Tooth-Borne Orthodontic Molar Distalizer Library

“…Before light curing excessive remnants were being removed. The activation of the molar distalizers was done with class II elastics, during testing from beginning until the end with 1/4 inch (6.35mm), 6 oz (170 g) elastics were connected from the canine pad to a button on teeth 46 or 47 and 36 or 37 [60][61][62][63].…”

Upper First Molar and Second Premolar Distalization with Clear Aligner and Interradicular Skeletal Anchorage: A Finite Element Study

“…-Mesh size: 0.09 mm; The effects of 3/16 4.5 Oz elastics (Ormco Inc., Glendora, CA, USA) were simulated at two different elongation lengths: the first was 16 mm elongation in the configuration where the elastic was stretched towards the first premolar, while the second was 24.5 mm when the elastic was stretched towards the canine, varying the force vectors according to the angle between the elastic and the occlusal plane. The elongation lengths and released forces were derived from a previous study by Castroflorio et al [23].…”