The effect of variations in the length of wire and number of coils on the force produced by an orthodontic cantilever spring

Abstract

Orthodontic treatment has been around for quite some time, yet many more studies are required for improvement in providing a quality service to the patient. This is done in order to provide better qualities and methods in the achievement of optimal. The main aim being to achieve optimal occlusion and giving the patient best quality in both aesthetics and functionality. This study was carried out in order to provide the patient with an ideal combination of stainless steel wire (which include variations in arm length, number of coils and diameter of wire) to provide enough force on the teeth to cause movement without them being compromised. In fact, this study was carried out using different forms of a cantilever spring varying thicknesses of wire, number of coils, and arm length observing through graphs which combination would be best able to produce most deflection. The cantilever springs were manually crafted together with the coils and eventually were incorporated into the acrylic, giving a resemblance of and orthodontic appliance. A control was added for each diameter consisting of straight wire with no coils incorporated. The spring was placed stationary in front of a graph paper to take an approximate value. Weights (30g, 60g, 90g and 120g) were used to effect the deflection of wires, the results were tabulated and graphs were plotted. Precautions were taken in consideration in order to reduce error and provide the best results, in fact a metal apparatus was incorporated in this experiment which held the springs and graph in a constant position therefore minimizing completely the human and parallax error. The optimal force/deflection ratio was provided by 0.5mm wire with a 20mm arm for a single rooted tooth and by 0.7mm wire with a 20mm arm. One can conclude that the manufacture of the coil reduces the flexibility of the spring, however the addition of the coil simultaneously increases the length of wire incorporated into the spring. The increase in length increases the flexibility of the spring and offsets the effect of manufacture of the coil and therefore it is recommended that springs incorporate 20mm of wire and may include a coil to reduce the bulk of the appliance.