Comparison Of Shear Bond Strength, Adhesive Remnant Index And Enamel Damage Using Different Light Source In Debonding Of Orthodontic Brackets
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Date
2011
Authors
Al-yamani, Helmi Abobakr Qaid
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Light-curing orthodontic adhesives require light with sufficient intensity and defined wavelength to initiate polymerization. Insufficient light intensity and wavelength causes incomplete polymerization, which decreases shear bond strength (SBS) and render brackets unable to resist intra-oral forces of occlusion or orthodontic forces. During debonding of orthodontic brackets, adhesive remnants remain on the enamel surface and enamel damage (ED) may occur. This study compared the SBS of brackets when cured with two different light sources, the light-emitting diode (LED) and tungsten-quartz-halogen (TQH), and compare the adhesive remnant index (ARI) and ED after debonding. Enamel surfaces of 104 premolars were cleaned and photographed (T1) with a magnifying loupe 60X Olympus stereomicroscope with digital camera to evaluate enamel surfaces before bonding procedure according to a predetermined scale. The teeth were then etched with Self-Etching Primer and bonded with stainless steel brackets using Transbond Adhesive and divided into two groups. In group I, 52 stainless steel brackets were bonded to enamel with LED for 10 seconds and in group II, 52 stainless steel brackets were bonded to enamel with TQH for 20 seconds according to manufacturer’s instruction. All teeth were then stored in distilled water for one week to simulate oral environment. Before bracket debonding, each group was divided into subgroup A and B. In subgroup A, 26 brackets were removed using Instron machine (Instron) at a cross head speed of 1mm/min in order to measure and compare the SBS. In subgroup B, 26 brackets were removed using conventional pliers. After debonding, all enamel surfaces were re-analyzed. The area of residual resin on the enamel was measured and ARI percentages calculated. Resin remnants after debonding was cleaned with tungsten carbide bur and the enamel surfaces were polished with pumice and rubber cups. These surfaces were re-photographed (T2). The ED scores (T1) before bonding and (T2) after debonding were recorded and compared. Independent t-test and Chi-square test were applied.
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Keywords
Light-curing orthodontic adhesives require light , defined wavelength to initiate polymerization