An in vitro Evaluation of Shear Bond Strength of Adhesive Precoated Brackets

Abstract

Newer materials have been introduced in the field of ortho­ dontics to improve clinical efficacy as well as to simplify the tech nique. In an effort to reduce the time and steps to bond ortho dontic attachments, adhesive precoated (APC) brackets were introduced. In this study, an attempt is made to evaluate the shear bond strength (SBS) and debonding behavior of APC brackets compared with uncoated ceramic brackets. A total of 60 human premolar teeth were divided into two groups of 30 each, bonded with APC ceramic brackets and uncoated ceramic brackets. Group I bonded with APC brackets as pres­ cribed by the manufacturers and group II was bonded with con ventional bonding using Turbobond. After bonding, sthe samples were kept in distilled water at 37°C for 24 hours and a universal testing mechine was used to apply an occlusal shear force at a speed of 0.5 mm/min. The shear bond strength of the groups was compared using Student t­test and the debonding behavior were compared using Mann­Whitney’s U test. Mean shear bond strength and standard deviation of the groups were group I ­ 9.09 ± 2.5 MPa and group II ­ 12.95 ± 2.81 MPa. There were significant differences in bond strength observed between the two groups. The debonding behavior showed an adhesive remnant index score of 0.90 ± 0.08 for group I and 1.10 ± 0.04 for group II, which indicates there is significant difference between each other. When considering the values required for optimum bond strength, APC brackets in this study showed adequate bond strength and could be used for routine clinical use.