Bracket Failure Rate Research Articles

A 12-month clinical evaluation of a glass polyalkenoate cement for the direct bonding of orthodontic brackets

Glass polyalkenoate (ionomer) cements have the unique properties to physicochemically bond to enamel and base metals, and to leach fluoride over prolonged periods. These cements are hybrids of silicate and polycarboxylate cements and, like the silicate cements, retain a cariostatic action on adjacent enamel. This article reports on a 12-month clinical trial of a glass ionomer cement for the direct bonding of orthodontic brackets compared with a standard composite bonding adhesive. This study shows a significant difference in failure rates of direct-bonded orthodontic brackets cemented with a thick mix of Fuji I glass polyalkenoate cement (20%) compared with System I+ composite bonding resin (5%).

Bonding of clear plastic orthodontic brackets using an ultraviolet-sensitive adhesive

Numerous investigators have been involved in attempts to develop effective materials and methods for attaching orthodontic brackets directly to tooth surfaces to eliminate some of the present clinical disadvantages and problems related to the use of metal orthodontic bands. The objectives of the present study were to (1) test the usefulness of an ultraviolet-sensitive adhesive “bracketing” system under active orthodontic conditions, (2) determine both tensile and shear strength of the system, and (3) examine fracture patterns and locations at the various interfaces by means of a scanning electron microscope. Clear polycarbonate Begg-type and acrylic edgewise orthodontic brackets were bonded to preconditioned tooth surfaces, using an ultraviolet-sensitive adhesive. Clinical, mechanical, and scanning electron microscope studies were carried out at the State University of New York at Buffalo and the University of Western Ontario, Canada. It was found that the ultraviolet bonding system was clinically effective and the esthetics of the bonded brackets were excellent. The bracket failure rate for all teeth was 13.1 per cent (8/61), and the brackets remaining have been retained from 3 to 10 months under orthodontic conditions. The mean shear strength was found to be 821 p.s.i. (57.7 Kg. per square centimeter), and the mean tensile strength was found to be 508 p.s.i. (35.8 Kg. per square centimeter); both test results followed 30 days' immersion in water. The bracket-adhesive interface and the bracket itself were found to be the weakest links in the bonding system. The scanning electron microscopic observations revealed that there was good wetting at the adhesive-tooth interface; however, there was considerably less roughening of the bracket bases, possibly accounting in part for failure at the adhesive-bracket interface. It was concluded that the ultraviolet bonding system has clinical orthodontic potential because of (1) improved esthetic qualities, (2) adequate time for bracket placement but only 20 seconds for polymerization, (3) no time delay in applying orthodontic forces to the brackets, and (4) no necessity for finishing procedures.