ABSTRACT
The mean shear debonding force of stainless steel orthodontic brackets with microetched bases bonded with either a compomer or a resin-modified glass ionomer cement was assessed. In addition, the amount of cement remaining on the enamel surface following bracket removal was evaluated. Finally, survival time of orthodontic brackets bonded with these materials was assessed following simulated mechanical stress in a ball mill. Debonding force and survival time data were compared with those obtained for brackets bonded with a chemically cured resin adhesive, a light-cured resin adhesive, and a conventional glass ionomer cement. There were no significant differences in mean shear debonding force of brackets bonded with the compomer, resin-modified glass ionomer, chemically cured resin adhesive, or the light-cured resin adhesive. Brackets bonded with a conventional glass ionomer cement had a significantly lower mean shear debonding force than that recorded for the other materials. The Adhesive Remnant Index (ARI) mode score indicated that significantly less cement remained on the enamel following debonding of brackets cemented with resin-modified or conventional glass ionomers compared with other adhesives. The median survival time for brackets cemented with the compomer, resin-modified glass ionomer, chemically cured resin, or light-cured resin were significantly longer than for brackets cemented with conventional glass ionomer. The compomer and the resin-modified glass ionomer adhesive appear to offer viable alternatives to the more commonly used resin adhesives for bracket bonding.
Subject(s)
Acrylic Resins/chemistry , Aluminum Silicates/chemistry , Compomers , Composite Resins/chemistry , Dental Bonding , Glass Ionomer Cements/chemistry , Methacrylates/chemistry , Orthodontic Brackets , Resin Cements/chemistry , Silicates/chemistry , Acid Etching, Dental , Adhesives/chemistry , Bicuspid , Bisphenol A-Glycidyl Methacrylate/chemistry , Dental Debonding , Dental Enamel/ultrastructure , Evaluation Studies as Topic , Humans , Magnesium Oxide/chemistry , Materials Testing , Polycarboxylate Cement/chemistry , Stainless Steel/chemistry , Stress, Mechanical , Surface Properties , Survival Analysis , Time Factors , Zinc Oxide/chemistryABSTRACT
The purpose of this study was to investigate the time to first failure of stainless steel orthodontic brackets (Ormco Corp, Glendora, Calif) bonded with a light-cured resin adhesive (Transbond, 3M Unitek, Monrovia, Calif) and assess whether time to failure was related to the patient's age at the start of treatment or sex, the proficiency of the individual placing the brackets, or the presenting malocclusion. Data on 548 patients with 7118 bonded brackets were analyzed. Survival analysis was carried out on a single bracket per patient. In each patient, the first bracket to fail was studied. In cases where no brackets failed, the bracket with the shortest follow-up time was analyzed and handled as a censored observation in the formal analysis. Median time until first bracket failure was 442 days, and an overall failure rate of 6% was recorded. There were no significant differences in time to first failure of brackets with respect to the sex or age of the patient at the start of treatment (p = 0.168, and p = 0.261, respectively), operator proficiency in placing brackets (p = 0.189), or presenting malocclusion (p = 0.052). Performance of brackets bonded with Transbond does not appear to vary significantly according to the variables examined.
