Improving the handling properties of a composite resin for direct bonding

Two experiments were performed to improve the handling properties of the Concise enamel bond system for direct bonding. The first study dealt with viscosity. For various reasons, neither the orthodontic nor the restorative Concise composite resins were considered optimal. Trial-and-error mixtures of various combinations of composite paste and liquid resin were made until a paste/paste system with the desired consistency was obtained. By weight analysis and mathematical calculations, it was figured out that the desired consistency could be arrived at by adding about 15 drops of liquid resin to each jar of 16 Gm. composite paste. Thus, diluted Concise had a consistency that allowed exact placement of brackets without subsequent drifting out of position and facilitated removal of excess adhesive outside the bracket pads. The second experiment dealt with working time. The two diluted pastes A and B were mixed in ratios of 1:1, 1:2, and 2:1, and furthermore paste A was mixed with liquid resin B (for superfast set), and the working time in the mouth was examined. The mean working time that was obtained for placement of each bracket in the mouth with equal portions of the 15-drop Concise was about 30 seconds. By varying the ratios, faster or slower working times could easily be obtained (Table I). The advantages of the Concise system as a bonding agent and our experiences with it over the past 10 years are discussed. Detailed clinical recommendations for direct bonding of brackets and lingual retainers with this adhesive are given (Figs. 2 to 8).