Evaluation of various concentrations of alkaline surface treatment on interfacial bond strengths of amalgam bonded to amalgam

This study was done to assess the influence of alkaline surface modification on interfacial bond strength of existing fractured (old) amalgam restoration bonded to fresh amalgam. Old and Fresh amalgam interfaced samples were prepared by applying a 4-methacryloyloxyethy trimellitate anhydride (4-META) containing adhesive. The adhesive used was Amalgabond (Parkell, Farmingdale, NY 11735, USA). Four concentrations of calcium hydroxide Ca(OH)2 solutions were used as a surface modifiers for old amalgam to increase the pH of the amalgam surfaces. The concentrations used were 2.5, 5, 10 and 15%. Direct measurement of the interfacial bond strength was carried out using an electromechanical universal tensile testing machine at crosshead speed of 10mm per minute. Results show that all the calcium hydroxide modified samples produced the increased tensile bond strength (TBS) as compared to their control group. The highest values of bond strength were achieved using 15% Ca(OH)2 solution as surface modifier. Pretreatment of fractured amalgam with calcium hydroxide improves the bond strength of 4-META adhesives. Its use in repair of amalgam may therefore be considered.