BONDING OF A LIGHT-CURING GLASS-IONOMER CEMENT TO DENTAL AMALGAM

In the clinical situation, the need may arise for placement of a glassionomer cement over an existing amalgam restoration. This study assessed the tensile bond strength of a recently developed light-curing glass ionomer (Vitrabond)to dental amalgam (Dispersalloy), with and without the use of Scotchbond dual cure as an intermediary. Amalgam adherend specimens were prepared, then aged in water at 37-degrees-C for seven days. Immediately before being bonded, the amalgam surfaces were finished flat on 600-grit paper. Forty specimens were used for bonding in this condition, and another 40 were covered with a thin layer of Scotchbond, which was light-cured for 10 s. The glass-ionomer was applied to the adherend surface in two increments, each light-cured for 30 s. After being bonded, half the specimens were stored in water at 37-degrees-C, while half were stored in an environment of 95 +/- 5% RH at 37-degrees-C. The 24 hour tensile bond strengths, in MPa, were: for specimens stored in water, without Scotchbond 8.4 +/- 1.2, with Scothchbond 4.7 +/- 1.3; and for specimens stored in 95 +/- 5% RH, without Scothbond 9.2 +/- 2.1, with Scotchbond 4.6 +/- 1.5. The data were further analyzed by the Weibull distribution function. It was concluded that a strong reliable bond can be achieved between Vitrabond and set Dispersalloy, and that the use of Scothband as an intermediary is contra-indicated.