Application of a preliminary light-curing unit for enhanced bonding between a gold alloy and veneering materials

To evaluate the effectiveness of a preliminary light-curing unit when it was used in a procedure to bond veneering material to metal.

Two light-activated composite materials (Artglass and Cesead II) were separately placed onto gold alloy disks (Pontol LFC), and polymerized using one of the following three methods: (1) exposure with a high-intensity laboratory light-curing unit (Hyper LII) for 90 seconds; (2) exposure with a preliminary light-curing unit (Targis Quick) for 20 seconds, followed by exposure with the high-intensity unit for 90 seconds; and (3) exposure with the preliminary unit for 90 seconds, followed by exposure with the high-intensity unit for 90 seconds. Shear bond strengths were determined and compared by analysis of variance and post-hoc multiple comparison intervals. The curing depths of the two materials polymerized with the two curing units were determined using a scraping technique described by the International Organization for Standardization (ISO) 4049 with the aim of evaluating the difference in curing performance between the two units.

The group polymerized using the preliminary unit for 90 seconds showed statistically improved bond strengths over the group polymerized without the preliminary unit (P < 0.05) regardless of the materials. Regarding the Cesead II material, both groups polymerized using the preliminary unit also indicated significantly improved bond strength compared with the group polymerized with high-intensity only. Also, curing depth results revealed that the high-intensity unit demonstrated greater curing performance than the preliminary unit for both types of materials examined.