Tensile bond strength of repaired amalgam

This study evaluated the tensile strength of repaired high-copper amalgams and analyzed the different treatments of the amalgam interface prior to repair. One hundred specimens were divided into 10 groups: group 1 was left intact and was considered as the control group. In groups 2 through 8, the specimens were sectioned into halves after 10 days and were reconstructed with new amalgam. Groups 9 and 10 were condensed with time intervals of 15 minutes and all specimens were subjected to tensile loads in a Universal Testing Machine. The tensile strengths at the junction between old and new amalgam ranged between 50% to 79% of those of the control group and verified that the same type of amalgam and uncontaminated interfaces had higher strengths. The results also suggested that if an amalgam repair is anticipated, additional retention is critical to the longevity of the restoration.