Marginal Fracture vs Mechanical Properties of Amalgam

Abstract

The clinical marginal fracture characteristics of three commercial dental amalgams were evaluated and compared with a number of their mechanical properties to determine which properties would relate best to clinical performance. It was found that compressive strength, tensile strength, transverse strength, transverse deflection, and flow as determined by ADA Specification No. 1 were ineffective, whereas the rheological properties of dynamic creep, static creep, and slow compressive strength appeared effective in relating to marginal fracture.

Creep, corrosion and marginal fracture of dental amalgams

“…This leads to an increase in yi phase and decrease in y phase, both of which lead to an increase in creep. From the above analysis the difference in the creep resistance of amalgams from New True Dentalloy and 20th Century Micro alloy (Mahler et al, 1970 is quite expected because ofthe difference in particle size ofthe original alloy particle. The particle size of 20th Century Micro alloy is smaller than that in New True Dentalloy.…”

The effect of time on the marginal fracture behaviour of amalgam

“…The procedures used in the statistical analysis of marginal fracture data include ridit analysis based on categorizing occlusal photographs according to a standard set (Mahler et al., 1970), rank order analysis based on a continuous ranking of occlusal photographs (Osborne et al, 1976), the modified Wilcoxon two-sample test (Cvar, 1970), and other non-parametric techniques (Wilson & Ryge, 1963;Watson et ah, 1973). Although such procedures are satisfactory for showing where differences exist among alloys, they do not provide a direct measure or index of the extent of fracture.…”

Edge strength of indirect restorative materials

“…15 Many efforts have been made to evaluate the tendency for marginal fracture of various dental materials using different techniques. 12,[15][16][17][18][19][20][21][22][23] Although the concept of edge strength was introduced several decades ago, a well-defined methodology for edge strength measurement was only recently proposed. Edge strength is defined as the ability of restorative materials to withstand fracture of a thin edge and it is determined by measuring the force to fracture at a distance of 0.5 mm of the sample edges.…”