Edge-bevel fracture resistance of three direct-filling materials

Edge strength is defined in this study as the resistance to fracture of the beveled extension normally located at the cavosurface margin of a dental r estoration. The edge strength of direct-filling alloy restorations plays an important role in maintaining the integrity of margins at tooth-alloy inte rfaces during functional loading. The purpose of this study was to determin e the relative strength of an experimental consolidated silver material in comparison to other direct filling materials. The method used was designed as a simulation for relative edge-strength clinical properties. Stainless steel dies were formed from disks 5 mm thick, each with a centere d hole tapered (1/48) toward the bottom side of the disk A 41 degrees bevel , 0.5 mm wide as viewed from above, was placed on the top-side of the disk Dispersalloy (D) or Unison (U) amalgam, Z-100 composite (C), hand-consolida ted silver powder (HAg), or pneumatically consolidated silver powder (PAg) was used to fill the die opening. Excess was polished from both sides of th e disk with 600-grit abrasive paper. The sample was loaded from the beveled side with a 3 mm-in-diameter flat-ended plunger at a rate of 1.0 mm/minute until failure. Failure load and total energy to failure were recorded and compared. Tukey's multiple comparison test (p<0.05) ranked the materials (U )>(HAg)>(D)> (PAg)>(C) for fracture strength and (NAg)(D)> (U)>(PAg)>(C) fo r fracture energy.