Metal surface treatment: Characterization and effect on composite-to-metalbond strength

This study evaluated the effect of four methods of metal surface preparatio n and the use of silane on the bond strength between resin and a Noble meta l alloy. SEM Examination and x-ray energy-dispersive spectroscopy (EDS) of the various metal surface treatments was also performed. One-hundred metal disks were cast in a Noble metal alloy (Porcelain #76). Ninety disks were p olished flat and the surfaces received one of four abrasive treatments (n=2 0). 1) Roughening with a diamond bur at high speed; 2) Air abrasion with an intraoral sandblaster using alumina particles; 3) Air abrasion with KCP-20 00 and 4) Air abrasion with an intraoral sandblaster using silanated silica covered alumina particles (CoJet-Sand). Half the specimens from each treat ment group (n=10) were silanated prior to bonding procedures (All-Bond 2 ad hesive system, Pertac-Hybrid composite). Specimens were stored in distilled water at 37 degrees C and thermocycled prior to shear strength testing. Th e 10 remaining metal disks were used for scanning electron microscopy and x -ray energy-dispersive spectroscopy (EDS). Scanning electron microscopy exa mined the micromorphology of the metal surfaces produced by the four abrasi ve treatments and x-ray energy-dispersive spectroscopy (EDS) to evaluate ch anges in surface composition. Two untreated disks served as controls. One-w ay ANOVA and Tukey's HSD post-hoc test demonstrated that air abrasion with CoJet-Sand and silane resulted in significantly higher resin-to-metal bond strength than all other metal surface treatments, while roughening with a d iamond bur produced the lowest bond strength. Resin-to-metal bond strength was similar for all other particle abrasive treatments with or without sila ne. Using silane significantly improved bond strength only for metal surfac es treated with CoJet-Sand. An increase in AZ concentration was observed on metal surfaces sandblasted with aluminum oxide, and an increase in the con centration of both AZ and Si was observed on surfaces air-abraded with CoJe t-Sand.