Influence of metal cleaning methods on the resin bond strength to NiCr alloy.

ABSTRACT

OBJECTIVES: The purpose of this laboratory study was to evaluate the influence of different metal cleaning methods on the bond strength of various resin bonding systems and its durability to a NiCr alloy. The hypothesis was that the resin bond strength and its durability is related to the cleaning method and to the bonding system used. METHODS: Plexiglas tubes filled with composite resin were bonded to NiCr disks using three different bonding systems tribochemical silica-coating and silanization of the alloy, acrylization of the alloy, or bonding with a phosphate monomer containing composite resin. For each bonding system, three cleaning methods were used after the last air abrasion step cleaning with a stiff brush, ultrasonic cleaning in alcohol or in a neutral detergent. For each combination 20 samples were bonded. Subgroups of 10 bonded samples were tested for tensile strength following storage for either 3 or 150 days. In addition, the 150-day samples were thermal cycled 37,500 times. The statistical analyses were made by ANOVA, followed by multiple pair-wise comparison of the groups using Scheffe and t-tests with Bonferroni-Holm correction. RESULTS: The mean tensile bond strengths ranged from 34.8 to 49.2 MPa after 3 days and from 2.1 to 43.1 MPa after 150 days. Acrylization of the alloy did not provide durable bond strength to NiCr alloy over storage time. Cleaning the alloy surface with alcohol provided statistically significant higher bond strength than the other cleaning methods after 3 days. SIGNIFICANCE: Alloy cleaning methods after air abrasion have a significant influence on the resin bond strength.