Fretting Corrosion Behavior of Ni-based Dental Alloy

Objective: Precision attachment is a popular design of modern removable partial denture (RPD). The male/female components of precision attachment are typically made of dental alloys. Although the manufacturing of these components geometry-specific locking mechanism, micro-motion occurs, and saliva penetrate into this junction of metals, fretting corrosion is produced by relatively small-scale motions between components that are induced by cyclic occlusion loading. The fretting corrosion behavior of typical Ni-based (VBV) dental alloy in artificial saliva and air mediums has been investigated in this research.

Methods: The VBV dental alloy samples (n=20) were polished by the water-proof sand papers. The samples were randomly divided into test group and control group. The fretting corrosion experiments were performed by a hydraulic fretting test rig equipped with liquid container. The systematic studies have been conducted on the fretting corrosion behavior of VBV dental alloy in air and artificial saliva mediums. Combined with the analysis on the frictional dynamic behavior, interfacial damage after fretting corrosion test was assessed using scanning electrical microscope.

Results: VBV dental alloy only has elliptic and quasi-rectangular F-D curves at the artificial saliva environment. At the air condition, there are linear F-D curves when the imposed amplitude was 3ƒÝm. The wear traces are approximately elliptic shape with locally irregular contours. VBV dental alloy have a larger damage area in artificial saliva, while the deeper wear scar occurs in the air condition. Wear morphologies showed pits and corrosion holes in fretting furrow of VBV dental alloy under artificial saliva condition.

Conclusions: 1. artificial saliva medium could transform the partial slip regime to small displacement amplitude; 2. artificial saliva increases the friction coefficient under large amplitudes and the area of wear scar; 3. the fretting corrosion main mechanisms of VBV dental alloy under artificial saliva are the combination of abrasive wear and electrochemical corrosion.