The first method that provides visible microscopic mechanical undercuts on the inner surface of the fixed partial dentures retainers was developed at the Virginia Commonwealth University School of Dentistry.
This method, also known as the “lost salt crystal” technique is consisted of particle-roughened retainers by incorporating salt crystals into the retainer patterns to produce roughness on their inner surface.
Among resin-bonded fixed partial dentures, Virginia bridge is a reflection of the metal surface finishing technique that has been employed as much as anything else over time. This used to be a time-saving method with more retention achieved compared to the technique of etching.
Virginia Salt Bridge is achieved by air abrasion with aluminium oxide. On the working cast, the abutments are coated with a model spray, and a lubricant is then applied.
Sieved cubic salt crystal are sprinkled over the surface in a uniform monolayer, leaving a 0.5 millimeters border without crystal at the periphery of the pattern.
Retainer patterns are fabricated from resin, removed from the cast-resin is polymerized, cleaned with a solvent, and placed in water in an ultrasonic cleaner to dissolve the salt crystals.