Intaglio etching
Adding water reduces the density of the fluid. In saturated form it comes in 45 degrees Baumé. Use a Baumé hydrometer to find the solution strength. The nitric acid is mixed at 1/5th ratio with water. If using the ferric chloride bath face the plate upside down on small pieces of wood about ¼ from the bottom allowing the iron oxide to fall to the bottom of the bath. The mordants most commonly used for etching copper, zinc, steel, and other metal plates are ferric chloride (most safe), nitric acid and the Dutch mordant. Nitric acid turns brilliant blue-green after etching copper or brass, and a cloudy gray after etching zinc. An acid bath can be used several times for the same type of metal, but separate baths must be made for each metal. When mixing always pour the acid into the water.
It may be concluded that the etching with hydrofluoric acid at the tested concentrations (1%, 5%, and 10%) does not influence the fatigue failure load of feldspathic ceramic inlays cemented on premolars.Process: Intaglio: Etching: Acid Zinc Plate Regarding the fracture mode, there was a predominance of interfacial fracture (50%), followed by cusp fracture (34.6%). Fatigue data were analyzed by one-way analysis of variance. The tested samples were analyzed under a stereomicroscope for failure analysis. The initial load (585.5 N) was applied on the slopes of the cusps (labial and palatal/lingual, simultaneously) through a cylinder attached to the test machine (Instron ElectroPuls E3000). The restorations were cemented and the fatigue failure load (in N) was determined using the staircase method (10 Hz 10 5 cycles in each step).
The inner surfaces of the inlays were etched and received an application of a silane coupling agent the dentin and enamel were treated appropriately for the luting system (RelyX ARC, 3M-ESPE). Preparations were scanned and restorations were milled by a computer-aided design / computer-aided manufacturing system. Teeth were randomly assigned to three groups (n=20): HF1, HF5, and HF10 (etching with hydrofluoric acid for 60 seconds at concentrations of 1%, 5%, and 10%, respectively). A total of 60 upper premolars were embedded in plastic cylinders with acrylic resin (up to 3 mm below the cement-enamel junction) and prepared using a device specially designed for that purpose. The aim of this study was to evaluate the effect of etching, with different hydrofluoric acid concentrations at the intaglio surface of feldspathic ceramic inlays, on the fatigue failure load of restored premolars.