Removing saliva contamination from porcelain veneers before bonding

Contamination of the fitting surfaces of porcelain veneers with saliva at the try-in stage is almost inevitable.

This study used bond strength tests to examine the effect of salivary contamination on Scotchbond adhesive/composite luting material bond to porcelain and evaluated the effectiveness of various procedures used (acetone, phosphoric acid) to overcome such contamination.

Bond strength test specimens were prepared with porcelain adherends. Surfaces of the adherends were cut flat, sandblasted, and divided into 12 groups, each of which received a different surface treatment. After bonding and storage for 24 hours, tensile bond strength values were measured on an Instron machine. Fracture modes were determined with a scanning electron microscope.

Salivary contamination of porcelain surfaces significantly reduced the resin cement-to-porcelain bond from 29.2 +/- 4.5 MPa to 10.3 +/- 4.5 MPa (P <.05). Silane applied to the porcelain, a few days before contamination, resulted in increasing the bond strength from 10.3 +/- 4.5 MPa to 29.9 +/- 8.1 MPa (P <.001). The most effective method of dealing with salivary contamination was by applying silane before the try-in stage and, after the try-in, the porcelain was treated with phosphoric acid for 60 seconds and a fresh layer of silane applied. The bond strength value achieved after this method was 45.0 +/- 9.0 MPa.

Contamination of porcelain surfaces with saliva is detrimental to the resin cement-to-porcelain bond. Of the many procedures investigated to overcome this contamination, the use of phosphoric acid to clean the contaminated surface was the most beneficial.