What treatment must be applied to the intaglio surface of a porcelain veneer before cementing?

The proper treatment for the intaglio surface of a porcelain veneer before cementation is to apply a silane coupling agent. This step is crucial because silane acts as an adhesive promoter that enhances bonding between the porcelain and the resin cement used for seating the veneer. The silane molecules bond chemically with the silica on the porcelain surface, thereby improving the mechanical strength and stability of the bond.

Using phosphoric acid, whether at 37% or 15%, is primarily a technique applied in etching enamel or dentin to prepare those surfaces for bonding with resin-based materials. Hydrochloric acid, while sometimes used in dental procedures, is not suitable for preparing porcelain due to its potential to damage the porcelain surface.

Therefore, the application of a silane coupling agent is essential for ensuring a strong and durable bond between the porcelain veneer and the underlying tooth structure during the cementation process. This step ultimately leads to better clinical outcomes and longevity of the restoration.