Porcelain repair materials, when properly chosen and used, provide some bond strength in bonding to porcelain. The bond strength is decreased by thermocycling and long-term storage in water. Currently available products are affected differently by these conditions. Surface roughening by rotary instruments and chemical etching by hydrofluoric acid or APF enhances the bond strength. The long-term clinical performance of the porcelain repair materials is not well documented. The council is preparing guidelines to evaluate these materials under the Acceptance Programs of the council. These guidelines will include requiring information on the laboratory and chemical data on these products to demonstrate their safety and efficacy.