Yes, the “universal” category of adhesives (not to be confused with 7th Generation “All-in-One” adhesives) can be used for everything::
- Hydrophobic enough to be used as a single-layer adhesive.
- Any etching technique: total-etch, self- etch, or selective-etch modes.
- Both direct and indirect clinical procedures using light-cure, dual-cure, or self-cure materials (without the need for a separate self-cure activator).
- Can bond to indirect substrates (low film thickness < 10 µm).
However, not all new “universal” adhesives are created equal. Some are more hydrophobic (with optimized water content), or several require a 2nd hydrophobic resin layer. Also, some require a separate self-cure activator in order to be used with dual-cure/self-cure restorative materials. In addition, some contain silane, claiming to be effective as a coupling agent, but BISCO research has shown that silane is not effective because Bis-GMA and other resins in the formula inhibit the condensation reaction. The condensation reaction occurs between the silanol (-Si-OH-) and ceramic substrate’s –OH group, slowly liberating water molecules to form stable siloxane (-Si-O-Si-) bonds. The liberation of water molecules is essential for the condensation reaction to continue, which can be inhibited by the presence of extra resin, which slows water evaporation (Le Chatelier’s principle).