State of the art etch-and-rinse adhesives.
OBJECTIVE
The aim of this study was to explore the therapeutic opportunities of each step of 3-step etch-and-rinse adhesives.


METHODS
Etch-and-rinse adhesive systems are the oldest of the multi-generation evolution of resin bonding systems. In the 3-step version, they involve acid-etching, priming and application of a separate adhesive. Each step can accomplish multiple goals. Acid-etching, using 32-37% phosphoric acid (pH 0.1-0.4) not only simultaneously etches enamel and dentin, but the low pH kills many residual bacteria.


RESULTS
Some etchants include anti-microbial compounds such as benzalkonium chloride that also inhibits matrix metalloproteinases (MMPs) in dentin. Primers are usually water and HEMA-rich solutions that ensure complete expansion of the collagen fibril meshwork and wet the collagen with hydrophilic monomers. However, water alone can re-expand dried dentin and can also serve as a vehicle for protease inhibitors or protein cross-linking agents that may increase the durability of resin-dentin bonds. In the future, ethanol or other water-free solvents may serve as dehydrating primers that may also contain antibacterial quaternary ammonium methacrylates to inhibit dentin MMPs and increase the durability of resin-dentin bonds. The complete evaporation of solvents is nearly impossible.


CONCLUSIONS
Manufacturers may need to optimize solvent concentrations. Solvent-free adhesives can seal resin-dentin interfaces with hydrophobic resins that may also contain fluoride and antimicrobial compounds. Etch-and-rinse adhesives produce higher resin-dentin bonds that are more durable than most 1 and 2-step adhesives. Incorporation of protease inhibitors in etchants and/or cross-linking agents in primers may increase the durability of resin-dentin bonds. The therapeutic potential of etch-and-rinse adhesives has yet to be fully exploited.
Department of Oral Biology, Medical College of Georgia, School of Dentistry, Augusta, GA, USA. dpashley@mail.mcg.edu
David H
DH
Pashley
Franklin R
FR
Tay
Lorenzo
L
Breschi
Leo
L
Tjäderhane
Ricardo M
RM
Carvalho
Marcela
M
Carrilho
Arzu
A
Tezvergil-Mutluay
D000134:Acid Etching, Dental / Q000379:methods; D000890:Anti-Infective Agents / Q000737:chemistry; D001840:Dental Bonding; D003804:Dentin / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D004791:Enzyme Inhibitors / Q000737:chemistry; D006801:Humans; D019279:Resin Cements / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D014867:Water / Q000737:chemistry
D000890:Anti-Infective Agents; D017220:Dentin-Bonding Agents; D004791:Enzyme Inhibitors; D019279:Resin Cements; D012997:Solvents; D014867:Water