Bonding agents have hydrophilic and hydrophobic groups. The hydrophobic group binds which structure?
Calcium in enamel
Hydroxyapatite group in hard tissue
Resin in restoration
Collagen in dentin
Ideally, a dentin bonding agent should have both hydrophilic and hydrophobic ends. The hydrophilic end displaces the dentinal fluid to wet the surface. The hydrophobic end bonds to the composite resin.
Bonding: The forces or energies between atoms or molecules at an interface that hold two phases together.
Mechanism of bonding:
Dentin adhesive molecule has a bifunctional structure:
M-R-X
Where,
M is the double bond of methacrylate which copolymerizes with composite resin.
R is the spacer which makes the molecule large.
X is a functional group for bonding, which bonds to an inorganic or organic portion of dentin.
Ref: Textbook of Operative Dentistry, Nisha and Amit Garg, 3rd edition, Pg no:239