Origin of interfacial droplets with one-step adhesives.
Contemporary one-step self-etch adhesives are often documented with interfacial droplets. The objective of this study was to research the origin of these droplets. Two HEMA-rich and one HEMA-free adhesive were applied to enamel and dentin, with the lining composite either immediately cured or cured only after 20 min. All one-step adhesives exhibited droplets at the interface; however, the droplets had two different origins. With the HEMA-free adhesives, droplets were located throughout the adhesive layer and were stable in number over time. With the HEMA-rich adhesives, the droplets were observed exclusively at the adhesive resin/composite interface, and their number increased significantly when the composite was delay-cured. Only the latter droplets caused a significant drop in bond strength after delayed curing. While the droplets in the HEMA-free one-step adhesives should be ascribed to phase separation, those observed with HEMA-rich adhesives resulted from water absorption from dentin through osmosis.
Van Landuyt
K L
KL
Leuven BIOMAT Research Cluster, Department of Conservative Dentistry, School of Dentistry, Oral Pathology and Maxillo-Facial Surgery, Catholic University of Leuven, B-3000 Leuven, Belgium.
Snauwaert
J
J
De Munck
J
J
Coutinho
E
E
Poitevin
A
A
Yoshida
Y
Y
Suzuki
K
K
Lambrechts
P
P
Van Meerbeek
B
B
D000042:Absorption; D001840:Dental Bonding; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008964:Molar, Third; D009995:Osmosis; D044367:Phase Transition; D019279:Resin Cements / Q000737:chemistry*; D018709:Statistics, Nonparametric; D014867:Water
C505694:Clearfil S3 Bond; D017220:Dentin-Bonding Agents; C498353:G-Bond; D008689:Methacrylates; D019279:Resin Cements; D014867:Water; C005044:hydroxyethyl methacrylate