The effect of dimethyl sulfoxide (DMSO) on dentin bonding and nanoleakage of etch-and-rinse adhesives.
OBJECTIVE
The objective was to examine the effect of a solvent dimethyl sulfoxide (DMSO) on resin-dentin bond durability, as well as potential functional mechanisms behind the effect.


METHODS
Microtensile bond strength (μTBS) was evaluated in extracted human teeth in two separate experiments. Dentin specimens were acid-etched and assigned to pre-treatment with 0.5mM (0.004%) DMSO as additional primer for 30s and to controls with water pre-treatment. Two-step etch-and-rinse adhesive (Scotchbond 1XT, 3M ESPE) was applied and resin composite build-ups were created. Specimens were immediately tested for μTBS or stored in artificial saliva for 6 and 12 months prior to testing. Additional immediate and 6-month specimens were examined for interfacial nanoleakage analysis under SEM. Matrix metalloproteinase (MMP) inhibition by DMSO was examined with gelatin zymography. Demineralized dentin disks were incubated in 100% DMSO to observe the optical clearing effect.


RESULTS
The use of 0.5mM DMSO had no effect on immediate bond strength or nanoleakage. In controls, μTBS decreased significantly after storage, but increased significantly in DMSO-treated group. The control group had significantly lower μTBS than DMSO-group after 6 and 12 months. DMSO also eliminated the increase in nanoleakage seen in controls. 5% and higher DMSO concentrations significantly inhibited the gelatinases. DMSO induced optical clearing effect demonstrating collagen dissociation.


CONCLUSIONS
DMSO as a solvent may be useful in improving the preservation of long-term dentin-adhesive bond strength. The effect may relate to dentinal enzyme inhibition or improved wetting of collagen by adhesives. The collagen dissociation required much higher DMSO concentrations than the 0.5mM DMSO used for bonding.
Institute of Dentistry, University of Oulu and Oulu University Hospital, Oulu, Finland; Institute of Dentistry, University of Turku, Turku, Finland; The Nordic Institute of Dental Materials (NIOM), Oslo, Norway. Electronic address: leo.tjaderhane@oulu.fi.
Leo
L
Tjäderhane
Pekka
P
Mehtälä
Polliana
P
Scaffa
Cristina
C
Vidal
Virve
V
Pääkkönen
Lorenzo
L
Breschi
Josimeri
J
Hebling
Franklin R
FR
Tay
Fabio D
FD
Nascimento
David H
DH
Pashley
Marcela R
MR
Carrilho
D003738:Dental Cements; D003804:Dentin / Q000737:chemistry*; D004121:Dimethyl Sulfoxide / Q000737:chemistry*; D008422:Materials Testing; D036103:Nanotechnology
D003738:Dental Cements; D004121:Dimethyl Sulfoxide
DMSO; Dentin bonding; Durability; Human; Long-term; Matrix metalloproteinase; Nanoleakage