Influence of chlorhexidine concentration on the durability of etch-and-rinse dentin bonds: a 12-month in vitro study.
OBJECTIVE
To investigate the effect of 0.2% and 2% chlorhexidine (CHX) used as a therapeutic primer on the long-term bond strengths of two etch-and-rinse adhesive systems.


METHODS
Adper Scotchbond 1XT (SB1) and XP-Bond (XPB) were evaluated. Etched dentin substrates were assigned to 6 treatment groups: (1) 0.2% CHX + SB1; (2) 2% CHX + SB1; (3) SB1 (control); (4) 0.2% CHX + XPB; (5) 2% CHX + XPB; (6) XPB (control). Composite buildups were made and beams prepared for microtensile bond strength testing. Beams were divided into 3 subgroups and either immediately pulled to failure or stored in artificial saliva for 6 or 12 months prior to testing. Data were evaluated with three-way ANOVA. Additional adhesive interfaces were prepared to investigate nanoleakage expression by TEM.


RESULTS
SB1 and XPB showed similar immediate bond strength values with or without CHX pretreatment (p > 0.05). After 12 months, bonds fell from 43.9 +/- 9.5 MPa to 20.1 +/- 5.4 MPa and from 39.6 +/- 9.4 MPa to 14.2 +/- 5.0 MPa in control specimens for SB1 and XPB respectively, while bond fell only from 41.9 +/- 9.6MPa to 33.2 +/- 8.3 MPa and 38.3 +/- 8.9 MPa to 26.5 +/- 10.9 (for SB1 and XPB, respectively) when 0.2% CHX was previously used. CHX concentration did not affect bond strength values (0.2% vs 2%, p > 0.05). Nanoleakage increased during aging in controls, but reduced silver deposits were found in CHX-treated specimens.


CONCLUSIONS
Chlorhexidine significantly reduced the loss of bond strength seen in control bonds. Since no bacterial growth was present in the aging conditions, the results of this study suggest that endogenous factors thought to degrade the adhesive interface can be inhibited by CHX. Further in vivo trials should confirm the role of CHX in bond durability.
Breschi
Lorenzo
L
Department of Biomedicine, Unit of Dental Sciences and Biomaterials, University of Trieste, Trieste, Italy. lbreschi@units.it
Cammelli
Federica
F
Visintini
Erika
E
Mazzoni
Annalisa
A
Vita
Francesca
F
Carrilho
Marcela
M
Cadenaro
Milena
M
Foulger
Stephen
S
Mazzoti
Giovanni
G
Tay
Franklin R
FR
Di Lenarda
Roberto
R
Pashley
David
D
D000134:Acid Etching, Dental / Q000379:methods*; D002710:Chlorhexidine / Q000737:chemistry; D001840:Dental Bonding / Q000379:methods*; D003763:Dental Leakage; D003799:Dental Stress Analysis; D017220:Dentin-Bonding Agents / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D008964:Molar, Third; D011480:Protease Inhibitors / Q000737:chemistry; D013718:Tensile Strength
D017220:Dentin-Bonding Agents; D011480:Protease Inhibitors; C532387:XP-Bond; D002710:Chlorhexidine