Adhesion of a two-step etch-and-rinse adhesive on collagen-depleted dentin.
OBJECTIVE
To evaluate microtensile bond strength and interfacial nanoleakage expression of adhesive interfaces created by XP-Bond on human deproteinized dentin immediately after bonding and after 6 months of artificial aging.


METHODS
Noncarious human molars were selected, middle/deep dentin substrates were exposed, and either assigned to group 1 (XP-Bond applied on collagen-depleted dentin) or to group 2 (XP-Bond applied in accordance with manufacturers' instructions). In group 1, the etched dentin surface was treated with 10% NaOCl for 60 s to remove the exposed demineralized organic matrix before XP-Bond application. Composite/dentin beams were obtained in accordance with the microtensile nontrimming technique and either pulled to failure after 24 h or after 6 months' artificial aging. Data were analyzed with two-way ANOVA and Tukey's post-hoc test (p < 0.05). Interfacial nanoleakage evaluation was performed on additional adhesive interfaces to quantify the amount of silver tracer along the interface.


RESULTS
The use of NaOCI before XP-Bond application (group 1: 18.9 +/- 5.8 MPa) reduced immediate bond strength by 62% compared to controls (group 2: 49.9 +/- 10.3 MPa; p < 0.5). After 6 months of artificial aging, the bond strength of groups 1 and 2 significantly decreased to 10.1 +/- 2.7 MPa and 35.2 +/- 8.7 MPa, resp (p < 0.05). Interfacial nanoleakage expression along XP-Bond adhesive interfaces was increased either by sodium hypochlorite or by artificial aging.


CONCLUSIONS
The role of collagen fibrils is pivotal for the bonding of XP-Bond to dentin, as decreased immediate bond strength and reduced bond stability over time was found on collagen-depleted dentin.
Saboia
Vicente P A
VP
Department of Restorative Dentistry, Federal University of Ceará, Fortaleza, Brazil.
Nato
Fernando
F
Mazzoni
Annalisa
A
Orsini
Giovanna
G
Putignano
Angelo
A
Giannini
Marcelo
M
Breschi
Lorenzo
L
D000134:Acid Etching, Dental / Q000379:methods*; D003094:Collagen; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003763:Dental Leakage / Q000145:classification; D003764:Dental Materials / Q000737:chemistry; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D016877:Oxidants / Q000737:chemistry; D016622:Silver Staining; D012973:Sodium Hypochlorite / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D013997:Time Factors
D003188:Composite Resins; D003764:Dental Materials; D017220:Dentin-Bonding Agents; C444701:Filtek Z250; D016877:Oxidants; C532387:XP-Bond; D003094:Collagen; D012973:Sodium Hypochlorite