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Impact of shelf-life simulation on bonding performance of universal adhesive systems
Carlos Enrique Cuevas-Suárez1, Tatiana S Ramos2, Stéfani Becker Rodrigues3
1Dental Materials Laboratory, Academic Area of Dentistry, Autonomous University of Hidalgo State, Circuito Ex Hacienda La Concepción S/N, San Agustín Tlaxiaca, Hgo, 42160 Mexico; Department of Restorative Dentistry, School of Dentistry, Federal University of Pelotas. Gonçalves Cháves 457, Pelotas, RS 96015-560, Brazil.
Objectives:
To evaluate the micro-tensile bond strength to dentin (μTBS), the degree of conversion (DC) and nanoleakage expression (NL) of eight dental adhesives considering their expiry date (as-received, half-life and or end of shelf-life) after shelf-life simulation.
Methods:
Five universal adhesives (Single Bond Universal, SBU; Tetric Bond Universal, TBU; OneCoat Universal, OCU; OptiBond Universal, OBU; and Prime&Bond Elect, P&B), two two-step self-etch adhesives (Clearfil SE, CSE; and AdheSE, ASE) and one two-step etch-and-rinse adhesive (Adper Singlebond 2, ASB) were evaluated. Shelf-life was simulated by storing the materials in an acclimatization chamber for different periods of time. The μTBS was tested in accordance with ISO/TS 11,405. DC was evaluated by means of FTIR spectroscopy. NL was evaluated after ammoniacal silver challenge. The significance level of α=0.05 was used for all statistical analyses.
Results:
The μTBS to dentin of TBU, P&B, ASE, and ASB adhesive systems remained stable throughout the shelf-life periods evaluated, while for SBU, OCU, OBU, and CSE, decreased significantly after evaluation in the 'half-life' or 'end of shelf-life' condition (p<0.05). Except for P&B, ASE and OBU, the degree of conversion significantly decreased after the shelf-life simulation (p<0.05). OCU, ASE, and CSE showed significantly increased percentage of silver deposition within the adhesive layer (p<0.05).
Significance:
Storing conditions and progressively longer storage time affect the performance of universal adhesives systems.
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