title: The effect of the presence and presentation mode of co-initiators on the microtensile bond strength of dual-cured adhesive systems used in indirect restorations.
abstract: This study compared the microtensile bond strength (microTBS) of indirect resin composite restorations to dentin when fifth-generation adhesive systems were either light-activated or left in the uncured state prior to cementation. The systems used in this study were Prime&Bond NT (NT-Dentsply) and Excite (EX-Ivoclar-Vivadent) or their dual-cured versions containing co-initiators with different presentation modes (as solution or salts) Prime&Bond NT Dual-cure (NTD-Dentsply) and Excite DSC (DSC-Ivoclar Vivadent). The bonding agents were applied to the flattened occlusal dentin surfaces of 40 human third molars according to the manufacturers' instructions and were light-activated (XL3000/3M ESPE) for 10 seconds (LP) or left in the uncured state (SP). The respective resin cements Calibra (Dentsply Caulk) and Variolink II (Ivoclar Vivadent) were applied to pre-cured resin composite discs (2 mm thick/Z-250/3M ESPE) that were fixed to the bonded dentin surfaces. The restored teeth were light-activated according to the manufacturers' instructions for five minutes after cementation and water-stored at 37 degrees C for 24 hours. The teeth were then both mesial-distally and buccal-lingually sectioned to obtain bonded specimens (0.8 mm2). Each specimen was tested in tension at a crosshead speed of 0.5 mm/minute until failure. The data (MPa [SD]) were analyzed by 3-way ANOVA and Tukey's post-hoc test (p < .05). The results showed that the presence of a co-initiator decreased microTBS for NT, while no significant difference in microTBS was noted between EX and DSC, regardless of the curing mode. All SP groups exhibited lower microTBS than the LP groups. The results suggest that coinitiators presented as a solution may decrease microTBS to dentin of the evaluated adhesive systems in indirect resin composite restorations. Light-activation of the adhesive layer prior to indirect cementation was crucial for higher microTBS on dentin.
authors.affiliation: Department of Restorative Dentistry, Operative Dentistry Division, Piracicaba School of Dentistry, State University of Campinas, Piracicaba, SP, Brazil.
authors.forename: Samantha Cristine Santos Xisto Braga
authors.initials: SC
authors.lastname: Cavalcanti
authors.forename: Marcelo Tavares
authors.initials: MT
authors.lastname: de Oliveira
authors.forename: Cesar Augusto Galvão
authors.initials: CA
authors.lastname: Arrais
authors.forename: Marcelo
authors.initials: M
authors.lastname: Giannini
mesh_terms: D003188:Composite Resins; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D007284:Inlays; D019279:Resin Cements / Q000737:chemistry*; D055116:Self-Curing of Dental Resins / Q000379:methods*; D013718:Tensile Strength
chemical_list: D003188:Composite Resins; D017220:Dentin-Bonding Agents; D019279:Resin Cements