Bonding effectiveness of contemporary composite cements to dentin after 6-month water storage

Purpose: To evaluate the bonding effectiveness to dentin of eight dual-cure composite cements after 6-month water storage. Materials and Methods: This study is a follow-up of a recent study that investigated the 1-week bonding effectiveness of feldspathic ceramic blocks luted to dentin using the same composite cements and experimental protocol. The microtensile bond strength (μTBS) of different composite cements, including two etch-and-rinse cements (Calibra, Dentsply; Variolink II, Ivoclar-Vivadent), two self-etch cements (Panavia F2.0, Kuraray; Clearfil Esthetic Cement, Kuraray), and four self-adhesive cements (Unicem, 3M ESPE; Maxcem, Kerr; Monocem, Shofu; G-Cem, GC), was measured using a standardized μTBS protocol after 6-month water storage. As control, a two-step self-etch adhesive (Clearfil SE, Kuraray) combined with a microhybrid restorative composite (Clearfil AP-X, Kuraray) was used. Twenty-seven human third molars were used with specific preparation, and after 6-month water storage, microspecimens were prepared and subjected to a μTBS test. Results: The mean μTBS varied from 0 to 26.1 MPa, the latter being measured for the control adhesive composite combination. All specimens prepared using the self-adhesive composite cements Maxcem and Monocem failed during specimen processing. Most specimens failed at the dentin-cement interface, except the self-etch composite cement Panavia F2.0 that failed in 53% of the cases at the cement-ceramic interface and the control of which all specimens failed in the resin part of the microspecimens. Conclusion: The largely varying bonding effectiveness recorded for the different composite cements highlights the need for material specifications. Such specifications should also include a bond durability test as the specimens in the present study that were subjected to 6-month water storage. To lute ceramic restorations that allow light transmission to a sufficient degree, a conventional light-curable adhesive and composite should be considered.