Interfacial Characteristics of Self-Adhesive Cements Bonded to Dentin

Objectives: Self-adhesive cements represent an attractive approach in indirect restorative procedures. They are supposed chemically interact with dental hard tissues. This study aimed to assess which is the real interaction of self-adhesive resin cements with dentin in comparison with conventional systems that require a separate acid-etching step or those using a self-etching primer. Methods: Composite overlays (AElite All Purposes) were luted on mid-coronal dentinal surfaces using an etch-and-rinse cement (Calibra), a self-etching system (Panavia F 2.0) and four auto-adhesive cements (Multilink Sprint; Rely X Unicem; G-Cem; Bis-Cem). Cements were used in dual-cure mode. After 24-h storage (37°C at 100% humidity), samples were sectioned into 1-mm thick slabs subsequently grinded until getting a thickness of 5-6µm. Cement interaction with dentin was characterized using a specific staining technique (Masson's trichrome) that specifically identifies exposed collagen at the dentin/cement interface and scanning electron microscopy (SEM). Results: Conventional acid etching produced decalcified and partially-infiltrated adhesive interfaces differing from the application of self-etching primer. No hybrid layer neither decalcified dentin except in the case of Multilink Sprint and/or resin tag formation were detectable at the interfaces bonded with self-adhesive cements. Conclusion: Self-adhesive cements produce a partial demineralization/infiltration of the smear layer and limited or no interaction with underlying dentin, that most of the times remains unaffected.