Microscopic aspects of the hybrid layer formed by the SE 1-step Futurabond M (Voco) adhesive system applied to normal and sclerotic dentin.

STUDY OBJECTIVES In vitro evaluation and comparison of the adhesion of a generation-7 adhesive system to normal and sclerotic dentin. MATERIALS AND METHODS For this study, sound teeth as well as teeth with sclerotic dentin, which had been extracted for periodontal reasons, were prepared. Class 5 cavities were prepared, then restored by means of the SE 1-step Futurabond M (Voco) adhesive system, as well as the Estelite Sigma Quick (Tokuyama Dental) composite resin. For teeth with sclerotic dentin, the hypermineralized superficial layer was removed by means of round bur on low speed, then the adhesive system and composite resin were applied. These teeth were prepared for microscopic study according to the protocol specific to each microscope. For the study involving the confocal microscope, the adhesive was mixed with the Evans Blue dye before being applied to the tooth, then the same protocol was followed. RESULTS When applied to normal dentin, Futurabond M (Voco), the generation-7 adhesive system, forms a hybrid layer with a depth of 20-25 μm, while it can be noted that it pervades 6-8 μm into the dentinal tubules. When applied to sclerotic dentin, it was noted that the adhesive system does not pervade into the tubules, with an approximately 10-15 μm depth of the hybrid layer. CONCLUSIONS The adhesion to sclerotic dentin shows particular aspects. When it is desired to employ generation-7 adhesive systems (SE 1-step) on sclerotic dentin, the therapeutic approach needs to include the following supplementary stages: removal of the superficial hypermineralized layer, as well as predemineralization with 37% phosphoric acid; they are the only stages that might improve the adhesion to this substrate.