In vivo Dentinal Fluid Movement through Hybrid Layer

Single-step adhesives are actually considered permeable to fluid movement after polymerisation acting as semi-permeable membrane. Purpose: The tested hypothesis was to evaluate in vivo the dentinal fluid movement through hybrid layer and adhesive. Materials and Methods: cavities were performed in vivo on vital teeth under local anesthesia (Mepivacaine hydrochloride 2% with adrenaline 1/100.000) and rubber dam isolation. Scotchbond 1 (3M-ESPE) was applied on exposed dentin following manufacturers’ instructions. The oxygen inhibited resin layer was removed by acetone with a cotton pellet. The surface was gently air dried. An impression was immediately obtained by vinyl polyxiloxane (President Jet light, Coltene). Replicas were obtained by polyether impression material (Permadyne Garant, 3M-ESPE). Replica samples were gold coated and observed under SEM. Results: Replica specimens showed droplets formation on the adhesive layer surface. Deep dentin showed larger droplets than superficial dentin. No droplets were observed on the enamel. Conclusions: The droplets formation in vivo confirms the adhesive permeability to water flow from vital dentin and HL. This finding suggested that adhesive is a wet substrate that may greatly affect the coupling of more hydrophobic restorative or luting resin materials.