Thickness and morphology of resin-infiltrated dentin layer in young, old, and sclerotic dentin

The purpose of the present study was to evaluate the morphology of the resi n tags and the resin-infiltrated dentin layer (RIDL) of several bonding sys tems in superficial vs deep young, old, and sclerotic human dentin. Dentin was obtained after the removal of occlusal enamel from bonding systems (Opt iBond FL; Prime&Bond 2.0; Scotchbond Multi-Purpose Plus and Scotchbond 1; O ne Step). Each bonded specimen was then sectioned into two halves. One half was polished using a standard procedure to evaluate RIDL thickness and mor phology by SEM. The other half was demineralized and deproteinized to evalu ate the presence and the morphology of resin tags. RIDL was thinner in supe rficial dentin than in deeper dentin for all the materials tested regardles s of the type of dentin. Sclerotic and old dentin showed thinner RIDL, with short resin tags, and fewer lateral branches than normal dentin.