Selection of sealing material is a problem in terms of long-term durability. In this regard, we have been investigating the in vitro structure and in vivo retention of composite resin sealant with BIS-GMA. Bi-dimensional and three-dimensional analysis by AFM highlights a homogeneous structure with no structural retaining areas of the material. Comparative in vivo and vitro evaluation of sealing resin revealed a correlation of the analyzed aspects in terms of the retention of the material used.