Adhesion of a glass ionomer cement to human radicular dentine

The adhesion of cements to root canal surfaces is a crucial factor for strengthening non-vital teeth--weakened due to extensive loss of tooth structure--by cemented posts. The aim of this study was to determine the tensile strength of a glass ionomer cement (Ketac-Cem) on root canal walls following pretreatment with conditioners. Upon cleaning and shaping, 56 straight root canals--divided into seven groups--were conditioned with one of the following solutions: NaOCl (1%) + EDTA (20%), H3PO4 (37%), HNO3 (2.5%), citric acid (6%), polyacrylic acid (10% and 20%) and NaCl (0.9%) as control. Standardized dentine cylinders were prepared out of the coronal half of each root perpendicular to the root axis and subsequently split. The exposed root canal areas were coated with Ketac-Cem. Using an universal testing machine a tensile force was applied to Ketac-Cem up to fracture. Pretreatment with EDTA-NaOCl provided the strongest bond strength (2.2 MPa). The median values for the other conditioning solutions ranged from 1.2 to 1.9 MPa. The significantly weakest bond (0.5 MPa) was recorded for NaCl. The elimination of the smear layer appeared to be an essential factor in order to improve the adhesion.