Endofill interfered negatively with the bond to root dentine along its full length and in the TA when post fixation was delayed for 7 days. Bond strength decreased from crown to apex in all groups.

Composite resin restoration plays an important role in recovering tooth strength. With regard to fracture mode, restoration and endodontic treatment increased the incidence of periodontal involvement, which was demonstrated by association with the finite element mechanical test method.

Both 24% and 50% hydrogen peroxide exposure increased the bond strength of resin to the posts, irrespective of the application time.

The aim of this study was to assess the influence of the shape of custom cast dowel and cores on their removal by the use of ultrasound technique. Twenty-four single-rooted bovine teeth were prepared and had cast dowel fixed with zinc phosphate cement. The teeth were randomly divided into two groups: group I- received custom cast dowel and cores made without the coronal portion anatomy, simulating removal this portion with a bur, and group II- received cores that reproduced the coronal anatomy. Both were treated with an ultrasound device in two three-minute cycles (US). The force necessary for dowel removal was determined using a mechanical test machine. In the second stage of the study, the custom cast dowel and cores were again cemented and no ultrasound vibration was used on them (C). Data were submitted to the two-way anova (2 x 2) and Tukey test (P < 0.05), resulting in decreased tensile strength values (Kgf): GIC (49.85 +/- 11.10); GIIC (48.22 +/- 11.09); GIIUS (32.36 +/- 6.21) and GIUS (8.0 +/- 7.52). It was concluded that the shape of the core without the anatomic coronal portion facilitated removal of intra-radicular retention only when associated with the use of ultrasound.