Resistência de união de pinos de fibra de vidro adaptáveis ao conduto radicular fragilizado

Abstract

In order to increase the retention of prefabricated intraradicular post, new materials and techniques have been proposed. The objective of this work was to evaluate the bond strength to the displacement of different prefabricated fiberglass post and the intraradicular dentin substrate. Sixty uniradicular bovine teeth, without apparent defects of similar dimensions, were extracted and stored in distilled water. The teeth were divided into 4 groups (n = 60) with the standardization of the roots at 19 mm in length. Group 1 (G1) used tapered post on weakened roots, group 2 (G2) re-tapered post with composite resin (anatomical post) on weakened roots, group 3 (G3) used tapered post, but on non-weakened roots, group 4 (G4) cylindrical post that have a glove adaptable to the post and root canal in fragile roots. All groups had their roots prepared 14mm deep for cementing the pins. Groups G1, G2 and G4 had root canal preparation using Largo # 1, # 2, # 3 drills and drill 702 for standardized root enlargement and weakening. The G3 also had the preparation of the root canal carried out by the sequence of the three Largo drills, but followed by the use of the specific drill for formatting the conduit recommended by the manufacturer. After cementing the post with self-adhesive cement, the roots were fixed with the aid of low melting wax on an acrylic resin base and sectioned by the precise cutting machine transversely to its longitudinal axis, resulting in 2 discs of 1mm thickness in each of the three thirds evaluated. The specimens were subjected to compressive loads on the post next to the universal testing machine with a speed of 0.5 mm / min with 5000 N until the moment of displacement. Bond strength was calculated considering the adhesive area. Statistical analysis was performed using the Kruskal Wallis test followed by Mann Whitney at a 95% confidence level (P <0.05). The results of the comparison of the sum of values between the different groups showed that groups 2 and 3 had the highest values without statistical differences between them. Groups 1 and 4 showed the lowest values (p <0.05). The comparison between the different thirds of the same group showed, for group 1, that the bond strength was greater in the cervical than in the apical third. For the other groups, there was no significant difference. In the comparative analysis of the groups, in the cervical third, groups 2 and 3 showed the highest union resistance values followed by groups 1 and 4. For the middle third, the values indicated the following order: G2> G3> G1 = G4. Finally, the comparative analyzes between the values of the apical third of all groups show the following order: G2> G3> G4> G1 (p <0.05). We can conclude that the anatomical post improved the resistance to displacement