Avaliação de técnicas para confecção e cimentação de retentores intrarradiculares reforçados por fibra

Abstract

Due to the great loss of coronal structure, endodontically treated teeth usually require intraradicular retainers to enable and retain coronal restorative material. In the last decades the glassfber post have been widely indicated as being aesthetic, presenting the possibility of cementation in a single session and biomechanical behavior like the dentin structure. The use of glassfiber post is consolidated in the literature; however, luting is a complex procedure and adds several steps with high technical sensitivity. Thus, simplified and eliminating clinical steps are indicated. In this scenario, a novel concept of glassfiber post obtained by the CAD/CAM system appeared in the market. This new model of post can be feasible, since they promise a better adaptation to the walls of the root, increasing the retention by friction, besides the possibility of milling both the post/core in a single body eliminating the stage of preparation of core in composite resin. Thus, the general aim of this study is to evaluate, by means of laboratory studies, simpliced alternatives for luting and confection of fiber reinforced resin intraradicular retainers. The study was divided into three specific objectives. Specific objective 1- Evaluate the time when the coronal dentin hybridization is performed, before or after cementing glassfiber post with self adhesive resin cements (SARCs), as well the use of SARC as bonding agent to resin composite core filling. Specific objective 2 – Evaluate the mechanical properties of flexural proprieties and modulus of the novel concept of glassfiber post and to evaluate the structural characteristics of fiber and matrix ratio, fibers per mm2 and presence of voids inside the post. Specific objective 3 – To evaluate the biomechanical behavior of endodontically treated teeth rehabilitated with glassfiber post milled by CAD/CAM and its relationship with the coronaral remaning. The results showed that: 1) The use of sefl-adhesive only, as hybridization was shown to demonstrate adequate bond strength to composite resin. The time of coronal dentin hybridization did not affect the bond strength of composite resin. 2) CAD/CAM milled glassfiber post have mechanical properties and structural characteristics similar to prefabricated post. Regardless of the manufacturing method (prefabricated or milled), voids within the structure contribute strongly to the fragility of post. 3) 6 CAD/CAM-fabricated glassfiber post had the same fracture resistance of prefabricated glassfiber post. In absence of remaining coronal dentin, endodontically treated teeth restored with milled post presents higher strain and major potential of fractures irreparable. Therefore, it is concluded that materials that aim to simplify the steps and the digital flow are promising, however more studies are needed so that the glassfiber post CAD/CAM-fabricated are consolidated as a first alternative.