Effects of irrigation of the intraradicular space with intermediates, after the use of chlorhexidine, on the adhesion interface with the self-etching adhesive system

Abstract

Chlorhexidine is used prior to the application of the condition-and-wash adhesive systems in order to provide greater longevity to the adhesive interface in the dentin. There is controversy as to whether it is also recommended for self-etching adhesive systems, as it is believed that it may negatively interfere with the bonding process with dentin. There are doubts about the cementation of fiberglass pin with conventional resin cement and the Universal adhesive system. However, ethanol and acids have been recommended for irrigation prior to chlorhexidine in order to minimize undesirable effects without compromising their efficacy. The objective of the present study will be to evaluate the effects of the irrigation protocols of the intraradicular space prepared for fiberglass pin, with 95% ethanol (ET) or 1% peracetic acid (AP) prior to the chlorhexidine digluconate a (Relyx Ultimate) and the Universal Self-etching Adhesive (Scotchbond Universal), by means of an evaluation of the precipitation of residues and their chemical composition, influence on the adhesive interface between the root dentine and the cement system with conventional resin cement (Relyx Ultimate) bond strength, fracture pattern, and intradentinal penetrability of the cementation system. For the last three analyzes, the specimens will be evaluated at 24 h and at 6 months after cementation of the fiber pin. The roots will be standardized in 17mm, 120 root canals will be instrumented up to instrument F5 and filled with AH Plus and gutta percha. Then, the pin preparation will be done with Drills Wide and DC1, in 11 mm. 40 specimens will be selected and divided into 4 groups (n = 10), with irrigation protocols: G1 (AD), distilled water; G2 (CHX), CHX; G3 (ET-CHX), ET and CHX and G4 (AP-CHX), AP and CHX. After the cleavage of the roots in the vestibular-lingual region, the presence and chemical constitution of the precipitates in SEM and ESD will be evaluated on the surface of the cervical, middle and apical thirds of the intraradicular space. The remaining 80 specimens will be divided into 4 groups (n = 20) and subdivided into 2 subgroups (n = 10), according to the time of evaluation. After performing the irrigation protocols, the pin will be cemented with conventional resin cement and Universal adhesive system. In each group will be analyzed by bond strength test, fracture pattern and dentin penetrability 24 hours and 6 months after the cementation of the pin. The results will be submitted to the Anova or Kruskal Wallis tests, except in the evaluation of the residue precipitation where the Kruskal Wallis test (± = 5%) will be performed. To evaluate the bond strength, fracture pattern and dentin penetrability, the irrigation protocol will be: G1 (AD-I) irrigated with distilled water and cementation will be done with Relyx Ultimate and the Universal adhesive system. The pin will be cleaned with ethanol and passed on two layers of adhesive; the G1-like G2 (CHX-I), with prosthetic space irrigated with CHX and pin cementation identical to G1; G3 (ET-CHX-I) identical to G2, with irrigation with 95% ethanol and CHX; G4 (AP-CHX-I) identical to G3 and irrigation with 1% peracetic acid. The specimens of groups G5, G6, G7 and G8 will be similar to G1, G2, G3 and G4 respectively but will remain in distilled water for analysis after 6 months of pine cementation. Fluorescent dye will be added to the adhesive system and to the resin cement allowing evaluation under confocal fluorescence microscopy. The specimens will be included in a polyester resin matrix that will be sectioned into three sections and subjected to the push-out test, obtaining the amount of force required to displace the obturation. For the evaluation of the fracture pattern, they will be examined in stereomicroscope. And, for the analysis of the dentin penetrability, we will evaluate in confocal microscope. Finally, the results will be submitted to Kruskal Walli, Dunn, ANOVA and Tukey tests.