Influence of provisional cementation and cleaning protocol of prosthetic space for glass fiber post over adhesion interface on radicular dentin

Abstract

The aim of this study is to evaluate the influence of two cleaning protocols of prosthetic space prepared for glass fiber post, using irrigation with sodium hypochlorite 2,5%(NaOCl 2,5%) followed by EDTA 17%, once again NaOCl 2,5% and distilled water (IM) or through passive ultrasonic irrigation (PUI) with energized distilled water for 4 cycles of 15seconds. After the provisional cementation of a metallic intracanal post with different temporary cements containing zinc oxide without eugenol (Relyx Temp NE or Temp-Bond NE) or calcium hydroxide (Hidro C), over intradentin penetrability and bond strength of resin cement on self-etching cervical, middle and radicular apical thirds. Sixty roots of human teeth with similar root and endodontic anatomies will be patterned with the length of 17,0 mm from the apex. The canal roots will be amplified up to F5 instrument and obturated with cement containing epoxy resin (AH Plus; Dentsply DeTrey GmbH, Konstanz, GER). After 7 days, the prosthetic space will be prepared sequentially with dental drills type Largo #3 and #4, and concluded by the specific #2 from White Post DC system (FGM, Joinville, SC, BR). The roots will be randomly divided into 6 groups (n = 10, each group), according to the irrigation protocol and provisional cement used: G1 (Relyx Temp NE + IM), G2 (Temp-Bond NE +IM), G3 (Hydro C + IM), G4 (Relyx Temp NE + PUI), G5 (Temp-Bond NE + PUI) e G6(Hydro C + PUI). Metal posts will be temporarily cemented on prosthetic space extension 4using provisional cement previously cited and kept in relative humidity about 90%, at 37ºC. After 7 days, the metal posts will be removed and the prosthetic space will be undergone to one of the previously cited irrigation protocols. As soon as the prosthetic space is dry, the fiber post DC 2 (FGM, Joinville, SC, BR) will be cemented using the resin cement (U200) embodied to Rhodamina B. After 7 days, transversal sections with 2 mm of thickness of cervical, middle and radicular apical thirds will be produced. Those sections will be undergone to a push-out mechanical test in an electromechanical testing machine at speed of0,5 mm/minute. After the test conclusion, the fracture pattern will be classified in adhesive, cohesive or mixed throughout microphotography analysis obtained by scanning electron microscopy. The dentin penetrability of resin cement will be assessed by confocal laser scanning microscopy, where it will initially be obtained the root canal area, and posteriorly, the cement penetration area on radicular dentin with Image J program. The relation between those areas will be converted to percentage of intradentin penetration. The data obtained through these tests will assessed by Shapiro Wilk test, and subsequently, through ANOVA and Tukey or Kruskal Wallis and Dumn (p = 0,05). (AU)