Evaluation of debris removal and uncontrolled removal of dentin after ultrasonic irrigation in curved root canals, and of the efficacy of supplementary methods for removal of remaining filling material, with the aid of micro-CT

• Grant number: 17/18263-9
• Support Opportunities: Regular Research Grants
• Duration: May 01, 2018 - October 31, 2020
• Field of knowledge: Health Sciences - Dentistry - Endodontics
• Principal Investigator: Giulio Gavini
• Grantee: Giulio Gavini
• Host Institution: Faculdade de Odontologia (FO). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated researchers: Elaine Faga Iglecias ; George Táccio de Miranda Candeiro ; Laila Gonzales Freire

Abstract

The aim of this project is to evaluate, by computed microtomography (micro-CT): (i) the influence of the degree of curvature of the root canals: a) on the removal of dentin debris by passive ultrasonic irrigation (PUI) and b) Uncontrolled removal of dentin after the use of PUI; (ii) The effectiveness of the XP-Endo Finisher Retreatment (R) instrument, and two final irrigation methods (Eddy, sonic system, and PUI) for the removal of filling materials in endodontic retreatment of curved canals. Mesial canals will be selected from thirty-six permanent human lower molars (24 with moderate curvature and 12 with sharp curvature). After preoperative scanning with an X-ray Microtomography, the canals will be prepared with a Reciproc R25 instrument. In experiment 1, the teeth will be divided into 2 groups: CM group (n = 12 - mesial channels with moderate curvature) and Group CA (n = 12 - mesial channels with sharp curvature). Both groups will receive passive ultrasonic irrigation (PUI) and then will be re-scanned. In experiment 2, the 24 channels with moderate curvature will be obturated by the thermoplastic technique of continuous wave and the removal of filling materials will be done with the system Protaper Retreatment. This phaze will be complemented by the use of the XP-Endo Finisher R # 30.00 system, followed by repreparing the canal with the Reciproc R40 instrument. Finally, the complementary techniques of irrigation will be employed: Sonic system, Eddy, or PUI. After the end of each step the specimens will be scanned again for analysis of the postoperative images. In experiment 1 the removal of dentin debris and uncontrolled wear of the root canal walls will be quantified. In the experiment 2, the post-obturation filling volumes and the remaining volumetric percentage of this material will be analyzed: after its removal with the Protaper Retreatment system; After using XP-Endo Finisher Retreatment; After re-preparation with the R40 instrument and after the use of the complementary irrigation system (Eddy or PUI). The data collected will be tabulated for the accomplishment of the statistical analysis, using GraphPad Prism 7 software, being considered significant when p <0.05. (AU)