Abstract
This study evaluated the efficiency of using a single instrument from three different rotary multi-file systems and compared them with that of a reciprocating single-file for endodontic retreatment by means of micro-CT. Sixty extracted canines were prepared using a size F2 ProTaper Universal file and obturated. After 30 days of storage at 37ºC and 100% humidity, the teeth were randomly divided into four groups (n=15) based on the type of instrument used to retreatment: ProTaper Next (PTN), ProTaper Gold (PTG), TRUShape 3D (TS), and WaveOne (WO). The canals were retreated using only the size 40 instrument from each system according to the manufacturer's recommendations for torque and speed. The time required to remove the filling material was recorded in seconds. The amount of initial and residual filling material and the quantity of dentin removed were assessed by means of micro-CT. Data were statistically analyzed (ANOVA and Kruskal-Wallis) at a 5% significance level. TS instruments required the highest (p<0.05) amount of time (mean, 384.80 ±144.92) compared with the WO (229.67±68.16) and PTG (248.67±64.22) and not so different from PTN instruments (327.67±133.3). No differences in the amount of dentin removed, initial and residual filling volume, and percentages of filling material were observed among the groups. The use of a single rotary instrument from the PTG, TS, and PTN systems was as effective as that of the single-file reciprocating WO system. However, none of the instruments was able to remove the filling materials completely.
Highlights
The permanence of filling materials in the root canal can compromise the success of an endodontic retreatment procedure because the remaining filling materials that adhere to the dentin walls can shelter microorganisms and necrotic remains leading to the development of intraradicular infection, which can interfere with the adhesion of new filling materials to the walls [1,2]
Previous studies have shown that WO files are similar to other rotary and reciprocation systems for the removal of gutta-percha from the root canals [4,5,6,10,20]
The mean percentage of remaining filling material using the WO instrument was 5.26%, which is within the range reported in the literature (2.98%–26.65%) for this instrument and for the heat-treated version of this file, WaveOne Gold
Summary
The permanence of filling materials in the root canal can compromise the success of an endodontic retreatment procedure because the remaining filling materials that adhere to the dentin walls can shelter microorganisms and necrotic remains leading to the development of intraradicular infection, which can interfere with the adhesion of new filling materials to the walls [1,2]. The use of single-file systems such as WaveOne (WO; Dentsply Sirona, Ballaigues, Switzerland) for endodontic retreatment has been suggested [7,10] This instrument operates in a counterclockwise reciprocating motion with proprietary kinematics that require a specific motor. TRUShape 3D (TS; Dentsply Tulsa dental Specialities) instruments are heat-treated and designed to produce an eccentric motion They have a symmetrical triangular cross-section with a 0.06 taper in the apical 2 mm and a variable taper along the rest of the file (denoted as /.06v) [15,16]. The aim of this ex vivo study was to evaluate the effects of using only one rotary instrument from the three different endodontic multi-file systems (PTG, PTN, and TS) and compare them with the reciprocating single-file system (WO) for the endodontic retreatment of mandibular canines. In addition to the operative time, the amount of filling material left in the canal and quantity of dentin removed were assessed by means of micro-computed tomography (micro-CT)
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