Retreatment of Experimental Carrier-Based Obturators with the Remover NiTi Instrument: Evaluation of Apical Extrusion and Effects of New Kinematics

Abstract

The objective of this study is to evaluate the retreatment time and weight of apically extruded debris yielded by two different kinematics during the removal of different root canal filling materials. Forty straight single-rooted extracted teeth were instrumented with HyFlex CM files and obturated with two different techniques: 25.04 HyFlex experimental carrier-based obturators (Coltène/Whaledent, Altstätten, Switzerland) (group 1) or 25.04 single gutta-percha cones (Roeko Coltène/Whaledent, Altstätten, Switzerland) (group 2) and Guttaflow Bioseal as the sealer. Samples were divided into four subgroups (n = 10) according to the used kinematics for the removal of root canal filling materials: continuous rotation (A) or retreatment motion (B) with a Remover and HyFlex EDM Nickel-Titanium instruments activated with a CanalPro Jeni micromotor (Coltène/Whaledent, Altstätten, Switzerland). Time for retreatment was digitally recorded, and debris extruded from the apex was collected in Eppendorf tubes and weighted with an analytical balance. Data on retreatment time and apical extrusion were statistically analyzed with the Kruskal–Wallis test ( p < 0.05 ). Working length was achieved in all the retreated samples. The removal of root filling material resulted significantly faster with the Jeni mode ( p < 0.001 ), and the difference was significant for the removal of both filling materials ( p < 0.05 ). No significant differences on debris extrusion between single cone and experimental obturators groups were noted ( p > 0.05 ), and no significant differences between kinematics (continuous rotation vs. Jeni motion) were observed ( p > 0.05 ). All the tested retreatment strategies lead to an extrusion of material from the apex, and the weight of apically extruded debris was similar. The use of the innovative CanalPro Jeni kinematics accelerates the time for the removal of root filling materials.

Assessing the impact of obturation techniques, kinematics and irrigation protocols on apical debris extrusion and time required in endodontic retreatment

“…The sonic device EDDY was selected because few data are available on its influence on the apical extrusion in different experimental conditions [25]. Remover instrument was used to reshape 3 canals for simulating clinical conditions of a multirooted tooth [4]. In addition, the shaping procedure was completed with Hyflex EDM 40.04 to optimise the root canal disinfection [27].…”

“…One hundred and forty‐four single‐rooted teeth extracted for periodontal/orthodontic reasons were stored at 4°C in distilled water and selected according to the following criteria: single straight canal (<20° angle of curvature) without endodontic treatment, completely formed apex and the lack of canal calcifications [4]. Preoperative digital X‐rays of each root were performed in buccolingual and mesiodistal direction to ensure standardised samples.…”

“…The working length (WL) was established by subtracting 1 mm from this measurement. Canals were instrumented with Hyflex EDM system following the manufacturer's instructions (Coltène, Whaledent, Altstatten, Switzerland) [4].…”

“…Apical extrusion of foreign materials has been associated with negative outcomes including periapical inflammation and postoperative pain [1][2][3]. This undesirable consequence is caused by many factors including the obturation technique, instrument and kinematics [4].…”

“…Dedicated retreatment instruments are manufactured for continuous rotation [15]; however, the use of reciprocating files for retreatment procedure has been investigated [4]. Recently, a new patented hybrid kinematics was integrated in new motor CanalPro Jeni (Colténe, Whaledent, Altstätten, Switzerland).…”