Ertuğrul Karataş

Effect of ProTaper Universal, Endoflare, Revo-S, HyFlex Coronal Flaring Instruments, and Gates Glidden Drills on Crack Formation

INTRODUCTION The aim of the present study was to evaluate crack formation after flaring root canals with Gates Glidden drills and ProTaper Universal (SX; Dentsply Maillefer, Ballaigues, Switzerland), Endoflare (MicroMega, Besançon, France), Revo-S (MicroMega), and HyFlex (Coltene-Whaledent, Allstetten, Switzerland) flaring instruments. METHODS One-hundred eight mandibular molars were selected. Eighteen teeth were left unprepared to serve as negative controls; the experimental groups consisted of the mesiobuccal and mesiolingual root canals of the remaining 90 teeth, which were instrumented with the following coronal flaring instruments: Gates Glidden drills and ProTaper Universal SX, Endoflare, Revo-S SC1, and HyFlex 25.08 instruments. All roots were then sectioned perpendicular to the long axis at 1, 2, 3, 4, 6, and 8 mm from the cementoenamel junction. The sections were inspected under a stereomicroscope, and any crack formations were recorded. The data were analyzed using the chi-square test (P = .05). RESULTS The Gates Glidden drills resulted in a higher rate of crack formation than that noted in the control group (P < .05). Flaring of the root canals using the ProTaper Universal, Endoflare, Revo-S, and HyFlex instruments resulted in crack formation similar to that of the control group (P > .05). CONCLUSIONS The use of the Gates Glidden drills resulted in the formation of the most cracks. However, the results for the ProTaper Universal, Endoflare, Revo-S, and HyFlex flaring instruments were similar to those of the control group in terms of crack formation.

The Effects of Mtwo, R-Endo, and D-RaCe Retreatment Instruments on the Incidence of Dentinal Defects during the Removal of Root Canal Filling Material

INTRODUCTION The aim of this study was to compare the incidence of dentinal defects after retreatment procedures with different nickel-titanium rotary retreatment files. METHODS One hundred-eighty mandibular premolars were randomly assigned to 6 groups (n = 30 teeth per group). One group was left unprepared, and the remaining 5 groups were prepared with K-files (Dentsply Maillefer, Ballaigues, Switzerland) and filled with gutta-percha and AH plus sealer (Dentsply Maillefer, Ballaigues, Switzerland). Of these 5 groups, 1 group was left filled and received no further treatments; in the other groups, removal of the filling material was performed with Mtwo R (VDW, Munich, Germany), D-RaCe (FKG Dentaire, La Chaux-de-Fonds, Switzerland), R-Endo instruments (Micro-Mega, Besançon, France), or Hedström files (Dentsply Maillefer). Roots were then sectioned 3, 6, and 9 mm from the apex and observed under a microscope. The presence of dentinal defects was noted. Chi-square tests were performed to compare the incidence of dentinal defects between the groups. A Pearson correlation test was performed to check the correlation between defects and root level or remaining dentin thickness. RESULTS No defects were observed in the unprepared group. Dentinal defects were detected in all retreatment groups. Retreatment groups showed significantly more defects than the filled but no retreatment group (P < .05). There was no significant difference in the occurrence of defects between retreatment groups (P > .05). There was no correlation between the appearance of defects and level of the root or remaining dentin thickness. CONCLUSIONS Under the experimental conditions, all retreatment techniques used in this study created defects in the root dentin.

Effect of Agitation of EDTA with 808-Nanometer Diode Laser on Removal of Smear Layer

INTRODUCTION Near-infrared diode lasers can be used for several applications, which range from disinfection to smear layer removal in endodontics. This study evaluated the efficacy of agitation of 15% EDTA with an 808-nm diode laser on removal of the smear layer. METHODS Sixty extracted human maxillary central incisor teeth were instrumented up to ProTaper F4 (Dentsply Maillefer, Ballagues, Switzerland) and then randomly divided into 6 groups (n = 10 for each group) according to the different final irrigating protocols as follows: 5% sodium hypochlorite for 120 seconds performed with the NaviTip (Dentsply Maillefer, Ballaigues, Switzerland) (control group); 15% EDTA for 120 seconds performed with the NaviTip; and agitation of 15% EDTA with an 808-nm diode laser for 10, 20, 30, and 40 seconds. Specimens were observed under a scanning electron microscope, and open dentinal tubules were counted using Adobe Photoshop software (Adobe Systems, San Jose, CA). The data were analyzed with 1-way analysis of variance and Tukey post hoc tests (P = .05). RESULTS The number of open dentinal tubules was higher in the middle thirds than in the apical thirds. The differences between the apical and middle thirds were statistically significant (P < .05). Statistically significant differences were also found between the control group and the other groups in both the middle and apical thirds of the root canals (P < .05). CONCLUSIONS The results indicated that agitation of 15% EDTA with an 808-nm diode laser for 20 seconds was effective in removing the smear layer in the apical thirds of root canals.

In Vitro Fracture Resistance of Roots Obturated with Epoxy Resin–based, Mineral Trioxide Aggregate–based, and Bioceramic Root Canal Sealers

INTRODUCTION The aim of this study was to evaluate the fracture resistance of teeth filled with 3 different endodontic sealers. METHODS Seventy-five single-rooted extracted mandibular premolars were decoronated to a length of 13 mm. The teeth were randomly divided into 5 groups (n = 15 for each group). In group 1, the teeth were left unprepared and unfilled (negative control), and in group 2, the teeth were left unobturated (positive control). The rest of the roots were prepared by using the ProTaper System up to a master apical file size of F3: group 3, bioceramic sealer (Endosequence BC sealer) + gutta-percha; group 4, mineral trioxide aggregate-based sealer (Tech Biosealer Endo) + gutta-percha; and group 5, epoxy resin-based sealer (AH Plus Jet) + gutta-percha. All root specimens were stored for 2 weeks at 100% humidity to allow the complete setting of the sealers. Each specimen was then subjected to fracture testing by using a universal testing machine at a crosshead speed of 1.0 mm/min(-1) until the root fractured. The force required to fracture each specimen was recorded, and the data were analyzed statistically. RESULTS The fracture values of groups 3 and 5 were significantly higher than those of group 4 (P < .05). There was no significant difference between groups 3 and 5 (P > .05). CONCLUSIONS In contrast to Tech Biosealer Endo, Endosequence BC and AH Plus Jet sealer increased the force to fracture in root-filled single-rooted premolar teeth.

Comparison of apically extruded debris after root canal instrumentation using Reciproc® instruments with various kinematics

AIM To assess the amount of apically extruded debris using Reciproc(®) instruments with different kinematics (150° counter clockwise [CCW]-30° clockwise [CW], 270° CCW-30° CW, 360° CCW-30° CW and continuous rotation). METHODOLOGY Forty-eight maxillary central incisors were selected and assigned to four root canal shaping groups as follows (n = 12): 150° CCW-30° CW, 270° CCW-30° CW, 360° CCW-30° CW and continuous rotation. Reciproc R25 and R50(®) instruments were used in all groups. Apically extruded debris was collected and dried in preweighed Eppendorf tubes. The weight of extruded debris was assessed with an electronic balance. The data were analysed with one way analysis of variance and LSD post hoc tests (P = 0.05). RESULTS The 150° CCW-30° CW and 270° CCW-30° CW reciprocating motions extruded significantly less debris than continuous rotation (P < 0.05). However, no significant differences were found between the 360° CCW and 30° CW reciprocating motion and the continuous rotation (P > 0.05). CONCLUSIONS All instrument movements were associated with apically extruded debris. However, the 150° CCW-30° CW and 270° CCW-30° CW reciprocating motions were associated with less extrusion than continuous rotation.

Effect of movement kinematics on the cyclic fatigue resistance of nickel–titanium instruments

AIM To compare the cyclic fatigue resistance of new generation OneShape and WaveOne instruments when used with different kinematics. METHODOLOGY An artificial canal, made of stainless steel with an inner diameter of 1.5 mm, a 60° angle of curvature and a curvature radius of 3 mm, was used for cyclic fatigue test of new generation OneShape and WaveOne instruments. Groups were as follows (n = 20): 150°-30°, 210°-30°, 360°-30° and continuous rotation. The time to fracture was recorded in seconds, and the data were analysed statistically using a two-way anova and LSD tests (P = 0.05). RESULTS Cyclic fatigue resistance was significantly affected by the movement kinematics (P < 0.001). The cyclic fatigue resistance of the new generation OneShape instruments increased significantly when operated in various reciprocation motions (150° CW-30° CCW, 210° CW-30° CCW and 360° CW-30° CCW) compared with the continuous rotation mode. New generation OneShape instruments had significantly more resistance to fracture under cyclic loading than WaveOne instruments (P < 0.001). CONCLUSIONS When using new generation OneShape and WaveOne instruments, all the reciprocating motions (150° CW-30° CCW, 210° CW-30° CCW and 360° CW-30° CCW) resulted in extended fatigue life when compared with continuous rotation.

Quantitative evaluation of apically extruded debris during root canal instrumentation with ProTaper Universal, ProTaper Next, WaveOne, and self-adjusting file systems.

Objectives: The aim of this study was to compare the amount of apically extruded debris during preparation with ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Next (Dentsply Maillefer), a reciprocating single-file (WaveOne; VDW GmbH, Munich, Germany), and a self-adjusting file (SAF; ReDent Nova, Ra′anna, Israel). Materials and Methods: Fifty-six intact mandibular premolar teeth were randomly assigned to four groups. The root canals were prepared according to the manufacturers′ instructions using the ProTaper Universal, ProTaper Next, WaveOne, and SAF. Apically extruded debris was collected in preweighted Eppendorf tubes during instrumentation. The net weight of the apically extruded debris was determined by subtracting the preweights and postweights of the tubes. The data were statistically analyzed using the one-way analysis of variance and the least significant difference tests at a significance level of P < 0.05. Results: A measurable amount of debris was apically extruded in all groups, and the amounts of debris extrusion in the groups were statistically significant (P < 0.001). The ProTaper Next and WaveOne groups resulted in less debris extrusion than the ProTaper Universal group (P < 0.05), and the SAF group resulted in the least debris extrusion. Conclusions: Within the limitations of the present study, it can be concluded that all systems extruded debris beyond the apical foramen.

Quantitative evaluation of apically extruded debris with Twisted File Adaptive instruments in straight root canals: reciprocation with different angles, adaptive motion and continuous rotation

AIM To evaluate the influence of movement kinematics when using Twisted File Adaptive instruments (SybronEndo, Orange, CA, USA) (TF Adaptive) on the amount of apically extruded debris. METHODOLOGY Forty-eight extracted mandibular incisor teeth were selected. The teeth were randomly divided into four groups (n ꞊ 12), and the root canals were instrumented using the following movement kinematics: TF Adaptive motion, 90° clockwise (CW) to 30° counterclockwise (CCW) reciprocating motion, 150°CW to 30°CCW reciprocating motion or continuous rotation. TF Adaptive instruments were used for all groups. Debris extruded apically during instrumentation was collected in pre-weighed Eppendorf tubes, and after drying, the mean weight of the debris was assessed with an electronic balance. The data were analysed statistically using a one-way analysis of variance. RESULTS The 90° CW to 30° CCW reciprocating motion produced the highest mean extrusion value, and this was significantly greater when compared with continuous rotation (P < 0.05). 150° CW to 30° CCW reciprocating, adaptive and continuous rotation motions produced similar amounts of debris extrusion (P > 0.05). CONCLUSION Movement kinematics affected the amount of apically extruded debris when using Twisted File Adaptive instruments.

Cyclic fatigue analysis of Reciproc R25® instruments with different kinematics.

This study aimed to compare the cyclic fatigue resistance of Reciproc® instruments when used with different kinematics (150° counterclockwise (CCW)-30° clockwise (CW), 270° CCW-30° CW, 360° CCW-30° CW and continuous rotation). Various kinematics were tested in steel canals with a 3 mm radius and a 60° angle of curvature as follows (n = 20): 150° CCW-30° CW, 270° CCW-30° CW, 360° CCW-30° CW and 360° CCW (rotary motion). Reciproc R25® instruments were used until fracture occurred. The time to fracture was recorded in seconds. The data were statistically analysed using a one-way analysis of variance and Tukeys post-hoc tests (P = .05). The cyclic fatigue resistance of Reciproc R25® instruments used with various kinematics in decreasing order was as follows: 150° CCW-30° CW > 270° CCW-30° CW = 360° CCW-30° CW > 360° CCW rotary motion. The 150° CCW-30° CW reciprocating motion had the best performance in time to fracture. All reciprocating motions (150° CCW-30° CW, 270° CCW-30° CW and 360° CCW-30° CW) resulted in a longer mean duration to failure compared with the 360° CCW rotary motion.

Incidence of Dentinal Cracks after Root Canal Preparation with Twisted File Adaptive Instruments Using Different Kinematics

INTRODUCTION The purpose of the present study was to assess the effect of root canal instrumentation using Twisted File Adaptive instruments (Axis/SybronEndo, Orange, CA) with different kinematics (adaptive motion, 90° clockwise [CW]-30° counterclockwise [CCW], 150° CW-30° CCW, 210° CW-30° CCW, and continuous rotation) on crack formation. METHODS One hundred five mandibular central incisor teeth were selected. Fifteen teeth were left unprepared (control group), and the remaining 90 teeth were assigned to the 5 root canal shaping groups as follows (n = 15): adaptive motion, 90° CW-30° CCW, 150° CW-30° CCW, 210° CW-30° CCW, continuous rotation, and hand file. All the roots were sectioned horizontally at 3, 6, and 9 mm from the apex with a low-speed saw under water cooling, and the slices were then viewed through a stereomicroscope at 25× magnification. Digital images of each slice were captured using a camera to determine the presence of dentinal cracks. RESULTS No cracks were observed in the control group, and the continuous rotation group had more cracks than the reciprocation groups (90° CW-30° CCW, 150° CW-30° CCW, and 210° CW-30° CCW) (P < .05). Both the continuous rotation and adaptive motion groups had significantly more dentinal cracks than the hand file group (P < .05). Regarding the different sections (3, 6, and 9 mm), there was a significant difference between the experimental groups at the 9-mm level (P < .05). CONCLUSIONS The incidence of dentinal cracks is less with TF Adaptive instruments working in 210° CW-30° CCW reciprocating motion compared with working in continuous rotation and adaptive motion.