Evaluation of apically extruded debris during the removal of canal filling material using three different Ni-Ti systems and hand files in teeth with simulated apical root resorption.

AIM: To compare the weight of apically extruded debris produced during the removal of root canal filling material using various files in extracted teeth with simulated apical root resorption. METHODOLOGY: The root canals of one hundred and twenty extracted mandibular premolar teeth were prepared with Revo-S files and filled using a cold lateral compaction technique with gutta-percha and a resin-based sealer (AdSeal; Meta-Biomed, Cheongwon, Korea). Sixty teeth were randomly assigned to four control groups (hand file, ProTaper Universal retreatment file, D-RaCe retreatment file, and Reciproc file) for the removal of root canal filling material. The apical portion of the remaining 60 teeth was modified to simulate apical root resoption, and the teeth were then randomly divided into 4 experimental groups (using the same techniques as in the control groups) for the removal of root canal filling material. Apically extruded debris was collected into pre-weighed Eppendorf tubes and then dried. The mean weight of the apically extruded debris was assessed with an analytical balance to an accuracy of 10-4  g. Data were analysed using two-way analysis of variance and a Tukey's post hoc test. RESULTS: In the simulated apical root resorption groups, all file systems were associated with significantly more debris extrusion compared to the groups without simulated resorption (P < 0.05). The amount of apically extruded debris was greatest in the hand file groups compared with the other groups (P < 0.05). In the groups with simulated apical root resorption, the Reciproc system was associated with the least weight of apically extruded debris (P < 0.05), whereas there was no significant difference between the ProTaper Universal retreatment and D-RaCe files (P > 0.05). In the groups without simulated apical root resorption, there was no significant difference between Reciproc, ProTaper Universal retreatment and D-RaCe retreatment files (P> 0.05). The time required to remove the root canal filling material was as follows: hand file > ProTaper Universal retreatment = D-RaCe retreatment > Reciproc (P < 0.05). CONCLUSIONS: The weight of apically extruded debris was significantly greater in teeth with simulated apical root resorption than in those teeth without simulated apical root resorption. Hand files were associated with significantly more apically extruded debris in all groups during removal of root canal filling material.

Cyclic fatigue resistance of new reciprocating glide path files in 45- and 60-degree curved canals.

AIM: To compare the cyclic fatigue resistance of R-PILOT and WaveOne Gold Glider files in curved artificial canals. METHODOLOGY: A total of 60 new R-PILOT and WaveOne Gold Glider files were tested in artificial canals with 45° and 60° angles of curvature. Fifteen new files of each brand were tested in both canals. Cyclic fatigue resistance was determined by recording the time to file fracture in the artificial canals. The length of each fractured fragment was also recorded. An independent sample t-test was used to analyse the data. RESULTS: In the canal with a 45° angle of curvature, no significant differences were observed between the R-PILOT and WaveOne Gold Glider files (P > 0.05). In the canal with a 60° angle of curvature, WaveOne Gold Glider files had greater cyclic fatigue resistance than R-PILOT files (P < 0.05). There was no difference between the files in terms of the lengths of fractured fragments in canals with 45° and 60° angles of curvature (P > 0.05). CONCLUSIONS: WaveOne Gold Glider files exhibited greater cyclic fatigue resistance than R-PILOT files in artificial canals with a 60° angle of curvature.

Resistance to cyclic fatigue of PathFile, ScoutRaCe and ProGlider glide path files in an S-shaped canal.

AIM: To compare the cyclic fatigue resistance (CFR) of PathFile, ProGlider and ScoutRaCe nickel-titanium (NiTi) rotary instruments used in an S-shaped artificial canal. METHODOLOGY: A total of 90 instruments were tested in an S-shaped artificial canal (n = 30 for each group: PathFile (size 16, 2% constant taper), ProGlider (size 16, variable taper between 2% and 8% along the shaft) and ScoutRaCe (size 15, 2% constant taper). All files were rotated until fracture. The number of cycles to failure was counted to determine CFR. The length of each fractured fragment was measured in millimetres. The CFR was analysed statistically with the Kruskal-Wallis test. The fragment length was analysed using one-way analysis of variance and Tukey's post hoc tests. RESULTS: The ProGlider instruments were associated with significantly greater CFR than the PathFile and ScoutRaCe files in the apical curvature (P < 0.05). There was no significant difference between the CFR of the PathFile and ScoutRaCe files in the apical curvature (P > 0.05). ProGlider, PathFile and ScoutRaCe instruments exhibited similar CFR in the coronal curvature (P > 0.05). CONCLUSIONS: The ProGlider files had greater cyclic fatigue resistance than the PathFile and ScoutRaCe files in the apical curvature of an artificial S-shaped canal.

Laboratory comparison of cyclic fatigue resistance of WaveOne Gold, Reciproc and WaveOne files in canals with a double curvature.

AIM: To compare the resistance to cyclic fatigue of WaveOne Gold (WOG), Reciproc and WaveOne (WO) nickel-titanium files in an artificial root canal with a double (S-shaped) curvature. METHODOLOGY: A total of 120 new WOG primary, Reciproc R25 and WO primary files were tested in an artificial, stainless steel canal with an S-shape (diameter, 1.4 mm and length, 18 mm). Forty files from each system were rotated until fracture to calculate the number of cycles to failure (NCF). The length of each fractured fragment was recorded. Data were analysed using one-way analysis of variance and Tukey's post hoc tests. RESULTS: The WOG primary (apical curvature: 928.87 ± 293.69; coronal curvature 1102.32 ±397.39 NCF) had higher cyclic fatigue resistance than Reciproc R25 and WO primary in the apical and coronal curvatures (P < 0.05). The Reciproc R25 file (745.63 ± 253.49 NCF) had significantly greater cyclic fatigue resistance than the WO primary (583.89 ± 183.38 NCF) in the apical curvature (P < 0.05). There was no significant difference in the cyclic fatigue resistance of the Reciproc R25 and WO files in the coronal curvature (883.63 ± 282.56 and 916.53 ± 268.21 NCF, respectively) (P > 0.05). There was no difference in fractured fragment lengths of the WOG primary, Reciproc R25, and WO primary files in either the apical or coronal curvature (P > 0.05). CONCLUSIONS: WaveOne Gold primary files exhibited greater cyclic fatigue resistance than Reciproc R25 and WO primary in an artificial canal with an S-shape.

Apically extruded debris during root canal preparation using Vortex Blue, K3XF, ProTaper Next and Reciproc instruments.

AIM: To assess the amount of debris extruded apically during root canal preparation using various nickel-titanium instrumentation systems. METHODOLOGY: Sixty extracted single-rooted mandibular premolar human teeth were randomly assigned to four groups (n = 15 teeth for each group). The canals were then instrumented with the following instrument systems: Vortex Blue (VB; Dentsply Tulsa Dental, Tulsa, OK, USA), K3XF (SybronEndo, Orange, CA, USA), Reciproc (VDW, Munich, Germany) and ProTaper Next (PTN; Dentsply Maillefer, Ballaigues, Switzerland). Apically extruded debris during instrumentation was collected into pre-weighed Eppendorf tubes. The Eppendorf tubes were then stored in an incubator at 70 °C for 5 days. The weight of the dry extruded debris was established by subtracting the pre-instrumentation and post-instrumentation weight of the Eppendorf tubes for each group. The data were analysed using one-way analysis of variance (anova) and Tukey's post hoc tests. RESULTS: Vortex Blue and PTN files were associated with significantly less apically extruded debris than the K3XF and Reciproc files (P < 0.05), but there was no significant difference between the VB and PTN files or between the K3XF and Reciproc files (P > 0.05). CONCLUSIONS: All instruments were associated with apical extrusion of debris. VB and PTN files were associated with less debris extrusion compared to the other systems.

Effect of coronal flaring on apical extrusion of debris during root canal instrumentation using single-file systems.

AIM: To evaluate the effect of coronal flaring on the amount of debris extruded apically during root canal preparation using the Reciproc, WaveOne (WO) and OneShape (OS) single-file systems. METHODOLOGY: Ninety extracted single-rooted mandibular incisor teeth were randomly assigned to six groups (n = 15 for each group) for canal instrumentation. Endodontic access cavities were prepared in each tooth. In three of the six groups, coronal flaring was not performed; coronal flaring was performed with Gates-Glidden drills on all teeth in the remaining three groups. The canals were then instrumented with one or other of the following single-file instrument systems: Reciproc, WO and OS. Debris extruded apically during instrumentation was collected into pre-weighed Eppendorf tubes. The tubes were then stored in an incubator at 70 °C for 5 days. The weight of the dry extruded debris was established by subtracting the pre-instrumentation and post-instrumentation weight of the Eppendorf tubes for each group. Data were analysed using one-way analysis of variance (anova) and Tukey's post hoc tests (P = 0.05). RESULTS: Reciproc and WO files without coronal flaring produced significantly more debris compared with the other groups (P < 0.05). There was no significant difference in apical extrusion of debris amongst the other groups (P > 0.05). CONCLUSIONS: All single-file systems caused apical extrusion of debris. Performing coronal flaring prior to canal preparation reduced the amount of apically extruded debris when using Reciproc or WO systems.

Influence of a glide path on apical extrusion of debris during canal preparation using single-file systems in curved canals.

AIM: To evaluate the effect of a glide path on the amount of apically extruded debris during canal preparation using single-file systems in curved canals. METHODOLOGY: Ninety extracted mandibular molar teeth were randomly assigned to six groups (n = 15 for each group) for canal instrumentation. Endodontic access cavities were prepared in each tooth. In three of the six groups, a glide path was not created whereas a glide path was created using PathFile instruments on the mesial canals of all teeth in the remaining three groups. The mesial canals of the teeth were then instrumented with the following single-file instrument systems: WaveOne, Reciproc and OneShape. Debris extruded apically during instrumentation was collected into pre-weighed Eppendorf tubes. The tubes were then stored in an incubator at 70 °C for 5 days. The weight of the dry extruded debris was established by subtracting the pre-instrumentation and post-instrumentation weight of the Eppendorf tubes for each group. The data obtained were analysed using one-way analysis of variance (anova) and Tukey's post hoc tests. RESULTS: The OneShape file was associated with less debris extrusion than the Reciproc and WaveOne files when canal instrumentation was performed without a glide path (P < 0.05). However, no significant difference was found between the Reciproc and WaveOne files (P > 0.05). There was no significant difference amongst the OneShape, Reciproc and WaveOne files when a glide path was created before canal preparation in curved root canals (P > 0.05). All systems extruded significantly less debris in groups with a glide path than in groups without a glide path (P < 0.05). CONCLUSIONS: All instruments were associated with apical extrusion of debris. Creating a glide path prior to canal instrumentation reduced the amount of apically extruded debris in curved canals.

Comparative evaluation of cyclic fatigue resistance of D-RaCe and ProTaper retreatment instruments in curved artificial canals.

AIM: To compare the cyclic fatigue resistance of D-RaCe and ProTaper rotary nickel-titanium (NiTi) retreatment files when used in curved artificial canals. METHODOLOGY: A total of 120 new D-RaCe DR2 and ProTaper D3 retreatment files were tested in stainless steel artificial canals having 45° and 60° angles of curvature. Thirty instruments of each of the file systems were tested in both angles of curvature (n = 30). The retreatment instruments were rotated until fracture to calculate the number of cycles to failure. The length of each fractured fragment was recorded. Data were analysed by independent sample t-test. Fractured surfaces of the instruments were analysed by scanning electron microscopy. RESULTS: In the canal with 45° angle of curvature, no significant difference was observed between the retreatment systems (P > 0.05); on the other hand, in the canal with 60° angle of curvature, D-RaCe DR2 instruments had greater cyclic fatigue resistance than ProTaper D3 (P < 0.05). No difference was observed between the retreatment instruments regarding the lengths of fractured fragments (P > 0.05). The fracture surfaces of the instruments had morphologic characteristics of ductile fracture. CONCLUSIONS: D-RaCe DR2 instrument exhibited greater cyclic fatigue resistance than ProTaper D3 only in root canals with 60° angle of curvature.