Effect of different irrigation activation methods on non-infected dentinal tubule penetration of medicaments: A CLSM study.

Background: The whole root canal disinfection is crucial in terms of long-term endodontic success. In this context, applying medicaments following effective irrigation activation procedures becomes an important point. Aims: The purpose of this study was to evaluate and compare the efficacy of various irrigation activation techniques on non-infected dentinal tubule penetration of calcium hydroxide (CH), double (DAP), and triple (TAP) antibiotic pastes. Materials and Methods: A total of 180 extracted human permanent mandibular premolar single-rooted teeth were selected and randomly divided into a control group and four main groups according to the irrigation activation procedures (n = 36) as KTP laser irradiation, conventional needle, NaviTip FX, sonic (SI) and ultrasonic activation (UI) procedures. Each group was randomly subdivided into three subgroups according to the medicament type (n = 12); CH, DAP, and TAP. After the activation procedures, the root canals were filled with CH, TAP, and DAP mixed with 0.1% fluorescent rhodamine B isothiocyanate. Specimens were sectioned at 2, 5, and 8 mm from the apex, and all the sections were examined under a confocal laser scanning microscope to calculate the dentinal tubule penetration. Data were analyzed using a three-way analysis of variance and Tukey's post hoc tests (P = 0.05). Results: TAP provided a statistically significant greater penetration than the other groups (P < 0.05). UI provided a statistically significant higher dentinal tubules penetration area than other activation procedures (P < 0.05). Conclusion: Medicament penetration depends on the type of medicament, activation procedures, and root canal level. The TAP may be preferred following the ultrasonic activation in terms of long term root canal treatment success.

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.

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.

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.

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.

Efficacy of manual and mechanical instrumentation techniques for removal of overextended root canal filling material.

OBJECTIVE: To compare the efficacy of manual and mechanical instrumentation techniques, including ProTaper Universal retreatment system, Mtwo retreatment system, Reciproc system, and Hedström files, regarding removal of overextended root canal filling material. MATERIALS AND METHODS: Eighty extracted human mandibular premolar teeth were prepared at the apical foramen level using Revo-S rotary files and subsequently obturated. The root canal filling material was deliberately extruded from the apex. Samples were transferred to glass vials that simulated the periapical area. Eighty samples of overfilled teeth were randomly assigned to four equal groups (n = 20) for removal of the root filling material with ProTaper Universal retreatment files (Group 1), Mtwo retreatment files (Group 2), Reciproc system (Group 3), and hand files (Group 4). Removal of the root canal filling material and additional preparation were performed by individual instruments from each different system up to a #40 size. The external apical surface of the teeth and the surrounding glass vials were checked using a dental operation microscope with ×12.5 magnification. Samples were divided into two groups based on whether removal of the overextended root canal filling material was successful or not. The Fisher's exact test was used to detect any significant difference between the groups (α = 0.05). RESULTS: The success rate for removal of overextended gutta-percha was greater for the Mtwo (30%) and hand files (30%) compared with the ProTaper (20%) and Reciproc (10%). However, no significant statistical differences existed among the experimental groups (P > 0.05). CONCLUSIONS: This study demonstrated that all tested systems had similar efficacy in removing overextended root canal filling material.

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.

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.

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.

Influence of different surface treatments on push-out bond strengths of fiber-reinforced posts luted with dual-cure resin cement.

OBJECTIVES: The objective was to evaluate whether fiber postsurface conditioning with air abrasion or erbium:yttrium-aluminum-garnet (Er:YAG) laser would influence the bond strength of dual-cure resin cement to the fiber-reinforced (FRC) posts. MATERIALS AND METHODS: Twenty-one FRC posts were divided into three groups according to surface treatment methods as follows: An untreated control group air abrasion with Al2O3group, and Er:YAG laser treated group with 150 mJ parameter. Fiber posts were then built up to dual-cure resin cement. Eighteen specimens were set and sectioned perpendicularly along the long axis of the post using a saw. Two disks (thickness of 2 mm) were obtained from each specimen (n = 12). Remaining three posts were stored for scanning electron microscopic evaluation. Push out test was performed on the each specimen and the values were recorded as MPa. The data were analyzed using one-way analysis of variance and Tukey post-hoc tests (P < 0.05). RESULTS: The bond strength values for the groups were as follows: Control (15, 28 MPa), air abrasion group (19, 73 MPa), and Er:YAG group (17, 84 MPa). Air abrasion affected the bond strength significantly (P < 0.05). CONCLUSION: Air abrasion attained higher bond strengths when FRC posts were luted to dual-cure resin cement. Additional studies should be designed with different types and parameters of laser devices to understand the effect of these devices on bond strength.

The effect of reciprocation versus rotational movement on the incidence of root defects during retreatment procedures.

AIM: To compare the incidence of dentinal defects caused by reciprocating and rotary techniques during retreatment procedures. METHODOLOGY: One hundred and twenty extracted mandibular premolars with single canals were selected. Twenty teeth were left unprepared. The root canals in the remaining 100 teeth were prepared with K-files up to size 35 and filled with Gutta-percha and AH Plus sealer using a passive cold lateral compaction technique. Twenty canals were filled and received no further treatment. Eighty teeth were divided into four groups (n = 20 in each) to undergo the removal of the root filling. In groups 1 and 2, the root filling was removed using ProTaper Retreatment files and Reciproc files, respectively, and the canals were not refilled. In groups 3 and 4, the root filling was removed using ProTaper Retreatment files and Reciproc files, respectively, and the canals were then refilled using a conventional cold lateral compaction technique. The roots were sectioned horizontally at 3, 6 and 9 mm from the root apex and observed under a stereomicroscope at 20× magnification. Defects were categorized as no defect, incomplete defect and fracture. The differences between the groups were analysed using the chi-square exact test (P = 0.05). RESULTS: No defects were observed in the unprepared and filled groups, in contrast to the experimental groups. In the coronal thirds, groups 2 and 4 had more dentinal defects than groups 1 and 3 (P < 0.05). In the middle thirds, group 4 had more defects than group 1 (P < 0.05). In the apical thirds, group 2 had fewer defects than did group 3 and group 4. Also, group 3 had more defects than group 1 (P < 0.05). When comparing the experimental groups, there were no significant differences with regard to fracture (P > 0.05). CONCLUSIONS: Both nickel-titanium systems were associated with dentinal defects during retreatment procedures in extracted premolar teeth.

Efficacy of different irrigation techniques in the removal of calcium hydroxide from a simulated internal root resorption cavity.

AIM: To evaluate the efficacy of six irrigation techniques to remove calcium hydroxide (CH) from a simulated internal root resorption cavity. METHODOLOGY: The root canals of 100 single-rooted teeth were prepared using the ProTaper system to size F5. The roots were split longitudinally, and standardized simulated internal root resorption cavities were prepared in the two root halves. The root halves were reassembled, and CH was placed into the root canals, with the exception of five teeth that served as the negative control group. Another five teeth (the positive control group) were not subjected to the CH removal procedure. Ninety teeth were randomly divided into six experimental groups (n = 15), according to the final irrigation techniques used: conventional syringe irrigation (CSI), CanalBrush (CB), passive ultrasonic irrigation (PUI), self-adjusting file (SAF) system, EndoActivator (EA), and apical negative pressure irrigation (EndoVac system). Five millilitres of 3% NaOCl and 17% EDTA were used in all experimental groups during the CH removal procedure. The amount of remaining CH was evaluated under a stereomicroscope at 20 ×magnification, using a 4-grade scoring system. The data were statistically compared using the Kruskal-Wallis and Mann-Whitney U-tests (P < 0.05). RESULTS: Remnants of CH in simulated internal root resorption cavities were found in all experimental groups. SAF and PUI were superior to the other groups (P < 0.05); however, there was no significant difference between the SAF and PUI (P > 0.05). There were also no significant differences between the CSI, CB, EA and EndoVac groups (P > 0.05). CONCLUSIONS: None of the irrigation techniques was able to completely remove CH from a simulated internal root resorption cavity.

Efficacy of various irrigation protocols on the removal of triple antibiotic paste.

AIM: To compare the efficacy of irrigation protocols on the removal of triple antibiotic paste (metronidazole, ciprofloxacin and minocycline) (TAP) from artificial grooves in root canals. METHODOLOGY: Root canals in 72 extracted single-rooted teeth were prepared using ProTaper rotary instruments up to size F5. The roots were split longitudinally and a standardized groove was prepared in the apical part of one segment. TAP was placed in the grooves, and the root halves were reassembled. The roots were randomly divided into six experimental groups according to the irrigation protocol used: distilled water, 1% NaOCl, 2.5% NaOCl, 100% ethanol, 17% EDTA and passive ultrasonic irrigation (PUI) with 1% NaOCl. The root segments were disassembled, and the amount of TAP remaining was evaluated under a stereomicroscope at 20× magnification using a four-grade scoring system. The data were evaluated statistically using Kruskal-Wallis and Mann-Whitney U-tests with a 95% confidence level (P = 0.05). RESULTS: There were significant differences amongst the groups (P < 0.001). Passive ultrasonic irrigation (PUI) with 1% NaOCl removed significantly more TAP than the other irrigating solutions (P < 0.05). Distilled water, 1% NaOCl, ethanol and EDTA were associated with significantly more remaining TAP. CONCLUSIONS: PUI with 1% NaOCl was more effective in removing TAP from artificial grooves in root canals than other irrigating solutions without ultrasonic agitation. It was not possible completely to remove TAP from root canals.

The bond strength of endodontic sealers to root dentine exposed to different gutta-percha solvents.

AIM: To evaluate the effects of various gutta-percha solvents on the push-out bond strength of several root canal sealers on root dentine. METHODOLOGY: The root canals of 210 single-rooted human teeth were prepared with the ProTaper System (Dentsply Maillefer, Ballaigues, Switzerland) up to a master apical file size of F4, and the following variables evaluated for bond strength: solvent type (chloroform, eucalyptol and orange oil), time (2 and 5 min), sealer type (AH Plus, MTA Fillapex and Sealapex) and root thirds (coronal, middle and apical). After canal filling, three 1-mm-thick slices were obtained from each root sample, and the bond strength of the test materials was measured using a push-out test set-up at a cross-head speed of 1 mm min(-1) . The data were analysed using four-way factorial anova (P = 0.05). RESULTS: Bond strength was significantly affected by solvent type and time (P < 0.001). The use of chloroform for 5 min in the root canal decreased bond strength of all sealers (P < 0.001). Eucalyptol and orange oil did not affect the bond strength of the sealers (P > 0.05). In all conditions, the push-out bond strength was highest for AH Plus and lowest for MTA Fillapex (P < 0.001). Bond strength values decreased in a corono-apical direction in all groups (P < 0.001). CONCLUSIONS: Chloroform used for 5 min during retreatment decreased the bond strength of AH Plus, Sealapex and MTA Fillapex to root dentine.