Quantitative evaluation of apically extruded debris with different single-file systems: Reciproc, F360 and OneShape versus Mtwo

Assessment of Vertical Force Generated with Single File Systems during Shaping of Constricted Root Canals

OBJECTIVES

 This study aimed to evaluate the shaping force generated with OneShape (OS) and HyFlex EDM (HEDM) systems designed for single file shaping, in comparison with ProTaper Next (PTN).

MATERIALS AND METHODS

 Maxillary premolar teeth received access cavity preparation and their canals were shaped with OS, HEDM, or PTN to size 25 according to manufacturer's instructions with consistent pressure on the files to give a gentle "in-and-out" movements of 2 mm amplitude. The canal shaping was completed with a total of three insertions. After each insertion, 1% NaOCl irrigation and recapitulation with K-file size 15 were performed. The vertical shaping force was measured using a force gauge (M5-20 Advanced Digital Force Gauge; Mark-10 Corporation, NY).

STATISTICAL ANALYSIS

 The shaping time was analyzed by using a one-way analysis of variance (ANOVA) test and differences between the mean apical and coronal maximum force values were analyzed using the Kruskal-Wallis and Mann-Whitney U tests. The level of significance was set as 0.05.

RESULTS

 The magnitude of the vertical forces increased with successive advancements of the instruments within the canal. During canal shaping procedures in all groups, the apical and coronal maximum force values of the OS and HEDM ranged from 2.5 to 7.2 N and 1.3 to 2.9 N, respectively. PTN generated the lowest maximum apical forces during the second and third insertions (p < 0.05). HEDM generated significantly less maximum coronal forces than both OS and PTN during the first insertion while the use of OS was associated with the highest amount of force values in the second and third insertions (p < 0.05). In terms of shaping time, no significant differences were detected among the three tested systems (p = 0.606).

CONCLUSION

 The tested single file systems were associated with higher shaping forces in the apical direction that were significant in the second and third insertions.

Assessment of Debris Extrusion in Curved Canals: An In Vitro Analysis of Various Single-File Endodontic Instrumentation Systems

Objectives

Rotary single-file endodontic systems are commonly used for root canal treatment. However, very few studies have evaluated the apical extrusion of debris generated by these systems during canal preparation at normal body temperature in laboratory conditions. The aim of this study was to evaluate the amount of apically extruded debris caused by seven different single-file endodontic instrumentation systems at body temperature in mandibular molar teeth with curved root canals.

Methods

One hundred forty mandibular first permanent molars were randomly divided into seven groups (n = 20) to be prepared by one of the following systems at 35°C: Reciproc Blue (REC Blue), WaveOne Gold (WOG), One Reci (OR), Neoniti, HyFlex EDM (HEDM), One Curve (OC), or XP Shaper (XPS). Debris was collected into preweighted Eppendorf tubes. The weight of the extruded debris was recorded by subtracting the weight of the tooth-free apparatus from the post-procedure weight. Data were analyzed by one-way ANOVA and Tukey's tests (p  < 5%).

Results

REC Blue, WOG, and OR groups extruded significantly more debris from the apex than XPS, OC, and Neoniti groups (p  < 0.05). No significant difference was observed among the XPS, OC, Neoniti, and HEDM groups (p  > 0.05).

Conclusion

All the instruments were associated with debris extrusion. However, REC Blue, WOG, and OR extrude significantly more debris than other instruments. The amount of debris with different files was REC Blue > OR > WOG > HEDM > OC > Neoniti > XPS. XPS, Neoniti, and OC caused significantly less extrusion of debris than REC Blue, WOG, and OR.

Effect of Movement Kinematics and Heat-Treated Alloys on the Apical Extrusion of Debris: An In Vitro Study

BACKGROUND

Apically extruded debris can be affected by some features of the file systems such as kinematics or metallurgic properties.

AIMS

This in vitro study aimed to evaluate the effect of movement kinematics (reciprocation or rotation) and heat-treated alloys (C.Wire) on the amount of debris extrusion.

METHODS

Seventy-two mesiobuccal root canals were assigned into three experimental groups related to the single-file system used (n = 24): two rotational; One Shape (Conventional Ni-Ti), One Curve (C.Wire), and one reciprocating; and One Reci (C.Wire). The file systems were used according to the advisable speed and torque according to the manufacturers' suggestion. The weight of debris was calculated by subtracting the preweights from postweights of Eppendorf tubes. Kruskall-Wallis and Mann-Whitney U tests were used to analyze the data (P = 0.05).

RESULTS

One Shape produced the greatest amount of extruded debris compared with One Curve (P < 0.001) and One Reci (P < 0.001), respectively. No statistical difference was found between One Curve and One Reci concerning amount of apical debris extrusion (P = 0.489).

CONCLUSION

Metallurgical properties of files may affect apical debris extrusion. Alloy type is an important factor in the amount of debris extrusion. File kinematics does not affect apical debris extrusion.

Effect of treatment variables on apical extrusion of debris during root canal retreatment: A systematic review and meta-analysis of laboratory studies

Background

This study aimed to systematically and comprehensively review the effect of various treatment variables on apically extruded debris (AED) during non-surgical root canal retreatment (NSRCRT).

Methods

The study protocol is shared in the Open Science Framework database (https://osf.io/kjtdg/?view_only=17060180705745ec9dae9a01614f3880). An electronic search was conducted up to July 2022 to reveal related studies. Two reviewers critically assessed the studies for eligibility against inclusion and exclusion criteria and data extraction. Quantitative data synthesis was performed, and the risk of bias in the studies was also evaluated.

Results

Forty-six studies were included in the systematic review and 14 in the meta-analysis. Conflicting or limited evidence was found for the effect of sealer type, obturation technique, and solvent use. The manual instrumentation increased the amount of AED compared to rotary instrumentation during the removal of filling materials (P<0.001). There was no significant difference in the amount of AED between the use of rotary and reciprocating files during the removal of filling materials (P=0.181).

Conclusion

Rotary instruments can be recommended instead of manual instruments during the removal of filling materials to control the amount of AED. Further studies with a low risk of bias are needed to clarify the effect of other treatment variables on AED during NSRCRT.

Comparative Evaluation of Debris Expulsion Beyond Apex During Re-root Canal Treatment by Utilizing Two Re-treatment Rotary Files and Two Reciprocating Files: An In-Vitro Study

AIM

This study aimed to assess and compare debris quality expelled beyond the apex during re-treatment using two reciprocating and two re-treatment rotary files.

MATERIALS AND METHODS

A total of 80 healthy human mandibular premolars excised for orthodontic therapy were selected. Distilled water was used to sterilize the teeth before they were preserved. The canals were widened and coronal access was created so that the F2 ProTaper universal system could be used. For the obturation, we utilized gutta-percha cones and AH plus sealant. All samples were cone-beam computed tomography (CBCT) recorded. Teeth were separated into four groups (n=20); Group 1: ProTaper re-treatment, Group 2: Mtwo re-treatment, Group 3: WaveOne gold, and Group 4: Reciproc. The re-instrumented process included collecting the extruded debris in Eppendorf tubes and then drying it off by evaporating the distilled water. The weight of the tube with debris was subtracted from the weight of the tube without debris to get the dry debris weight. Post-retreatment CBCT was recorded for all samples. Mean apical debris extrusion values were obtained, after which necessary statistical analysis was obtained using SPSS Statistics, version 21 (IBM Corp., Armonk, NY) to obtain the results. A one-way analysis of variance (ANOVA) and the student t-test were utilized for statistical analysis to compare the different experimental groups. Post-hoc Bonferroni tests were used to compare several groups.

RESULT

No statistical difference (p>0.05) was identified in the filler material that was left over across all groups. The reciprocating files discharged more material compared with re-treatment file systems.

CONCLUSION

The Reciproc files expelled more waste than WaveOne gold, ProTaper re-treatment, and Mtwo re-treatment file systems. Reciprocating file systems showed better cleaning efficiency compared to the re-treatment file systems.

To Evaluate Different Endodontic Instrumentation Systems Regarding Post-Operative Pain After Endodontic Therapy: A Clinical Study

BACKGROUND

Despite substantial breakthroughs in instrumentation systems and pharmaceutical interventions, pain following endodontic therapy remains a serious concern. The effect of the type of endodontic instrumentation system in post-operative pain after endodontic therapy has been a matter of debate.

AIM

To evaluate different endodontic instrumentation systems, namely Reciproc (GmbH, Munich), OneShape® (MicroMega, France), Protaper Gold (Dentsply Sirona, USA), and Hyflex® EDM (Coltène/Whaledent Inc., USA) file systems, regarding post-operative pain after endodontic therapy Methods and materials: The endodontic department treated healthy patients aged 20 to 50 years who were experiencing symptoms of irreparable pulpitis in one or more maxillary molars or mandibular molars. Five hundred was the determined size of the sample. The study participants were divided into five categories, each comprising 100 participants. These categories were: Category 1: Reciproc instrumentation system. Category 2: OneShape® instrumentation system. Category 3: ProtaperGold instrumentation system. Category 4: HyFlex® EDM instrumentation system. Category 5: Control (stainless steel K-files). Following endodontic therapy, these scores were recorded at 6 hours, 12 hours, 24 hours, 48 hours, and 72 hours using the VAS scale.

RESULTS

The visual analog scale (VAS) score (mean±SD) in the control group was 0.73± 0.40 (<0.001). The VAS score in the Reciproc group was 0.43± 0.05 (<0.001). The VAS score in the OneShape® group was 0.36±0.09 (<0.001). The VAS score in the Protaper Gold group was 0.41 ±0.08 (<0.001). The VAS score in the HyFlex® EDM group was 0.55 ±0.02 (<0.001). The VAS score in all instrumentation techniques at 72 hours follow-up was lesser in comparison to a control group with meaningful statistical significance (<0.001). However, the post-operative pain among the Reciproc, OneShape®, Protaper Gold, and HyFlex® EDM instrumentation systems was not different clinically when compared among themselves. However, VAS values were greater in OneShape® and HyFlex® EDM compared to Reciproc and Protaper Gold, showing increased post-operative pain in OneShape and HyFlex® EDM compared to Reciproc and Protaper Gold. It was also observed that there was a decline in the VAS score in all instrumentation systems as the follow-up period increased from 6 hours to 72 hours, with maximum post-operative pain at 6 hours of follow-up and minimum post-operative pain at 72 hours of follow-up. However, the decline was lesser in OneShape® and HyFlex® EDM in comparison to Reciproc and Protaper Gold, with increased post-operative pain in OneShape® and HyFlex® EDM in comparison to Reciproc and Protaper Gold.

CONCLUSION

Post-operative pain at all follow-ups of endodontic procedures was less in Reciproc, OneShape®, Protaper Gold, and HyFlex® EDM than in the control group. VAS scores were higher in the OneShape® and HyFlex® EDM groups compared to the Reciproc and Protaper Gold groups, indicating increased post-operative pain with OneShape® and HyFlex® EDM instruments in comparison to Reciproc and Protaper Gold.

Correlation between Tooth Position Parameters and Apical Fenestration: A Cone-Beam Computed Tomography Study

This study aimed to assess the relationship between apical fenestration-a defect in the alveolar bone involving the root apex-and tooth position in all tooth groups, excluding the third molars, utilizing cone-beam computed tomography (CBCT) images. A total of 800 CBCT scans (400 maxillary and 400 mandibular) from patients undergoing various treatments were examined by a single professional (radiologist and endodontist). Statistical analyses, including the chi-square test or Fisher's exact test, were conducted using R software 2.7.3 (R Foundation, Vienna, Austria). Results indicated a significant association (p ≤ 0.05) between apical fenestration and tooth position. In the upper teeth, apical fenestrations were notably present in the mesio-buccal (17.17%) and disto-buccal (11.07%) roots of the first molars. Conversely, apical fenestrations in the lower teeth were relatively less frequent. The study revealed a negative correlation between apical fenestration and mesial inclination, rotation, and extrusion in the upper teeth. However, a positive correlation was observed between apical fenestration and lingual inclination in the upper teeth. In conclusion, this study illuminates the distribution of apical fenestration and its correlation with tooth positions, offering insights into factors influencing this defect in dental anatomy. The findings enhance our understanding of nuanced relationships between tooth position and apical fenestration in the upper and lower dental arches.

Evaluation of Pain Following the Use of Different Single-file Glide Path Systems: A Randomized Clinical Trial

INTRODUCTION

This study aimed to evaluate postoperative pain intensity following glide-path preparation using the ProGlider (PG) and WaveOne Gold Glider (WOGG) systems in asymptomatic teeth with necrotic pulp and periapical lesions.

METHODS

In this randomized clinical trial (ClinicalTrials.gov ID: NCT05955742) maxillary and mandibular molars with asymptomatic apical periodontitis of 78 patients (age, 18-65 years) were included. The patients were randomly divided into 3 groups: control (n = 26), PG (n = 26), and WOGG (n = 26). All the systems were used according to the manufacturer's instructions, and all the root canal treatments were completed by a single operator within 2 sessions. Postoperative pain was assessed using a numerical rating scale at 6, 12, 18, 24, 48, and 72 hours. Analgesics administered and abscess formation were also recorded. Statistical analyses were performed using the Mann-Whitney U, Bonferroni Dunn, Friedman, Chi-square, and Fisher exact tests.

RESULTS

The postoperative pain at 12 and 18 hours was lower in the WOGG group than in the other groups (P < .05). The postoperative pain scores at 6 and 24 hours were higher among women than among men (P < .05). The highest postoperative pain scores were observed at 6 hours (P < .05).

CONCLUSIONS

The WOGG glide-path file system was associated with less postoperative pain than the other systems. Abscess formation and analgesic use were higher in the PG group than in the other groups. Postoperative pain was greater in women than in men.

The use of sodium hypochlorite mixed with etidronic acid during canal preparation increases debris extrusion

The purpose of this study was to compare the impact of different irrigation protocols on debris extrusion. Single-rooted teeth were distributed into groups based on the irrigation protocols (n = 40): 2.5% NaOCl (biomechanical preparation: 20 mL and final irrigation: 5 mL); 2.5% NaOCl (biomechanical preparation: 20 mL) + 17% EDTA (final irrigation: 2 mL) + 2.5% NaOCl (final irrigation: 3 mL); and a mixture of 5% NaOCl +18% HEDP (biomechanical preparation: 20 mL and final irrigation: 5 mL). The canals were prepared using a reciprocating instrument size 40/0.06. For final irrigation, the groups were reassigned based on the agitation methods (n = 10): (a) no agitation; (b) ultrasonic; (c) sonic; and (d) continuous rotation. The control group (n = 10) received saline solution without agitation. The amount of debris extruded was measured by weight and analysed using One-way ANOVA (α < 0.05). The subgroups treated with NaOCl + HEDP mixture showed a significantly higher amount of extruded debris (p < 0.05), while there was no difference among agitation methods in all groups (p > 0.05).

The effect of different kinematics on apical debris extrusion with a single-file system

To compare the amount of extruded debris caused by different motions using a single-file system. Fifty mandibular first molar teeth were randomized into 5 groups (n = 10) according to the motion tested: Optimize Torque Reverse (OTR), TF Adaptive Motion (TFA), continuous rotation (CR), reciprocation motion (+ 150°, -30°) (REC), and Jeni motion (Jeni). One Curve single file 25/06 (Micro-Mega, Besançon, France) was used in all experimental groups. The root canals were irrigated with 2.5% NaOCl, and the extruded debris were collected at pre-weighted glass vials. The glass vials were kept inside an incubator for one week at 70 °C to dry out the irrigating solution. The extruded debris was quantified by subtracting the pre-instrumentation from the post-instrumentation weight of the glass vials. The time required for each instrumentation procedure was digitally recorded. All data were analyzed statistically with one way ANOVA and post hoc Tukey test (P < 0.05). All the motions extruded apically debris with Jeni mode caused significantly less debris extrusion than TFA, REC, and CR (P < 0.05) while no significant difference emerged with OTR. Preparation time was not significantly different in all groups. Within the limits of the present study, all the kinematics produced apically debris extrusion, with Jeni reporting a similar amount of debris compared with OTR and significantly less than TFA, REC, and CR. Preparation time was similar among the tested kinematics.

Influence of rotary and reciprocating kinematics on the accuracy of an integrated apex locator

We evaluated in vitro the influence of nickel-titanium instruments kinematics on the accuracy and variation of root canal working length measurements, performed with an integrated apex locator, at glide path and at the end of shaping. Forty-four mandibular incisors, included in an alginate model, were allocated at random to two groups: reciprocating and rotary. Working length was determined at glide path stage and at the end of shaping. Measurements given by the integrated apex locator were matched with visual measurements. The apex locator accuracy was based on inter-group comparison. The variation in working length was based on intra-group comparison. Kinematics influenced the accuracy of measurements only after shaping (p < 0.05), and not in the glide path (p > 0.05). Rotary had values closer to the visual measurements. Diminishing of measures occurred after shaping for reciprocating (p < 0.05); and at glide-path stage for rotary (p > 0.05). The integrated apex locator was more accurate with rotary kinematics.

Postoperative pain perception and associated risk factors in children after continuous rotation versus reciprocating kinematics: A randomised prospective clinical trial

To compare the postoperative pain of continuous rotation and reciprocating movements after pulpectomy of non-vital primary molars and determine associated risk factors. 146 children aged 4-8 years with one primary molar indicated for pulpectomy were randomly assigned to two equal groups: those instrumented with continuous rotation motion (Hyflex EDM Coltene/Whaledent) and reciprocating motion (Reciproc R25 (VDW)). A 4-point pain scale was used to assess postoperative pain frequencies, which were compared at different intervals using the Chi-square test. Postoperative pain risk factors were determined using logistic regression analysis. There was no statistically significant difference between the follow-ups. Gender, pulp status, and radiographic radiolucency increased the risk of postoperative pain incidence. Postoperative pain likelihood in children with chronic apical periodontitis was 8.72 times that of children with necrotic pulps. Postoperative pain after instrumentation with both kinematics was comparable. Postoperative pain incidence is increased by preoperative pulp condition, radiographic radiolucency, and gender.

Comparative Evaluation of Extrusion of Apical Debris in Primary Maxillary Anterior Teeth Using Two Different Rotary Systems and Hand Files: An In Vitro Study

Successful outcome of pulp therapy depends on good chemomechanical preparation of the canals. This is completed with the help of various upcoming rotary and hand files. However, during this preparation, there might be an apical extrusion of the debris which may result in postoperative complications. The aim of this study was to evaluate and compare the number of debris apically extruded during canal preparation using two different pediatric rotary file systems and conventional hand file systems in primary teeth. 60 primary maxillary central incisors that were extracted due to trauma or untreated dental caries with no signs of resorption were taken. Canal preparation was executed using three different file systems: Group A: Group A hand K file system, Group B Kedo S Plus, Group C Kedo SG Blue. For each of these files using the Myers and Montgomery model, the pre- and post-weight of the eppendorf tube was assessed to quantify the number of apical debris. The maximum extrusion of apical debris was noticed with the Hand K-file system. The least debris was noticed in the Kedo S Plus file system. Statistical analysis revealed that there were highly significant differences in apical extrusion and debris when comparing hand files and rotary files and also between the two rotary files used. Apical debris collection is an unavoidable outcome of canal instrumentation. Among the file systems compared, rotary files had lesser extrusion when compared to hand files. Among the rotary files, Kedo S plus showed normal extrusion compared to SG Blue.

Microcomputed tomographic analysis of the efficiency of two retreatment techniques in removing root canal filling materials from mandibular incisors

This study aimed to evaluate the removal effect of the ProTaper Next system (PTN) combined with manual nickel-titanium Hedström (MNiTiH) files or chloroform on filling materials of mandibular incisors by microcomputed tomography (micro-CT). Sixty-four extracted human mandibular incisors were finally selected and assigned to two groups (n = 32) based on root canal morphology after instrumentation. Two subgroups (n = 16) were formed based on two retreatment methods. The volume of residual filling materials (RFMs) and the surface area covered by RFMs were analyzed by micro-CT, the apical extrusion and the time taken for removing the filling materials were recorded. A smaller percentage of the volume of RFMs and less surface area covered by RFMs occurred in PTN combined with MNiTiH groups and round-shaped canal incisors (P < 0.05). The time taken for removing the filling materials was not significantly different in all groups (P > 0.05). The apical extrusion was significantly less in PTN combined with MNiTiH groups than in PTN combined with chloroform groups (P < 0.05). Neither of the two methods rendered root canals completely free from filling materials. PTN combined with MNiTiH could reduce the apical extrusion and remove filling materials more efficiently than PTN combined with chloroform.

A Comparative Evaluation of the Apically Extruded Debris from Root Canals Prepared by R-Motion NiTi File System

Background

Apically extruded debris (AED) is an inherent concern during root canal treatment for both endodontists and general practitioners. The present study investigates the AED of the novel R-Motion single-file reciprocating system compared to standard single reciprocating and multifile rotary systems.

Materials and Methods

Fifty-six moderately curved palatal roots of upper maxillary first molars were selected for the present study. The samples were then divided randomly into four groups (n = 14)- Group I: R-motion (RM), Group II: WaveOne Gold (WOG), Group III: ProTaper Next (PTN), and Group IV: HyFlex EDM (HFEDM). The researcher has modified Myers and Montgomery's method to simulate human body temperature. Vials were used to collect debris and weighted using a 0.00001 sensitive balance before and after instrumentation. The instrumentation of all experimented groups was done at 37°C, terminated at master apical file #25. An auto syringe with a side vented needle was used to deliver 8 ml of deionized water for irrigation of each sample during preparation. Vials were stored in a dry sealed desiccator which contained CaSO₄ crystals, for 24 hr before weighing. The weight of the collected debris was obtained by subtracting the preinstrumentation weight from the postinstrumentation weight for each vial. The Kruskal-Wallis and Mann-Whitney U tests were performed to analyse the statistical difference in the amount of debris between the tested groups at a 0.05 significance level.

Results

The RM system produced less debris extrusion than all tested groups, with a significant difference between the former and the WOG and the PTN systems. However, WOG, PTN, and HFEDM showed no statistically significant difference in the amount of AED.

Conclusion

All tested groups produced apical debris in different amounts. The RM produced substantially less AED than WOG and PTN. Meanwhile, WOG, PTN, and HFEDM caused a comparable amount of AED.

Comparison of apical debris extrusion of different generation nickel-titanium instrument systems

BACKGROUND AND AIM

The aim of this study is to evaluate the apical debris extrusion amounts and preparation times of four different nickel-titanium systems with a similar cross-section design-Mtwo, RECIPROC, RECIPROC blue, and VDW.ROTATE.

MATERIALS AND METHODS

Eighty human mandibular central incisors were divided into four equal groups (n = 20). The test apparatus was inserted into an assembly that provided root canal temperature. Preparation times were recorded using a stopwatch, and the amount of extruded debris was collected in pre-weighed Eppendorf tubes. After drying, the net amount was determined by subtracting the previously measured Eppendorf tube weights from the total weight.

RESULTS

The Mtwo had the largest amount of debris, but there was no significant difference among the other groups. The VDW.ROTATE completed the preparation in a significantly shorter time than the RECIPROC blue and Mtwo.

CONCLUSION

Compared to other files, the Mtwo sequence produced significantly more debris and required significantly more time to complete the whole root canal preparation.

Postoperative Pain Following Root Canal Instrumentation Using ProTaper Next or Reciproc in Asymptomatic Molars: A Randomized Controlled Single-Blind Clinical Trial

Aim: The development of postoperative pain following root canal instrumentation may impair patient’s comfort and undermine their trust in the dentist. This study assessed the effect of root canal instrumentation techniques (rotary (PTN; ProTaper Next®) and reciprocating (R; Reciproc®)) on the postoperative pain intensity (primary outcome) and tenderness on biting (secondary outcome) of patients’ asymptomatic molars. Methodology: This study protocol was registered with ReBec-WHO (U1111-1182-2800). From a pool of 112 patients evaluated for eligibility (healthy adults (≤18 years old)), with a single asymptomatic molar (maxillary or mandibular) indicated for root canal treatment, diagnosed with asymptomatic irreversible pulpitis (including chronic hyperplastic pulpitis), 75 were randomly allocated in similar proportions to receive the intervention (two-appointment root canal therapy) in either the PTN or R group. The allocated procedures were performed using standardized protocols. Participants (blinded to the instrumentation technique) rated their pain intensity at 6, 12 and 24 h and from day 2 to day 7 following the root canal instrumentation appointment using a VAS and an NRS; the ibuprofen tablets taken and the presence of tenderness on biting were recorded. The instrumentation time was registered. Univariate and multivariate statistics measured the effect of independent variables on the outcomes. Results: From the 75 patients allocated, 8 patients (4 from each group) were lost; in total, 33 patients were analyzed in the PTN group and 34 in the R group. The frequencies of postoperative pain (p > 0.05) and tenderness on biting (p > 0.05) were similar between groups. The medication intake (mean of 1.31 tablets) and the time of instrumentation (approximately 11 min) were similar between groups. Conclusion: ProTaper Next and Reciproc® caused a slight risk of tenderness on biting and contributed to similar self-reported postoperative pain (low intensity) up to 7 days following root canal shaping.

COMPARATIVE EVALUATION OF THE EFFECT OF DIFFERENT ROTARY INSTRUMENT SYSTEMS ON THE AMOUNT OF APICALLY EXTRUDED DEBRIS

Objectives: The purpose of our study is to examine in vitro the amount of debris extrusion from the apical after root canal preparation with different rotary instruments. Materials and Methods: In present study, 60 single root single-canal lower premolar human teeth were used. The teeth were randomly selected and divided into 4 main groups (n=15). Root canals are shaped by using 2Shape, One Curve and XP-3DEndo Shaper working in rotational motion and WaveOne Gold working reciprocal motion. Later, the weight of each eppendorf tube was weighed on a precision scale and the amount of debris extrusion from the apical was determined with 10ˉ4 precision by subtracting the empty weight of the tube. Since the parametric test assumptions were fulfilled in the evaluation of the data obtained regarding the amount of debris extrusion from the apical of file systems by loading them into the SPSS 22.0 program, One-Way Variance analysis was used and the level of error was taken as 0.05. Results: When the amount of debris extrusion from the apical is ordered from high to low, it was seen that there are 2Shape, One Curve, XP-Endo Shaper, WaveOne Gold. However, the difference between study groups was not statistically significant (p> 0.05). Conclusions: Considering the results obtained in terms of debris extrusion from the apical about the new generation files with different metallurgy, kinematics, structural features, designs and different configurations that we used ın present study, it was seen that these systems would not show any difference in terms of the effect of debris on the success of endodontic treatment.

Comparative Evaluation of Apically Extruded Debris during Pulpectomy Procedure in Primary Molar Teeth Using Two Different Rotary Systems and Hand Files: An In Vitro Study

Background

Successful outcome of endodontic treatment depends on chemomechanical preparation of the tooth. However, during canal preparation, debris may extrude through the apical foramen causing postoperative complications. The aim of this study is to evaluate and compare the amount of apically extruded debris during the pulpectomy procedure in primary molar teeth using two different rotary files and hand files.

Materials and Methods

Distal roots of sixty extracted primary molars were divided into three groups: group A: Prime Pedo™ pediatric rotary files, group B: DXL-Pro Pedo™ pediatric rotary files, and group C: hand files. Myers and Montgomery experimental model was used. Preweighed Eppendorf tubes were used to collect apically extruded debris. The tubes were then placed in an incubator at 70°C for 5 days. The weight of the debris attained was determined. The data were analyzed using ANOVA and post hoc Bonferroni test.

Results

Hand files produced more apical debris extrusion (P < 0.05). Prime Pedo™ pediatric rotary files produced the least debris (P < 0.05).

Conclusion

Prime Pedo™ and DXL-Pro Pedo™ pediatric rotary files extruded significantly lower amount of debris apically during pulpectomy as compared to hand files. Rotary files can be considered an alternative to hand files in pediatric endodontics.

Quantitative Evaluation of Apically Extruded Debris of Root Canal Dentin Layer with WaveOne, ProTaper Next, ProTaper Gold Rotary File Systems

Endodontic flare-up or post-operative pain occurs when debris such as necrotic pulp tissue, dentin chips, irrigants, and microorganisms are extruded from the apical foramen intraoperatively into the periradicular tissue during root canal instrumentation. This study compared the amount of apical debris extrusion of the root canal dentin layer after using reciprocating and rotary file systems (WaveOne, ProTaper Next and ProTaper Gold). Sixty extracted human maxillary central incisors with one canal and closed apex were included in the study. Samples were randomly and equally divided into three groups (n = 20) according to the file systems used for preparation of the root canal. Teeth in the WO group were instrumented by WaveOne, while the PTN group were instrumented by ProTaper Next, and teeth samples in the PTG group were cleaned and shaped by ProTaper Gold. The mean apically extruded debris weight in grams was estimated using the modified Myers and Montgomery experimental model. Analysis of variance (ANOVA) test was used for the comparison of debris weight in three groups. Post hoc LSD test was applied for pairwise comparison of debris weight. The α value of significance was 0.05. The WO group had significantly lower mean debris weight than the PTN and PTG groups (p = 0.001). Post hoc pairwise comparison revealed that there was a statistically significant difference in mean debris weight between the WO group and PTN group (0.0215 vs. 0.0341, p = 0.001); and the WO group and PTG group (0.0215 vs. 0.0324, p = 0.003). Root canal preparations with different file systems were associated with apical extrusion of the debris from the root canal dentin layer. However, the WaveOne system resulted in a comparatively lower amount of apical debris layer extrusion than the ProTaper Next and ProTaper Gold rotary file systems.

Effect of mode of rotation on apical extrusion of debris with four different single-file endodontic instrumentation systems: Systematic review and meta-analysis

This systematic review and meta-analysis evaluated whether single-file endodontic instrumentation systems with the reciprocating type of motion are responsible for more debris extrusion than single-file endodontic instrumentation systems with the full rotational type of motion. Electronic and manual searches were performed following the recommendations of Preferred Reporting Items for Systematic Reviews and Meta-Analysis - PRISMA. We included studies comparing rotary (Neoniti and/ OneShape) versus reciprocating (WaveOne and/ Reciproc) systems. We evaluated the quality of studies and performed statistical analysis using R-Project software. Eight studies of high quality were included to perform the meta-analysis. Subgroup analysis was also done. The overall risk of bias was too low. In conclusion, single-file reciprocating systems tend to generate more extrusion of debris than single-file rotary systems.

Kinematics of 'Adaptive Motion' under constant torque values

INTRODUCTION

To demonstrate the unknown kinematics of complex adaptive motion with respect to disclosed values, the aim of the present study was (i)to analyze the adaptive motion and (ii)to compare the effects of constant torque values on kinematics.

METHODS

A new endodontic motor(Aseptico AEU-28SYB Elements) and 8:1 contra-angle handpiece were used for analysis. A pilot test was conducted for synchronizing the external experimental stress on the shaft of the target object and the inbuilt torque sensor of the motor source. A load setup was developed by attaching universal precision weights to the shaft of the of the target object. The groups were adaptive motion with no load(TFA-0), adaptive motion with 100 gcm(TFA-100), and 200 gcm(TFA-200) constant load. The peak-to-peak based phase identification method was used to analyze the kinematics. Student's t and Mann Whitney U tests were used where applicable(α=0.05).

RESULTS

A noteworthy observation was the inconsistent kinematics of the TFA-100 compared to the kinematics of TFA-0 and TFA-200. TFA-100 presented mixed-phased kinematics, which consisted of both quaternary(n=33) phases similar to that of TFA-200, and dual(n=17) phases similar to that of TFA-0. The sequence of these quaternary and dual phases of TFA-100 was arbitrarily changing. The kinematic parameters of dual-phase intermittent motion of TFA-0 and TFA-100 and quaternary-phase reciprocating motion of TFA-100 and TFA-200 revealed significant differences(p<0.05).

CONCLUSIONS

The main conclusions of the present study are the kinematics of adaptive motion was demonstrated and the 100 gcm load is not sufficient for predictable and constant operation in reciprocating mode.

Assessment of postoperative pain after single-visit root canal treatment using rotary and reciprocating file systems: an in vivo study

Background

Various instrument kinematics used in single-visit endodontics influence the occurrence of pain after endodontic therapy. This study aimed to evaluate the occurrence of pain after mechanical instrumentation with Hyflex EDM (HEDM) and WaveOne Gold (WOG) during single-visit endodontic therapy.

Methods

Sixty patients diagnosed with asymptomatic irreversible pulpitis and normal apical tissues in mandibular premolar teeth were included in the study for single-visit root canal therapy. The patients were divided into two groups (n = 30) according to the rotary instrument used during root canal preparation (group A [HEDM] and group B [WOG]). Pain was evaluated after endodontic therapy at 8, 24, and 48 h intervals using the visual analog scale (VAS). Data obtained were analyzed using the chi-square test, independent t-test, MannWhitney U test, and Wilcoxon matched-pairs test.

Results

Statistically significant differences were observed between the two groups (P < 0.001) at 8, 24, and 48 h, with WOG exhibiting less pain than HEDM files.

Conclusion

Postoperative pain was lower in the WOG file system than in the HEDM file system after single-visit root canal therapy at 8, 24, and 48 h.

Apically Extruded Debris in Curved Root Canals Using a New Reciprocating Single-File Shaping System

INTRODUCTION

The present study addresses the influence of 5 different shaping file systems on apical debris extrusion (AED) using 2 different irrigation protocols.

METHODS

One hundred fifty mandibular first permanent molars were divided into 2 groups and 10 subgroups. The mesial root canals were shaped using One Reci (MicroMega), WaveOne Gold Primary (Dentsply Sirona, York, PA), and ProTaper Next (Dentsply Sirona) using reciprocating motion and One Curve (MicroMega) and ProTaper Next using continuous rotation. The first group and the second one were respectively irrigated with 10 and 5 mL distilled water.

RESULTS

When the same instrumentation technique was used, the G10 mL subgroups showed statistically lower AED than the G5 mL subgroups (P < .05). The One Reci and One Curve subgroups, in both groups, produced statistically lower AED than the remaining subgroups.

CONCLUSIONS

The cross section of the instrument could be the main parameter in determining the amount of AED. The irrigation volume used during the shaping procedure might affect the amount of AED.

Current technology in endodontic instrumentation: advances in metallurgy and manufacture

Since the introduction of nickel-titanium endodontic instruments, there have been a myriad of developments which can be confusing and sometimes contradictory. This article seeks to review and articulate these advances, and allow the reader to better understand the benefits and the limitations of the systems available. Ultimately, this helps clinicians to engage more confidently with trade and have a more informed choice of the most appropriate file to use for each individual endodontic case. All this should facilitate more predictable endodontic outcomes.

Apical debris extrusion of full-sequenced rotary systems in narrow ribbon-shaped canals

The apically extruded debris caused by TruNatomy System (TRN), RACE EVO system (RE) and VDW Rotate (VR) systems in mandibular anterior teeth with ribbon-shaped root canals were compared. The root canals (n = 20 in each group) were irrigated with NaOCl 2.5%, and the extruded debris was collected at pre-weighted Eppendorf tubes. The amount of apically extruded debris (mg) and the treatment time (s) were recorded. Tukey pairwise comparisons were performed to compare groups with a 95% confidence level. VR had significantly less debris extrusion values and treatment time than RE and TRN (P < 0.05). Although no difference was observed between RE and TRN in terms of apically extruded debris (P > 0.05), a significant difference in favour of RE was observed in terms of treatment time (P < 0.05). All the instruments extruded debris at varying weights.

Apically extruded debris associated with ProTaper Next, ProTaper Gold and TruNatomy systems: An in vitro study

Background. This research aimed to investigate and compare the amount of apically extruded debris after root canal preparation using ProTaper Next, ProTaper Gold, and TruNatomy systems. Methods. Forty-five extracted mandibular premolar teeth with single canals with similar lengths were used. The root canals were prepared using ProTaper Next (Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Gold (Dentsply Maillefer, Ballaigues, Switzerland), or TruNatomy (Dentsply Maillefer, Ballaigues, Switzerland) files. Apically extruded debris during preparation was gathered into preweighed Eppendorf tubes. Then the Eppendorf tubes were incubated at 70°C for five days. The Eppendorf tubes were weighed again to determine their final weight plus the extruded debris. Results. The TRN system resulted in significantly less debris extrusion than the PTN system (P <0.05). There was no significant difference between the PTN and PTG groups and between the PTG and TRN groups (P >0.05). Conclusion. All the instrumentation systems caused apical extrusion of debris. However, the TRN system resulted in significantly less debris extrusion than the other systems.

Debris Extrusion Using Reciproc Blue and XP Endo Shaper Systems in Root Canal Retreatment

This study aimed at assessing the performance of Reciproc Blue (RB) and XP Endo Shaper (XPS), used for canal retreatment on extracted teeth, in terms of debris extrusion and obturating materials removal. Thirty mandibular premolars were prepared to ProTaper X2 file, obturated using warm vertical compaction, and then incubated for 28 days at 100% humidity at 37°C. Teeth were randomly assigned into two groups, according to the system used for retreatment (RB and XPS). During retreatment, debris extruded beyond the apex was collected in preweighed Eppendorf tubes, and the retreatment time was measured. Afterward, the teeth were longitudinally sectioned to assess the remaining obturating materials. Data were statistically analyzed using the Mann-Whitney test and chi-square test at a 95% confidence level. All the samples had extruded debris at varying weights ranging from 0.125 mg to 3.680 mg. XPS extruded less debris than RB, but no difference was detected (Mann-Whitney test; P > 0.05). RB and XPS required 54.9 ± 17.9 and 22.3 ± 9.3 seconds to perform retreatment procedures, respectively (Mann-Whitney test; P < 0.05). The sealer was found in all the samples. Compared to the RB group, fewer samples with remaining gutta-percha were found in the XPS group (Chi-square test; P < 0.05). None of the files fractured during the retreatment procedure. The tested files appear to extrude debris beyond the apex. Although XPS was able to remove the gutta-percha completely from the majority of the canals, it was unable to remove the sealer.

Impact of root canal curvature and instrument type on the amount of extruded debris during retreatment

Objectives

The aim of the current study was to assess whether the amount of extruded debris differs for straight and severely curved root canals during retreatment using H-files, R-Endo, Reciproc and ProTaper Universal Retreatment (PTU-R) files. Additionally, the area of residual filling material was evaluated.

Materials and Methods

Severely curved (n = 104) and straight (n = 104) root canals of maxillary molar teeth were prepared with WaveOne Primary file and obturated with gutta-percha and AH Plus sealer. Root canal filling materials were removed with one of the preparation techniques: group 1: H-file; group 2: R-Endo; group 3: Reciproc; group 4: PTU-R (n = 26). The amount of extruded material and the area of the residual filling material was measured. The data were analyzed with 2-way analysis of variance (ANOVA) and 1-way ANOVA at the 0.05 significance level.

Results

Except for Reciproc group (p > 0.05), PTU-R, R-Endo, and H-file systems extruded significantly more debris in severely curved canals (p < 0.05). Each file system caused more residual filling material in severely curved canals than in straight ones (p < 0.05).

Conclusions

All instruments used in this study caused apical debris extrusion. Root canal curvature had an effect on extruded debris, except for Reciproc system. Clinicians should be aware that the difficult morphology of the severely curved root canals is a factor increasing the amount of extruded debris during the retreatment procedure.

Shaping Ability and Debris Extrusion of New Rotary Nickel-Titanium Root Canal Instruments

The aim was to evaluate the canal straightening and the amount of apically extruded debris associated with five rotary nickel-titanium when preparing curved root canals. A total of 100 root canals in extracted human teeth (angles of curvatures 20°–30°; radii 5.9–13.5 mm) were divided into five groups (n = 20/group). The groups were balanced with respect to the angle and the radius of canal curvature. The root canals were prepared using conventional austenite 55-NiTi alloy instruments F360, F6 SkyTaper (both Komet, Lemgo, Germany), and the heat-treated NiTi Jizai, Silk-Complex and Silk-Standard instruments (all Mani, Tochigi, Japan) to an apical size 25. The amount of extruded debris was assessed with a micro balance. Statistical analysis was performed using Kruskal–Wallis test with Bonferroni correction at a significance level of p < 0.05. During canal preparation, neither instrument fractures nor procedural preparation errors were noticed. Regarding canal straightening, the use of Jizai instruments resulted in the significantly lowest straightening (p < 0.05), while no significant differences were obtained between all other groups (p > 0.05). Regarding the amount of apically extruded debris, no significant differences between all groups were obtained (p > 0.05). Within the limitations of this study, all instruments performed well, and especially the Jizai instruments showed an excellent shaping ability.

Three Dimensional mapping of the root apex: distances between apexes and anatomical structures and external cortical plates

This study aimed to determine the mean distances between apexes of the maxillary posterior teeth and the maxillary sinus, between apexes of the mandibular posterior teeth and the mandibular canal, and between the root apexes of all teeth and the adjacent cortical plates. A total of 800 cone-beam computed tomography (CBCT) scans (400 maxillary and 400 mandibular) were obtained from patients indicated for several treatments. The proximity between apexes and anatomical structures, and the relationship between apexes and adjacent cortical plates were assessed together with the risk of over-instrumentation. Paired-sample comparisons were performed by using the paired t-test. The means were compared by ANOVA, Kruskal-Wallis and Dwass-Steel-Critchlow-Fligner tests. a) Most of the apexes classified as A (high-risk proximity) were observed in maxillary first and second molars, in mandibular first and second molars, and in second premolars in relation to near anatomical structures. b) A predominance of class A (86.42%) was noticed in the first premolars, between apexes of maxillary teeth and adjacent cortical plates. c) The distance between apexes of mandibular teeth and buccal cortical plates showed a predominance of medium-risk proximity (B) in all the groups, except the first premolars, with the highest risk (82.22%), and the second molars, with low-risk proximity (C) to distal and mesiobuccal apexes (91.77% and 89.62%). CBCT images are important for endodontic diagnosis and treatment, since many teeth have high risk proximity to near anatomical structures and adjacent cortical plates.

Assessment of various endodontic instrumentation systems on the amount of apically extruded bacteria - An in vitro study

Aim:

The objective of this in vitro study was to assess the effect of different endodontic instrumentation systems on the amount of apically extruded bacteria.

Materials and Methods:

One hundred and twenty freshly extracted human mandibular premolars with single canal were collected. Endodontic access cavities were prepared and then contaminated with an Enterococcus faecalis suspension (ATCC 29212). After incubation at 37°C for 24 h, the root canals were instrumented with K flare files, F360 Single file system, K3XF files, Heroshaper files, Protaper Next files, and Hyflex EDM Single file system. During instrumentation, apically extruded bacteria were collected in the vials containing 0.9% NaCl. Samples were taken from the vials and incubated in brain–heart infusion agar medium for 24 h.

Statistical Analysis:

The number of colony-forming units was determined, and data were statistically analyzed using one-way analysis of variance and post hoc Tukey test.

Conclusions:

Both rotary and hand instrumentation systems extruded intracanal bacteria through the apical foramen, Group 1 (Hand K Flare files) showed maximum, whereas, Group 5 (Protaper Next) and Group 6 (Hyflex EDM) showed the least extrusion.

An in vitro endodontic model to quantify the accessory canal filling potential of the vertical and lateral condensation techniques

The purpose of this study was to determine the accessory canal filling potential of vertical and lateral condensation techniques in simulated root canals. A total of 130 prepared transparent, straight-simulated root canals with nine accessory canals (0.02 mm), prepared at different levels from the apical, were obturated with vertical (n = 100) and 30 lateral condensation (n = 30) techniques. 50.33% of the accessory canals obturated with vertical condensation were completely filled with gutta-percha; 37.78% completely filled with gutta-percha and sealer. 61.11% of the accessory canals were completely filled with sealer only using the lateral condensation technique. The vertical condensation technique filled the accessory canals more frequently than the lateral condensation techniques. The lateral condensation technique was not capable of delivering gutta-percha to any of the accessory canals. The apical third showed the lowest accessory canal filling frequency with both techniques.

Evaluation of apically extruded debris during the canal preparation using new heat-treated nickel-titanium files in curved canals

This study compared the amount of apically extruded debris associated with different heat-treated Ni-Ti rotary systems during the preparation of curved root canals of mandibular molars. Sixty extracted human mandibular molars were selected. EdgeFile, K3XF, OneCurve (OC) and ROTATE files were used to prepare both mesial canals of teeth. The initial weight of each Eppendorf tube to be used was calculated using an analytical balance prior to instrumentation. After instrumentation, the tubes were then stored for 5 days in an incubator at 70°C. Each tube was reweighed, and 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. All files caused apical extrusion of debris. There was no statistical difference between the ROTATE, EdgeFile, OC and K3XF systems (P > 0.05). All the heat-treated Ni-Ti rotary systems led to similar apical debris extrusion during the canal preparation.

Apically Extruded Debris following Programmed Over Instrumentation of Curved Canals with Three Nickel Titanium Rotary Instruments

OBJECTIVES

 This in vitro study aimed to compare the amount of mixed and dried debris extruded with three endodontic NiTi (nickel-titanium) systems at three levels beyond the major apical foramen. The null hypothesis is that there would be no differences between the different rotary systems in terms of apically extruded debris.

MATERIALS AND METHODS

 Forty-eight roots of human extracted molars with 20 to 40-degrees curvature were divided randomly into three groups (n = 16) instrumented with ProTaper Next, BT RaCe, and WaveOne Gold, respectively. Instrumentation was performed at the major foramen and over instrumented 0.5 mm, 1.0 mm and 1.5 mm beyond. Irrigation was performed with sodium hypochlorite. Apically extruded debris was collected.

RESULTS

 Comparison of mixed extruded debris (solution/debris)and dried debris according to group and level of instrumentation showed that WaveOne Gold at the foramen and ProTaper Next beyond the foramen (p < 0.0001) resulted in significantly less extruded debris than other files and within the four levels using repeated measures analysis of variance (p < 0.0001b).

CONCLUSIONS

 All systems exhibit extruded debris during instrumentation but in different amounts.

Effects of the endodontic access cavity on apical debris extrusion during root canal preparation using different single-file systems

Objectives

This study was conducted to evaluate the effects of traditional and contracted endodontic cavity (TEC and CEC) preparation with the use of Reciproc Blue (RPC B) and One Curve (OC) single-file systems on the amount of apical debris extrusion in mandibular first molar root canals.

Materials and Methods

Eighty extracted mandibular first molar teeth were randomly assigned to 4 groups (n = 20) according to the endodontic access cavity shape and the single file system used for root canal preparation (reciprocating motion with the RCP B and rotary motion with the OC): TEC-RPC B, TEC-OC, CEC-RPC B, and CEC-OC. The apically extruded debris during preparation was collected in Eppendorf tubes. The amount of extruded debris was quantified by subtracting the weight of the empty tubes from the weight of the Eppendorf tubes containing the debris. Data were analyzed using 1-way analysis of variance with the Tukey post hoc test. The level of significance was set at p < 0.05.

Results

The CEC-RPC B group showed more apical debris extrusion than the TEC-OC and CEC-OC groups (p < 0.05). There were no statistically significant differences in the amount of apical debris extrusion among the TEC-OC, CEC-OC, and TEC-RPC B groups.

Conclusions

RPC B caused more apical debris extrusion in the CEC groups than did the OC single-file system. Therefore, it is suggested that the RPC B file should be used carefully in teeth with a CEC.

Effect of different laser-assisted irrigation activation techniques on apical debris extrusion

Objective: The aim of this study was to compare apical debris extrusion when neodymium-doped yttrium aluminium garnet (Nd:YAG) lasers, erbium-doped yttrium aluminium garnet (Er:YAG) or photon-induced photoacoustic streaming (PIPS) are used for irrigation activation.Materials and methods: A total of 60 extracted human mandibular premolar teeth have similar dimensions were included and the samples were split into four groups according to the irrigation technique (n = 15): conventional needle irrigation, PIPS, Er:YAG and Nd:YAG. ProTaper Universal system up to F4 was used for root canal instrumentation. Bidistilled water was used as an irrigation solution during instrumentation and irrigation activation. Apically extruded debris was collected into preweighed Eppendorf tubes during instrumentation and irrigation activation procedures. The tubes were then kept in an incubator at 70 °C for 5 days. The initial weight of the tube was subtracted from the final weight and the result was recorded as the weight of dry extruded debris. The data were evaluated statistically using a one-way ANOVA test followed by least significant difference post hoc test (p < .05).Results: Conventional needle irrigation caused significantly less debris extrusion than laser-assisted irrigation activation groups (p < .05). Laser-assisted irrigation activation groups caused statistically similar debris extrusion (p > .05).Conclusion: Laser-assisted irrigation activation techniques caused more debris extrusion when compared to conventional needle irrigation.

Influence of Negotiation, Glide Path, and Preflaring Procedures on Root Canal Shaping-Terminology, Basic Concepts, and a Systematic Review

INTRODUCTION

Negotiation, glide path, and preflaring are essential steps in root canal shaping procedures. This report aimed to discuss the terminology, basic concepts, and clinical considerations of negotiation, glide path, and preflaring procedures and the influence of these steps on root canal shaping.

METHODS

This systematic review was undertaken following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The protocol has been registered with the International Prospective Register of Systematic Reviews (number CRD42019127021). A comprehensive literature search was performed by 2 independent reviewers using a selected search strategy in 2 electronic databases (PubMed and Scopus) until January 28, 2019. A further search was performed manually in endodontic journals. Studies investigating or comparing at least 1 shaping property resulting from root canal instrumentation with a glide path or preflaring in human extracted teeth or clinical studies were included.

RESULTS

The literature shows that the definition of glide path and preflaring procedures remains controversial, which requires an elaboration in the American Association of Endodontists' Glossary of Endodontic Terms. After the removal of irrelevant and duplicated articles, 98 articles were included. The impact of glide path preparation and preflaring on working length determination, apical file size determination, canal transportation, separation of endodontic files, shaping time, dentinal microcrack formation, and extrusion of debris was discussed. Because of heterogeneity among the included studies, quantitative synthesis was not performed for most of the parameters.

CONCLUSIONS

An evidence-based guideline is needed to define and correlate the basic concepts and current applications of each step of contemporary advancements in root canal instruments. Glide path preparation reduces the risk of debris extrusion, has no influence on the incidence of dentinal crack formation, and improves the preservation of the original canal anatomy. The creation of a glide path may have no impact on Reciproc files (VDW, Munich, Germany) in reaching the full working length. Preflaring increases the accuracy of working length determination. Further randomized clinical trials are required to evaluate the effect of a glide path and preflaring on root canal treatment outcomes.

Ex-Vivo Comparison of Torsional Stress on Nickel-Titanium Instruments Activated by Continuous Rotation or Adaptive Motion

This study aimed to evaluate the effect of adaptive motion applied to conventional nickel-titanium (NiTi) rotary instruments on torsional stress generation during shaping procedure. One hundred and twenty mesio-buccal canals of molars were randomly assigned to two groups according to the kinetics; adaptive motion (AD) and continuous rotation (CR). Each group was divided into four subgroups (n = 15) according to the NiTi instrument systems: HyFlex EDM, One Curve, Twisted File Adaptive, and ProTaper Next. A glide path was established with PathFile #1, for each file group being used with either of the kinetic movements. During the instrumentation with the designated motion and file system, the generated torque was measured via the control unit and acquisition module. Based on the acquired data, the maximum and total torque were calculated. The data were statistically analyzed using Kruskal–Wallis and Mann–Whitney tests at a significance level of 95%. The maximum and total torque generated by all instruments were significantly reduced by the adaptive motion (p < 0.05). In the CR group, HyFlex EDM generated the highest maximum and total stress. In the AD group, HyFlex EDM showed the highest maximum torsional stress, and One Curve showed the highest total torsional stress (p < 0.05). The TF Adaptive instrument with adaptive movement produced the lowest maximum and total torsional stress (p < 0.05). Under the conditions of this study, the use of adaptive motion would be useful to reduce the torsional stress of instrument and root dentin. The reduction of torsional stress through adaptive motion may enhance the durability of instruments and reduce the potential risk of dentinal cracks.

Apical periodontitis healing and postoperative pain following endodontic treatment with a reciprocating single-file, single-cone approach: A randomized controlled pragmatic clinical trial

This trial assessed post-operative pain and healing of apical periodontitis following endodontic therapy with a reciprocating system compared to a crown-down technique with hand files and lateral compaction filling. One-hundred and twenty nonvital anterior teeth with apical periodontitis were randomly treated using either a reciprocating single file followed by matching-taper single-cone filling or a hand file and lateral compaction filling. Postoperative pain was assessed during the 7 days after the treatment, using a visual analogue scale and a verbal rating scale. Apical healing was assessed using the periapical index score after a 12-month follow-up. The hypothesis tested was that both protocols were equivalent and present similar effectiveness in healing periapical lesions. Data were analyzed through two one-sided tests, t-tests, as well as Mann-Whitney and Chi-squared tests (α = 0.05). Logistic regression was used to investigate the association of clinical and demographic factors with the success of treatment. Regardless of the assessment time, no difference in incidence (38%-43% at first 24h), intensity of postoperative pain, and incidence of flare-up (≈ 3%) was observed between the two endodontic protocols. Both protocols resulted in a similar healing rate of apical periodontitis. After 12 months, the success rate ranged from 73% to 78% and the difference between the treatments fell within the pre-established equivalence margin (-0.1; -0.41 to 0.2). Endodontic treatment combining a reciprocating single file with matching-taper single cone showed similar clinical effectiveness to the treatment using hand-file instrumentation and the lateral compaction filling.

Debris Apically Extruded by Two Reciprocating Systems: A Comparative Quantitative Study

Objective  The objective of this study was to quantify the amount of debris apically extruded after instrumentation with two reciprocating systems.

Materials and Methods  Forty-two single-rooted mandibular premolars with only one straight root canal and apical diameter compatible with a no. 15 K-file were randomly divided into two groups ( n  = 21) according to the instrument used: ProDesign R (Easy Equipamentos; Belo Horizonte, Minas Gerais, Brazil) and Reciproc Blue (VDW; Munich, Germany). Dry Eppendorf tubes were weighed three consecutive times for the initial mean weight. A silicone stopper was then fitted into the mouth of the tube. Each tooth was inserted through the stopper up to the cementoenamel junction and instrumented with one of the two systems to the predetermined working length (18 mm). The root canals were instrumented per root thirds. At each instrumented root third, the canal was irrigated with 3 mL of double-distilled water, followed by patency control. Each stopper was then separated from the tube and tubes were incubated at 70°C for 5 days. Tubes were again weighed, and the amount of extruded debris was calculated by subtracting the initial mean weight from the final mean weight.

Statistical Analysis  Results were analyzed using the Mann–Whitney test at a 5% significance level.

Results  No significant difference was observed in debris extrusion between the ProDesign R and Reciproc Blue systems ( p = 0.7557).

Conclusions  The two reciprocating systems tested produced similar amounts of postinstrumentation apically extruded debris.