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Effect of finishing instrumentation using NiTi hand files on volume, surface area and uninstrumented surfaces in C-shaped root canal systems
Abstract
Aim:
To assess the effect of 90º-oscillatory instrumentation with hand files on the following morphological parameters (volume, surface area and uninstrumented surface) in C-shaped root canals after instrumentation using a single-file reciprocation system (Reciproc; VDW, Munich, Germany) and a Self-Adjusting File System (SAF; ReDent Nova, Ra'anana, Israel).
Methodology:
Twenty mandibular second molars with C-shaped canals and C1 canal configurations were divided into two groups (n = 10) and instrumented with Reciproc and SAF instruments. A size 30 NiTi hand K-file attached to a 90º-oscillatory motion handpiece was used as a final instrumentation in both groups. The specimens were scanned using micro-computed tomography after all procedures. Volume, surface area increase and uninstrumented root canal surface were analysed using CTAn software (Bruker-microCT, Kontich, Belgium). Also, the uninstrumented root canal surface was calculated for each canal third. All values were compared between groups using the Mann-Whitney test and within groups using the Wilcoxon's signed rank test.
Results:
Instrumentation with Reciproc significantly increased canal volume compared with instrumentation with SAF. Aditionally the canal volumes were significantly increased after 90º-oscillatory instrumentation (between and within group comparison; (P < 0.05). Regarding the increase in surface area after all instrumentation protocols, statistical analysis only revealed significant differences in the within groups comparison (P < 0.05). Reciproc and SAF instrumentation yielded an uninstrumented root canal surface of 28% and 34%, respectively, which was not significantly different (P > 0.05). Final oscillatory instrumentation significantly reduced the uninstrumented root canal surface from 28% to 9% (Reciproc) and from 34% to 15% (SAF; P < 0.05). The apical and middle thirds exhibited larger uninstrumented root canal surfaces after the first instrumentation that was significantly reduced after oscillatory instrumentation (P < 0.05).
Conclusions:
The Reciproc and SAF system were associated with similar morphological parameters after instrumentation of mandibular second molars with C-shaped canals except for a higher canal volume increase in the Reciproc group compared to the SAF. Furthermore, the final use of 90º-oscillatory instrumentation using NiTi hand files significantly decreased the uninstrumented canal walls that remained after Reciproc and SAF instrumentation. This article is protected by copyright. All rights reserved.
... The possible causes of treatment failure in C-shaped canal included the presence of a gap between root canal filling and root dentin, isthmus, a missing canal, overfilling and iatrogenic problems such as file separation, transportation or perforation [6,7]. The prepared canal wall after canal preparation could be ranged from 10% to 88% [4,[8][9][10][11][12][13][14] which resulted in residual bacteria. Another concern was the thin canal wall that could be at least 0.27 mm after canal preparation in C-shaped canals [4]. ...
... Cleaning and shaping this canal were challenging because it was impossible for the instrument to contact all surface areas of the canal. The percentage of prepared canal area in C-shaped canals was approximately 10%-80% from previous studies [4,[8][9][10][11][12][13][14]. In the present study, the percentage of prepared canal area was 31.86 ± 10.72% for the XR group and 30.26 ± 11.59% for the TN group. ...
... The minimum dentin thickness of the C-shaped canal before canal preparation was approximately 0.58 mm at the lingual wall and 0.96 mm at the buccal wall, with the lowest value being 0.26 mm at the apical third [5,18]. Minimum dentin thickness from previous studies could be <0.5 mm after canal preparation [4,14] especially at the concavity of the root. The thickness at the mesial canal was usually thinner than at the distal canal especially at the mesiolingual canal [14]. ...
This study aimed to evaluate and compare the shaping abilities and minimum dentin thickness of minimally invasive rotary instruments via micro‐computed tomography. Twelve 3D‐printed C‐shaped canal models from a mandibular molar were divided into two groups, and root canals were prepared with either XP‐endo Rise (XR) or TruNatomy (TN) systems. Pre‐ and post‐preparation evaluations included canal volume, prepared area and minimum dentin thickness. No significant differences were found in canal volume change (XR: 22.66 ± 4.28%, TN: 23.02 ± 5.10%), prepared canal area (XR: 31.86 ± 10.72%, TN: 30.26 ± 11.59%) and minimum dentin thickness (XR: 0.30 ± 0.05 mm, TN: 0.28 ± 0.05 mm) between groups ( p > 0.05). The canal volume change in the middle third was significantly higher than that in the coronal and apical thirds ( p < 0.05) in both groups. In conclusion, XR demonstrated comparable shaping abilities and minimum dentin thickness to TN in preparing 3D‐printed C‐shaped canals.
... Micro-computed tomographic (micro-CT) studies evaluating the preparation of C-shaped canals showed that rotary, reciprocating, and even self-adjusting instrument systems failed to completely prepare these canals, leaving high amounts of unprepared canal surfaces (range, 28%-66%) [8][9][10] . Root canal areas that remain unprepared as identified by micro-CT imaging may not be significantly cleaned or disinfected by the irrigant solution and therefore can exhibit remnants of bacterial biofilms and/or pulp tissue 11 . ...
... Root canal areas that remain unprepared as identified by micro-CT imaging may not be significantly cleaned or disinfected by the irrigant solution and therefore can exhibit remnants of bacterial biofilms and/or pulp tissue 11 . Combinations of 2 or more techniques or instruments have been proposed in an attempt to improve the quality of preparation and the access of irrigants into complex anatomic areas 9,12 and have the potential to be useful in improving cleaning and disinfection of teeth with complex anatomies. ...
... Even though C-shaped canals represent 1 of the most challenging conditions for root canal treatment, there are no studies thus far evaluating the ability of different preparation procedures and strategies to promote their disinfection. In addition, there are only a few micro-CT studies assessing the shaping of these anatomically complex cases [8][9][10]13,19 . Therefore, the present study aimed to evaluate the disinfection and shaping of C-shaped root canals promoted by 2 preparation protocols through a correlative micro-CT and molecular microbiology approach. ...
Introduction
This ex vivo study compared the disinfection and shaping abilities of 2 preparation protocols in C-shaped canals.
Methods
Mandibular second molars with type I C-shaped canals were pair matched based on micro–computed tomographic (micro-CT) analysis and distributed into 2 groups. The canals were contaminated with a mixed bacterial culture and prepared using 2 protocols, both with 2.5% sodium hypochlorite irrigation: XP-endo Shaper (FKG Dentaire, La Chaux-de-Fonds, Switzerland) supplemented with XP-endo Finisher (FKG Dentaire) (XP-E) and BioRaCe (FKG Dentaire) supplemented with a Hedström file (Dentsply/Sirona, Tulsa, OK) (BR-Hed). Micro-CT scans and intracanal bacteriologic samples were taken before (scan #1 and sample 1) and after preparation (scan #2 and sample 2) and after the supplementary step (scan #3 and sample 3). Canal shaping was evaluated by micro-CT imaging, and disinfection was assessed by quantitative polymerase chain reaction.
Results
Micro-CT data from the XP-E (n = 21) and BR-Hed (n = 23) protocols revealed no significant differences between groups regarding shaping parameters (canal volume, surface area, structure model index, and prepared walls) after preparation and after the supplementary step (P > .05). All these parameters significantly increased after each preparation step (P < .05), except for structure model index changes after the XP-endo Finisher (P > .05). Bacteriologic data from the XP-E (n = 21) and BR-Hed (n = 22) groups showed that 14 (66.7%) and 10 (45.5%) S2 samples still had detectable bacteria, respectively. The corresponding figures for supplementary steps with the XP-endo Finisher and Hedström file were 11 (52.4%) and 10 (45.5%), respectively. Bacterial counts in sample 1 significantly decreased in samples 2 and 3 in both groups (P < .01). Intragroup comparison between sample 2 and sample 3 showed a 66% reduction in counts after using the Hedström file and 18% after using the XP-endo Finisher (P > .05 for both groups). The quantitative bacterial reduction was not different between groups (P > .05).
Conclusions
The XP-endo Shaper and BioRaCe systems have similar disinfecting and shaping abilities in C-shaped canals. Supplementary steps with the Hedström file and the XP-endo Finisher were similarly effective in improving shaping, but this was not sufficient to enhance disinfection. About half of the cases, in both groups, still harbored detectable amounts of bacteria.
... This anatomy is usually more prevalent in second mandibular molars with fused roots containing several internal variations in its cross-sections, high canal volumes, large apical diameters and small amount of dentine thickness towards the radicular groove (21,22). These complexities make the proper cleaning, shaping and obturation often complicated, especially in the apical third (22)(23)(24)(25)(26). For this reason, it is important to evaluate techniques for removing the filling material during retreatment of C-shaped canals, without removing excessive amount of dentine next to the groove region. ...
... Micro-CT has the advantage to be a non-destructive research method that permitted to evaluate quantitative and qualitative 3D data of root filling material removal (11,35). Another advantage was that the specimen could be analyzed at different stages of the treatment procedure serving as its own control (25). A limitation of the study could be the small sample size so the results should be interpreted with caution. ...
... As mentioned before, the apical portion of the C-shaped canal systems are connected by ribbon-like isthmi in which instruments could hardly be inserted making it complicated to shape and obturate (23)(24)(25)31). Thus, in C-shaped retreatment procedures, these complications might also be expected when removing the RFM as revealed by our results. ...
Objective:
The aim of this study was to evaluate the use of Self-adjusting file (SAF) system and Hedström (H) file for removing remaining filling material (RFM) from C-shaped canals.
Methods:
20 C-shaped mandibular second molars with C1 configurations were instrumented, filled with tagger´s hybrid technique. Samples were divided into 2 groups (n=10). Reciproc R25 and a Mtwo 35/04 file were used for retreatment in both groups. Then, a 2.0 SAF file (group I) and a #35 H file (group II) were used as supplementary steps for RFM removal. Micro-CT scanning was performed after every procedure. Total volumes were calculated and converted into percentages. Also, the minimum wall thickness at 3, 5, 7 mm from apex was calculated. The Prism 7.0 software was used as the analytical tool with a significance of 5%.
Results:
Initial obturation removal was approximately 64% in group I and 67% in Group II. The apical third had the highest values of RFM. The use of a H file significantly reduced the RFM compared to SAF in the total canal length respectively (30% vs 18%) and at 1-3 mm and 3-6 mm when compared to the use of SAF. A statistically significant decrease of RFM and minimum wall thickness were observed in both groups (P<0.05).
Conclusion:
None of the retreatment techniques completely removed RFM. The apical region was the more unaffected area. Also, the SAF file was less effective than the H file in removing the RFM. Although C-shaped canals possesses thinner dentinal wall thickness, no excessive dentine removal was observed after each instrument use.
... This anatomy is usually more prevalent in second mandibular molars with fused roots containing several internal variations in its cross-sections, high canal volumes, large apical diameters and small amount of dentine thickness towards the radicular groove (21,22). These complexities make the proper cleaning, shaping and obturation often complicated, especially in the apical third (22)(23)(24)(25)(26). For this reason, it is important to evaluate techniques for removing the filling material during retreatment of C-shaped canals, without removing excessive amount of dentine next to the groove region. ...
... Micro-CT has the advantage to be a non-destructive research method that permitted to evaluate quantitative and qualitative 3D data of root filling material removal (11,35). Another advantage was that the specimen could be analyzed at different stages of the treatment procedure serving as its own control (25). A limitation of the study could be the small sample size so the results should be interpreted with caution. ...
... As mentioned before, the apical portion of the C-shaped canal systems are connected by ribbon-like isthmi in which instruments could hardly be inserted making it complicated to shape and obturate (23)(24)(25)31). Thus, in C-shaped retreatment procedures, these complications might also be expected when removing the RFM as revealed by our results. ...
... After the different instrumentation protocols, reconstructed images were geometrically registered with the preoperative datasets using the DataViewer software (Bruker-microCT, Kontich, Belgium) for a quantitative comparison of the morphological parameters before and after the shaping procedures. 23 Both canal volume (mm 3 ) and surface areas (i.e., amount of dentin removal) were measured by subtracting the scores for the treated canals from those recorded for the untreated counterparts using the CTAn v.1.12 software (Bruker-microCT, Kontich, Belgium). ...
... software (Bruker-microCT, Kontich, Belgium). [23][24] Matched images of the surface areas of the canals before and after the action of the endodontic instrument and/or ultrasonic tips were examined to evaluate the amount of unprepared canal wall surface after the instrumentation techniques used in this study. This parameter was expressed as a percentage of the number of static surface voxels to the total number of surface voxels. ...
... This parameter was expressed as a percentage of the number of static surface voxels to the total number of surface voxels. 23,24 The pre-and post-instrumentation scans were superimposed to determine the percentage of increase in volume and non-instrumented surface area. ...
To evaluate the influence of novel ultrasonic tips as an auxiliary method for the rotary preparation of flattened/oval-shaped canals. Forty-five mandibular incisors were selected and divided into one of three experimental groups (n = 15): Group PFCP – ProDesign Logic 25/.05 + Flatsonic + Clearsonic + Prodesign Logic 40/.01; Group FCP – Flatsonic + Clearsonic + ProDesign Logic 40/.01; and Group PP – Prodesign Logic 25/.05 + Prodesign Logic 40/.05. The teeth were scanned preoperatively and postoperatively using microcomputed tomography. The percentage values for increase in volume, non-instrumented surface area, dentin removal, degree of canal transportation, and centering ratio between the experimental groups were examined. Data were analyzed using the non-parametric Kruskal-Wallis and Dunn’s tests (p < 0.05). Group PFCP showed the greatest volume increase in the total portion of the root canal and the lowest percentage of non-instrumented surface area. Regarding the degree of transportation in the buccolingual direction, statistically significant differences between groups PFCP and PP were observed at the coronal third of the canal. In the mesiodistal direction, no statistically significant differences were observed at the coronal, middle, and apical thirds. As for the centering ratio, statistically significant differences were found in the buccolingual direction. In the mesiodistal direction, no statistically significant differences were observed at the coronal, middle, and apical thirds. The use of novel ultrasonic tips combined with rotary instruments in group PFCP provided a significant increase in volume and reduced the percentage of non-instrumented areas during the preparation of flattened/oval-shaped canals.
... A similar study using micro-CT to assess shaping protocols in type I C1 C-shaped extracted mandibular molars reported different percentages of unprepared areas: 28% after Reciproc and 34% after the self-adjusting file (SAF) instrumentation. 30 Other researchers reported 33% and 30% of unprepared canal areas for Reciproc Blue and XP-endo Shaper, respectively, 7 while higher values of unprepared areas were reported in a previous study using the ProTaper rotary system (66%) and the SAF system (41%). 31 The in vitro study of Gazzaneo et al 32 recently reported high disinfecting abilities of XP-endo Shaper, reporting 11.70% of unprepared canal surfaces in C-shaped anatomies. ...
... It favors the accumulation of debris into the isthmus recesses during canal instrumentation, which impedes the flow of the filling materials during root canal filling. 35 Possible strategies to overcome these limitations suggested in the literature are complementary instrumentation techniques to reduce the unprepared canal surfaces, 30,36 and the use of passive ultrasonic irrigation or XP-endo Finisher to significantly reduce the accumulation of hard tissue debris, 7 and probably this should be considered as final treatment protocols in C-shaped root canal anatomies. ...
Objective This study compared the shaping ability of TRUShape and XP-endo Shaper systems on C-shaped root canals replicas using microcomputed tomography (micro-CT).
Material and Methods Thirty three-dimensional replicas based on a mandibular second molar classified as C1 type I C-shaped canal were randomly divided into two groups ( n = 15): TRUShape (G.TRU) and XP-endo Shaper (G.XP) and instrumented with each system according to the manufacturer's instructions. Changes in volume and surface and the unprepared area of the root canal were measured by scanning on micro-CT before and after instrumentation.
Results The unprepared areas were 39% in the G.TRU and 43% in the G.XP group with no significant difference between them ( p > 0.05), but both the tested systems left a high percentage of unprepared root canal walls of C-shaped root canals.
Conclusion TRUShape and XP-endo Shaper showed a high rate of unprepared areas with similar results after C-shaped root canals replicas for root canal preparation.
... Reconstructed images from before and after the procedure were geometrically superimposed, and the data were compared with the DataViewer software v1.5.2 (Bruker-microCT, Kontich, Belgium). The analysis included the binarization of the root canals and measurement of the volume (mm 3 ) and surface area (mm 2 ) of the full canals using CTAn v.1.14.4 [23]. The total canal volume was measured from the root canal orifice to 1 mm short of the apical foramen. ...
... The angular rotation to file fracture differed depending on the kinematics used. High torsional loading during glide path preparation of constricted or narrow canals was also simulated, resulting in the maximum torsional strength and angular rotation of the file to fracture [21][22][23][24]27]. The authors evaluated the torsional properties at the last 3 mm of the file, as this area is more prone to fracture than the 5-mm region [28]. ...
Aim
To evaluate the influence of different kinematics on the efficiency and safety of an engine-driven file for glide path preparation in second mesiobuccal canals (MB2) of maxillary molars. In addition, the torsional resistance of the file was assessed after use.
Methodology
Thirty-six maxillary first and second molars with two canals in the mesiobuccal root were selected and the anatomy of the canals was verified by micro-CT. The teeth were divided into 4 groups (n = 9) according to the kinematics used for glide path preparation: continuous rotation (CR), 30°/150° reciprocation (REC 30°/150°), 30°/90° reciprocation (REC 30°/90°), and 90° optimum glide path motion (OGP 90°). The duration of the procedure, number of canals in which the file reached the full working length (RFWL), canal volume before and after the procedure, rate of file fracture, and file torsional strength after use were evaluated. The ANOVA and Tukey tests or Kruskal–Wallis and Dunn tests were used for statistical analysis.
Results
No significant differences among the groups were found for procedure duration, success at reaching the FWL, distance from the file to apex, and number of fractured files (P > 0.05). The CR group showed a significant decrease in rotation angle compared with REC 90° and OGP 90° groups (P < 0.05). There was no significant difference in canal volume among the groups (P > 0.05).
Conclusion
The type of kinematics used did not affect the efficiency, success rate, and shaping ability of the file during glide path preparation. CR seems to induce more torsional stress than the other kinematics.
Clinical relevance
The glide path preparation of narrow canals such as the MB2 is difficult and accidents such as file fracture may occur. This study showed that reciprocation with different file angulations can be safer during this challenging stage.
... Although nickel-titanium (NiTi) rotary instruments significantly reduces the occurrence of procedural errors during mechanical preparation, previous studies found that a high percentage of C-shaped canal wall was untouched by rotary, reciprocation or selfadjusting file instrumentation techniques (Solomonov et al. 2012, Amoroso-Silva et al. 2017. The use of supplemental irrigation regimens such as sonic and ultrasonic irrigation improves the debridement efficacy of C-shaped anatomical system (Cheung & Cheung 2008, Yin et al. 2010. ...
... The maximum individual values of AUCW approximated 50% in both groups. The results are similar to those reported in previous studies of C-shaped canals enlarged and shaped with various NiTi systems (Yin et al. 2010, Solomonov et al. 2012, Amoroso-Silva et al. 2017. A study on XP-endo Shaper shaping in oval-shaped canals reported that the percentage of unprepared area was 17.3% (Lacerda et al. 2017). ...
... Despite natural variations in the morphology of this group of teeth, attempts were made to ensure the comparability of the groups regarding root canal morphology. Similar to what has been done in previous studies (25)(26)(27)(28), a micro-CT screening of the volume, surface area, and root canal anatomy of each specimen was performed. Based on these measurements, 2 similar teeth were grouped and further allocated in 1 of the 2 groups. ...
... The efficacy of instrumentation was evaluated by means of high-resolution micro-CT imaging, similar to previous studies (26,31,32). This technology allows canal scanning before and after instrumentation, thus verifying changes in the anatomy of the root canal, such as the noninstrumented canal area (14,27), accumulation of hard tissue debris (15,(33)(34)(35), and volume of dentin removed. Noninstrumented canal areas may be colonized by biofilms and serve as a potential cause of persistent infection, which may compromise the treatment outcome (33,35). ...
Introduction:
The aim of this study was to assess the influence of contracted endodontic cavities (CECs) on root canal detection, instrumentation efficacy, and fracture resistance assessed in maxillary molars. Traditional endodontic cavities (TECs) were used as a reference for comparison.
Methods:
Thirty extracted intact maxillary first molars were scanned with micro-computed tomographic imaging at a resolution of 21 μm, assigned to the CEC or TEC group (n = 15/group), and accessed accordingly. Root canal detection was performed in 3 stages: (1) no magnification, (2) under an operating microscope (OM), and (3) under an OM and ultrasonic troughing. After root canal preparation with Reciproc instruments (VDW GmbH, Munich, Germany), the specimens were scanned again. The noninstrumented canal area, hard tissue debris accumulation, canal transportation, and centering ratio were analyzed. After root canal filling and cavity restoration, the sample was submitted to the fracture resistance test. Data were analyzed using the Fisher exact, Shapiro-Wilk, and t tests (α = 0.05).
Results:
It was possible to locate more root canals in the TEC group in stages 1 and 2 (P < .05), whereas no differences were observed after stage 3 (P > .05). The percentage of noninstrumented canal areas did not differ significantly between the CEC (25.8% ± 9.7%) and TEC (27.4% ± 8.5%) groups. No significant differences were observed in the percentage of accumulated hard tissue debris after preparation (CEC: 0.9% ± 0.6% and TEC: 1.3% ± 1.4%). Canal transportation was significantly higher for the CEC group in the palatal canal at 7 mm from the apical end (P < .05). Canal preparation was more centralized in the palatal canal of the TEC group at 5 and 7 mm from the apical end (P < .05) and in the distobuccal canal of the CEC group at 5 mm from the apical end (P < .05). There was no difference regarding fracture resistance among the CEC (996.30 ± 490.78 N) and TEC (937.55 ± 347.25 N) groups (P > .05).
Conclusions:
The current results did not show benefits associated with CECs. This access modality in maxillary molars resulted in less root canal detection when no ultrasonic troughing associated to an OM was used and did not increase fracture resistance.
... Thus, a biomechanical preparation technique that combines NiTi instrumentation, ultrasonic irrigation, and intracanal medications is recommended. This approach ensures the establishment of a sterile environment prior to obturation and promotes optimal treatment outcomes [24,25]. For the present case, these guidelines were strictly followed during treatment, and bioceramic sealers were used, which improve longterm prognosis by minimizing leakage and enhancing periapical healing [26]. ...
Root canal anatomy can greatly vary by tooth and among teeth with the same type. The aim of this case report was to describe the management of a C-shaped canal in 21-year-old male Saudi patient presented with severe pain in the left second premolar mandibular tooth. It was diagnosed with cone beam computed tomography (CBCT). The C-shaped configuration exhibited fins, web-like connections, or an elongated ribbon-shaped appearance, which rendered cleaning, shaping, and obturation difficult. The use of modern endodontic tools, such as CBCT system; dental operating microscope, which facilitates cleaning and shaping; and bioceramic sealers accelerated sealing and healing. After 24 months of follow-up, clinical and radiographic evaluation revealed the absence of signs and symptoms; reduction in the size of the periapical lesion; and starting of complete healing.
... When using instruments with a diameter smaller than the diameter of the root canal, it is likely that an increased area of the canal wall will remain untreated [38]. Furthermore, in canals with oval, flat or irregular morphology, much larger areas will remain uncleaned [39]. Micro-CT studies have shown that in round canals, between 10% and 50% of their total area remains unprepared [40]. ...
The endodontic treatment of immature permanent teeth with necrotic pulp is a significant clinical challenge. The success of regenerative endodontic procedure is highly dependent on disinfection of the root canal and an accurate anatomical knowledge of the root canal. The aim of this study was to use micro-computed tomography (micro-CT) analysis to investigate the configuration of root canals in the upper permanent third maxillary molars with incomplete root development in their coronal, apical and middle third portions. Thirty immature third permanent maxillary molars were scanned using a micro-CT system. Then, we measured the diameters and areas of the root canal in the coronal, middle and apical third of the roots. The ratio between the long and short diameter of each root canal was then calculated and the canals were divided into several groups: round, oval, long oval, flat and irregular. The round configuration was not observed in the distobuccal and mesiobuccal roots in any of their anatomical regions. Oval and long oval canals predominated in the distobuccal root. The greatest variations were observed in the mesiobuccal root, with the ribbon-shaped canal predominating in the middle region and an irregular shape in the apical region. In the coronal region of the palatal canal, the round configuration predominated; in the middle third, we observed an almost equivalent distribution between round and oval configurations; apically, the oval shape predominated. In conclusion, we observed significant complexity and variation in the morphology and configuration of root canals in immature permanent molars, thus generating additional obstacles for the success of regenerative endodontics.
... In the PN and WG group, the untouched surface area was 18.75% and 22.69%, respectively. The results are less than those reported in previous studies about the instrumentation of the C-shaped canals in mandibular molars with different NiTi systems [50][51][52][53] . ...
Aim
To investigate the effect of instrumentation using Protaper Next (PN, Dentsply Sirona, Maillefer, Ballaigues, Switzerland) and Waveone Gold (WG, Dentsply Sirona, Maillefer, Ballaigues, Switzerland) systems on the area of untouched surface (US), accumulated hard tissue debris (AHTD), and the filling ability of two obturation techniques on the percentage of void within C-shaped root canals of mandibular first premolars.
Methodology
64 mandibular first premolars with C-shaped canals were scanned, matched and assigned to 2 shaping groups (n = 32): PN and WG. Following instrumentation, specimens were randomly assigned into two obturation subgroups (n = 16): continuous wave compaction (CWC) and single-cone (SC) techniques. The US% and AHTD% after instrumentation and the vol% of void after obturation were calculated from micro-computed tomography. Data were analyzed using comparisons for two groups (PN vs WG) or two subgroups (CWC vs SC) at α = 0.05.
Results
For PN and WG, 18.75% and 22.69%, respectively, of the canal wall remained untouched (p > 0.05). For both groups, the apical third had higher US% than the coronal third (p < 0.05). Instrumentation with WG left more debris (26.48%) than PN (8.36%) in the apical 1-3mm (p < 0.05). In PN and WG group, the vol% of void had no significant difference between the CWC and SC subgroups(p > 0.05). The apical region had significantly more voids than the coronal region of the canal space in the two obturation subgroups regardless of which system was applied (p < 0.05).
Conclusions
Both PN and WG systems were associated with similar US after instrumenting C-shaped canals of the mandibular first premolar. WG left significantly more AHTD compared with PN in the apical region. In PN or WG group, SC yielded similar obturation quality when compared with CWC. Both CWC and SC obturation techniques provided poorer filling quality in the apical region than in the coronal region.
Clinical Significance
Micro-CT evaluation of the PN and WG shaping C-shaped canals in mandibular first premolars showed similar effects on the percentages of untouched canal wall. The PN produced less hard tissue debris in the apical regions compared with the WG. The SC yielded similar obturation quality compared with the CWC.
... A histologic and scanning electron microscopy study showed that unprepared areas still contain residual pulp and/or bacterial cells despite an extensive irrigation protocol 1 8,21,22 . Therefore, in teeth with complex canal anatomy, including oval canals, additional strategies are recommended to optimize root canal shaping, such as circular filling with Hedströem files or ultrasonic tips 23,24 . Apical transportation after canal preparation depends on the degree and radius of curvature, canal anatomy, and the instrument used. ...
Current instrumentation systems cannot fully prepare oval root canal systems. This may cause accumulation of hard tissue debris and fail to eliminate bacteria from areas inaccessible to instrumentation, which could perpetuate periapical inflammation and jeopardize the success of endodontic treatment
Aim
To evaluate the performance of two endodontic systems in oval canals by investigating the changes in volume, unprepared areas, and centering ability of XP-endo Shaper (XPS) and WaveOne Gold (WOG) in oval canals using microcomputed tomography (micro-CT)
Materials and Method
Thirty mandibular canines were scanned before and after preparation with WOG (25/.07 and 35/.06) or XPS (30/.01) to evaluate the volume, surface area, and canal centralization at 4 mm and 10 mm from the apical foramen
Results
Volume and surface area increased significantly after preparation with both systems (p<0.05). However, no significant difference was observed in the unprepared areas, regarding either the entire canal (26.21% for WOG and 30.10% for XPS), or the apical segment (18.82% for WOG and 14.63% for XPS) (p >0.05)
Conclusions
Both systems maintained canal centralization, with no difference between them. XPS and WOG had similar shaping abilities in the mandibular canine, but left almost one third of the unprepared areas.
... Ideally, the endodontic retreatment should completely remove any preexisting filling material since it may contain microorganisms and may also act as a physical barrier, blocking the action of irrigation solutions and proper sealing of the new filling. However, several studies have shown that complete removal of the filling material is not possible, especially in complex anatomies [5][6][7][8][9][10][11][12][13][14][15]. ...
Objectives:
This study evaluated the efficiency of WaveOne Primary files (Dentsply Sirona) for removing root canal fillings with 2 types of movement: reciprocating (RCP) and continuous counterclockwise rotation (CCR).
Materials and methods:
Twenty mandibular incisors were prepared with a RCP instrument (25.08) and filled using the Tagger hybrid obturation technique. The teeth were retreated with a WaveOne Primary file and randomly allocated to 2 experimental retreatment groups (n = 10) according to movement type: RCP and CCR. The root canals were emptied of filling material in the first 3 steps of insertion, until reaching the working length. The timing of retreatment and procedure errors were recorded for all samples. The specimens were scanned before and after the retreatment procedure with micro-computed tomography to calculate the percentage and volume (mm3) of the residual filling material. The results were statistically evaluated using paired and independent t-tests, with a significance level set at 5%.
Results:
No significant difference was found in the timing of filling removal between the groups, with a mean of 322 seconds (RCP) and 327 seconds (CCR) (p < 0.05). There were 6 instrument fractures: 1 in a RCP motion file and 5 in continuous rotation files. The volumes of residual filling material were similar (9.94% for RCP and 15.94% for CCR; p > 0.05).
Conclusions:
The WaveOne Primary files used in retreatment performed similarly in both RCP and CCR movements. Neither movement type completely removed the obturation material, but the RCP movement provided greater safety.
... Various techniques have been advocated to evaluate the residual filling materials left in the root canal after retreatment, including radiographic imaging [42], clearing techniques, sectioning, and microscopic evaluation [43,44]. Recently, micro-CT imaging with high resolution has been praised in numerous studies because it is a noninvasive technique that allows accurate quantification measurements at different stages of the treatment, the specimen thus serving as its control [1,45]. However, micro-CT usage can lead to artifacts in the reconstructed images, such as beam-hardening, complicating the interpretation of the image [46]. ...
This study aimed to evaluate the effectiveness of the Endostar REvision system (Poldent, Warsaw, Poland) in the removal of filling materials from oval root canals using sonic irrigation as an additional cleaning method. Thirty human-extracted mandibular premolars with oval canals were prepared using the ProTaper Universal system (Dentsply Maillefer, Ballaigues, Switzerland) up to instrument F1 (20/.07), and then filled by the continuous wave vertical compaction technique using pulp canal sealer EWT (Sybron Dental Specialties, Orange, CA, USA). The teeth were randomly divided into two groups (n = 15) according to the instrumentation system and the additional cleaning method, as follows: REvision (30/.08, 25/.06) with EQ-S sonic activation (Meta Biomed, Chungcheongbuk-do, Korea), REvision (30/.08, 25/.06) without additional activation. All specimens were sectioned longitudinally at 3 and 7 mm from the apex, and analyzed using digital microscopy (KEYENCE, Osaka, Japan) to measure the total area of the residual obturation materials, followed by SEM analysis. The data on the percentage of remaining filling material were analyzed by Kruskal–Wallis one-way Analysis of Variance on ranks. None of the retreatment protocols completely removed the filling material from the root canals (p > 0.05); the retreatment technique using sonic activation showed statistically less residual filling materials than the retreatment technique using irrigants without activation at the coronal third (p < 0.05), whilst no significant difference was found between both tested groups at the apical and middle thirds (p > 0.05). The REvision system showed promising results in the removal of filling materials from oval canals.
... Rotary instrumentation yields an uninstrumented root canal surface area between 28.0 and 34.0% (Amoroso-Silva et al. 2017;Zhao et al. 2019), and 41.6% (Yin et al. 2010) for rotary and manual instrumentation, respectively, in permanent teeth. In the present study in primary teeth, uninstrumented area in fused teeth and manual instrumentation was 62.0%. ...
Abstract
Purpose
Pulpectomy may be indicated in restorable primary teeth exhibiting irreversible pulpitis or pulpal necrosis. The purpose of this study was to compare the cleaning and shaping efficacy of NiTi systems (Reciproc® Blue and MTwo®) with manual stainless-steel instrumentation in primary molars using micro-CT analysis.
Methods
Fifty-seven maxillary second primary molars were scanned using micro-CT. Teeth with three divergent roots were divided randomly (n = 15) according to instrument type (K file, MTwo®, and Reciproc® Blue). Teeth with root fusion were instrumented manually as a separate group (n = 12). Pre- and post-instrumentation micro-CT images were superimposed, and the instrumentation area (IA) and procedural complications were recorded.
Results
No statistically significant differences in IA between file systems was observed in the non-fused teeth. The mean IA of fused roots was significantly lower than in the non-fused distobuccal (p = 0.003) and palatal (p < 0.001) roots. The root segment had a significant effect on IA (p < 0.001) and the highest mean IA was observed in the apical third. Manual instrumentation had fewer procedural complications compared with rotary systems.
Conclusion
No differences were determined in the cleaning and shaping effectiveness of all systems in non-fused teeth. Uninstrumented areas (> 60%) occurred in both non-fused and fused primary teeth with fewer procedural complications observed after manual instrumentation.
... These procedural errors impede endodontic therapy and, therefore, increase the risk of treatment failure 2 . Additionally, instrumentation with currently available NiTi systems will always leave root canal surfaces untouched [3][4][5] . These areas may harbor microorganisms that might result in treatment failure 6,7 . ...
Aim
Micro-CT assessment of preparation of moderately single- and double curved root canals using three single-file reciprocating NiTi-systems: S1 Plus Standard (Sendoline, Täby, Sweden; S1P), WaveOne Gold Primary (Dentsply Sirona, Ballaigues, Switzerland; WOG), Reciproc R25 (VDW, Munich, Germany; REC)
Materials and Methods
Seventy-five moderately curved mandibular molars with two separate mesial root canals were assigned to three experimental groups (n=25): S1P, WOG, REC by forming matched triples according to curvature (15-40°), radius (≤18 mm) and type of curvature (single- or double-curved). Teeth were scanned before and after root canal preparation with a resolution of 10.5 μm using micro-computed tomography (Bruker SkyScan 1272, Bruker Corporation, Belgium). The following parameters were assessed: changes in root canal volume and surface area, percentage of unshaped canal walls, structure model index, canal transportation and centering ratio. Data were analyzed using 2- and 3-way ANOVA with Tukey's and Scheffés post hoc tests (significance level of 5%).
Results
No significant differences among groups were observed concerning all parameters. The type of curvature had no significant effect on all tested parameters. Within all experimental groups, canal transportation increased significantly from the apical to the coronal region, of which the majority was directed towards the furcational area.
Conclusions
Preparation with the three NiTi-systems did not result in significantly different dimensional changes and there was no significant effect of the type of curvature on all tested parameters.
... The major goal of mechanical instrumentation by using different nickel-titanium files is to expand the root canal and along with irrigation protocols, clear pulp tissue, infected dentin layers, and biofilms attached to the root canal surface. However, the instruments and irrigating solutions cannot be reaching the complete root canal walls due to some anatomical intricacies of teeth and it may influence the root canal treatment outcome [35,36] negatively. The biological and mechanical targets of (RCT) can achieve through effective cleaning and shaping of the root canal system. ...
The success of endodontic treatment depends on root canal preparation which is extremely important duringthe root canal treatment. The root canal instrumentation phase by using nickel-titanium instruments will help in theeffectiveness of other procedures, such as facilitating irrigation and aspiration and three-dimensional obturation of canals.The objective of this review reviews all the data in regards to the efficiency of two nickel-titanium rotary instrumentswhich are pro-taper next files and pro-taper universal files compared with different instruments in endodontics andwhich conducts are most used and appropriate for optimal root canal instrumentation. For such, we carried out asystematic review of the literature, using all the databases included in PubMed and Google Scholar. The search retrieved401 articles, of which, after applying the exclusion/inclusion and quality criteria, 12 articles were selected for an in-depthanalysis. Among the main results, we highlight two nickel-titanium rotary instruments that were used to aid the cleaningand shaping in root canal treatment, in addition to presenting several aspects such as different types of instrumentsystems, the efficiency of instruments during cleaning and shaping, and updating studies of their effect in the rootcanal treatment and re-treatment. This review concluded the rotary instrumentations especially pro-taper next files andpro-taper universal files illustrated great cleaning efficiency during root canal treatment and root canal re-treatmentcompared with hand stainless steel files and different instruments.
... 22 Angiogenesis is key for the regeneration of the pulp-dentin complex. 6,23 In preliminary experiments, we showed that HUVECs and hDPSCs co-cultured at a ratio of 5:1 formed more tubule structures in the early stage, but began to collapse at about 6 h. As the tubule structures were not sufficiently stable, we added TNF-α to the co-culture system to improve stability. ...
We recently demonstrated that a co-culture system of human umbilical vein endothelial cells (HUVECs) and human dental pulp stem cells (hDPSCs) could enhance angiogenesis ability in vitro. However, whether tumor necrosis factor α (TNF-α) could promote blood vessel formation during pulp regeneration remained unknown. The aim of this study was to investigate the effects of TNF-α on the formation of endothelial tubules and vascular networks in a co-culture system of hDPSCs and HUVECs. hDPSCs were co-cultured with HUVECs at a ratio of 1:5. The Matrigel assay was performed to detect the total tubule branching lengths and numbers of branches, and the Cell-Counting Kit 8 assay was performed to examine the effect of TNF-α on cell proliferation. Real-time polymerase chain reactions and western blot were used to detect vascular endothelial growth factor (VEGF) mRNA and protein expression. The Matrigel assay showed significantly greater total branching lengths and numbers of branches formed in the experimental groups treated with different concentrations of TNF-α compared with the control group. The decomposition times of the tubule structures were also significantly prolonged (P < 0.05). Treatment with 50 ng/ml TNF-α did not significantly change the proliferation of co-cultured cells, but it significantly increased the VEGF mRNA and protein expression levels (p < 0.05). In addition, the migration abilities of HUVECs and hDPSCs increased after co-culture with TNF-α (p < 0.05). TNF-α enhanced angiogenic ability in vitro in the co-culture system of hDPSCs and HUVECs.
... The ability of Hedströem files to remove root filling material was tested in oscillatory movement; this presented better results relative to the filing movements, leading to better centralization of the preparation, less occurrence of canal transportation, in addition to standardizing the movement kinematics (Amoroso-Silva et al., 2017;Rasquin, de Carvalho, & Lima, 2007). However, the results showed that stainless steel files were less effective than XP-endo Shape; in addition their super-elasticity, their ability to expand and contract may have been more effective than the stainless steel files used with the conventional technique. ...
The aim of this study was to evaluate three reciprocating systems and complementary cleaning methods on filling material removal during retreatment of flattened canals. Thirty‐six mandibular incisors were prepared using rotary instruments up to size 25.08 and filled using the single‐cone technique. Subsequently, the teeth were divided into three groups (n = 12) according to retreatment procedures: Reciproc Blue (RB): 25/0.08 and 40/0.06; ProDesign R (PDR): 25/0.06 and 35/0.05; and WaveOne Gold (WOG): 25/0.07 and 35/0.06. The remaining filling volume materials were assessed by means of micro‐CT imaging before and after retreatment. After this, the specimens were subdivided into three groups according to complementary cleaning methods: XP‐Endo Shaper (30/0.01); passive ultrasonic irrigation (PUI); 60° oscillatory instrumentation with #30 H‐file, and micro‐CT scan was taken. Then, the roots were cut in half and the samples were analyzed by scanning electron microscope (SEM). The data were analyzed statistically using Kruskal–Wallis and Dunn's Multiple Comparison test with significance level of 5%. None of the reciprocating files promoted complete removal of filling material and there was no statistical difference between the groups, regardless instrument size (p > 0.05). Complementary cleaning methods increased remnant filling removal (p < 0.05). XP‐endo Shaper significantly reduced the amount of filling material in the apical and middle thirds, compared with H‐files (p < 0.05), with no difference with PUI. In the SEM, there was no statistical difference among the instruments (p > 0.05). The reciprocating systems showed similar effectiveness in removing root filling material. Complementary cleaning method with the XP‐Shaper enhanced filling material removal.
... The results from studies investigating the amount of unprepared root canal wall are contradictory: In a study using C-shaped root canals the SAF left more uninstrumented root canal wall (34%) than Reciproc instruments (VDW) (28%) 48 . After preparation of oval-shaped root canals the SAF performed clearly superiorly compared with BioRace or Reciproc (Bio-Race 32.38% vs Reciproc 18.95% vs SAF 16.08% untouched areas) 49 . ...
In the present study root canal preparation in curved root canals in extracted teeth was compared using either the vibratory Self-Adjusting File (SAF) or the rotary BioRace NiTi system. The issues investigated were longitudinal and cross-sectional preparation shape, root canal cleanliness and the incidence of procedural mistakes. No significant differences were found with respect to the above-listed topics investigated in this study. Both NiTi systems can be recommended for clinical use.
... Regarding the materials and methods employed here, the samples were analyzed by micro-CT before and after root canal preparation and later analyzed by SEM for assessing the cleaning of root canal. Micro-CT has been used for this purpose [24,25] because it has the advantage of not being invasive and not destroying the samples for confirmation of results. ...
Introduction
The aim of this study was to compare root preparation of deciduous teeth with WaveOne Large (WO) and ProTaper F4 (PT) instruments with or without passive ultrasonic irrigation (PUI).
Methods and Materials
Forty-eight deciduous teeth were scanned before and after root preparation and divided in four groups (n=12): WO+EDTA (WO); WO+EDTA with PUI (WOPUI); PTF+EDTA (PT); and PT+EDTA with PUI (PTPUI). Root canal enlargement by micro-computed tomography and root canal cleaning by scanning electron microscopy (SEM) were analyzed. Data were submitted to two-way ANOVA and Tukey’s tests to analyze the root canal volume variation, and Kruskal-Wallis followed by Friedman and Wilcoxon tests were used to evaluate the cleaning efficacy. The level of significance was set at 0.05.
Results
No significant difference occurred in total volume between groups (P>0.05). On analysis by thirds of the root canal, there was a difference in volume between WO (cervical) compared to WO and PT (apical), and PTPUI (middle and apical) (P<0.05). When cleaning of the thirds within the same group was compared, there was a significant difference in all groups (P<0.05). Among the groups, in the thirds, in the cervical a difference occurred (P=0.028), and the pairwise comparisons indicated statistically difference between WO and PT, and WO and PTPUI (P<0.05). In the pairwise comparisons among thirds, in the groups, difrences occured in all of them when compared the cervical and apical thirds (P<0.05).
Conclusion
Passive ultrasonic irrigation has not improved the smear layer removal in deciduous teeth. Despite the differences in performance between WO and PT instruments, both were suitable for preparation of deciduous teeth.
... Key problems encountered during cleaning and shaping C-shaped canals include difficulty in removing pulp tissue and necrotic debris, excessive hemorrhage, working length determination, and persistent discomfort during instrumentation. Because of the large volumetric capacity of the C-shaped canal system, housing transverse anastomoses, and irregularities [32], many techniques have been advocated for the enlarging, shaping, cleaning, disinfecting, and filling of these canal systems [89][90][91][92][93][94][95]. ...
While the prevalence of C-shaped canals is low in many parts of the world, the incidence may be high in specific countries and ethnic populations. One of the contributing factors that masks more detailed information on this anatomical variation is the difficulty in using periapical radiographs alone to determine its presence. While the literature is replete with studies that indicate that mandibular second molar and first premolar may exhibit this variation most often, other teeth such as the maxillary molars may also demonstrate this anatomical complexity.
... Reciprocating motion allows preparation with a lower number of instruments [8]. However, the importance of using more than one instrument to promote better root canal cleaning with less debris and uninstrumented root canal wall, including different diameters, has been demonstrated [6,7,9]. ...
Objectives:
To evaluate the shaping ability and cleaning after oval root canal preparation using one or more instruments in reciprocating or rotary motion.
Materials and methods:
Oval-shaped mandibular incisors were selected, based on the radiographic diameter (2 ≤ diameter ratio ≤ 4), and assigned according to root canal preparation (n = 18): single-file (Reciproc R40); two reciprocating files (Unicone size 20 and 40, .06 taper) or Mtwo rotary files until a size 40, .06 taper instrument. Root canal preparations were performed using an open root canal model. Scanning was performed before and after preparation using SkyScan 1176 with a voxel size of 17.42 μm. Volume, percentage of debris, and percentage of uninstrumented surface were analyzed in the entire root canal and in each root canal third. Data were compared using ANOVA and Tukey or Kruskal-Wallis and Dunn tests (α = 5%).
Results:
The initial volume were similar among the groups (p > .05). Unicone preparation was associated with higher debris, increase in root canal volume and uninstrumented surface in entire root canal and in the middle third (P < .05). Mtwo was associated with lower uninstrumented surface in the entire root canal and in the cervical third. The apical third were similar for the three preparations.
Conclusions:
Unicone system using two instruments in reciprocating motion resulted in higher increase in volume. However, less remaining debris was observed when Reciproc single-file and Mtwo rotary systems were used.
Clinical relevance:
A preparation that volumetrically increases the root canal is not necessarily associated with better cleaning. Shaping and hard-tissue debris removal depends on root canal anatomy, kinematics, number of instruments, and instrument design.
... Another reported effect of clinical success in endodontics is the maintenance of original canal shape and lack of any canal aberrations [7]. The main goal of root canal therapy is to remove pulp tissue, layers of infected dentine and biofilms attached to the root canal surface; yet, this requires enlargement of root canals for mechanical instrumentation and access of irrigants [31]. Larger apical preparations and tapers have been related to improvement of disinfection and cleaning procedures [10,11]. ...
Key Clinical Message
A major cause for endodontic failure is the inability to treat all anatomy. Studies report endodontic retreatments contain 42% missed canals. This case illustrates dentin preservation of a molar with an uninstrumented mesiobuccal‐3 canal revealed post‐GentleWave Procedure. Efficient cleaning and disinfection with maintained healing to 18 months is demonstrated.
... Current endodontic techniques include mechanical instrumentation and irrigation. Mechanical instrumentation is required to enlarge the root canals to allow for access of irrigants [10]. Therefore, larger apical preparations and tapers have been related to improved disinfection and cleaning procedures [11,12]. ...
Introduction: Primary root canal treatment success depends on a number of variables, including debridement and disinfection of the root canal system to remove all bacteria and diseased pulpal and dentinal tissues. Complex root canal anatomy, such as concealed isthmuses, apical deltas and lateral canals, hinder this objective, making instrumentation of these regions nearly impossible. Recent advancements within the endodontic space have focused on improved cleaning and disinfection techniques that will enhance cleaning and debridement, even in difficult to navigate anatomy within the apical third.
Background: This case study explores the effectiveness of the GentleWave® Procedure in treating a maxillary second molar diagnosed with irreversible pulpitis and symptomatic apical periodontitis that also featured complex apical root canal anatomy that was undetected until obturation was completed.
Methods: A minimally invasive endodontic protocol was utilized to maximize preservation of tooth structure. The tooth was conservatively accessed followed by minimal instrumentation to a size 25/04 for creation of a fluid path and to facilitate future placement of root canal obturation material. Multisonic Ultracleaning™ and debridement were accomplished with the GentleWave Procedure. After obturation with gutta-percha and sealer, a final radiograph revealed a clinically significant obturation with previously unseen lateral canals and an isthmus within the apical third.
Results: The previously diagnosed symptomatic apical periodontitis had fully resolved by the three-week followup visit. This case report demonstrates a viable minimally invasive endodontic treatment for uncovering root canal systems with complex apical anatomy utilizing the GentleWave Procedure.
Introdução: O tratamento endodôntico visa a preservação do dente comprometido por lesões pulpares, que podem ter anatomias variadas, dificultando o sucesso do tratamento. O canal radicular c-shaped tem formato de “C” é uma alteração anatômica, mais facilmente encontrada em segundos molares, principalmente nos inferiores, é parecida com uma fenda e sua morfologia pode dificultar a identificação radiográfica simples. Por esse motivo, a tomografia de alta resolução é o exame ideal para o diagnóstico desse tipo de variação. Compreender a anatomia das raízes dentárias é importante para procedimentos odontológicos nesse caso o tratamento de canal. Durante o tratamento o conhecimento detalhado das raízes permite ao endodontista identificar canais radiculares, localizar possíveis anomalias anatômicas entre esses a forma de C, logo verificar os diferentes tipos de radiologia, pois desempenham um papel importante na identificação dos canais radiculares e no planejamento dos tratamentos endodônticos. Objetivo: é mostrar através de uma revisão de literatura a variação da anatomia dental em forma de C dos molares inferiores, que podem interferir no sucesso do tratamento endodôntico. Metodologia: Pesquisa bibliográfica e exploratória com revisão da literatura a partir do levantamento de referências técnicas analisadas por meios de escritos e eletrônicos, livros, artigos científicos, estudos e relatos de casos usando palavras chaves: endodontia, anatomia dentária, molar em forma de c e radiografias. Resultados: Dentre 247 artigos pesquisados, 15 foram selecionados para fundamentar o trabalho. Considerações Finais: Cada paciente deve ser tratado de forma individualizada, levando em consideração suas peculiaridades anatômicas, histórico clínico e necessidades específicas.
Background
This study investigated the prevalence and morphology of C‐shaped and non‐C‐shaped root canal systems in permanent mandibular first (PM1) and second (PM2) premolars using retrospective analysis of cone‐beam computed tomography (CBCT) scans, and panoramic radiographs.
Methods
CBCT scans from 2000 patients were screened for the presence of premolars with C‐shaped canals and then assessed at three axial levels to determine the canal classification. The teeth were also assessed for Vertucci configuration, number of roots, and radicular grooves. Pre‐existing panoramic radiographs were evaluated to identify features specific to PM1/2 with multiple canals or C‐shaped anatomy.
Results
A total of 1576 PM1 and 1424 PM2 from 880 patients were evaluated. The overall prevalence of C‐shaped canals was 2.2% (3.3% PM1, 1.0% PM2), with 49 (5.6%) patients presenting with at least one C‐shaped mandibular premolar. There were 2.3 ± 0.6 and 2.4 ± 0.5 different classifiable cross‐sections per tooth for PM1 and PM2, respectively. The sudden disappearance or bifurcation of a canal on panoramic radiographs was associated with the presence of multiple canals ( P < 0.001) or C‐shaped anatomy ( P = 0.03).
Conclusions
There was substantial variation in cross‐sectional anatomy within and between C‐shaped premolars, which will affect endodontic treatment planning. © 2023 Australian Dental Association.
Objective:
The objective of this study was to evaluate 2-dimensional (2D) and 3D morphometric parameters of C-shaped root canals on cone beam computed tomography (CBCT) and microcomputed tomography (microCT) images using nanocomputed tomography (nanoCT) as the reference standard.
Study design:
Sixty mandibular molars with C-shaped canals were individually scanned using nanoCT and microCT. Cone beam computed tomography acquisitions were then performed with 4 CBCT systems, using high and standard resolutions. The 2D parameters of roundness and major and minor diameters were obtained in the cross sections of the root canals at 1, 2, and 3 mm from the root apex. The 3D parameters of surface area, volume, and structure model index were measured considering the entire extension of the root canals. Absolute error (AE) in measurement was calculated against the nanoCT values. Data were statistically analyzed with the Shapiro-Wilk test and analysis of variance (α = 0.05).
Results:
No significant differences in AE were discovered for the 2D parameters among microCT and the CBCT scans. The AE values for the 3D parameters of volume and surface area were significantly smaller in microCT compared to all CBCT units (P < .05). Significantly lower AE values for surface area were observed in high resolution compared to standard resolution for all CBCT units (P < .05). Structure model index did not differ significantly among microCT and all CBCT protocols.
Conclusions:
Cone beam computed tomography images showed accuracy for evaluating 2D parameters and over- and underestimation for 3D parameters.
Shaping ability evaluation of taper ./01 instruments in large root canals, by microcomputed tomography (micro‐CT) and scanning electron microscopy (SEM). Maxillary central incisors with large diameter root canals were divided into two groups (n = 10): XP‐Endo Shaper (FKG‐Dentaire, Switzerland) and manual instrumentation (FKG‐Dentaire). Two‐ and three‐dimensional parameters from cervical to apical root thirds were evaluated by micro‐CT. Apical stop was evaluated by SEM images. Data were analysed by ANOVA and Tukey tests (α = 5%). XP‐Endo Shaper allowed a regular biomechanical preparation with less dentinal wear compared with manual instrumentation, which showed excessive wear of the thin root canal walls (p < 0.05). Roundness and SMI showed similarity between both protocols (p > 0.05). XP‐Endo Shaper SEM showed a regular and well‐defined shape of the apical foramen suggesting the formation of the apical stop. Reduced diameter and taper instruments promoted a conservative wear and a well‐defined apical stop formation in large root canals.
The success of endodontic treatment depends on many factors. One of the most important is the proper root canal obturation. In the treatment of apical periodontitis, temporary sealers are used to improve healing process of the infected periodontium, which contain calcium hydroxide on different bases: hydrophilic and hydrophobic. If there are remnants of temporary sealants, the doctor cannot guarantee the good root canal obturation. Complete removal of temporary sealers from the root canal system and dentine tubules is ensured by the use of special irrigants. The aim. Evaluate the application of adhesion of epoxy resin sealant after temporary root canal filling. Materials and methods . Samples of 60 intact molars were randomly distributed into six groups. In the samples of the 1st group, a sealant based on epoxy resins was used; In the 2nd group, before applying the sealer, dentin samples were additionally treated with liquid for drying and degreasing the hard tissues of the tooth. In the samples of teeth in the 3rd and 4th group, a paste with calcium hydroxide on a hydrophilic basis with calcium hydroxide was applied to the dentin section. Then epoxy sealer was used for permanent obturation. In the samples of teeth in the 4th group, dentin was applied liquid for drying and degreasing the hard tissues of the tooth before the use of epoxy sealer. In the samples of teeth in the 5th and 6th groups, a hydrophobic paste containing calcium hydroxide and silicone-based iodoforms was applied to the dentin section before the application of epoxy sealer. In the samples in the 6th group, dentin was pretreated with liquid for drying and degreasing the hard tissues of the tooth. In the samples of all groups, the adhesive shear strength was determined on the test machine «SYNTHEZ 5» (France). After the tests, the samples were studied by scanning electron microscopy (SEM). The results of the study showed adhesive shear strength in the 1st group of (9,1±1,2) MPa, in the 2nd group – (11,4±1,1) MPa, in the 3rd group – (8,0±1,1) MPa, in the 4th group – (10,5±1,1) MPa, in the 5th and 6th groups – (7,6±1,3) MPa and (10,3±1,1) MPa, respectively. Samples treated with a liquid for drying and degreasing the hard tissues of the tooth under SEM showed the penetration of epoxy sealer into the dentin tubules. Conclusion . The adhesive strength of the epoxy resin-based sealant after the application of pastes for temporary filling of root canals ranges from (9,1±1,2) МРа до (11,4±1,1) MРa. Residual fragments of pastes on hydrophilic and hydrophobic bases reduce the strength of adhesion of the root sealаnt to dentin.The use of liquid for drying and degreasing the hard tissues of the tooth allows to remove the remnants of the paste from the root canal as much as possible and increases the strength of adhesion of the root sealant to the dentin.
Introduction
The aim of this study was to compare, using micro-computed tomography, the preparation of mesial canals of mandibular molars with the Reciproc and XP-endo Shaper systems, evaluating changes in dentin and canal volume, the percentage of untouched walls, the volume of accumulated hard tissue debris and root canal deviation in the apical third.
Methods
Twenty-four mandibular molars with two mesial root canals and a single foramen were anatomically paired and divided into two experimental groups (n=12) according to the system used. The specimens were scanned before and after preparation with a SkyScan 1176 microtomograph (Bruker-microCT, Kontich, Belgium) at a resolution of 17.42 μm. The resulting data were statistically compared at a significance level of 5% using Student's t-test and the Mann-Whitney test.
Results
A significant difference was observed in untouched surface area for the total canal and for the cervical and middle thirds, with the lowest untouched surface area in the XP-endo Shaper group (P <0.05). The volume of accumulated hard tissue debris was significantly higher in the Reciproc group in the total canal as well as in the middle and apical thirds. There was no significant difference between the groups regarding the volume of dentin removed or the increase in canal volume and surface area (P >0.05).
Conclusion
The XP-endo Shaper touched more walls and left less accumulated hard tissue debris in the root canal system than did the Reciproc system.
Chemomechanical preparation is intended to clean, disinfect, and shape the root canal. This step is of utmost importance during treatment of infected teeth with apical periodontitis, because treatment outcome depends on how effectively the clinician eliminates bacteria, their products, and necrotic tissue that would serve as substrate for bacterial regrowth. Nonetheless, curvatures and complex internal anatomical variations of the root canal system can pose a high degree of difficulty in reaching these goals. In infected teeth, bacteria may persist not only in difficult-to-reach areas such as isthmuses, ramifications, dentinal tubules, and recesses from C-shaped or oval/flattened canals, but also in areas of the main canal wall that remain untouched by instruments. If bacteria withstand chemomechanical procedures, there is an augmented risk for post-treatment apical periodontitis. This article discloses the reasons why some areas remain unprepared by instruments and discusses strategies to circumvent this issue and enhance infection control during endodontic treatment/retreatment of teeth with apical periodontitis.
Introduction:
This study compared the cyclic fatigue and the canal transportation promoted by Twisted File (TF) Adaptive and Navigator EVO systems when used with 2 different motions.
Methods:
Forty mesiobuccal roots of maxillary molars were scanned by using micro-computed tomography imaging before and after root canal preparation with the 2 instrument systems used with 2 motions (adaptive and continuous rotation). Samples were divided into 4 groups: TFA, TF Adaptive instruments under adaptive motion; TFC, TF Adaptive instruments under continuous motion; NA, Navigator instruments under adaptive motion; and NC, Navigator instruments under continuous motion. Root canals were prepared until 35.04 instruments. Apical transportation was analyzed by using micro-computed tomography at 3 levels: 3, 6, and 9 mm from the apex. The cyclic fatigue tests were performed by using a custom-made device. Ten instruments of each brand were activated by using a 6:1 reduction handpiece powered by a torque-controlled motor using the preset programs "custom mode" and "TF Adaptive" to activate 25.06 and 35.04 instruments. Kruskal-Wallis and Dunn tests were used to assess canal transportation, centering ability, and canal volume. The Student t test was used to evaluate cyclic fatigue (P = .05).
Results:
At 3 and 9 mm, the canal transportation and centering ability were similar in all groups (P > .05). At 6 mm, TFC presented higher canal transportation toward furcal region than NA and NC (P < .05). After canal preparation, TFA promoted great dentinal excision, presenting higher canal volume than NA and NC (P < .05). Higher cyclic fatigue resistance was observed under continuous than adaptive motion regardless of system or tip/diameter of the instrument (P < .05).
Conclusions:
Both systems can be used under adaptive or continuous rotation. However, the life span of the instruments was higher when used under continuous rotation. Small canal transportation occurred when mesiobuccal root canals from maxillary molars were prepared until 35.04 instruments.
Aim:
To evaluate oval root canal preparation using one or two instruments in counter-clockwise or clockwise reciprocating motion.
Methodology:
The radiographic diameter of mandibular human incisors was evaluated and oval canals were selected (2? Diameter Ratio ?4). Fifty-seven teeth were assigned to root canal preparation (n=19): Reciproc 40 (R40) in a counter-clockwise reciprocating motion; MTwo size 40, .06 taper (M 40.06) in a clockwise reciprocating motion or MTwo size 20, .06 taper and size 40, .06 taper (M 20/40.06) in a clockwise reciprocating motion. MTwo instruments were coupled to an ENDO DUAL motor, turning 150? clockwise and 30? counter-clockwise. Scanning was performed before and after root canal preparation using a SkyScan 1176 micro-computed tomography. Volume, percentage of debris and percentage of uninstrumented surface were analyzed in the entire root canal and in each third of the canal. Data were compared using ANOVA and Tukey?tests or Kruskal-Wallis and Dunn tests.
Results:
The Reciproc and MTwo systems using different kinematics were associated with a similar increase in root canal volume. Additionally, both system had similar percentage of uninstrumented surface (p>0.05). Mtwo size 20, .06 taper and size 40, .06 taper was associated with significantly lower debris (p<0.05) in the middle third (0.56%) when compared to R40 (1.31%) and M size 40, .06 taper (1.54%).
Conclusions:
The conventional reciprocation motion for R40 and the clockwise reciprocation motion for MTwo resulted in similar root canal preparations. Less remaining debris was present in the middle third when two instruments with different diameters were used. This article is protected by copyright. All rights reserved.
This study evaluated the shaping characteristics of the ProTaper Gold system (PTG; Dentsply Maillefer, Ballaigues, Switzerland) and compared it with that of the ProTaper Next (PTN, Dentsply Maillefer) and ProTaper Universal (PTU, Dentsply Maillefer) systems using micro-computed tomographic imaging.
Twenty-four mandibular first molars with 2 separate mesial canals were matched anatomically using micro-computed tomographic scanning (SkyScan1174v2; Bruker-microCT, Kontich, Belgium) with a voxel size of 19.6 μm. Canals were prepared with PTG, PTU, or PTN rotary systems to F2 or X2 instruments, respectively, and scanned again. Coregistered images were evaluated for 2- and 3-dimensional morphometric measurements of canal transportation, centering ability, untouched canal walls, and remaining dentin thickness. Data were statistically compared using Kruskal-Wallis and 1-way analysis of variance tests (α = 5%).
Overall, PTN showed significantly higher percentage values of static voxels than PTG and PTU systems (P < .05). Surface area, perimeter, and minor diameter were higher in the PTG and PTU groups than in the PTN group (P < .05). No difference was observed in form factor, roundness, major diameter, aspect ratio, or structure model index (P > .05). PTG (0.11 ± 0.05 mm) and PTN (0.09 ± 0.05 mm) produced significantly less transportation than PTU (0.14 ± 0.07 mm) (P < .05), and the percentage decrease in dentin thickness was significantly lower for PTG (22.67 ± 2.96) and PTN (17.71 ± 5.93%) (P ≥ .05) than PTU (29.93 ± 6.24%) (P < .05).
PTG and PTN produced less transportation and maintained more dentin than PTU. PTN had less canal wall contact than PTG and PTU, but all file systems were able to instrument moderately curved mesial root canals of mandibular molars without clinically significant errors.
Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.
Objectives:
The aim of this study was to introduce a methodology to map irrigant spreadability within the root canal space using micro-computed tomography (micro-CT).
Materials and methods:
Mandibular molars presenting Vertucci's types I and II canal configurations were selected, and four scans using isotropic resolution of 19.5 μm were accomplished per tooth: prior to treatment (S1), after glide path (S2) and after root canal preparation (S3 and S4). A contrast solution (CS) was used to irrigate the canals at stages S2 and S4. The touched and untouched surface areas of the canals, the volume of irrigant-free areas and the percentage volume occupied by the CS were calculated. Density, surface tension and the spread pattern of the CS and 2.5% NaOCl were also evaluated.
Results:
In the type I mesial root, there was an increase in the percentage volume of free-irrigated areas from S2 to S4 preparation steps, whilst in the distal roots and type II mesial root, a decrease of irrigant-free areas was observed. The use of CS allowed the quantification of the touched surface area and the volume of the root canal occupied by the irrigating solution. Density (g/mL) and surface tension (mN/m) of the CS and 2.5% NaOCl were 1.39 and 47.5, and 1.03 and 56.2, respectively. Besides, a similar spread pattern of the CS and 2.5% NaOCl in a simulated root canal environment was observed.
Conclusions:
This study introduced a new methodology for mapping the irrigating solution in the different stages of the root canal preparation and proved useful for in situ volumetric quantification and qualitative evaluation of irrigation spreading and irrigant-free areas.
Clinical relevance:
Micro-computed tomographic technology may provide a comprehensive knowledge of the flush effectiveness by different irrigants and delivery systems in order to predict the optimal cleaning and disinfection conditions of the root canal space.
Introduction
The aim of the present study was to evaluate the cutting efficiency of 2 new reciprocating instruments, Reciproc and WaveOne.
Methods
Twenty-four new Reciproc R25 and 24 new WaveOne Primary files were activated by using a torque-controlled motor (Silver Reciproc) and divided into 4 groups (n = 12): group 1, Reciproc activated by Reciproc ALL program; group 2, Reciproc activated by WaveOne ALL program; group 3, WaveOne activated by Reciproc ALL program; and group 4, WaveOne activated by WaveOne ALL program. The device used for the cutting test consisted of a main frame to which a mobile plastic support for the handpiece is connected and a stainless steel block containing a Plexiglas block (inPlexiglass, Rome, Italy) against which the cutting efficiency of the instruments was tested. The length of the block cut in 1 minute was measured in a computerized program with a precision of 0.1 mm. Means and standard deviations of each group were calculated, and data were statistically analyzed with one-way analysis of variance and Bonferroni test (P < .05).
Results
Reciproc R25 displayed greater cutting efficiency than WaveOne Primary for both the movements used (P < .05); in particular, Reciproc instruments used with their proper reciprocating motion presented a statistically significant higher cutting efficiency than WaveOne instruments used with their proper reciprocating motion (P < .05). There was no statistically significant difference between the 2 movements for both instruments (P > .05).
Conclusions
Reciproc instruments demonstrated statistically higher cutting efficiency than WaveOne instruments.
This ex vivo study evaluated the disinfecting and shaping ability of 3 protocols used in the preparation of mesial root canals of mandibular molars by means of correlative bacteriologic and micro-computed tomographic (μμCT) analysis.
The mesial canals of extracted mandibular molars were contaminated with Enterococcus faecalis for 30 days and assigned to 3 groups based on their anatomic configuration as determined by μCT analysis according to the preparation technique (Self-Adjusting File [ReDent-Nova, Ra'anana, Israel], Reciproc [VDW, Munich, Germany], and Twisted File [SybronEndo, Orange, CA]). In all groups, 2.5% NaOCl was the irrigant. Canal samples were taken before (S1) and after instrumentation (S2), and bacterial quantification was performed using culture. Next, mesial roots were subjected to additional μCT analysis in order to evaluate shaping of the canals.
All instrumentation protocols promoted a highly significant intracanal bacterial reduction (P < .001). Intergroup quantitative and qualitative comparisons disclosed no significant differences between groups (P > .05). As for shaping, no statistical difference was observed between the techniques regarding the mean percentage of volume increase, the surface area increase, the unprepared surface area, and the relative unprepared surface area (P > .05). Correlative analysis showed no statistically significant relationship between bacterial reduction and the mean percentage increase of the analyzed parameters (P > .05).
The 3 instrumentation systems have similar disinfecting and shaping performance in the preparation of mesial canals of mandibular molars.
Introduction: The newly developed single-file systems
claimed to be able to prepare the root canal space with
only 1 instrument. The present study was designed to
test the null hypothesis that there is no significant difference
in the preparation of oval-shaped root canals using
single- or multiple-file systems. Methods: Seventy-two
single-rooted mandibular canines were matched based
on similar morphologic dimensions of the root canal
achieved in a micro–computed tomographic evaluation
and assigned to 1 of 4 experimental groups (n = 18) according
to the preparation technique (ie, Self-Adjusting
File [ReDent-Nova, Ra’anana, Israel], WaveOne [Dentsply
Maillefer, Ballaigues, Switzerland], Reciproc [VDW,
Munich, Germany], and ProTaper Universal [Dentsply
Maillefer] systems). Changes in the 2- and 3-
dimensional geometric parameters were compared
with preoperative values using analysis of variance
and the post hoc Tukey test between groups and the
paired sample t test within groups (a = 0.05). Results:
Preparation significantly increased the analyzed parameters;
the outline of the canals was larger and showed
a smooth taper in all groups. Untouched areas occurred
mainly on the lingual side of the middle third of the
canal. Overall, a comparison between groups revealed
that SAF presented the lowest, whereas WaveOne
and ProTaper Universal showed the highest mean
increase in most of the analyzed parameters (P < .05).
Conclusions: All systems performed similarly in terms
of the amount of touched dentin walls. Neither
technique was capable of completely preparing the
oval-shaped root canals.
C-shaped canals are anatomic features that present the clinician with both diagnostic and operational challenges. The aim of this study was to compare the efficacy of the Self-Adjusting File (SAF; ReDent, Ra'anana, Israel) in shaping C-shaped canals with that of the rotary ProTaper file system (Dentsply-Maillefer, Ballaigues, Switzerland).
Sixteen mandibular second molars and 4 maxillary second molars with C-shaped canals were obtained, originating from native Chinese population. They were divided into 2 equal groups of 10 teeth each, based on similar canal morphology as presented in preliminary micro-computed tomography-derived images. One group was shaped using the SAF, whereas the other was shaped using the ProTaper file system. Reconstructed micro-computed tomographic images before and after treatment were superimposed over each other, and the percentage of the canal wall unaffected by the procedure was calculated. Comparison of the 2 groups for this parameter was performed using the Student t test.
When treated with the SAF, 41% ± 14% of the canal walls remained unaffected by the procedure, whereas 66% ± 6% of the wall area was unaffected when using ProTaper, which was significantly higher than that of the SAF-treated group (P < .001).
The SAF was more effective than the ProTaper file system in shaping the walls of C-shaped root canals.
The purpose of this study was to investigate the relation between the radiographic features of C-shaped mandibular second molars and the cross-sectional shapes of their root canal system. Fifty-eight extracted mandibular second molars with fused roots were collected from a native Chinese population. The teeth were scanned at 0.5-mm interval thickness by micro-computed tomography (microCT) and observed at 11 levels. The 54 teeth that possessed a C-shaped canal system were further examined. Their radiographic appearances were classified into three types according to discernible radiographic features. The results were subject to the Kruskal-Wallis statistical test. In these 54 molars, 16 teeth (29.63%) showed a type I radiographic image, 22 (40.74%) type II, and 16 (29.63%) type III. In the type I category, the C1 and C4 canal configurations were mostly found in the apical area. Categories C2 and C3 were the main configurations in the middle and apical areas in type II and III. The type III had more C2 canals in middle area than type II. These results suggested that it was possible to predict the presence and the configuration of C-shaped canal system by the radiographic appearance.
The purpose of this study was to assess dentin removal during root canal preparation by different operators using a NSK reciprocating handpiece. Eighty-four human single-rooted mandibular premolars were hand instrumented using Triple-Flex stainless-steel files (Kerr) up to #30, weighed in analytical balance and randomly assigned to 4 groups (n=21). All specimens were mechanically prepared at the working length with #35 to #45 Triple-Flex files (Kerr) coupled to a NSK (TEP-E10R, Nakanishi Inc.) reciprocating handpiece powered by an electric motor (Endo Plus; VK Driller). Groups 1 to 4 were prepared by a professor of Endodontics, an endodontist, a third-year dental student and a general dentist, respectively. Teeth were reweighed after root canal preparation. The difference between weights was calculated and the means of dentin removal in each group were analyzed statistically by ANOVA and Tukey's test at 5 % significance level. The greatest amount of dentin removal was found in group 4, followed by groups 2, 3 and 1. Group 4 differed statistically from the other groups regarding dentin removal means [p<0.001 (group 1); p=0.005 (group 2); and p=0.001 (group 3)]. No statistically significant difference was found between groups 1 and 2 (p=0.608), 1 and 3 (p=0.914) and 2 and 3 (p=0.938). In conclusion, although the group prepared by a general dentist differed statistically from the other groups in terms of amount of dentin removal, this difference was clinically irrelevant. The NSK reciprocating handpiece powered by an electric engine was proved an effective auxiliary tool in root canal preparation, regardless of the operator's skills.
Introduction:
A novel S-shaped rotary file was developed to conform to nonround canal cross sections. However, the instrument should also perform well in small curved canals. This study used micro-computed tomographic scans to test the effects of TRUShape (Dentsply Tulsa Dental Specialties, Tulsa, OK) and a conventional rotary on canal geometry.
Methods:
Twenty mandibular molars with independent mesial canals were submitted to preoperative micro-computed tomographic scans (20-μm resolution). Canals were randomly allocated to 2 groups using Vortex (Dentsply Tulsa Dental Specialties) and TRUShape for shaping according to the directions for use. Scans were obtained after size 20/.06 and 30/.06; the following outcome variables were calculated: dentin volume, smallest radicular wall thickness, treated canal surface, canal transportation, and accumulated hard tissue debris. The number of preparation errors was tabulated; data were statistically contrasted using repeated measures and factorial analyses of variance.
Results:
The initial canal sizes were similar in both groups. Both instruments promoted preparation with no overt procedural errors. Vortex removed significantly more dentin both at size #20 and #30 (P < .02). Significantly (P < .02) more radicular wall dentin remained toward the furcation in the TRUShape group (1.02 ± 0.25 mm vs 0.94 ± 0.22 mm). The untreated surface at size #20 was 28.5 ± 13.9 and 19.4 ± 8.9 (P < .05), and it was 15.1 ± 8.5 and 11.3 ± 4.9 (P > .05) at size #30 for TRUShape and Vortex, respectively. Canal transportation at size #30 varied between 85 ± 57 μm and 179 ± 65 μm; the overall transportation scores were significantly lower for TRUShape (P < .05).
Conclusions:
TRUShape provided conservation of dentin by limiting dentin removal and in the absence of substantial canal transportation. In the present study, the use of TRUShape in the mesial canals of mandibular molars did not result in decreased amounts of unprepared canal surface.
Abstract:
Introduction: The goal of the present study was to evaluate the morphometric aspects of the internal anat- omy of the root canal system of mandibular second molars with C-shaped canals. Methods: Fifty- two extracted second mandibular molars with C-shaped canals, fused roots, and radicular grooves were selected from a Brazilian population. The samples were scanned with a micro–computed tomographic scanner at a voxel size of 19.6 mm. The root canal cross sections were re- corded as C1, C2, C3, and C4 root canal configurations according to the modified Melton classification. Morphometric parameters, including the major and mi- nor diameters of the root canals, the aspect ratio, the roundness, and the tridimensional configuration (merg- ing, symmetric, and asymmetric), were evaluated. Re- sults: The 3-dimensional reconstruction images of the teeth indicated an even distribution within the sample. The analysis of the prevalence of the different cross- sectional configurations of the C-shaped molars re- vealed that these were predominantly of the C4 and C3 configurations (1 mm from the apex) and the C1 and C2 configurations in the cervical third. According to the morphometric parameters, the C1 and the distal aspect of the C2 configurations exhibited the lowest roundness values and higher values for the area, major diameter, and aspect ratio in the apical third. Conclu- sions: Mandibular molars with C-shaped root canals ex- hibited similar distributions of symmetric, asymmetric, and merging type canals. The C1 configuration and the distal aspect of the C2 configuration exhibited the highest area values, low roundness values, and large apical diameters.
AimTo evaluate, using micro-computed tomography, the preparation of long-oval root canals using a single reciprocating system versus a multiple-file rotary system.MethodologyDistal canals of thirty mandibular molars were selected and randomly assigned to one of two instrument groups (n=15): Reciproc 40 (VDW, Munich, Germany) or BioRaCe System (FKG Dentaire, La Chaux-de-Fonds, Switzerland). The teeth were scanned before and after preparation of the canal by a SkyScan 1172 micro-computed tomography scanner at 11μm resolution. Morphometric variations were measured by volume increases and by the remaining untreated canal surface area in the entire canal and as well as in each third of the canal. Data was compared using the Mann-Whitney test.ResultsThe Reciproc system left significantly more areas untouched (p<0.001) in the cervical and middle thirds (18.14% and 21.82%) as compared to BioRaCe (8.14% and 11.35%). The Reciproc system had the greatest increase in volume of both the entire canal and the apical third (p<0.5).Conclusions
Neither technique was able to completely prepare the outline of long-oval canals. The Reciproc system removed more tooth structure. The BioRaCe left fewer untouched dentine walls in the more oval thirds of the canal while Reciproc left fewer in the apical third.This article is protected by copyright. All rights reserved.
Introduction
The aim of this study was to describe the canal shaping properties of ProTaper Next (PTN; Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Universal (PTU; Dentsply Tulsa Dental Specialties, Johnson City, TN), and WaveOne (Dentsply Maillefer) nickel-titanium instruments in mandibular first molars by using micro–computed tomographic (micro-CT) scanning.
Methods
A total of 36 maxillary first molars with 2 separate mesial canals and 1 distal canal were selected and scanned preoperatively and postoperatively by using micro-CT scanning with a voxel size of 30 μm. Canals were prepared with PTU, PTN, and WaveOne systems under hypochlorite irrigation. The volume of the untreated canal; the volume of dentin removed after preparation; the amount of the uninstrumented area; and the transportation to the coronal, middle, and apical thirds of canals were measured. The preparation time and instrument failure were also recorded.
Results
Instrumentation of canals increased their volume and surface area. The distal canals had a significantly higher proportion of unprepared surfaces than mesial canals (P < .05). The PTN system produced less transportation than the WaveOne and PTU systems in the apical third of the mesial canals (P < .05). There was no significant difference on apical transportation in distal canals among the 3 instrument systems. Instrumentation with WaveOne was significantly faster than with the other 2 instruments (P < .05).
Conclusions
The PTN, PTU, and WaveOne instruments shaped root canals in mandibular first molars in vitro without significant shaping errors. The curved canals prepared using PTN had less apical transportation than the canals prepared using WaveOne and PTU.
The newly developed single-file systems claimed to be able to prepare the root canal space with only 1 instrument. The present study was designed to test the null hypothesis that there is no significant difference in the preparation of oval-shaped root canals using single- or multiple-file systems.
Seventy-two single-rooted mandibular canines were matched based on similar morphologic dimensions of the root canal achieved in a micro-computed tomographic evaluation and assigned to 1 of 4 experimental groups (n = 18) according to the preparation technique (ie, Self-Adjusting File [ReDent-Nova, Ra'anana, Israel], WaveOne [Dentsply Maillefer, Ballaigues, Switzerland], Reciproc [VDW, Munich, Germany], and ProTaper Universal [Dentsply Maillefer] systems). Changes in the 2- and 3-dimensional geometric parameters were compared with preoperative values using analysis of variance and the post hoc Tukey test between groups and the paired sample t test within groups (α = 0.05).
Preparation significantly increased the analyzed parameters; the outline of the canals was larger and showed a smooth taper in all groups. Untouched areas occurred mainly on the lingual side of the middle third of the canal. Overall, a comparison between groups revealed that SAF presented the lowest, whereas WaveOne and ProTaper Universal showed the highest mean increase in most of the analyzed parameters (P < .05).
All systems performed similarly in terms of the amount of touched dentin walls. Neither technique was capable of completely preparing the oval-shaped root canals.
Root canal treatment may be performed on teeth with irreversibly inflamed dental pulps to prevent apical periodontitis or on teeth with apical periodontitis to treat it. The presenting condition of the root canal surface may therefore vary from that of an intact pulp- dentine complex, through partially degraded pulp tissue with infection, to a dentine surface coated with a mature bacterial biofilm (1). Subsequent treatment procedures will alter the surface in ways that depend upon the root canal anatomy, the instruments used, the strategy and mode of their use, and the chemicals used to facilitate debridement. The effects range from displacement and/or deformation of soft and/or hard tissue components, to changes in the biological, mechanical, and chemical properties of the root canal dentine surface. These changes may have a profound effect on the survival of the tooth, both in terms of progression of apical periodontitis and the long-term integrity of the tooth. An evidence-based synthesis of the literature on the chain of events associated with the effects of root canal treatment, on the internal dentine surfaces, has required subjective assimilation. The mass of published, largely laboratory data, relevant to the topic is heterogenous and contradictory, leaving room for conjecture, differences of opinion, and further questions. The original questions posed in laboratory studies were not guided by clinical outcome data and therefore lacked relevant focus. The synthesized view presented below is based on the authors' interpretation of the literaturefindings, sought systematically by hand and electronic search methods.
To evaluate the anatomical features of C-shaped canal systems in Chinese mandibular second molars by cone-beam computed tomography (CBCT).
A total of 608 patients of Chinese descent with healthy, well-developed mandibular second molars were enrolled. These patients were referred to the West China Hospital of Stomatology and required radiographic examination by CBCT as part of their routine dental treatment. Of the 608 examined CBCT images, 528 showed unilateral intact molars and 80 showed bilateral intact molars. Bilateral molar data were only used to analyse the distribution of unilateral and bilateral occurrences of C-shaped canals. The following in vivo CBCT observations were made: (i) frequency and type of root; (ii) frequency of C-shaped canals by gender, age and tooth position (left versus right); (iii) the classification of cross-sectional canal images of C-shaped canals; and (iv) unilateral and bilateral occurrences of C-shaped canals.
Fused roots were present in 39% of molars. A C-shaped canal system was present in 39% of the teeth. This prevalence did not differ with gender, age and tooth position. Most (81%) of the C-shaped canals in individuals with bilateral molars were symmetrical. Most of the canals with uninterrupted 'C'-shapes appeared to divide into two or more canals towards the canal terminus.
There was high prevalence of C-shaped canals in the mandibular second molars of Chinese population. The canal systems varied considerably in their anatomical configuration.
The aim of this study was to assess the shaping potential of a novel nickel-titanium instrument, the self-adjusting file (SAF), in long oval root canals in distal roots in mandibular molars.
Twenty mandibular molars with long oval distal root canals were selected and scanned preoperatively and postoperatively by using micro-computed tomography at an original resolution of 20 μm. Canals were shaped with the SAF, three-dimensionally reconstructed, and evaluated for volume, surface area, canal transportation, and prepared surface. Data were statistically contrasted by using paired t tests and regression analysis.
Preoperatively, canal volume was 7.73 ± 2.13 mm(3), and canal area was 42.83 ± 8.14 mm(2). Volumes and surface areas increased significantly (P < .001) by 4.84 ± 1.73 mm(3) and 3.34 ± 1.73 mm(2), respectively, and no gross preparation errors were detected. Unprepared canal surface varied between individual canals, and mean unprepared surface was 23.5% ± 8.9%. Prepared areas were significantly larger compared with rotary canal preparation done in a previous study. Canal transportation scores were higher in the coronal root canal third (106 ± 50 μm) compared with the apical third (81 ± 49 μm).
In vitro, preparation of long oval-shaped root canals in mandibular molars with the SAF was effective and safe. Moreover, shapes generated with the SAF were more complete compared with rotary canal preparation.
The aim of this study was to determine whether the debridement quality of the single-file F2 ProTaper instrumentation technique is comparable to a full conventional ProTaper sequence in both round and oval-shaped root canals.
Fifty-four recently extracted vital lower incisors were instrumented with either a full range of ProTaper Universal instruments in rotary motion (group 1) or with the single-file F2 ProTaper technique in reciprocating motion (group 2). Teeth were previously classified as round or oval-shaped by means of bidirectional radiographs, resulting in 24 round canals, 24 oval canals, and 12 controls. After instrumentation, the roots were demineralized, and the apical 3 mm was multi-sliced and processed for histologic examination. The percentage of residual pulp tissue (PRPT) was calculated with the aid of image analysis software. Univariate analysis of variance was used to verify the variables influencing PRPT.
Both canal shape and technique significantly influenced PRPT (P < .05). Oval-shaped canals displayed much more PRPT than round canals in both techniques (P < .05). The difference in PRPT between the techniques depended on the root canal shape, since a significant interaction between canal shape and technique was observed (P < .05). Group 1 displayed considerably less PRPT in oval canals than group 2 (P < .05), whereas in round canals no significant difference was found between the 2 techniques (P > .05).
The single-file F2 ProTaper technique displayed similar PRPT to the full range of ProTaper instruments in round canals. However, the debridement quality of the single-file F2 ProTaper technique was suboptimal in oval canals.
To evaluate the effect of apical preparation size on irrigant flow inside a root canal during final irrigation with a syringe and two different needles types, using a Computational Fluid Dynamics (CFD) model.
A validated CFD model was used to simulate the irrigant flow from either a side-vented or a flat 30G needle positioned inside root canals having sizes of 25, 35, 45 and 55, all with a .06 taper, at 3 mm short of working length (WL). Velocity, pressure and shear stress in the root canal were evaluated.
Different preparation sizes resulted in minor differences in the flow pattern in the apical root canal. Major differences were observed between the two needle types. The side-vented needle could not achieve irrigant replacement to the WL even in a size 55, .06 taper root canal. Significant irrigant replacement was evident almost to the WL in size 35, 45 and 55, .06 taper root canals with the flat needle. The maximum shear stress decreased as the preparation size increased. The flat needle developed higher mean pressure at the apical foramen. Both needles led to a similar gradual decrease in apical pressure as the preparation size increased.
Apical preparation size affected irrigant replacement, the shear stress on the canal wall and the pressure at the apical foramen. Root canal enlargement to sizes larger than 25 appeared to improve the performance of syringe irrigation. Adequate space between the needle and the canal wall should be ensured to allow for an effective reverse flow of the irrigant towards the canal orifice.
The aim of this part of an ongoing study was to describe the dentin removal ability of a novel nickel-titanium instrument, the self-adjusting file (SAF), by using micro-computed tomography.
Twenty maxillary incisors were scanned preoperatively at 20-microm resolution and postoperatively after up to 6 minutes of preparation with an SAF with 1.5-mm or 2-mm diameter. SAFs were operated with continuous irrigation in a handpiece that provided an oscillating, in-and-out movement. Changes in canal volume compared with preoperative values as well as unprepared canal surface area were determined. Data were normally distributed and compared by analysis of variance and regression analyses.
Preoperatively canal volumes were statistically similar in both groups (9.86 +/- 3.97 mm3 and 9.80 +/- 2.67 mm3). Volumes increased during preparation to 13.58 +/- 3.85 mm3 (after 6 minutes with SAF 1.5 mm) and 16.43 +/- 3.64 mm3 (after 5 minutes with SAF 2.0 mm), and overall canal shapes were adequate. Unprepared canal surface area decreased from 63.0% +/- 15.1% (2 minutes with SAF 1.5 mm) to 8.6% +/- 4.1% (5 minutes with SAF 2.0 mm).
Preparation of straight root canals in maxillary anterior teeth left little canal surface uninstrumented after shaping with the SAF. The timeframe of clinical application will depend on the amount of desired dentin removal and done with an SAF selected on the basis of apical gauging.
The purpose of this study was to assess the efficacy of instrumentation of C-shaped canals with ProTaper rotary system and traditional instruments by using micro-computed tomography (micro-CT).
Twenty-four mandibular molars with C-shaped canals were selected in pairs and sorted equally into 2 groups, which were assigned for instrumentation by ProTaper rotary system (ProTaper group) or by K-files and Gates-Glidden burs (Hand Instrument group). Three-dimensional images were constructed by micro-CT. The volume of dentin removed, uninstrumented canal area, time taken for instrumentation, and iatrogenic error of instrumentation were investigated.
Hand Instrument group showed greater amount of volumetric dentin removal and left less uninstrumented canal area than ProTaper group (P < .01). The time needed for instrumentation was shorter for ProTaper group than for Hand Instrument group (P < .05). No instrument breakage occurred in both groups, but more conspicuous procedural errors were detected in Hand Instrument group than for ProTaper group.
It was concluded that ProTaper rotary system maintained the canal curvature with speediness and few procedural errors, whereas traditional instrumentation can clean more canal surface.
This study evaluated the prepared surface areas of oval-shaped canals in distal roots of mandibular molars using four different instrumentation techniques.
Teeth were prescanned and reconstructed using micro-computed tomography (MCT) scans at low resolution (68 microm). Forty-eight molars with ribbon-shaped/oval distal root canals were selected and randomly assigned to four groups. Distal canals (n = 12 each) were prepared by circumferential filing using Hedström files to apical size #40 (group H/CF); with ProTaper nickel-titanium rotaries to finishing file 4 (F4) considering the distal canal as 1 canal (group PT/1); ProTaper to F4 considering buccal and oral aspects of the distal canal as 2 individual canals (group PT/2); ProTaper to F4 in a circumferential filing motion (PT/CF). Before and after shaping, teeth were evaluated using MCT at 34-microm resolution. The percentage of prepared surface was assessed for the full canal length and the apical 4 mm. Statistical analysis was performed using analysis of variance and Bonferroni/Dunn multiple comparisons.
Preoperatively, canal anatomy was statistically similar among the groups (p = 0.56). Mean (+/- standard deviation) untreated areas ranged from 59.6% (+/-14.9, group PT/2) to 79.9% (+/-10.3, PT/1) for the total canal length and 65.2% to 74.7% for the apical canal portion, respectively. Canals in group PT/1 had greater untreated surface areas (p < 0.01) than groups PT/2 and PT/CF. Among all groups, amounts of treated surface areas were statistically similar in the apical 4 mm.
Preparations of oval-shaped root canals in mandibular molars left a variable portion of surface area unprepared regardless of the instrumentation technique used. However, considering oval canals as two separate entities during preparation appeared to be beneficial in increasing overall prepared surface.
Aim:
To introduce a new concept, the self-adjusting file (SAF), and discuss its unique features compared with current rotary nickel-titanium file systems.
The new concept:
The SAF file is hollow and designed as a thin cylindrical nickel-titanium lattice that adapts to the cross-section of the root canal. A single file is used throughout the procedure. It is inserted into a path initially prepared by a # 20 K-file and operated with a transline- (in-and-out) vibration. The resulting circumferential pressure allows the file's abrasive surface to gradually remove a thin uniform hard-tissue layer from the entire root canal surface, resulting in a canal with a similar cross-section but of larger dimensions. This holds also for canals with an oval or flat cross-section, which will be enlarged to a flat or oval cross-section of larger dimensions. The straightening of curved canals is also reduced because of the high pliability of the file and the absence of a rigid metal core. Thus, the original shape of the root canal is respected both longitudinally and in cross-section. The hollow SAF file is operated with a constant flow of irrigant that enters the full length of the canal and that is activated by the vibration and is replaced continuously throughout the procedure. This results in effective cleaning even at the cul de sac apical part of the canal. The SAF has high mechanical endurance; file separation does not occur; and mechanical failure, if it occurs, is limited to small tears in the latticework.
Conclusion:
The SAF represents a new step forward in endodontic file development that may overcome many of the shortcomings of current rotary nickel-titanium file systems.
This study aimed to evaluate the safety and efficacy of a method of using nickel-titanium rotary instruments for preparing the C-shaped root canal system. Forty-three human mandibular second molars with a C-shaped canal configuration were prepared with a crown-down approach to an apical dimension of size 30 by using a combination of ProFile and HERO instruments. Micro-computed tomography was used to examine the canal diameter and the remaining thickness of the dentin wall along the root canal. Results showed that only isolated regions in cross section of the C-shaped canal were physically prepared by the rotary instruments. The furcal wall (concave aspect of the "C" in cross section) of all clinically identifiable canals had a similar thickness at a distance 1-7 mm from the apical constriction both before and after instrumentation. More dentin was removed from the outer (convex aspect of the "C") than the furcal aspect at the apical region, but the converse was true more coronally. All prepared canals showed a taper that matched that of the last instrument used. It was concluded that cleaning of the C-shaped canal system is incomplete with the use of rotary instruments and should be assisted by ultrasonic irrigation. Although rotary instruments seemed to be safe in such canals, further enlargement to an apical dimension greater than size 30 (0.06 taper) is not recommended.
Computed tomography was used to evaluate root canals prepared by nickel-titanium (Ni-Ti) hand and stainless steel hand endodontic instruments. Thirty-six single-rooted teeth of similar shape and canal size were divided into three groups. The teeth were scanned by computed tomography before instrumentation. In group A, canals were instrumented using a quarter turn/pull technique with K-flex files. In group B, canals were prepared with Ni-Ti hand files (Mity files) using the same technique as group A. Group C was prepared with Ni-Ti hand files (Mity files) using a reaming technique. Instrumented teeth were again scanned using computed tomography, and reformated images of the uninstrumented canals were compared with images of the instrumented canals. Ni-Ti instruments (Mity file) used in a reaming technique caused significantly less canal transportation (p < 0.05), removed significantly less volume of dentin (p < 0.05), required less instrumentation time (p < 0.05), and produced more centered and rounder canal preparations than K-flex stainless steel files used in a quarter turn/pull technique. The computed tomography imaging system used in this study provided a repeatable, noninvasive method of evaluating certain aspects of endodontic instrumentation.
The cross-sectional canal morphology and minimum widths of buccal and lingual canal walls were studied in 20 mandibular molars with C-shaped roots and canal orifices. The roots were mounted in clear resin blocks and sectioned transversely at 1-mm intervals. A total of 154 cross-sections were evaluated with an image analyzer. Twelve different longitudinal canal configurations were identified. The most prevalent were types 1-2 and 1-2-1 with each type occurring in four roots. Evaluation of the cross-sectional morphology showed that the configurations were complete "C" (27%), incomplete C (64%), and non-C (9%). The mean value for the minimum width of the lingual canal wall was 0.58 +/- 0.21 mm and the buccal wall was 0.96 +/- 0.26 mm. This suggests that there is a higher risk of root perforation at the thinner lingual walls of C-shaped canals during shaping and post canal preparation procedures. Both buccal and lingual canal walls were frequently narrower at mesial locations.
The purpose of this study was to investigate the anatomical features of C-shaped root canal system in mandibular second molars using micro-computed tomography (microCT). Fifty-eight extracted mandibular second molars with fused roots were collected from a native Chinese population. The teeth were scanned into layers of 0.5-mm thickness by microCT and measurements were made at eleven levels. The ratio of the depth of the deepest part of the groove to the buccal-lingual thickness of the cross-section of the root was calculated for each tooth. The canal shapes of the scanned cross-sections were assessed and classified according to a modified Melton's method. Results were subject to the Kruskal-Wallis test. Of the 58 molars, 54 had a C-shaped canal system with a mean groove-to-thickness ratio of 47.96%; the four teeth without a C-shaped canal had a mean ratio of 14.82%. Most orifices (98.1%) were found within 3 mm below the cementoenamel junction. Of teeth with a C-shape canal system, a majority demonstrated an orifice with an uninterrupted "C" configuration. Seventeen canals divided in the apical portion, most of which did so within 2 mm from the apex. The cross-sectional shape varied drastically along the length of the canal. Teeth with a high groove-to-thickness ratio had at least one section with C1, C2, or C3 configuration. The canal shape in middle and apical thirds of C-shaped canal systems could not be predicted on the basis of the shape at the orifice level. Section 2 of this paper addressed the correlation between the radiographic appearance and these microCT images.
The purpose of this study was to investigate three-dimensional (3-D) morphology of C-shaped root canal system using micro-computed tomography (microCT) and 3-D reconstruction. There were 102 extracted mandibular second molars with fused roots collected from a native Chinese population. The teeth were scanned by microCT and reconstructed by 3-D software. The 98 teeth that possessed a C-shaped canal system were further analyzed. The 3-D reconstructed images of canals were classified into three categories: merging type (type I), symmetrical type (type II), and asymmetrical type (type III). The cross-sectional images of each tooth were submitted to computer analysis, and the minimum canal wall thickness was measured. In these 98 molars, 32 (32.65%) teeth showed a merging type appearance, 38 (38.78%) a symmetrical type and 28 (28.57%) an asymmetrical type. The minimum canal wall thickness in type I was thicker than that in type II or type III in the apical and middle portion (p < 0.05). Being fully aware of the configuration of C-shaped root canal system and the location of minimum wall thickness will ensure more efficient root canal treatment.
This in vivo, prospective, randomized, single-blinded study histologically compared biofilm/necrotic debridement efficiency of a hand/rotary technique versus a hand/rotary/1 min ultrasound technique in the mesial roots of necrotic, human mandibular molars. The hand/rotary group consisted of 20 mesial roots. The hand/rotary/ultrasound group consisted of 20 mesial roots prepared with the same hand/rotary technique followed by 1 min of ultrasonic irrigation, per canal, utilizing an ultrasonic needle in a MiniEndo unit. Following extraction, histologic preparation and staining, 0.2 mum cross-sections from the 1- to 3-mm apical levels were evaluated for percentage of biofilm/necrotic debris removal. Cleanliness results at the 1-, 2- and 3-mm levels for the hand/rotary and hand/rotary/ultrasound techniques, respectively, were: Canals, 80% versus 95%, 92% versus 99%, and 95% versus 100%; Isthmuses, 33% versus 83%, 31% versus 86%, 45% versus 91%. Statistical analysis revealed mean percent canal and isthmus cleanliness values to be significantly higher for hand/rotary/ultrasound technique at all levels evaluated.