Canals Of Mandibular Molars Research Articles

A Multimethod Assessment of a New Customized Heat-Treated Nickel-Titanium Rotary File System.

This study aimed to compare three endodontic rotary systems. The new Genius Proflex (25/0.04), Vortex Blue (25/0.04), and TruNatomy (26/0.04v) instruments (n = 41 per group) were analyzed regarding design, metallurgy, and mechanical performance, while shaping ability (untouched canal walls, volume of removed dentin and hard tissue debris) was tested in 36 anatomically matched root canals of mandibular molars. The results were compared using one-way ANOVA, post hoc Tukey, and Kruskal–Wallis tests, with a significance level set at 5%. All instruments showed symmetrical cross-sections, with asymmetrical blades, no radial lands, no major defects, and almost equiatomic nickel–titanium ratios. Differences were noted in the number of blades, helical angles, cross-sectional design, and tip geometry. The Genius Proflex and the TruNatomy instruments had the highest and lowest R-phase start and finish temperatures, as well as the highest and lowest time and cycles to fracture (p < 0.05), respectively. The TruNatomy had the highest flexibility (p < 0.05), while no differences were observed between the Genius Proflex and the Vortex Blue (p > 0.05). No differences among tested systems were observed regarding the maximum torque, angle of rotation prior to fracture, and shaping ability (p > 0.05). The instruments showed similarities and differences in their design, metallurgy, and mechanical properties. However, their shaping ability was similar, without any clinically significant errors. Understanding these characteristics may help clinicians to make decisions regarding which instrument to choose for a particular clinical situation.

Micro-CT evaluation of four final irrigation protocols on hard-tissue debris removal from mesial roots of mandibular molars containing isthmus.

To evaluate by means of microcomputed tomography (micro-CT), the efficacy of four final irrigation protocols in the removal of hard-tissue debris (HTD) in mesial roots of mandibular molars containing isthmus. Forty standardized mesial roots of extracted mandibular molars presenting isthmus were selected. The root canals were prepared and randomly divided into 4 groups (n = 10): EA, EndoActivator (Dentsply Sirona); EC, Easy Clean (Easy Dental Equipment, Belo Horizonte, Brazil); XPF, XP-Endo Finisher (FKG Dentaire, La Chaus-de Fonds, Switzerland); and PUI, passive ultrasonic irrigation using Irrisafe tip (Satelec Acteon, Merignac, France). Each final irrigation protocol was performed in two cycles (60s), using, respectively, 2.5% sodium hypochlorite and 17% EDTA. Micro-CT scans were obtained pre-operatory, post-preparation, and post-irrigation. The percentage of HTD reduction was calculated. Data was analyzed statistically (ANOVA and Kruskal-Wallis, significance set at 5%). The percentage of HTD reduction was greatest for the XPF group (77.92%), followed by EA (62.92%), PUI (47.48%), and EC (32.65%). Statistical differences (p < .05) were found between XPF and EC only. A significant difference (p < .05) was found between XPF and EC in all thirds and between PUI and EC in the middle third. XPF, EA, and PUI were similarly effective in HTD reduction. However, none of the evaluated protocols was able to completely remove all the debris. Final irrigation protocols aim to clean the canal complexities that are not addressed by the shaping procedures. Micro-CT allowed to assess the removal of hard-tissue debris in the isthmus and canals of mandibular molars.

Middle mesial canal

The occurrence, instrumentation, and obturation of the isthmus between the mesiobuccal and mesiolingual canals in mandibular first molars were studied. The morphology of these middle mesial canals was as follows: eight fins, two confluent canals, and two independent canals. Failures of root canal treatment are mainly due to missed canals and ignorance about the anatomy of the root canal system. The middle mesial (MM) canal is one such type of canal in mandibular molars which is often missed. This case series explain and illustrates three cases with middle mesial canals which is treated successfully.

Effect of kinematics on the torque/force generation, surface characteristics, and shaping ability of a nickel‐titanium rotary glide path instrument: An ex vivo study

AbstractAimTo evaluate the effect of various rotational motions on the torque/force generation, surface wear, and shaping ability of the ProGlider glide path instrument (Dentsply Sirona).MethodologyMesiobuccal and mesiolingual canals of mandibular molars were selected based on the canal volume, length, angle of curvature (25°–40°), and radius of curvature (4–8 mm) after micro‐computed tomographic scanning. The samples were randomly assigned to four groups (n = 13, each) according to movement kinematics [continuous rotation (CR; 300 rpm), optimum torque reverse motion (OTR; 180° forward and 90° reverse when torque &gt;0.4 N cm), time‐dependent reciprocal motion (TmR; 180° forward and 90° reverse), and optimal glide path motion (OGP; a combination of 90° forward, 90° reverse, 90° forward, and 120° reverse)]. Instrumentation was performed with an automated root canal instrument and torque/force analysing device. Maximum torque/force values, canal volume changes, and canal‐centring ratios at 1, 3, 5, and 7 mm were evaluated. Surface defects (pits, grooves, microcracks, blunt cutting edges, and disruption of cutting edges) and spiral distortion on the ProGlider instrument were scored at the tip and 5 mm short of the tip before and after five consecutive uses with scanning electron microscopy. The Kruskal–Wallis test followed by Dunn's post‐test with Bonferroni correction and Wilcoxon signed‐rank test were used to analyse the data (α = 0.05).ResultsOptimal glide path motion generated significantly less clockwise torque and greater upward force than other groups (p &lt; .05). OGP resulted in significantly fewer surface defects than CR (p &lt; .05). In OGP and CR, the tip exhibited more surface defects than 5 mm short of the tip (p &lt; .05). CR resulted in greater volume changes than OGP and TmR (p &lt; .05) and greater centring ratios (i.e., more deviation) than OGP at 1 mm and OTR at 3 mm (p &lt; .05).ConclusionsUnder laboratory conditions using the ProGlider instrument, OGP generated significantly less clockwise torque and greater upward force than the other rotatory motions. OGP generated fewer superficial defects than CR, and the three modes of reciprocal rotation better maintained the apical curvature of root canals than CR with the ProGlider instrument.

Shaping ability of non-adaptive and adaptive core nickel-titanium single-file systems with supplementary file in ribbon-shaped canals analysed by micro-computed tomography.

This study compared shaping ability between two single-file systems and before/after using supplementary file in untouched area, volume of removed dentin, maximum cut depth (the highest cut depth by main file) and remaining thinnest dentin (the thinnest root dentin after preparation). Ribbon-shaped distal canals of mandibular molars were prepared with non-adaptive core (WaveOne Gold) or adaptive core (XP-endo Shaper) files (n=15/group) and additionally prepared with a supplementary file (XP-endo Finisher), and the shaping ability was investigated using micro-computed tomography. XP-endo Shaper group demonstrated significantly less overall untouched area than WaveOne Gold group (38.21±6.98% vs. 47.68±9.16%) (p<0.05). No significant difference was detected between XP-endo Shaper and WaveOne Gold groups in volume of removed dentin (1.85±0.53 vs. 1.66±0.33mm3 ), maximum cut depth (0.10-0.28 vs. 0.10-0.29mm) and remaining thinnest dentin (0.66-0.80 vs. 0.78-0.88mm). Supplementary XP-endo Finisher treatment significantly decreased untouched area (11%-23% reduction) (p<0.05) with minimally cut root dentin (0.01-0.02mm).

The Impact of TruNatomy and ProTaper Gold Instruments on the Preservation of the Periradicular Dentin and on the Enlargement of the Apical Canal of Mandibular Molars

IntroductionThis study aimed to evaluate the preservation of periradicular dentin and the enlargement of the apical canal of mandibular molars with TruNatomy (Dentsply Sirona, Ballaigues, Switzerland) and ProTaper Gold (Dentsply Sirona) instruments. MethodsTwenty mandibular molars were scanned in a micro–computed tomographic device, anatomically paired, and distributed into 2 groups (n = 10). In the ProTaper Gold group, mesial and distal canals were prepared up to F2 (25/.08v) and F3 (30/.09v) instruments, whereas in the TruNatomy group, mesial and distal canals were enlarged up to the prime (26/.04v) and medium (36/.03v) instruments, respectively. After a new scan, the surface area, volume, unprepared areas, transportation, percentage of dentin removal, and dentin thickness parameters were calculated. Data were compared between groups using the Mann-Whitney test, the Student t test, and the nonmetric multidimensional scaling test with alpha set at 5%. ResultsNo difference was found between groups regarding unprepared canal areas and the reduction of dentin thickness (P > .05). Transportation was lower than 0.1 mm in all groups, and statistical differences were observed only at the apical third of the mesiobuccal canal with lower values in the TruNatomy group. ProTaper Gold removed more dentin than TruNatomy at the coronal level of mesial roots (1.8% and 1.0%, respectively) (P < .05). ConclusionsTruNatomy and ProTaper Gold were efficient for performing canal preparation in mandibular molars. The tested systems were similar in terms of untouched canal walls and remaining dentin thickness and slightly different in the apical transportation of mesial canals and the percentage of dentin removal at the coronal third but without clinically significant errors.

Guided endodontic treatment in a region of limited mouth opening: a case report of mandibular molar mesial root canals with dystrophic calcification

BackgroundThe endodontic treatment of calcified root canals in molars is a challenging and time-consuming procedure. Even with the aid of a surgical microscope, the risk of root perforation is high, especially in the furcation area. The purpose of this study is to report the Computer-Aided-Design and Manufacturing (CAD–CAM) workflow, the innovative strategies for the template ideation, and the guided endodontic treatment of a mandibular molar with dystrophic calcification in the mesial root canals.Case presentationA 58-year-old female patient, ASA I, was referred to endodontic treatment in the right first mandibular molar for prosthetic reasons. The mesiobuccal and mesiolingual canals appeared obliterated in the radiographic images. The absence of dental crown, tooth inclination, and the limited mouth opening of the region contributed to a poor visual reference of the tooth in the dental arch and the direction of the remaining lumens of the canals. Despite using surgical microscopy, the conventional technique led to the deviation of the mesiobuccal canal towards the furcation area. The obliteration of both mesial root canals was confirmed using the Cone Beam Computer Tomography. The clinical history associated with the tomography diagnosis was compatible with dystrophic calcifications in the pulp canals. The patient was submitted to an intra-oral scanning as well. The Digital Imaging and Communications in Medicine data (DICOM) were segmented. The Standard Tessellation Language (STL) files were processed following the CAD–CAM workflow, aiming to create two different endodontic templates with a new open design concept. The templates with open design allowed direct visualization of the operative field, irrigation, and dentin debris removal. The strategy of the guidance sleeves niche as half-cylinders allowed the drill insertion in a limited mouth opening region.ConclusionsThe digital planning and guided access permitted to overcome the case limitations and then re-establish the glide path following the original anatomy of the root canals. The guided endodontic represents a personalized technique that provides security, reduced risks of root perforation, and a significant decrease of the working time to access obliterated root canals even in the mesial root canal of mandibular molars, a region of limited mouth opening.

Influence of type of metal alloy and penetration limit in determining the working length with two apex locators

This ex vivo study aimed to evaluate the precision of two electronic foramen locators (Root ZX mini and RomiApex A15) inserting the manual Flexofile or NiTi endodontic files until reaching the apical foramen or surpassing it. Sixty mesial root canals of mandibular molars were selected. Root canal real length measurement and odontometry were performed after the access cavity surgery, cervical pre-flaring, and apical preparation. The precision of the electronic foramen locators was verified at each instrumentation phase, comparing the electronic measurements with the real length. The 3-way ANOVA test was used to evaluate the error of electronic measurements, and a significance level was set at 5%. At the first odontometry, the RZX was significantly more precise than the A15 (p&lt;0,0001). After the second odontometry, the best results were observed when the penetration limit was restricted to the apical foramen. After the third odontometry, statistical differences were found for apex locator (p&lt;0,0001), penetration limit (p&lt;0,05), and metallic alloy (p=0,01). Manual instruments used to perform the odontometry should be inserted only until the foramen level. The use of NiTi files improves the precision of electronic foramen locators.

Root canal length changes during mechanical preparation due to different cervical enlargement patterns.

This study aimed to evaluate the root canal real length (RL) changes due to the mechanical instrumentation use with different flaring magnitudes. After access cavity, 60 mesial root canals of mandibular molars were randomly separated in three groups: Hyflex EDM (HF; #25/.12, #10/.05 e #25/~), Reciproc Blue (RB; R25), and MTwo (M2; #10/.04, #15/.05, #20/.06 e #25/.06). The RL was defined as the apical limit, and 2.5% sodium hypochlorite irrigating solution was chosen. After the access cavity (RL 1), cervical flaring (RL 2), and complete chemical-mechanical preparation (RL 3), the RL was evaluated. The RL was evaluated by a blind examiner with the aid of a microscope (16x) placing the endodontic file stop at the coronary reference. When comparing length measurements, the RL was shorter before instrumentation than that after instrumentation. A reduction of 0.65 mm (HF), 0.61 mm (RB), and 0.48 mm (M2) was observed. However, among groups, no statistical differences were found (p > 0.05). Under the conditions tested, it can be inferred that all mechanical systems provoked RL variations, which emphasizes the need for constant verification of the odontometry, mainly before root canal obturation.

Micro-computed tomography assessment of dentinal microcracks after the preparation of curved root canals with rotary and reciprocal systems.

Root canal preparation with nickel-titanium (NiTi) instruments may lead to the formation of microcracks in the root canal wall. Vertical root fractures may initiate from dentinal cracks, and eventually necessitate tooth extraction. This study aimed to assess the effect of the instrumentation of curved root canals of mandibular molars with the 2Shape (2S) sequential rotary, EdgeFile® X1 (EFX1) reciprocating and NeoNiTi (NN) rotational single-file systems on the formation of dentinal microcracks with the use of micro-computed tomography (micro-CT). Thirty curved mandibular molar root canals were instrumented with the 2S, EFX1 and NN systems (10 in each group). The teeth underwent micro-CT before and after instrumentation. Next, the pre-instrumentation and post-instrumentation cross-sectional images were evaluated and compared for the detection of dentinal microcracks. The number of microcracks in each group was calculated and reported as percentage. The data was analyzed using the McNemar's test with the IBM SPSS Statistics for Windows software, v. 25.0 (α = 0.05). Out of the 29,280 cross-sectional images evaluated in this study, 11.5% showed dentinal microcracks (n = 3,362). On the post-instrumentation images, the frequency percentage of microcracks was 12.0% (n = 585) in the 2S group, 8.8% (n = 402) in the EFX1 group and 13.3% (n = 694) in the NN group. All of the microcracks detected on the post-instrumentation images were also present on the preinstrumentation images and no new microcracks were formed after root canal instrumentation with the aforementioned systems. Root canal instrumentation with the 2S, EFX1 and NN systems did not result in the formation of new dentinal microcracks.

Comparison of Canal Transportation and Centering Ability of One-G, EdgeGlidePath, and Neolix: A MicroComputed Tomography Study of Curved Root Canals

Aims A glide path is created prior to root canal instrumentation by nickel-titanium (NiTi) rotary files to increase the efficiency and safety of cleaning and shaping. This study aimed to assess root canal transportation in use of different glide path files in curved canals. Materials and Methods 30 sound mesiobuccal root canals of mandibular molars with 20° to 40° curvature were selected and randomly assigned to 3 groups of EdgeGlidePath (EGP, EdgeEndo), One-G (Micro-Mega), and Neolix (Neoniti). The specimens were scanned before and after glide path creation by microcomputed tomography (micro-CT). The pre- and postoperative micro-CT scans were superimposed, and the degree of canal transportation and centering ratio were measured at 1, 3, 5, and 7 mm distances from the apical foramen. Statistical Analysis. The data were analyzed by two-way and one-way ANOVA. Results The effects of distance from the apical foramen and instrument type and the interaction effect of the two were not significant on the centering ability of the files or canal transportation. Conclusion EdgeGlidePath, One-G, and Neolix files fabricated from the conventional NiTi alloy or heat-treated M-Wire alloy showed similar performance regarding centering ability and canal transportation in glide path preparation in curved canals.

Investigation of the Number of Root Canals in Mandibular Molars and Premolars Teeth in Ilam in 2020

Investigation of the Number of Root Canals in Mandibular Molars and Premolars Teeth in Ilam in 2020

Influence of apical preparation size and final irrigation protocol on the debridement of oval root canals.

This study assessed the influence of apical preparation size and final irrigation protocol on the debridement of the apical third of oval root canals of mandibular molars. Seventy-seven distal roots were divided into 7 groups (n = 11): Control: without instrumentation or irrigation; Group 30CI: ProTaper Next (up to size 30; PTN) + conventional irrigation (CI); Group 30UAI: PTN + ultrasonically activated irrigation (UAI); Group 30XPF: PTN + XP-endo Finisher (XPF); Group 40CI: PTN + ProDesign Logic (up to size 40; PDL) + CI; Group 40UAI: PTN + PDL + UAI; and Group 40XPF: PTN + PDL + XPF. The total volume of irrigating solutions used per root canal in all the experimental groups was 33 mL of 2.5% sodium hypochlorite (NaOCl) and 6 mL of 17% ethylenediaminetetraacetic acid (EDTA). After specimen processing and histological analysis under a digital microscope (100x), the percentages of untouched canal walls (UCW) and remaining debris (RD) were assessed using Image J software. A descriptive and exploratory analysis was conducted, indicating that the data failed to meet the assumptions of an analysis of variance. Therefore, generalized linear models were used to assess the effects of the different instrumentation and irrigation protocols, as well as the interaction among them, on the percentage of UCW and RD. No significant difference was found among the irrigation protocols regarding the percentage of UCW, irrespective of apical preparation size (p>0.05). However, UCW and RD were significantly lower in groups 40CI, 40UAI and 40XPF than in groups 30CI, 30UAI and 30XPF (p<0.05). The percentage of RD was significantly lower in the UAI and XPF groups than in the CI groups, irrespective of apical preparation size (p<0.05). The difference between preparation sizes 30 and 40, with respect to RD, was higher when CI was used (p<0.05). In conclusion, instrumentation up to apical preparation size 40 resulted in lower percentages of UCW and RD than up to apical preparation size 30. Use of UAI or XPF resulted in lower percentages of RD than CI.

Influence of access cavity preparation on the dentine thickness of mesial canals of mandibular molars prepared with reciprocating instruments

To evaluate the influence of traditional and conservative access cavity preparations on the remaining dentine thickness in the coronal third of mesial canals of extracted mandibular molars prepared with reciprocating instruments using micro-computed tomography as the analytical tool. Seventy extracted mandibular molars were scanned at a pixel size of 19μm. From this initial sample, 20 teeth were selected, pair-matched and distributed into two groups (n=10) according to the access cavity preparation: traditional (TradAC) or conservative (ConsAC). The root canals were sequentially enlarged with Reciproc Blue R25 (size 25, 0.08v taper) and R40 (size 40, 0.06v taper) instruments. A new scan was performed and the postoperative stacks were coregistered with their respective preoperative datasets. A colour-coded cross sections of the roots were created and used to identify and measure the smallest dentine thickness related to both MB and ML canals at 1.0-mm intervals from the furcation level of up to 5mm in the apical direction, in both mesial and distal aspects of the roots, before and after preparation. The statistical analyses were performed with paired-samples t-test, independent-samples Student T-test and Chi-Square test with a significance level of 5%. At all levels of both groups, dentine thickness before preparation was greater than after preparation (p<.05). No difference in the percentage of dentine reduction was observed between TradAC and ConsAC groups (p>.05), but a significantly greater reduction was observed to the distal aspect of the roots (p<.05). After root canal preparation, dentine thinner than 0.5mm was observed mostly along the distal aspect of the root (10% to 15%) of the MB and ML canals, with no influence of the access cavity type on its incidence to either mesial (X2 =1.66; p=.2) or distal (X2 =0.40; p=.5) directions. In the TradAC group, dentine thickness in most slices was greater than 1.0mm after preparation (n=124) whilst, in the ConsAC, it ranged from 0.5 to 1.0mm (n=136). Traditional or conservative access cavity preparation in extracted mandibular molars did not influence the remaining dentine thickness in the coronal third of mesial canals enlarged with thermomechanically treated nickel-titanium reciprocating instruments.

Static Cyclic Fatigue Resistance in Abrupt Curvature, Surface Topography, and Torsional Strength of R-Pilot and ProGlider Glide Path Instruments

IntroductionThis study aimed to compare ProGlider (Dentsply Sirona, Ballaigues, Switzerland) and R-Pilot (VDW, Munich, Germany) instruments in terms of their cyclic fatigue resistance using an artificial stainless steel canal showing an abrupt apical curvature, torsional resistance according to the ISO specification, and topographic changes on the instrument surface after glide path management in mesial canals of mandibular first molars with the abrupt curvature selected based on their micro–computed tomographic examination. MethodsEighty instruments were used: 40 ProGlider (size 0.16, .02v taper) and 40 R-Pilot (size 0.125, .04 taper) instruments. The cyclic fatigue resistance was tested in a static test model using an artificial canal with an abrupt apical curvature (angle of curvature of 90° and radius of curvature of 2 mm). The torsional resistance test was performed according to ISO 3630-1 specifications. To determine surface topography of the unused and used instruments, mesial root canals of mandibular molars with an abrupt apical curvature were selected to prepare a glide path with either the ProGlider or R-Pilot instrument. An optical profilometer and scanning electron microscopy were used to determine the surface properties. Normally distributed torsional and cyclic resistance data were analyzed using the Student t test, whereas quantitative data obtained by the optical profilometer were analyzed with the Kruskal-Wallis H test with a 5% significance threshold. ResultsThe R-Pilot showed significantly higher cyclic fatigue and torsional resistance than the ProGlider (P < .05). Angular deflection values were similar between instruments (P < .05). Measurements made from the blade area showed that the surface roughness values of the ProGlider were larger. Cutting blade measurements showed that unused instruments had significantly greater roughness values than used ones (P < .05). Although there was a 14% increase between the blade edge radii of the used and unused R-Pilot instruments, this difference was determined as 61% in ProGlider instruments. ConclusionsThe R-Pilot exhibited greater cyclic fatigue strength than the ProGlider when tested in an artificial canal with an inner diameter of 1.0 mm and an abrupt apical curvature. Torsional resistance of the R-Pilot was higher than the ProGlider, but the angular deflection values were similar. Glide path preparation in a mesial root canal with an abrupt apical curvature did not increase the surface roughness of both instruments but resulted in a greater blade edge radius.

The shaping ability of WaveOne Gold, TRUShape and XP-endo Shaper systems in oval-shaped distal canals of mandibular molars: A microcomputed tomographic analysis.

To compare the shaping ability of a heat-treated centric reciprocating file system (WaveOne Gold), a heat-treated eccentric rotary multifile system (TRUShape 3D Conforming Files), and a heat-treated expandable one-file rotary system (XP-endo Shaper) extending its activation time, in preparing oval-shaped root canals in extracted mandibular molars by means of microcomputed tomography (micro-CT) analysis. Thirty moderately curved oval-shaped distal roots of mandibular molars were selected. The normality of canal length, curvature angle, volume, surface area, structure model index, and aspect ratio were confirmed. The samples were randomly divided into three groups (n=10). Micro-CT scans were taken before and after canals were instrumented using WaveOne Gold (size 35, .06 taper), or TRUShape (size 30, .06v taper), both following the manufacturer's instructions, or XP-endo Shaper following a new protocol with extended activation time. The mechanical preparation time for each sample was recorded. Pre- and postoperative images were analysed for the percentage of unprepared canal areas and the percentage of removed dentine. Data were compared between groups using the statistical analyses one-way ANOVA and Tukey tests (p<.05). The percentage of unprepared canal areas was significantly higher with WaveOne Gold (% 11.5±4.0) and TRUShape (% 12.4±5.8) compared with XP-endo Shaper (% 5.2±2.6) (p<.05). XP-endo Shaper removed significantly more dentine (3.3±1.5mm3 ) than WaveOne Gold (1.8±0.8mm3 ) and TRUShape (1.9±0.8mm3 ) (p<.05). No significant differences were seen for mechanical preparation time between WaveOne Gold (79±31s), TRUShape (104±41s) and XP-endo Shaper (71±23s) (p>.05). The comparison of three recognized root canal filing systems has shown that with similar preparation times, the XP-endo Shaper removed more dentine (mm3 ) leaving less unprepared canal wall area (%) than WaveOne Gold and TRUShape when preparing oval-shaped root canals of extracted mandibular molars.

Micro–computed Tomographic Evaluation of the Quality of Root Canal Fillings in Mandibular Molars after Obturation for 54 Months

IntroductionThe present study evaluated the percentage volume of voids in root canals of mandibular molars that had been obturated for 54 months. MethodsThirty extracted human mandibular molars were instrumented and debrided. The teeth were assigned to 3 groups (n = 10) according to the filling technique and sealer used: the single-cone technique using AH Plus sealer (AHS; Dentsply Sirona Endodontics, Tulsa, OK) or EndoSequence BC sealer (BCS; Brasseler USA Dental LLC, Savannah, GA) and the warm vertical compaction technique using AH Plus sealer (AHW). The specimens were stored at 37°C and 100% humidity. Micro–computed tomographic imaging was used to scan each specimen 1 day 54 months after obturation. Data were analyzed using 1-way analysis of variance and the paired t test. ResultsThe percentage volume of voids in the teeth 1 day after obturation in the AHS group was higher than in the BCS group and the AHW group (P < .05). After 54 months, the proportion of voids decreased in all groups (P < .05). No significant difference was observed between the AHS group and the BCS group after 54 months. Teeth in the AHW group contained fewer voids than the AHS group (P < .05). ConclusionsVoids in root canal filling were reduced 54 months after obturation. The warm vertical compaction technique achieved better root canal filling quality in mandibular molars than the single-cone technique when using AHS after long-term storage at 100% humidity.

English

BACKGROUND Advances in root canal instruments have led to lesser frequency of dentinal crack formation. Not many studies have been reported in literature that compare crack formation using instruments based on control memory (CM) and M wire technology. The study intended to evaluate and compare the prevalence of dentinal cracks formed by ProTaper Next (Dentsply Maillefer, Ballaigues, Switzerland), HyFlex CM (Coltene, Whaldent) and Wave One (Dentsply, Maillefer) reciprocating file systems at the apical and middle third of the mesiobuccal root canal of mandibular molars under scanning electron microscope (SEM). METHODS Forty-five extracted sound human mandibular molars were decoronated and mesial roots were retained followed by root canal instrumentation using ProTaper Next, HyFlex CM and WaveOne reciprocating files. Roots were then sectioned perpendicular to the long axis of teeth and viewed under scanning electron microscope to detect the presence of cracks. RESULTS ProTaper Next system produced more cracks compared with HyFlex and Wave One (P &lt; 0.05) but there was no statistically significant difference between all the three groups. All the file systems showed more incidences of cracks in the apical third compared to middle third. CONCLUSIONS All the NiTi instruments produced cracks and the highest incidence of cracks was seen in the apical third compared to middle third region. KEY WORDS Dentinal Cracks, HyFlex CM, ProTaper Next, Root Canal, Wave One

C-Shaped configuration of the canal in mandibular molars: A case report

The primary concern of this case report is to discuss and review the different etiological features of c shaped canals, with its incidence, along with anatomical features, diagnosis and management of the c shaped configuration of the canal in the molars of the mandibular arch. Literature revealed that c shaped canal configuration is slightly a different variation that has a predilection towards the racial and most of the times or most commonly is seen in mandibular molars that too most commonly in second molar of the mandibular arch. This morphology when present in the canal may posses difficulty in shaping of the canal, cleaning of the canal as well as debridement of the canal along with obturation of the canal. The one of the most common way in the management of this c shaped canal morphology is done by with the help of usage of rotary instruments and can also with the use of hand instruments that too assisted with sonics as well as ultrasonics.

Analysis of Instrumentation Protocols Regarding the Quality of Mesial Canal Preparation in Mandibular Molars: A Micro–computed Tomographic Study

IntroductionThis study aimed to use micro–computed tomographic imaging to analyze the quality of the endodontic preparation of mesial canals in mandibular molars provided by 3 instrumentation protocols. MethodsForty-five extracted mandibular molars with 2 independent mesial canals were selected, and the initial micro–computed tomographic imaging was performed. The initial volume values of the canals were submitted to statistical analysis for paired division. The groups were determined according to the final enlargement of the canal and the working length adopted (ie, G25.06/+1 mm, G35.05/foramen, and G50.01/−1 mm). At the end of each instrumentation sequence, the root canals were scanned and analyzed with regard to the increase in the total and apical volume, centralization, and preparation transportation and the percentage of the total and apical uninstrumented walls. ResultsFor the intragroup comparison, the Wilcoxon test was used, and for the intergroup analysis, the Kruskal-Wallis and Dunn tests were used (P < .05). In the analysis of the canal total volume, a statistical difference was found between G25.06/+1 mm and the remaining groups (P < .05). In the apical third, a statistical difference was observed between G25.06/+1 mm and G50.01/−1 mm (P < .05). No statistical difference was found between the groups in terms of centralization and transportation of the preparation or in terms of the percentage of the total or apical uninstrumented walls. ConclusionsThe preparation of the mesial canals of mandibular molars up to larger tip files but with a lower taper at 1 mm before the foramen resulted in a larger volume of apical preparation, kept the preparation centralized, and provided safe apical dentin wear without excessive cervical wear.