Middle Third Of Root Canal Research Articles

Bioceramic and Resin-Based Sealers Removal Using XP-Endo Finisher: A Scanning Electron Microscopy Study

Abstract Objectives The aim of this study was to evaluate remaining filling materials of a bioceramic sealer (TotalFill BC sealer) and an epoxy resin sealer (AH Plus) after retreatment using a supplementary instrumentation (XP-endo Finisher). Materials and Methods Forty single-rooted teeth were selected for the study. The teeth were instrumented using ProTaper system and randomly divided into two groups (n = 20). Then they were obturated with either TotalFill BC/gutta-percha or AH Plus/gutta-percha using lateral compaction technique. Canals were retreated using ProTaper retreatment files and a solvent. The groups were subdivided (n = 10) according to the application or not of the XP-endo Finisher as a final step of retreatment. All roots were cleaved longitudinally and examined under scanning electron microscope to evaluate root canal filling remnants. A scoring system was utilized to quantify the amount of residual filling material at the three predetermined portions of each root canal.Statistical analysis was performed using IBM SPSS.25 with a significant value p < 0.05. Data were compared using the Mann–Whitney test and Kruskal–Wallis test. Results There was no statistically significant difference in the remaining filling materials for each third of the root canal after initial retreatment procedure between the TotalFill group and AH Plus group. Similar results were observed among the TotalFill groups with or without the application of XP-endo Finisher supplementary step. However, the remaining filling materials of AH Plus in the middle third of root canal were significantly less after the XP-endo Finisher application (p = 0.015). Conclusion No retreatment protocol tested in this study allowed the total elimination of root canal filling materials. The residual root canal filling materials is similar for the bioceramic and resinous sealers. The XP-endo Finisher is not effective in improving the removal of bioceramic root canal filling material while it is able to improve the removal of resinous cement.

The Influence of Thermomechanical Compaction on the Marginal Adaptation of 4 Different Hydraulic Sealers: A Comparative Ex Vivo Study

Since there are no data in the literature regarding the comparison of the marginal adaptation of hydraulic sealers when used with a single-cone technique or through thermomechanical compaction, this study aimed to evaluate the behavior of four different endodontic sealers used with the two above-mentioned obturation techniques by evaluating the marginal gap existing between the obturation materials and the dentinal walls through scanning electron microscopy. Given this objective, a total of 104 single-rooted, straight canal teeth were selected and divided into four subgroups according to the selected endodontic sealer ((AH) Plus Bioceramic Sealer (AHP), EndoSequence BC Sealer HiFlow (ES), C-Root SP (CR), and GuttaFlow Bioseal (GF)). Each tooth was decoronated and instrumented with the HyFlex EDM/CM systematics up to 30.04. After irrigation procedures, the teeth of each subgroup were divided into two groups and obturated according to two different obturation techniques: the single-cone technique (SC) and the thermomechanical compaction technique (TC). After the required sealer setting time, each tooth was sectioned in three parts at 3, 6, and 9 mm from the apex, and each section was observed with a scanning electron microscope. The marginal gap of each sample was measured using G* Power Software v3.1, and the statistical analysis was performed using the Kruskal–Wallis test, followed by a post hoc Dunn’s test. Results showed that there were not any statistically significant differences in terms of the marginal gap between the two different above-mentioned obturation techniques for each sealer, except for the middle third of root canals, where a statistically significant difference was found for AHP, ES, and GF sealers. In conclusion, the thermomechanical compaction of hydraulic sealers and gutta-percha guarantees better sealing than the single-cone technique when the root canal shape is not rounded.

Efficacy of different chelating agents in smear layer removal

Aim The aim of this study was to assess the ability of 17% EDTA, 10% citric acid, 2.25% peracetic acid and 1% phytic acid (IP6) in removing smear layer from root canal system of human teeth using scanning electron microscopic analysis. Materials and methods Forty freshly extracted single canal human mandibular premolars with nearly straight mature fully developed roots were used in this study. Teeth were decoronated perpendicular to their long axises leaving roots ∼ 13 ± 1 mm. Chemomechanical preparation was done using ProTaper instrument in a crown down technique up to F4 master apical file (40/0.06) with irrigation of 2.5% sodium hypochlorite throughout instrumentation. Depending on the used final irrigation solution, the samples were divided randomly into four experimental groups (n = 10). Group I: 17% EDTA. Group II: 10% citric acid. Group III: 2.25% peracetic acid. Group IV: 1% phytic acid. The experimental time periods were 1 min. These samples were prepared and then observed by using scanning electron microscopic analysis for the absence or presence of smear layer, there by analyzing their cleaning effectiveness in the coronal, middle, and apical thirds of the root canal system. Results In intergroup comparison, there was no statistically significant difference among the four groups. In intragroup comparison, there was no statistically significant difference between coronal and middle thirds. However, there were statistically significant differences between apical third versus both coronal and middle thirds in all tested groups. Conclusions The four tested final irrigation solutions can effectively remove the smear layer from the coronal and middle root canal thirds, but they did not completely remove the smear layer at the apical one third.

Reciprocating System for Secondary Root Canal Treatment of Oval Canals: CBCT, X-rays for Remnant Detection and Their Identification with ESEM and EDX

Aim of the study: to evaluate root filling remnants after secondary root canal treatments (SRCTs) of oval-shaped canals with X-rays and cone beam computed tomography (CBCT). The SRCTs were performed using reciprocating NiTi instruments. Methods: Single-rooted teeth (N = 64) were randomly treated with Reciproc Blue (RB) and filled with AH Plus/single cone (SC group) or AH Plus/Guttafusion (GF group). After seven days of storage in HBSS (Hanks balanced salt solution), Gates Glidden burs #2/3 and RB #25 and #40 were used for the SRCTs. The time to complete the procedure was measured. X-rays and CBCT were used to calculate, respectively, the area and the volume occupied by the remnants in the coronal, middle, and apical thirds of each canal. Environmental scanning electron microscopy (ESEM) and energy dispersive X-ray spectroscopy (EDX) were used for qualitative evaluation and morphology composition of the remnants in sectioned roots. A statistical analysis was performed using Sigma Plot (version 13, IBM, Armonk, NY, USA). The study was designed according to PRILE guidelines. Results: After the SRCTs, the middle thirds of the root canals showed the presence of remnants in both groups, as demonstrated by X-rays and CBCT. The GF group showed a statistically significant higher volume of remnants than the SC Group only in the middle third. The ESEM supported by the EDX revealed the remnant composition by the detection of trace elements of sealer and gutta-percha in all root canals. Conclusion: The study demonstrated that the middle third of root canals is a critical region where remnants were packed and spread in the buccal-lingual sides of canals. ESEM-EDX detected a fine layer of filling remnants in all root thirds, suggesting a larger canal contamination than the X-rays and CBCT examinations revealed.

Recursos imaginológicos utilizados no diagnóstico de reabsorções radiculares: estudo comparativo

ABSTRACT Objective: Compare the accuracy of early diagnosis of simulated internal root resorptions and external root resorption, using digital periapical radiography and cone beam computed tomography. Methods: Root resorption were simulated in extracted human teeth by demineralization with 5% nitric acid solution and 8% Sodium Hypochlorite in different periods (1 and 5 days). For the group external root resorption (n=12) composite resin cylinders were positioned on middle third of buccal surface of roots, to delimit application of demineralization substances. In group internal root resorptions (n=12) the teeth were sectioned longitudinally, and the composite resin cylinders were positioned in the middle third of root canals. The teeth were mounted in a dry mandible and evaluated by digital radiography and tomography. The images were evaluated by two examiners. Results: Analyzing the tomographic images in period of 1 day, the examiner 2 identified internal root resorptions that were not identified in radiographic images (p<0.05). No examiner was capable of diagnosing external root resorption irrespective of exam, in the group of 1 day (p>0.05). In 5 day period of induction, both exams identified internal root resorptions (p>0.05), however, the tomographic images were more effective in identifying external root resorption (p <0.05) for both examiners. Conclusion: Cone beam computed tomography was shown to be more effective than digital periapical radiography for detecting internal root resorptions with 1 day of induction. The imaginological resources used in this study were not able to early detect external root resorption.

The effectiveness of ethylenediaminetetraacetic, etidronic, and peracetic acids activated with ultrasonics or diode laser on calcium hydroxide removal from root canal walls.

To assess the efficiency of ethylenediaminetetraacetic acid (EDTA), etidronic (HEBP), and peracetic (PAA) acids agitated with ultrasonic energy or diode laser on removing calcium hydroxide (CH) dressings from root canal walls. Single root canals of eighty extracted human teeth were chemomechanically instrumented and filled with CH. Sixty teeth were divided into six experimental groups (n = 10) according to the applied irrigation regimens for the removal of CH: Group 1: 5.25% NaOCl-17% EDTA, Passive ultrasonic irrigation (PUI); Group 2: 5.25% NaOCl + 9% HEBP, PUI; Group 3: 5.25% NaOCl-2% PAA, PUI; Group 4: 5.25% NaOCl-17% EDTA, Diode laser-activated irrigation (LAI); Group 5: 5.25% NaOCl + 9% HEBP, LAI; Group 6: 5.25% NaOCl-2% PAA, LAI. The other 20 teeth were served as negative (n = 10) and positive controls (n = 10). The residuary amount of CH was scored in coronal, middle, and apical thirds of the root canals by using scanning electron microscope. The data were statistically analyzed using Kruskal-Wallis H with Bonferroni adjusted Mann-Whitney U test with a significance level of 0.05. Etidronic acid activated with ultrasonics or diode laser removed the highest amount of CH from the middle third of root canals, compared to the other irrigation regimens (P < 0.001). Although the residual CH scores of PAA-PUI, PAA-LAI, and EDTA-PUI, EDTA-LAI groups were not statistically different from each other (P > 0.05), lower amount of CH was observed in the PAA-PUI and PAA-LAI groups. Use of etidronic acid activated with ultrasonics or diode laser can be an appropriate irrigation regimen for CH removal from root canal system.

Accuracy of Root ZXII, E-PEX and FIND apex locators in teeth with vital pulp: an in vivo study.

This research evaluated, in vivo, the accuracy of three electronic apex locators - EALs (Root ZXII, E-PEX and FIND) in teeth with vital pulp submitted to biopulpectomy, preserving the periodontal stump. For this study, 90 single-rooted teeth with extraction indication were selected. After positive pulpal cold sensitivity test, pulp chamber access was performed. The cervical and middle thirds of root canals were instrumented with Reciproc R25, and the K#15 file was used as a standard instrument to determine working length, forming 2 groups: Constriction (insertion of the instrument until the apical constriction limit) and Foramen (insertion of the instrument until the foramen and then repositioning at constriction, without removing the file from the canal). The hand file was stabilized with a light-cured flow resin. After extraction, the samples were analyzed through microCT SkyScan 1272, with CTAN software, which evaluated the proximity between the tip of the file to the apical constriction, providing data for comparative analysis using Kruskal-Wallis and Dunn tests (p<0.05). There was a statistically significant difference in the abilities of the EALs to detect the apical constriction after reaching the foramen with Root ZX II showing higher accuracy (89%). However, there was no difference in the accuracy of the three EALs in detecting the apical constriction without reaching the foramen. Based on the present results, we conclude that EALs may show accurate measures in detecting apical constriction and foramen, even without damaging the periodontal stump in biopulpectomy.

Comparative Evaluation of Antifungal Activity of Octenidine: An In Vitro Confocal Laser Study

The aim of this study was to evaluate the antifungal efficacy of a novel endodontic irrigant octenidine against conventional irrigants sodium hypochlorite and EDTA on Candida albicans growth in the young and old population by calculating the number of colonies formed and by qualitative identification of dead/viable fungi by Confocal laser scanning microscopy (CLSM) method. The total number of samples used in the study was eighty samples after decoronation of the crown portion the middle third of root canal. Each group was subdivided into four subgroups with various irrigation protocols: (A) 17% EDTA + 5.25% NaOCl, (B) 100% Octenisept, (C) 17% EDTA + 5.25% NaOCl + 1% clotrimazole, and (D) phosphate buffer saline. After completion of irrigation ATCC samples (90028) of C. albicans were inoculated with 5 mL of peptone water each and incubated at 37°C for 72 hours to attain the turbidity corresponding to 0.5 McFarland standards CFU. Eight samples were analyzed for the formation of candidal colonies, and two samples for the assessment of viability of Candida by confocal laser scanning microscope in each subgroup. Comparison of antifungal efficacy of endodontic irrigants employed in the young and old populations revealed a significant reduction in the mean values of CFU and the mean values of percentage of non-viable microorganism by CLSM method. A positive relationship was revealed in the younger population which had a better antifungal efficacy than the older population in all the irrigant subgroups evaluated in the study. All the endodontic irrigants employed in our study had a good antifungal efficacy against Candida albicans. Octenisept had a maximum antifungal efficacy, while phosphate saline showed the least efficacy in both age groups, which was quantitatively evaluated by CFU method, and the same was confirmed through qualitative evaluation by CLSM method. Candida albicans plays a major role in the establishment and pathogenesis of failed root canal treatment. Age-related changes alter the adhesion potential of dentin, in turn influence the outcome of endodontic therapy. Octenidine, a novel antifungal agent, can be substituted over the conventionally used EDTA and NaOCl with less adverse effects.

Effects of Ultrasonic Removal of Fractured Files from the Middle Third of Root Canals on the Resistance to Vertical Root Fracture

IntroductionThis study aimed to analyze the effects of ultrasonic removal of fractured files from the middle third of root canals on the vertical root fracture resistance. MethodsThis study was an extension of a previous study assessing the effects of fractured file removal on dentinal microcracks. It included 18 bilaterally matched pairs of human mandibular incisors prepared and analyzed in the previous study. Briefly, 1 member of each pair was assigned to an ultrasonic or a control group. In the ultrasonic group, K-files were fractured in the middle third of canals followed by ultrasonic file removal and canal preparation. In the control group, the root canals were simply prepared. Micro–computed tomographic imaging was performed before and after treatment, and the cross-sectional root images were screened for microcracks. For the present study, 3-dimensional reconstruction was performed for volumetric assessments. The fracture resistance was measured using a universal testing machine. All data were statistically analyzed. ResultsFracture loads were significantly smaller in the ultrasonic group (P < .05). The percentage increase in the canal volume significantly influenced the root fracture resistance (P < .05), whereas microcracks had no significant effect (P > .05). ConclusionsUltrasonic removal of fractured instruments from the middle third of root canals lowers the vertical root fracture resistance, with increased dentin removal being the primary cause.

Impact of fractured file removal from the middle third root canal on vertical root fracture resistance: three-dimensional finite element analysis

Objective: To analyze effect of fractured file removal from the middle third root canal on root fracture resistance using finite element analysis, which provides a theoretical basis for clinical prognosis evaluation. Methods: Two finite-element models were established, the fractured file removal model (fractured file located in the middle third of root canals, followed by ultrasonic file removal and root canal preparation) and the control model (root canal preparation only), and compressive displacement dependencies on compressive force was computed and compared with experimental data for validation. The validated finite-element models were used to analyze the stress distribution differences during the initiation, propagation and completion of the crack between fractured file removal specimen and control one. Results: The critical breaking force of the fractured file removal specimen was 406 N, and the finite element simulation result was 396 N. The critical breaking force of the control specimen was 502 N, and the finite element simulation result was 483 N. The position of crack initiation in the finite element simulation was basically consistent with that in the experiment. The experimental data of compressive test and the results of finite-element computation were in agreement, thus validating the finite-element model. In the process of continuous pressure, the stress distribution of the control root is relatively uniform, and the location of crack initiation and the direction of propagation have a certain unpredictability. Compared with the control root, the stress concentration on the root with fracture file removal was obvious, especially on edges, and the number of cracks are much more. Because of the thinner radicular wall, the crack propagation rate is faster too. Therefore, the overall root fracture resistant is decreased obviously. Conclusions: During the fractured file removal procedure, amount of dentine removed should be minimized, and the edges and corners which caused by fractured file removal should be shaped to smooth in order to reduce the stress concentration and prevent the root from fracture.

Effect of continuous soft chelating irrigation protocol on removal of smear layer

Aim: The purpose of this study was to compare the efficacy of continuous soft chelating irrigation protocol with conventional irrigation protocol. Methodology: sixty extracted single-rooted human teeth were randomly divided into 5 groups (n =12) and instrumented using Protaper Universal nickel-titanium rotary instruments. In conventional irrigation group each canal was subsequently irrigated with 5.25% NaOCl followed with 17%EDTA (Group A), SmearClear (Group B) or SmearOFF (Group C). After that, all the specimens were subjected to irrigation with 5.25% NaOCl. In continous soft chelating irrigation group The irrigation while instrumentation and after instrumention was done with Chloroquick Low (9% hebp + 3% NaOCl) (Group D) and Chloroquick High (18% hebp + 5.25% NaOCl) (Group E). teeth were then processed for scanning electron microscopy (SEM), and the removal of the smear layer was examined in the coronal, middle, and apical thirds. Result: The efficacy of various agents for smear layer removal was assessed by comparison of groups using Kruskal Wallis ANOVA and Mann- Whitney U test. The results showed that there were no significant differences in Conventional irrigation protocol groups and continuous irrigation protocol group at coronal and middle thirds of root canals but at apical third Chloroquick High was able to remove more smear layer statistically when compared to all the groups (p_0.029). Conclusion: this in-vitro study both the protocols conventional as well as continuous soft chelating irrigation protocols were able to remove smear layer at coronal and middle third of the root canals but at apical third only continues soft chelating irrigation protocol performed with Chloroquick High shows better removal of smear layer.

Effects of ultrasonic removal of fractured files from the middle third of root canals on dentinal cracks: a micro‐computed tomography study

To evaluate the frequency of dentinal microcracks after ultrasonic removal of fractured files from the middle third of root canals using micro-computed tomography (micro-CT). Eighteen bilaterally matched pairs of human mandibular incisors extracted for periodontal reasons were included. The matched pairs of teeth were then divided into a control group and an experimental group, with one member of each pair assigned to each group. In the control group, the canals were instrumented using the ProTaper Next (PTN) system. In the experimental group, size 20K-files were fractured in the middle third of the root canals, followed by their ultrasonic removal. Subsequently, the canals were instrumented with the PTN system. All teeth were scanned using high-resolution micro-CT before (preoperative) and after (intraoperative) file removal and after (postoperative) root canal preparation. Pre-, intra-, and postoperative cross-sectional images of the roots were screened to identify the presence of dentinal defects. Two experienced observers evaluated the images twice in a blinded manner. The incidence of dentinal microcracks was noted and statistically analysed using Fisher's exact and McNemar's tests (P=0.05), with the root cross-section and the tooth root as the units of analysis, respectively. All fractured files in the experimental group were removed successfully. New microcracks were detected in 0.56% (93/16472) cross-sections (8/18 specimens) generated after file removal in the experimental group. These microcracks were detected 4-6mm below the root canal orifice and exhibited a width and length of 12-36μm and 48-72μm, respectively. They did not disappear or propagate after canal preparation. No new dentinal microcracks were observed in the control group. There was a significant difference in the incidence of new microcracks between the two groups (P<0.05). Ultrasonic removal of fractured files from root canals resulted in the formation of short microcracks in a small number of cross-sections in approximately half the specimens. Further studies are necessary to determine the cause and consequences of this finding.

Ex-vivo Smear Layer Removal Efficacy of Two Activated Irrigation Techniques After Reciprocating Instrumentation in Curved Canals.

Introduction:This study aimed to compare the effectiveness of two activated irrigation techniques in removing the smear layer after single-file reciprocating instrumentation in curved canals.Materials and Methods:Sixty distobuccal roots of maxillary molars were standardized to create a closed system, and then instrumented using WaveOne Primary (Dentsply Maillefer, Ballaigues, Switzerland) instruments. Fifty-four specimens were randomly distributed into 3 groups for final irrigation: Non-activated irrigation, passive ultrasonic irrigation (PUI), and EndoActivator (EA;Dentsply Maillefer, Tulsa, USA) irrigation. All specimens received 3 mL of 17% EDTA for 1 minute, followed by irrigation with 6 mL of 2.5% NaOCl. The apical, middle and cervical thirds of the specimens were analyzed using scanning electronic microscopy (SEM), and the amount of remaining smear layer on the canal walls was rated by three examiners using a five-category scoring system. Kendall’s concordance coefficient was used to assess inter-rater agreement. Kruskal-Wallis and Mann-Whitney (Bonferroni) tests were used to compare the scores.Results:Kendall’s concordance coefficient was ≥ 0.7, indicating an excellent level of agreement between the raters. No statistically significant difference in irrigation techniques efficacy for removal of the smear layer (p=0.061) was found for the apical third. The scores attributed to the specimens irrigated with the EA system were significantly lower than those of the other groups in the cervical and middle thirds (p< 0.05).Conclusions:The efficacy of the EA system in removing the smear layer in the cervical and middle thirds of root canals instrumented with reciprocating motion was significantly higher than that of either PUI or non-activated irrigation. Both EA and PUI performed similarly in apical third.

Mineral Trioxide Aggregate in the Treatment of External Invasive Resorption: A Case Report

AbstractExternal invasive root resorption may occur as a consequence of trauma, orthodontic treatment, intracoronal bleaching and surgical procedures and may lead to the progressive and destructive loss of tooth structure. Depending on the extent of the resorptive process, different treatment regimens have been proposed. A 20-year-old female patient presented with tooth showing signs and symptoms of pain in 21 with extensive invasive resorption in middle third of root canal. After root canal treatment, The resorption area was chemomechanically debrided using ultrasonic tips and irrigant solution. MTA was used to fill the resorptive defect and the coronal access was temporarily sealed. Radiographs at 3 and 12 months showed adequate repair of the resorption and endodontic success. Clinically, the tooth was asymptomatic and found to be functioning well.

Ultrastructural analysis of the root canal walls after simultaneous irrigation of different sodium hypochlorite concentration and 0.2% chlorhexidine gluconate

To determine whether sodium hypochlorite (NaOCl) with 0.2% chlorhexidine gluconate (CHX) leads to colour change and precipitate formation, and to ultrastructurally analyse the dentine surface after simultaneous irrigation with 0.5% NaOCl and 0.2% CHX. Four tubes in which 5ml of different NaOCl concentrations and 5ml 0,2% CHX were placed, were observed every 15 minutes in the first two hours and after 7 days. Mixture solutions were centrifuged at 800 rpm/4 min. A precipitate is observed under light-microscopy. Thirty-five single-rooted teeth were instrumented using crown-down technique with irrigation: Positive control: distilled water, Negative control: 0,5% NaOCl+15% EDTA, Experimental group: identical to the negative control, then canals were treated with 0.5% NaOCl+0.2% CHX. The longitudinal root sections were observed under scanning-electron-microscopy. The amount of debris was assessed with 5/score-system, and the results were analysed using the Mann-Whitney U test (p < 0.001). Change in colour was noticed immediately after the merger and it did not change with time. Mixture solutions showed considerable turbidity, but precipitate was observed only after centrifugation. Statistical analysis showed a significant difference in the dentinal wall purity when comparing the cervical and middle root canal thirds between the experimental and negative control group. The difference was also observed between the cervical and middle thirds compared to the apical third of the root canal within these groups. Interaction between NaOCl and CHX, as well as the creation of precipitates, depends not only on the concentration of NaOCl, but also on the concentration of CHX.

Carisolv as an endodontic irrigant in deciduous teeth: An SEM study

Root canal irrigation plays an important role in the debridement and disinfection of the root canal system. "The purpose of this study was to evaluate the efficacy of Carisolv , 1% sodium hypochlorite (NaOCl) gel, and 1% NaOCl solution as root canal irrigants in deciduous anterior teeth." THIRTY-six extracted deciduous anterior teeth were used. Root canals were flooded with NaOCl solution in Group A, NaOCl gel in Group B and Carisolv in Group C and incubated for 30 min. Scanning electron microscope photomicrographs of canal wall debris in the apical, middle and coronal thirds were scored. The results showed that regardless of irrigation regime, canals were consistently cleaner in the coronal and middle thirds than in the apical thirds. NaOCl solution, NaOCl gel, and Carisolv had comparable activity at coronal third and middle third of root canals. At the apical third, NaOCl solution cleaned canals better than NaOCl gel and Carisolv. Carisolv cleaned debris better than NaOCl gel at the apical third. Carisolv can be used as an adjunct to root canal preparation.

Root canal debris removal using different irrigating needles: An SEM study

This study was carried out to compare the efficacy of three irrigating needle designs in removal of debris from different parts of the root canal. Thirty human maxillary canines were prepared using HERO Shaper rotary system and irrigated with 1 ml of 5.25% sodium hypochlorite (NaOCl) after each instrument change. Three 25-gauge irrigation needle designs - brush-covered Navi Tip FX (Group I), side-vented needle RC Twents (Group II) and single-beveled (Group III) irrigating needles - were tested for their efficiency in debris removal in three different parts of the root canal (n=10 canals per group). Following instrumentation, the roots were vertically sectioned and divided into coronal, middle and apical thirds for observation under scanning electron microscope (×200 magnification). Debris on the canal wall was evaluated by using a four-scale scoring system described by Paque and his co-workers. The canals irrigated with brush-covered needle Navi Tip FX (Group I) showed lower average debris score, indicating greater removal of debris in coronal third as compared to middle and apical thirds, whereas the canals irrigated with side-vented needle (Group II) and single-beveled needle (Group III) exhibited lower average score in the middle third than coronal and apical thirds. All the three needle designs exhibited higher debris score in apical third of the root canal. Tukey multiple comparisons test was applied at a significance level of P>0.05. A statistically significant difference (P<0.05) was observed in the debris removal in the coronal and middle thirds of root canals irrigated with brush-covered Navi Tip FX (Group I) and side-vented (Group II) needles, respectively, when compared with other needle design groups. Within the limitations of this study, it can be concluded that all the needle designs tested were effective in certain regions of the root canal with apical third uncleaned. Side-vented needle by creating turbulence removed debris effectively in coronal and middle thirds.

Novel methodology to evaluate the effect of residual moisture on epoxy resin sealer/dentine interface: a pilot study

To evaluate the sealer/dentine interface associated with an epoxy resin sealer using the combination of Goldner's trichrome stain (GTS) and scanning electron microscopy (SEM) to verify the use of the experimental methodology. Extracted human maxillary incisors (6) were subjected to root canal treatment. Subsequent to pulp removal, canal instrumentation and smear layer removal using EDTA and NaOCl, teeth were randomly and equally assigned to a 'wet' or 'dry' group. The 'dry' group was desiccated (95% ethanol/suction/paper points/air-drying), whilst the 'wet' group was treated with a saline rinse/suction/single paper point. Canals were then filled with an epoxy-based resin sealer and warm vertical gutta-percha compaction. After 7-day storage at 37°C, roots from each group were sectioned into apical, middle and coronal horizontal subsections that were cut and split into paired halves and evaluated with GTS or SEM. With GTS sections, hybrid layer and sealer tubular penetration were measured (n=15 measurements/intracanal location/condition) and evaluated using a two-factor repeated measures analysis of variance. The SEM qualitative analysis of paired sections was included as a complementary confirmation of GTS analyses. In dry and wet groups, there was no conspicuous sealer/dentine interface hybrid layer, irrespective of canal location. However, dry specimens exhibited more uniform sealer distribution with deeper tubular penetration in the coronal and middle third (P<0.05). In contrast, there was decreased sealer distribution and tubule penetration in the apical third, regardless of moisture condition (P<0.05). The experimental methodology (combination of GTS and SEM) can be used to evaluate the intracanal resin sealer/dentine interface. The pilot data indicated that thorough drying of the root canal system may result in improved epoxy resin sealer distribution and deeper resin sealer tubular penetration, especially in the coronal and middle thirds of root canals.

Root Canal Preparation of Maxillary Molars With the Self-adjusting File: A Micro-computed Tomography Study

Introduction The aim of this study was to describe the canal shaping properties of a novel nickel-titanium instrument, the self-adjusting file (SAF), in maxillary molars. Methods Twenty maxillary molars were scanned by using micro–computed tomography at 20-μm resolution. Canals were shaped with the SAF, which was operated with continuous irrigation in a handpiece that provided an in-and-out vibrating movement. Changes in canal volumes, surface areas, and cross-sectional geometry were compared with preoperative values. Canal transportation and the fraction of unprepared canal surface area were also determined. Data were normally distributed and compared by analyses of variance. Results Preoperatively, mean canal volumes were 2.88 ± 1.32, 1.50 ± 0.99, and 4.30 ± 1.89 mm 3 for mesiobuccal (MB), distobuccal (DB), and palatal (P) canals, respectively; these values were statistically similar to earlier studies with the same protocol. Volumes and surface areas increased significantly in MB, DB, and P canals; mean canal transportation scores in the apical and middle root canal thirds ranged between 31 and 89 μm. Mean unprepared surfaces were 25.8% ± 12.4%, 22.1% ±12.0%, and 25.2% ± 11.3% in MB, DB, and P canals, respectively ( P > .05) when assessed at high resolution. Conclusions By using SAF instruments in vitro, canals in maxillary molars were homogenously and circumferentially prepared with little canal transportation.

Influence of cervical preflaring on determinationof apical file size in mandibular molars: SEM analysis

This study investigated the influence of cervical preflaring with different rotary instruments on determination of the initial apical file (IAF) in mesiobuccal roots of mandibular molars. Fifty human mandibular molars whose mesial roots presented two clearly separated apical foramens (mesiobuccal and mesiolingual) were used. After standard access opening and removal of pulp tissue, the working length (WL) was determined at 1 mm short of the root apex. Five groups (n=10) were formed at random, according to the type of instrument used for cervical preflaring. In group 1, the size of the IAF was determined without preflaring of the cervical and middle root canal thirds. In groups 2 to 5, preflaring was performed with Gates-Glidden drills, ProTaper instruments, EndoFlare instruments and LA Axxes burs, respectively. Canals were sized manually with K-files, starting with size 08 K-files, inserted passively up to the WL. File sizes were increased until a binding sensation was felt at the WL and the size of the file was recorded. The instrument corresponding to the IAF was fixed into the canal at the WL with methylcyanoacrylate. The teeth were then sectioned transversally 1 mm short of the apex, with the IAF in position. Cross-sections of the WL region were examined under scanning electron microscopy and the discrepancies between canal diameter and the diameter of IAF were calculated using the tool "rule" (FEG) of the microscope's proprietary software. The measurements (microm) were analyzed statistically by Kruskal-Wallis and Dunn's tests at 5% significance level. There were statistically significant differences among the groups (p<0.05). The non-flared group had the greatest discrepancy (125.30 +/- 51.54) and differed significantly from all flared groups (p<0.05). Cervical preflaring with LA Axxess burs produced the least discrepancies (55.10 +/- 48.31), followed by EndoFlare instruments (68.20 +/- 42.44), Gattes Glidden drills (68.90 +/- 42.46) and ProTaper files (77.40 +/- 73.19). However, no significant differences (p>0.05) were found among the rotary instruments. In conclusion, cervical preflaring improved IAF fitting to the canals at the WL in mesiobuccal roots of maxillary first molars. The rotary instruments evaluated in this study did not differ from each other regarding the discrepancies produced between the IAF size and canal diameter at the WL.