Third Of Root Canal Research Articles

Temperature Changes During Ultrasonic Irrigation with Different Inserts and Modes of Activation

This study evaluated temperature changes during passive ultrasonic irrigation. Root canals of three extracted maxillary canines were enlarged to size #45. Thermocouples were mounted 3, 6, and 9 mm from the apical foramen. Teeth were placed in a water bath at 37°C. Distilled water (20°C) was continuously delivered through an ultrasonic unit (group 1) or deposited into the root canal before ultrasonic activation (group 2); for activation, noncutting nickel-titanium (NiTi) inserts or stainless steel K-files #15, #25, and #35 were used. Before and during ultrasonic activation, temperatures were continuously measured for 210 seconds. Statistical analysis was performed using analysis of variance and Scheffé post hoc tests. Temperatures initially decreased by up to 7.4°C; these drops were significantly smaller in group 1 than in group 2 (p < 0.001) in the middle and apical root canal third. The decreases were followed by temperature rises for all inserts in group 2. However, in group 1, temperatures just reached baseline values in middle and apical thirds; in the coronal root canal third, lower temperatures were measured. In group 2, mean temperature rises were 7.7°, 7.5°, and 4.2°C in coronal, middle, and apical root canal thirds. Here, K-file type inserts size #35 generated highest and inserts size #15 the lowest temperatures rises; NiTi inserts were more effective than size #15 K-files and less effective than #35 K-files. Continuous flow negated the potential of ultrasonic activation to heat irrigation solutions. Noncutting NiTi instruments and large K-files were more effective than small K-files in warming deposited irrigants.

Bacterial Community Profiling of Cryogenically Ground Samples from the Apical and Coronal Root Segments of Teeth with Apical Periodontitis

Bacteria located at the apical part of infected root canals are arguably directly involved in the pathogenesis of apical periodontitis. This study was conducted to profile and further compare the bacterial communities established at the apical and middle/coronal segments of infected root canals. Extracted teeth with attached apical periodontitis lesions were sectioned so as to obtain two root fragments representing the apical third and the coronal two thirds. Root fragments were subjected to a cryogenic grinding approach. DNA was extracted from root powder samples and used as a template for bacterial community profiling using a 16S ribosomal RNA gene-based seminested polymerase chain reaction/denaturing gradient gel electrophoresis approach. The mean number of bands in apical samples from teeth with primary infections was 28, ranging from 18 to 48, whereas in the middle/coronal samples, it was also 28, ranging from 19 to 36. Findings showed that the profile of bacterial community colonizing the apical third of infected root canals is as diverse as that occurring at the middle/coronal thirds. A high variability was observed for both interindividual (samples from the same region but from different patients) and intraindividual (samples from different regions of the same tooth) comparisons. The methodology used to prepare and analyze samples was highly effective in disclosing a previously unanticipated broad diversity of endodontic bacterial communities, especially at the apical part of infected root canals.

Effectiveness of different final irrigation protocols in removing debris in flattened root canals

This study evaluated in vitro the capacity of debris removal from the apical third of flattened root canals, using different final irrigation protocols. Thirty human mandibular central incisors with a mesiodistal flattened root were prepared using rotary instrumentation by Endo-Flare 25.12 and Hero 642 30.06, 35.02, 40.02 files, irrigated with 2 mL of 1% NaOCl after each file. The specimens were randomly distributed into 5 groups according to the final irrigation of root canals: Group I: 10 mL of distilled water (control), Group II: 10 mL of 1% NaOCl for 8 min, Group III: 2 mL of 1% NaOCl for 2 min (repeated 4 times), Group IV: 10 mL of 2.5% NaOCl for 8 min, and Group V: 10 mL of 2.5% NaOCl for 2 min (repeated 4 times). The apical thirds of the specimens were subjected to histological processing and 6-microm cross-sections were obtained and stained with hematoxylin-eosin. The specimens were examined under optical microscopy at x40 magnification and the images were subjected to morphometric analysis using the Scion image-analysis software. The total area of root canal and the area with debris were measured in square millimeters. Analysis of variance showed no statistically significant difference (p>0.05) among the groups GI (2.39 +/- 3.59), GII (2.91 +/- 2.21), GIII (0.73 +/- 1.36), GIV (0.95 +/- 0.84) and GV (0.51 +/- 0.22). In conclusion, the final irrigation protocols evaluated in this study using the Luer syringe presented similar performance in the removal of debris from the apical third of flattened root canals.

Radiological evaluation of the morphological changes of root canals shaped with ProTaper™ for hand use and the ProTaper™ and RaCe™ rotary instruments

This study evaluated, by means of the radiography examination, the occurrence of deviations in the apical third of root canals shaped with hand and rotary instruments. Sixty mandibular human molars were divided into three groups. The root canals in group 1 were instrumented with ProTaper (Dentsply/Maillefer, Ballaigues, Switzerland) for hand use, group 2 with ProTaper and group 3 with RaCe. The images obtained by double superimposition of the pre- and postoperative radiographs were evaluated by two endodontists with the aid of a magnifier-viewer and a fivefold magnifier. Statistical analysis was performed using the Fisher-Freeman-Halton. The instrumentation using the ProTaper for hand use showed 25% of the canals with a deviation in the apical third, as did the ProTaper, while the corresponding figure for the RaCe (FKG Dentaire, La-Chaux-de-Fonds, Switzerland) was 20%, but these results were not statistically significant. There was no correlation between the occurrence of deviations in the apical third and the systems used.

Opinions and attitudes of endodontists and general dental practitioners in the UK towards the intra‐canal fracture of endodontic instruments. Part 2

To investigate the attitudes of general dental practitioners (GDPs) and endodontists in the UK towards management of fractured endodontic instruments. A questionnaire was sent to 330 systemically selected GDPs and all endodontists working in the UK (170). It was accompanied by a covering letter explaining the aims of the study and indicating that all the information given would remain confidential. Those who did not respond to the first mailing were sent another two mailings. Data were analysed using chi-square test at P <or= 0.05. The overall response rate was 75%. Only 18.5% of respondents reported that they would retrieve instruments located in the apical third of root canals with a significantly higher proportion of endodontists (25.9%) compared with that of GDPs (14%) doing so. A significantly higher proportion of endodontists (98.5%) used ultrasonics for removal of fractured instruments compared with GDPs (75.8%). The most common complication of fractured instrument retrieval was thought to be excessive removal of dentine (67%). The majority of respondents (88.5%) reported that they would leave the unsuccessfully removed file in situ and obturate the root canal. Both endodontists and GDPs were aware of the limitations of root canal anatomy when removal of fractured instruments was considered. Excessive removal of dentine, the most common complication associated with the removal process, suggests the need for more conservative techniques. Both endodontists and GDPs demonstrated a conservative approach when management of fractured instruments failed. Further studies regarding attitudes of GDPs and endodontists towards some specific aspects of fractured instruments management are required.

Efficacy of ProTaper Retreatment System in Root Canals Filled with Gutta-Percha and Two Endodontic Sealers

This study evaluated the efficacy of ProTaper Universal rotary retreatment system and hand files for filling material removal during retreatment and the influence of sealer type on the presence of filling debris in the reinstrumented canals. The canals of 60 palatal roots of first molars were obturated with gutta-percha and either a zinc oxide–eugenol–based or a resin-based sealer and reinstrumented: G1, EndoFill/hand files; G2, AH Plus/hand files; G3, EndoFill/ProTaper; G4, AH Plus/ProTaper. Roots were cleaved and examined with an optical microscope, and the amount of filling debris on canal walls was analyzed on digitized images. There was no significant difference ( P > .05) among the root canal thirds within each group. G3 presented significantly more filling debris than G1 in the cervical third ( P = .04). In the middle third, G2/G3/G4 showed more debris than G1 ( P = .03). The techniques were similar ( P = .64) in the apical third. All groups presented filling debris in the 3 canal thirds after reinstrumentation.

A survey on the experience of UK endodontists and general dental practitioners in the management of intra‐canal fractured endodontic files

Aim To investigate the attitudes of general dental practitioners (GDPs) and endodontists in the UK towards management of fractured endodontic file (SEF).Methodology A questionnaire was sent to 330 systemically selected GDPs and all endodontic specialists working in the UK (170). It was accompanied by a covering letter explaining the aims of the study and indicating that all information given would remain confidential. Those who did not respond to the first mailing were sent another two mailings comprising a differently worded covering letter and another copy of the questionnaire. Data were analysed using chi‐squared test at the 0.05 level of significance.Results The overall response rate was 75% (82.82% for endodontists and 70.92% for GDPs). 18.5% of respondents reported they would retrieve files located in the apical third of root canals with a significantly higher proportion of endodontists (25.9%) compared with that of GDPs (14%) doing so. A significantly higher proportion of endodontists (98.5%) used ultrasonics for removal of SEF compared with GDPs (75.8%). The most common complication of SEF retrieval was excessive removal of dentine (67%). The majority of respondents (88.5%) reported that they would leave the un‐removed file in situ and obturate the root canal.Conclusion This study showed that both endodontists and GDPs are aware of the limitations of root canal anatomy when removal of separated instruments is considered. Excessive removal of dentine, which was the most common complication associated with the removal process, suggests the need for more conservative techniques. Both endodontists and GDPs demonstrated a conservative approach towards unsuccessful management of SEF. Further studies regarding attitudes of GDPs and endodontists towards some specific aspects of management of SEF are required.

Evaluation of Smear Layer: A Comparison of Automated Image Analysis versus Expert Observers

Consistent and reproducible evaluation techniques of the smear layer in root canals in scanning electron microscopy studies are needed when comparing various instruments and techniques. In this study, the performance of 3 experienced blinded evaluators applying the Hulsmann technique was compared with a digital analysis method. Smear layer in the apical third of root canals of 35 freshly extracted teeth prepared by using nickel-titanium rotary instruments, Er:YAG and Er,Cr:YSGG lasers was scored on coded images. There was good agreement between the digital analysis method and the different evaluators (kappa analysis) across the range of the Hulsmann scores. Image analysis might be useful for evaluating the degree of smear layer removal in endodontic research.

Ultrastructural Analysis of Root Canal Dentine Irradiated with 980-nm Diode Laser Energy at Different Parameters

The purpose of this in vitro study was to investigate using the scanning electron microscope (SEM) the ultrastructural morphological changes of the radicular dentine surface after irradiation with 980-nm diode laser energy at different parameters and angles of incidence. There have been limited reports on the effects of diode laser irradiation at 980 nm on radicular dentin morphology. Seventy-two maxillary canines were sectioned and roots were biomechanically prepared using K3 rotary instruments. The teeth were irrigated with 2 mL of distilled water between files and final irrigation was performed with 10 mL of distilled water. The teeth were then randomly divided into five groups (n = 8 each) according to their diode laser parameters: Group 1: no irradiation (control); group 2: 1.5 W/continuous wave (CW) emission (the manufacturer's parameters); group 3: 1.5 W/100 Hz; group 4: 3 W/CW; and group 5: 3 W/100 Hz. Laser energy was applied with helicoid movements (parallel to the canal walls) for 20 sec. Eight additional teeth for each group were endodontically prepared and split longitudinally and irradiation was applied perpendicularly to the root surface. Statistical analysis showed no difference between the root canal thirds irradiated with the 980-nm diode laser, and similar results between the parameters 1.5 W/CW and 3 W/100 Hz (p > 0.05). When considering different output powers and delivery modes our results showed that changes varied from smear layer removal to dentine fusion.

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.

Assessment of the Deviation after Biomechanical Preparation of the Coronal, Middle, and Apical Thirds of Root Canals Instrumented with Three HERO Rotary Systems

The aim of the present study was to assess the risk of deviation of the root canals prepared by 3 HERO rotary systems, used solely or in association, by means of preoperative and postoperative imaging of a cross-section of their coronal, middle, and apical thirds. Fifty mesiobuccal canals of human first molars were randomly divided into 5 groups of 10 specimens each: group A, HERO 642; group B, HERO 642 + HERO Apical; group C, HERO Shaper; group D, HERO Shaper + HERO Apical; group E (control), NitiFlex files. Fisher exact test showed that the differences between the percentages of the presence of deviation and the differences observed between the proportions of instrumented and noninstrumented walls were not statistically significant. No system presented absolute effectiveness, because each of them produced morphologic changes and failed to instrument all the walls of the root canals. A level of significance of .05 was adopted.

Preparation of the coronal and middle third of oval root canals with a rotary or an oscillating system

To comparatively evaluate the preparation of oval root canals with a rotary or an oscillating system. The middle and coronal parts of 55 extracted permanent teeth with oval canals were prepared using FlexMaster (FM) rotary NiTi instruments and EndoEze AET (EE) stainless steel oscillating instruments. Pre- and postoperative images of cross-sections were superimposed to identify shifts in the center and to assess the percentage of untreated regions. In addition, the middle segment was investigated by scanning electron microscope (SEM) to determine debris and smear layer removal. The systems did not significantly differ in the shifts of the canal centers in the middle part of the root. Only a few of the preparations yielded an excellent result with no uninstrumented canal wall left. The SEM investigation demonstrated poor results for both systems regarding debris and smear layer removal, but no significant differences could be observed. Neither FM nor EE was capable of completely preparing oval root canals.

Influence of cervical preflaring on apical file size determination in maxillary lateral incisors

The purpose of this study was to investigate the influence of cervical preflaring on determination of the initial apical file in maxillary lateral incisors. Forty human lateral incisors with complete root formation were used. After standard access cavities, a size 06 K-file was inserted into each canal until the apical foramen was reached. The WL (WL) was set 1 mm short of the apical foramen. Four groups (n=10) were formed at random, according to the type of cervical preflaring performed. Group 1 received the initial apical instrument without previous preflaring of the cervical and middle root canal thirds. Group 2 had the cervical and middle root canal thirds enlarged with nickel-titanium Orifice Opener instruments. Group 3 had the cervical and middle root canal thirds enlarged with Gates-Glidden drills. Titanium-nitrite treated, stainless steel LA Axxess burs were used for preflaring the cervical and middle root canal thirds of group 4. Each canal was sized using manual K-files, starting with size 08 files with passive movements until the WL was reached. File sizes were increased until a binding sensation was felt at the WL, and the instrument size was recorded for each tooth. The apical region was then observed under a stereoscopic magnifier, images were recorded digitally and the differences between root canal and maximum file diameters were recorded (in mm) for each sample. Significant differences were found between the groups regarding the anatomical diameter at the WL and the first file to bind the canal (p = 0.01). The major discrepancy was found when no preflaring was performed (0.1882 mm average). Canals preflared with Orifice Opener instruments (0.0485 mm average) and Gates-Glidden drills (0.1074 mm average) also showed great discrepancy. The LA Axxess burs produced the smallest differences between anatomical diameter and first file to bind (0.0119 mm average). Instrument binding technique for determining anatomical diameter at WL was not accurate. Preflaring of the cervical and middle thirds of the root canal improved anatomical diameter determination; the instrument used for preflaring played a major role on determination of the anatomical diameter at the WL. Canals preflared with LA Axxess burs created a more accurate relationship between file size and anatomical diameter.

In vitro evaluation of endodontic debris removal as obtained by rotary instrumentation coupled with ultrasonic irrigation

The cleaning capacity of rotary Ni-Ti instrumentation using Profile GT files, coupled with irrigation energised by ultrasound, was evaluated. Thirty-six human mandibular incisors were instrumented in vitro using the crown-down technique with the Profile GT system to 1 mm from the anatomical apex to a size 30.04 taper file. The instrumented teeth were then divided randomly into four groups where various final irrigations were used: Group I: 100 ml of 1% NaOCl with a Luer-Lok syringe (control group); Group II, Group III and Group IV: final irrigation with 100 ml of 1% NaOCl energised by ultrasound for 1, 3 and 5 min, respectively. After biomechanical preparation, the apical thirds of the roots were submitted to histological processing and examination. The specimens were analysed at 40x magnification and the images submitted to morphometric analysis with an integration grid. anova showed a statistically significant difference (P < 0.01) between the irrigation techniques. Group I (Luer-Lok syringe) showed the highest percentage of debris (35.81 +/- 4.49) and was statistically different from the other groups energised by ultrasound: Group II (27.28 +/- 4.49), Group III (24.39 +/- 5.72) and Group IV (18.46 +/- 5.25). It was concluded that rotary instrumentation using Ni-Ti files associated with final irrigation of 1% NaOCl energised by ultrasound leads to better debris removal from the apical third of mesio-distally flattened root canal.

Efficacy of a New Brush-Covered Irrigation Needle in Removing Root Canal Debris: A Scanning Electron Microscopic Study

The usefulness of NaviTip FX, a brush-covered irrigation needle, in endodontic therapy has never been reported. Therefore, the purpose of this investigation was to evaluate the cleaning efficacy of this new brush-covered irrigation needle, the NaviTip FX. Thirty single-rooted teeth were randomly divided into two equal groups and instrumented using the crown-down technique with 0.04 taper ProFile. Following each file use, the canals were irrigated with 1 ml of 5.25% NaOCl using the NaviTip FX needle for group 1 or using the same needle without the brush for group 2. At the end of instrumentation, the roots were cut longitudinally and each half was divided into three equal parts. The specimens were then routinely prepared for scanning electron microscopic evaluation. The results showed that using the NaviTip FX produced cleaner coronal thirds of instrumented root canals compared to the control group. On the other hand, the middle and apical thirds were not statistically significantly different between the two groups. Further development of this irrigation technique to improve cleanliness of the apical and middle thirds is required before the NaviTip FX can be recommended for routine use during root canal therapy.

Morphologic and morphometric analysis of the root canal apical third cleaning after biomechanical preparation using 3.3% Ricinus communis detergent and 1% NaOCl as irrigating solutions

This study evaluated, by morphologic and morphometric analyses, the cleaning of apical third of root canals instrumented with nickel-titanium rotary files using different irrigating solutions. Twenty-seven single-rooted mandibular premolars were assigned to three groups (n=9), according to the irrigating solution used: Group I, distilled and deionized water; Group II, 1% NaOCl; and Group III, 3.3% Ricinus communis detergent. Biomechanical preparation was performed with Protaper Plusâ nickel-titanium files as follows: S1, SX and S2 at the cervical and middle thirds, and 25/02, 25/04, 25/06, 30/02, 30/04 and 30/06 to complete the instrumentation, operating at 1 mm from the root apex. Irrigation was done at each file change with 2 mL of irrigating solution, totalizing 20 mL for each tooth. After biomechanical preparation, the apical thirds were serially sectioned and histologically processed. The cross-sections were examined by an optical microscope (X40) connected to a computer. The images were captured and analyzed using a computer software and submitted to morphometric analysis with aid of a grid. The percentage of debris remaining at the apical third was calculated. Data were submitted to statistical analysis by ANOVA and Tukey test. The results showed no statistically significant difference (p>0.01) between the groups irrigated with 1% NaOCl and 3.3% Ricinus communis detergent, which presented the lowest percentage of debris at the apical third, 8.49% and 10.11%, respectively. The group irrigated with distilled and deionized water had the highest percentage of debris (15.58%) and was statistically different from the other groups (p<0.01). It may be concluded that 3.3% Ricinus communis detergent and 1% NaOCl had similar cleaning effectiveness on removal of debris from root canals.

A laboratory analysis of gutta‐percha‐filled area obtained using Thermafil, System B and lateral condensation

To determine the percentage of gutta-percha-filled area (PGFA) in the apical third of root canals when filled with either Thermafil, System B or lateral condensation. Sixty extracted human maxillary central incisor teeth were root filled as following: G1: lateral condensation (n = 20), G2: System B (n = 20) and G3: Thermafil system (n = 20). A horizontal section was cut 2 and 4 mm from the apical foramen of each tooth. The samples were prepared for microscopic analysis and photomicrographs of each apical surface were taken at a magnification of 50x. Through digital image analysis, the cross-sectional area of the canal and the gutta-percha was measured. The PGFA was calculated. The PGFA data obtained in the three groups were analysed using a nonparametric Friedman and Wilcoxon signed-rank tests. Significant differences in PGFA were found between the Thermafil System (G3) and both System B (G2) and lateral condensation (G1) (P < 0.01). The greatest PGFA occurred in the Thermafil group. No significant statistical difference was found between System B and lateral condensation (P > 0.05). The coated carrier gutta-percha system Thermafil produced significantly higher PGFAs than lateral condensation and System B techniques.

Endodontic Techniques for Scouting the Apical Thirds of Root Canals

It might be said that there are as many endodontic instrumentation techniques as there are operators, although no two clinicians perform the procedure in exactly the same manner. Despite differences, there are basic principles (correct diagnosis, adequate access, adequate irrigation, removal of the entire pulp, instrumentation to the minor constriction of the apical foramen, three-dimensional obturation, etc.) whose observance are consistent with long-term endodontic success. As a subset of these time-honored principles, there are guidelines and techniques for apical third "scouting" and instrumentation, which can also be considered universal, irrespective of the particular instruments or technique used for canal preparation. The purpose of this paper is to describe a scouting technique that is designed to optimize the apical part of root canal preparation. The author first heard the word "scouting" used in the context described by Dr. Clifford J. Ruddle.

Determination of the Minimum Instrumentation Size for Penetration of Irrigants to the Apical Third of Root Canal Systems

The purpose of this study was to determine the minimum instrumentation size required for the effective penetration of irrigants and elimination of debris and smear layer from the apical third of the root canals. The mesiobuccal canals of 40 freshly extracted human mandibular first molar teeth were instrumented using the crown-down technique. The teeth were divided into four test groups according to the size of their Master Apical File (#20, #25, #30, #35), and two control groups. After final irrigation, the removal of debris and smear layer from the apical third of root canals was determined under a scanning electron microscope. The data was analyzed using Kruskal-Wallis and Mann-Whitney tests. Based on the results, it appears that the minimum instrumentation size needed for penetration of irrigants to the apical third of the root canal is a #30 file.

Ex vivo analysis of the debris remaining in flattened root canals of vital and nonvital teeth after biomechanical preparation with Ni-Ti rotary instruments

The purpose of this study was to assess the presence of apical debris remaining in the apical third of flattened root canals of vital and nonvital teeth after biomechanical preparation with Ni-Ti rotary instruments. Fresh-extracted human mandibular incisors were used in this study. The teeth had clinical indication for extraction and were submitted to cold pulp vitality testing and radiographic examination. Eighteen teeth were selected and randomly assigned to two groups (n=9), according to the clinical diagnosis, i.e., pulp vitality or pulp necrosis. The canals were instrumented with the ProTaper NiTi rotary system in the following sequence: S1--up to the middle third; SX--at the cervical third; S2--up to the apical third; and S1, F1, F2, F3--at the working length. The canals were irrigated with 1% sodium hypochlorite, dried and were submitted to the histological processing. Sections from the apical third were analyzed by an optical microscope (X40) that was coupled to a computer where the images were captured and analyzed using specific softwares. A grid was placed over these images to assess the total canal area and the areas with debris. Mann-Whitney U-test showed no statistically significant difference (p>0.05) between the teeth with pulp vitality (6.49 +/- 3.39) and those with pulp necrosis (5.95 +/- 2.22). It may be concluded that the clinical condition of pulp tissue did not interfere with the amount of debris remaining in the apical third of flattened root canals prepared with Ni-Ti rotary instruments.