The effect of ketorolac buccal infiltration on postoperative endodontic pain: a prospective, double-blind, randomized, controlled clinical trial.

OBJECTIVES: The aim of the present double-blind, randomized, controlled clinical trial was to evaluate the effect of ketorolac buccal infiltration of on postendodontic pain of patients with symptomatic irreversible pulpitis in mandibular first/second molars. METHOD AND MATERIALS: Sixty patients meeting the inclusion criteria were evaluated. After receiving a standard inferior alveolar nerve block (IANB) followed by a buccal infiltration injection with lidocaine, half of the participants randomly received a supplemental buccal infiltration of 30 mg/mL ketorolac tromethamine and the other half received a buccal infiltration of normal saline adjacent to the periapical region of the tooth being treated. Afterwards, all participants received a single-visit root canal treatment. Pre- and postoperative (immediately after treatment, and at 2, 4, 6, and 24 hours) pain levels were evaluated via Heft-Parker visual analog scale (HP-VAS). Analgesic consumption was also recorded. The data were statistically analyzed using repeated-measures ANOVA and Friedman tests. The significance level was set at P < .05. RESULTS: There was a significant difference in postoperative pain between the two groups in overall evaluations and in each time interval (P < .001 and P = .043 respectively). Of those patients receiving ketorolac, 60% (18/30) did not require any analgesic consumption up to 24 hours postoperatively, whereas this number was 43% (13/30) for the placebo group. CONCLUSION: Ketorolac buccal infiltration could reduce the postoperative pain experienced by patients requiring endodontic treatment diagnosed with symptomatic irreversible pulpitis.

Incidence of Dentinal Crack Formation Using ProTaper Universal and WaveOne Systems in Straight and Curved Root Canals.

Introduction: This study aimed to compare dentinal micro crack formation following root canal instrumentation with ProTaper Universal (PTU) and WaveOne (WO) rotary systems in straight and curved root canals. Methods and Materials: One hundred mesiobuccal (MB) straight and curved canals of mandibular molars meeting inclusion criteria were divided into two control (n=10) and four experimental groups (n=20). After mounting the teeth and simulating the periodontal ligament, all the MB canals were coronally flared using Gates-Glidden drills #3 and 2 respectively. Then, in the experimental groups, the canals were instrumented with either PTU files (Sx, S1, S2, F1, F2), or Primary WO (25/0.08). Afterwards, roots were horizontally sectioned at 2, 4, and 6 mm from the apices, and evaluated under a microscope under 20× magnification. Data were analyzed with the Chi-Square and Kruskal-Wallis tests. The significance level was set at 0.05. Results: The control groups showed no cracks. There was no significant difference between the two systems in the straight root canals (P>0.05). But in the curved root canals, PTU produced significantly more cracks (P<0.05) with the complete crack type which was dominant (P=0.013) compared to WO. Conclusions: This in vitro study showed that in curved root canals, instrumentation with reciprocal WO system may be safer than full rotational PTU instruments regarding crack formation.

Treatment of a Four-Rooted Maxillary Second Molar Detected with Cone-Beam Computed Tomography.

The significance of clinician's knowledge about root canal anatomy and its possible variations cannot be overlooked. In some cases, taking advantage of complementary imaging techniques can help achieve a perfect flawless endodontic treatment. This article reports endodontic management of a second maxillary molar that had an uncommon anatomy of the chamber floor. After obtaining a cone-beam computed tomography (CBCT) image, the presence of a second palatal root was confirmed. All four roots were treated and patient's symptoms were resolved.

Students' Knowledge Comprehension after Implementation of Live Conventional Demonstration, Video Teaching and Video-Assisted Instruction Methods in Endodontic Practice.

INTRODUCTION: Video-assisted clinical instruction (VACID) has been found to be a beneficial teaching tool for various fields in dentistry. The aim of this interventional study was to compare the efficacy of live conventional demonstration (CD), video teaching, and VACID (video with explanation) methods in teaching of root canal treatment to undergraduate dental students. METHODS AND MATERIALS: Forty-two undergraduate senior dental students participated in this study. The students experienced this course for the first time and were randomly divided into three groups (n=14). Group A attended live CD on a patient; group B watched a professionally produced demonstration video without any verbal explanation during 1 h; and finally group C watched the same video alongside live explanation by a mentor during the 1.5 h (VACID). The whole process was performed by an experienced endodontist on maxillary central incisors. All of The students carried out a multiple choice question exam to evaluate their comprehension. The mean score of the experimental groups were compared using ANOVA test and multiple comparisons were carried out with Tamhane test. The level of significance was set at 0.05. RESULTS: There was significant difference among three groups according to the ANOVA test (P<0.05). Group VACID had the highest mean scores. There was significant difference between the groups VACID and VT (P=0.011); no significant differences were found in other inter-group comparisons. CONCLUSION: According to the results, VACID may improve the quality of endodontic training in undergraduate dental students.

In vitro Comparison of Apical Debris Extrusion Using Rotary and Reciprocating Systems in Severely Curved Root Canals.

INTRODUCTION: The aim of this in vitro study was to compare the amount of apically extruded debris after root canal preparation using rotary and reciprocating systems in severely curved root canals. METHODS AND MATERIALS: Thirty six extracted human mandibular first molars with 25-35° curvature in their mesiobuccal (MB) canal (according to Schneider's method) were cleaned and shaped with ProTaper and WaveOne systems. The extruded debris was collected and their net weight was calculated. To compare the efficiency of the two systems, the operation time was also measured. The data were analyzed with t-test. RESULTS: The amount of extruded debris in WaveOne group was significantly greater in comparison with ProTaper group (26%). The operating time for ProTaper was however, significantly longer than WaveOne. CONCLUSION: Both root preparation systems caused some degree of debris extrusion through the apical foramen. However, this amount was greater in WaveOne instruments.

Root Canal Anatomy and Morphology of Mandibular First Molars in a Selected Iranian Population: An In Vitro Study.

INTRODUCTION: The aim of this study was to evaluate root canal anatomy of mandibular first molars (MFM) in a selected Iranian Population using clearing technique. METHODS AND MATERIALS: A total of 150 extracted MFMs were cleared. The root canal morphology (including the root numbers and root length) and the anatomy of the root canal system (including is the number and type of canals based on Vertucci's classification, canal curvature according to Schneider's method and the presence of isthmus) was evaluated using the buccolingual and mesiodistal parallel x-rays and stereomicroscope. The data were analyzed using the chi-square test. RESULTS: Two and three roots were present in 96.7% and 33% of the teeth, respectively (P=0.0001). All the teeth (100%) had two canals in the mesial root, while 61.3% of the samples had one distal root canal (P=0.006). The root canal configuration in the mesial canal included type IV (55.3%) and type II (41.3%) (P=0.0001). In doubled-canalled distal roots, 68.8% and 24.3% were type II and type IV, respectively (P=0.0001). Isthmii were observed in 44.6% of mesial and 27.3% of distal roots (P=0.0001). CONCLUSION: The notable prevalence of type IV configuration in both roots of mandibular first molars, presence of isthmus and root curvature, necessitates the careful negotiation and cleaning of all accessible canal spaces.

Efficacy of Ketorolac Buccal Infiltrations and Inferior Alveolar Nerve Blocks in Patients with Irreversible Pulpitis: A Prospective, Double-blind, Randomized Clinical Trial.

INTRODUCTION: The purpose of this prospective, randomized, double-blind, placebo-controlled study was to determine whether ketorolac buccal infiltrations (BIs) helped to improve the success of inferior alveolar nerve blocks (IANBs) in patients with acute irreversible pulpitis (AIP). METHODS: Forty adult volunteers with AIP in a mandibular molar were included in this study. Patients were instructed to evaluate their pain by using a Heft-Parker visual analog scale. They were randomly divided into 2 groups (n = 20). All patients received standard IANB injection and after that a BI of 4% articaine with 1:100,000 epinephrine. After 5 minutes, 20 patients received a BI of 30 mg/mL ketorolac, and the other received a BI of normal saline (control group). Endodontic access cavity preparation (ACP) was initiated 15 minutes after the IANB when the patient reported lip numbness and had 2 electric pulp tests with no responses. The patient's pain during caries and dentin removal, ACP, and canal length measurements (CLM) was recorded by using Heft-Parker visual analog scale. Successful anesthesia was defined as no or mild pain during any of these steps, without the need for additional injection. Data were statistically analyzed by using Mann-Whitney U and χ(2) tests. RESULTS: Successful anesthesia after an IANB plus BI of articaine was obtained in 15% of patients in the control group at the end of CLM. Adding BI of ketorolac significantly increased the success rate to 40% (P < .05). Patient's pain during ACP and CLM was significantly lower in the ketorolac group (P < .05). CONCLUSIONS: Ketorolac BI can increase the success rate of anesthesia after IANB and BI with articaine in patients with AIP.

Radicular anatomy of permanent mandibular second molars in an Iranian population: A preliminary study.

BACKGROUND: Root morphology is of utmost importance to endodontic sciences. Since there are a few studies on the morphology of mandibular second molars' roots, and some anatomical variables are not evaluated before, the aim of this study was to investigate thoroughly radicular anatomy of this tooth. MATERIALS AND METHODS: This ex vivo study was performed on 150 intact mandibular second molars. After access cavity preparation and ensuring canal patency, Indian ink was injected into root canals from the orifices. The teeth became transparent using methyl salicylate storage. Then, they were inspected by an endodontist under a ×10 stereomicroscope regarding numerous root morphological variables. Data were analyzed using chi-square test and analysis of variance (α = 0.05). RESULTS: About 86.7% of teeth had two roots and 13.3% were single-rooted (P = 0.0001), of which, 50% were C-shaped (6.7% of all teeth, P = 0.0001). 86.7% of mesial roots were double canalled, whereas 75.3% of distal roots were single canalled (P = 0.0001). 71.45% and 95.3% of the mesial and distal roots had one apical foramen, respectively (P = 0.0001). Apical foramens were mostly central followed by lingual in most cases. Distances between apical foramen and apical constriction ranged between 0.27 and 0.40 mm (P = 0.0545). Distances between apical foramen and root apices ranged between 0.30 and 0.47 mm (P = 0.0001). Vertucci classifications of mesial canals were Type II in 62.6% and Type IV in 37.4%. 86.2% of single-canal distal roots were Type I. 66.7% of double-canal distal roots were Type II and 33.3% were Type IV (P = 0.0001). The mean root lengths from cervical to apex of mesial, distal, and single roots were 14.02 ± 0.85 (95% confidence interval [CI] = 13.87-14.17), 13.35 ± 0.91 (95% CI = 13.19-13.50), and 14.25 ± 0.72 mm (95% CI = 13.91-14.58), respectively. The extents of canal curvatures varied between 20° and 31° buccolingually (P = 0.0000), and between 19° and 27° mesiodistally (P = 0.0000). CONCLUSION: There was a considerable rate of eccentric apical foramen in mandibular second molars.

Reduction of Enterococcus faecalis in curved root canals after various sizes and tapers of canal preparation.

AIMS: The aim of this study was to evaluate the reduction of Enterococcus faecalis in curved root canals after various sizes and tapers of the canal preparation. MATERIALS AND METHODS: Mandibular first molars (n = 103) with curved mesiobuccal canals were divided into one control (n = 5) and 7 experimental (n = 14) groups, were inoculated with E. faecalis (ATTC 29212) and prepared with the following RaCe files (FKG Dentaire) as master apical file: Groups: 25.04, 25.06, 30.04, 30.06, 35.04, 35.06 and 40.06. All the experimental groups were irrigated with 2 mL of 1% sodium hypochlorite during instrumentation and finally rinsed with 17% ethylenediaminetetraacetic acid (EDTA) (2 mL) followed by 5.25% NaOCl (2 mL) and sterile distilled water. Colony counting was performed after incubation. STATISTICAL ANALYSIS USED: Resulting data were analyzed using one-way ANOVA and Tukey's post-hoc test, (P < 0.05). RESULTS AND CONCLUSIONS: All the experimental groups showed significant bacterial reduction (P < 0.001). Although the greater the size/taper or both led to more decreased amount of bacteria, differences between the groups with the identical size and different tapers, and among the groups with the same taper and different sizes were not significant. Based on this study, 25.04 along with using 2 mL of 1% NaOCl during instrumentation, and using 17% EDTA and 5.25% NaOCl as final rinse successively after the termination of preparation, can effectively reduce intra-canal bacteria and preserve root structure.

The minimum residual root thickness after using ProTaper, RaCe and Gates-Glidden drills: A cone beam computerized tomography study.

OBJECTIVE: The aim of this study was to evaluate the minimum residual root thickness (MRRT) of the danger zone after preflaring of the mesio-buccal (MB) canal of mandibular first molars using ProTaper, RaCe and Gates-Glidden (GG) drills as coronal shapers by cone beam computerized tomography (CBCT). MATERIALS AND METHODS: In this experimental study, the initial CBCT scans of 75 MB canals of mandibular first molars were provided within 1, 2, 3 and 4 mm of the furcation level. The samples were divided into three groups. The samples of ProTaper and RaCe groups were prepared up to F2 and #25.04 as the master apical file (MAF), respectively. The coronal preparation of the samples in the GG group was done using GG drills #2, #3 and #4 and canals were prepared till MAF # 25. After obtaining the postinstrumentation images, the MRRT and the amount of removed dentin were analyzed by t-test and ANOVA statistical analyses. RESULTS: The GG drills removed significantly more dentin than RaCe at all the sections (P < 0.05) and more than ProTaper at 3 mm from the furcation. Statistically there was no significant difference between ProTaper and RaCe groups (P > 0.05). There was no significant difference in MRRT between the groups (P > 0.05). The mean MRRT was not < 0.75 mm at all sections. CONCLUSION: Based on the results of this study, when an appropriate root thickness is initially present, all of the instruments that were investigated may safely be used as coronal shapers in MB canals of mandibular first molars.

The Effect of Size and Taper of Apical Preparation in Reducing Intra-Canal Bacteria: A Quantitative SEM Study.

INTRODUCTION: Bacteria and their byproducts are major etiologic factors in endodontic diseases. Prevention or reduction of root canal bacterial contamination is the main aim of endodontic treatment. The purpose of this in vitro study was to evaluate the effect of size and taper of master apical file (MAF) in reducing bacteria from the apical third of the curved canals using a quantitative scanning electron microscope (SEM) study. METHODS AND MATERIALS: Eighty-nine human mandibular first molars with curved MB canals (20(º)-35(º)) were divided into one control group (n=5) (without rotary instrumentation) and 6 experimental groups (n=14). The canals were prepared using RaCe rotary files to the MAF sizes 25/0.04, 25/0.06, 30/0.04, 30/0.06, 35/0.04 and 35/0.06, in groups 1 to 6, respectively. All the experimental groups were finally rinsed with 2 mL of 17% EDTA followed by 3 mL of 5.25% NaOCl. The mesial roots were split longitudinally. Remaining bacteria in the apical third of MB canals were evaluated using SEM (2000×). Data analysis was performed using one way ANOVA with Tukey's post hoc test. The level of significance was set at 0.05. RESULTS: All the experimental groups showed significant bacterial reduction (P<0.001). Although the greater size and/or taper resulted in decrease in bacteria, differences between the groups were not significant. CONCLUSION: Based on this in vitro study the MAF #25/0.04 had no significant difference compared to other groups with greater apical size/taper; all groups could effectively reduce intra-canal bacteria.

Effect of master apical file size and taper on irrigation and cleaning of the apical third of curved canals.

OBJECTIVE: Canal preparation generates a substantial amount of debris and smear layer (SL). The size and taper of the Master Apical File (MAF) affects on penetration of irrigants and subsequently canal cleaning efficacy. The aim of this study was to evaluate the effect of MAF size and taper on penetration of irrigants to the apical third of curved mesiobuccal (MB) canals of mandibular first molars. MATERIALS AND METHODS: Eighty-nine human mandibular first molars were divided into one control group (n=5) without rotary instrumentation and 6 experimental groups (n=14 each) that were prepared with the following RaCe rotary files as MAF: 25.04 (group1), 25.06 (group 2), 30.04 (group 3), 30.06 (group 4), 35.04 (group 5) and 35.06 (group 6). All the experimental groups were rinsed with 2 ml of 17 % EDTA followed by 2 ml of 5.25% NaOCl. Debridement of the MB canals was evaluated using scanning electron microscope (SEM). The data were statistically analyzed using Kruskal-Wallis and Mann-Whitney U tests (P<0.05). RESULTS: Group 6 (MAF=35.06) showed 100% acceptable debridement. This rate was 92.9% for MAF=35.04. In group 4 (MAF=30.06) smear layer (SL) was removed in the three-forth of the samples and debris was removed in 92.9% of them. Acceptable debridement was not achieved in most samples of groups 1 and 2 (25.04 and 25.06, respectively) and the mentioned two groups had statistically significant difference in this respect with the other groups (P<0.05). CONCLUSION: Based on this study, 30.06 may be considered as the minimum MAF size for acceptable debridement.

Computed tomography evaluation of residual root thickness after pre-flaring using gates Glidden drills: The sequence effect.

AIM: The aim of the present study is to evaluate the residual root thickness in mesiolingual (ML) canals of mandibular molars after pre-flaring using different sequences of Gates-Glidden (GG) drills. MATERIALS AND METHODS: Computed tomography (CT) scans of the ML canals of 60 mandibular first molars were provided from areas within 1, 2, 3 and 4 mm of the furcation area and minimum initial root thickness (MIRT) of concave areas was measured at each level. The samples were divided into two groups (G1 and G2) which were prepared by the step-back and crown-down techniques, respectively. In both groups, anti-curvature filing was used. On secondary CT images of the samples in the same position, the minimum residual root thickness (MRRT) and the amount of removed dentin were analyzed by t-test and ANOVA. RESULTS: There was no significant difference for MIRT between the two groups. The MRRT was greater in the G2 group in all the sections, with no significant difference between them. The average of MRRT was not <0.5 mm in any of the groups or sections. CONCLUSION: Based on the results of this study when the appropriate root thickness is present initially, GG drills used in any sequence may be suitable, safe and cost effective for pre-flaring of mesial canals of mandibular first molars with preserving the root thickness of furcation areas.

Tissue Necrosis due to Chloroform: A Case Report.

For many years, gutta-percha has been the root canal filling material of choice. Chloroform is one of the most efficient solvents widely used for gutta-percha removal in retreatment cases, despite being toxic and carcinogenic. The present case report discusses a chloroform extrusion through an existing perforation to the surrounding periodontal ligament space and subsequent necrosis in supporting bone and tissues, during an endodontic retreatment visit for an addicted patient. Subsequently, the management and preventive options are reviewed.

An in vitro study of mesiobuccal root thickness of maxillary first molars.

INTRODUCTION: Understanding the internal anatomy of root canal system can significantly influence outcomes of root canal treatment. The aim of this in vitro study was to measure the thickness of mesiobuccal root at different levels in maxillary first molars. MATERIALS AND METHODS: In this cross-sectional study, forty extracted human maxillary first molars were radiographed; accordingly, the mesial and distal root thicknesses of mesiobuccal (MB) roots were measured at four parallel horizontal levels. The samples were sectioned at the measured levels and then sections were scanned and saved in the computer. Buccal (B), Palatal (P), Mesial (M) and Distal (D) aspects of root thicknesses in single-canalled roots were measured. In two-canalled mesiobuccal roots, Distobuccal (DB) and Distopalatal (DP) aspects were evaluated alongside other measurements. Average radicular thickness in each aspect and each level was compared using ANOVA and t-test. RESULTS: A total of 25 had two canals and 15 had one canal in MB root. In single-canalled roots M and D aspects were the thinnest whereas in two-canalled samples, the thicknesses of DP and DB aspects were significantly less than others (P<0.001). The B and P had the greatest thicknesses in all the samples. CONCLUSION: The results showed that special attention should be paid to "danger zone" areas of mesiobuccal maxillary first molar roots in order to avoid technical mishaps.

Efficacy of MTAD, Glyde and EDTA in debridement of curved root canals.

INTRODUCTION: This study aimed to compare the efficacy of MTAD, Glyde and EDTA in removing the post-preparation smear layer and debris produced in apical third of curved molar root canals. MATERIALS AND METHODS: Forty extracted human maxillary first molars with curved mesiobuccal canals (30˚-35˚), similar root lengths and morphologies were divided into 3 experimental groups (n=12) and one control group (n=4). Canals were prepared by RaCe rotary files and were treated with the following materials between each two files: Group A (control group); 5 mL of distilled water, Group B; 1 mL of 17% ethylenediamine tetra-acetic acid (EDTA) for 1 min, Group C; BioPure(TM) MTAD (according to the manufacturer's instruction; 5mL for 5 min), and Group D; Glyde File Prep alternated with sodium hypochlorite (NaOCl) between each two files. Debridement of the apical third was evaluated using scanning electron microscope (SEM) (×5000). The data were statistically analyzed using the Kruskal-Wallis and Mann-Whitney U tests (P<0.05). RESULTS: Statistical analysis of the data showed that MTAD and 17% EDTA were effective in removing smear layer and debris from the apical thirds. MTAD was more effective than EDTA in smear layer removal. Glyde did not adequately debride curved root canals of molar teeth. CONCLUSION: MTAD and 17% EDTA were effective in debriding the apical third of curved molar root canals during endodontic treatment, whereas Glyde File Prep does not provide adequate debridement.

Canal-centring ability of three rotary file systems in simulated curved canals: a comparative study.

OBJECTIVE: To compare the canal-centring ability of M two , ProFile and RaCe rotary files, in simulated curved canals. MATERIALS AND METHODS: About 30 simulated canals were prepared by M two , ProFile and RaCe rotary files. Pre and post-operative pictures were super-imposed and transportations recorded. Measurements were carried out at five different points: Canal orifice (O); half-way to the orifice in the straight section (HO); the beginning of the curve (BC); the apex of the curve (AC); the end point (EP). Intra- and inter-group comparisons were carried out by Wilcoxon;s signed ranks test and Kruskal-Wallis test respectively, using SPSS 14.0 software. RESULTS: ProFile did not change canal centricity in any point. RaCe kept centricity at HO, BC, AC and EP. M two changed canal centricity in points BC, AC and EP. M two group kept the centricity significantly less than the other two groups at BC (P = 0.004), AC (P = 0.015) and EP (P = 0.01). There was no significant difference between these three rotary files at HO. However, the difference between RaCe, M two and ProFile was significant at O (P = 0.015). CONCLUSION: ProFile and RaCe rotary files remained better centred than M two rotary files.

Comparison of first accessory cone penetration after using stainless-steel and ni-ti spreaders in curved resin blocks.

INTRODUCTION: The purpose of this study was to compare first accessory gutta-percha penetration after the use of nickel-titanium (Ni-Ti) or stainless-steel spreaders in curved resin blocks. MATERIALS AND METHODS: Forty resin blocks with 30º and 45º curvatures (20 blocks for each) were prepared and #30 master cones were placed in canals. In part one, under 20 Newton pressure, Ni-Ti or stainless-steel spreaders were placed alongside the master cone and their penetration was measured with a millimeter ruler. In part two, after removing the spreader, one of the accessory cones (#15, #20 or MF) was substituted in the canal and its penetration was measured. The Mann-U Whitney test was used for the final evaluation. RESULTS: In both curvatures, the penetration of Ni-Ti spreaders were significantly more than stainless-steel spreaders (p<0.005). Penetration of the first accessory cones (#15 and MF) in Ni- Ti spreader group were also significantly more than stainless-steel group (p<0.05) (in both curvature groups). CONCLUSION: This study showed that Ni-Ti spreaders and #15 accessory cones penetrated deeper in curved canals than stainless spreaders and #15 accessory cones. Therefore, the use of NiTi spreader in lateral condensation technique is suggested for better results.

Technical quality of root canal treatment performed by undergraduate dental students.

INTRODUCTION: This study was carried out to evaluate the technical quality of root canal treatment (RCT) performed by undergraduate dental students at the Islamic Azad University in Tehran, Iran. MATERIALS AND METHODS: Four-hundred records of patients who had received RCT at faculty of dentistry, between the years 2004-2006 were evaluated. For each treated tooth at least three periapical x-rays were assessed: preoperative, working length measurement, and postoperative. Evaluation of root canal filling was based on two variables: length and density. The filling length was recorded as adequate, under- or overfilled. Density of filling was recorded as poor or adequate. Fillings with adequate length and density were recorded as acceptable. Detected iatrogenic errors were: ledge formations, root perforations, furcation perforations, strip perforations and presence of fractured instruments. Results were evaluated statistically using one-way ANOVA and Chi-square analysis. RESULTS: Out of the 400 teeth, 50.5% had at least one of the mentioned errors. Acceptable filling was observed in 32.5% of all studied teeth. Ledge was found in 17.5% of the teeth. Canal curvature was the most important factor associated with ledge formation (P<0.05). CONCLUSION: The technical quality of RCT performed by undergraduate dental students using step-back preparation and cold lateral condensation was classified as acceptable in 32.5% of the cases.

Comparison of Canal Preparation Pattern of K3 and ProTaper Rotary Files in Curved Resin Blocks.

INTRODUCTION: The purpose of this study was to evaluate and compare canal preparation pattern of K3 and ProTaper rotary files in curved resin blocks. MATERIALS AND METHODS: Twenty-four resin blocks were used in this experimental study and randomly divided into two groups. Their initial images were scanned. After preparation, their images were scanned again in the same position. Pre and post preparation images were superimposed by Photoshop software and the removed resin was measured in 5 different points, and then analyzed statistically by ANOVA and t-test. RESULTS: At O point (orifice), significantly (p<0.05) more outer canal wall was removed in the ProTaper group than in the K3 group. There was no significant difference at any other points of outer wall. Removed material of inner canal wall was not significantly different between the two groups. CONCLUSION: Under the condition of this study, both systems performed acceptable preparation pattern except at the beginning of the curve.