Gates Glidden Drills Research Articles

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

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. 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. 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. 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.

Effect of electric currents on antibacterial effect of chlorhexidine against Entrococcus faecalis biofilm: An in vitro study.

BackgroundThis in vitro study was mainly aimed to evaluate the effect of high-frequency alternating currents (AC) applied by an electronic apex locator (EAL) on the antibacterial properties of chlorhexidine (CHX) on E. faecalis biofilm.Material and MethodsThe root canals of 120 extracted human single-rooted teeth were prepared using Gates-Glidden drills and hand K-files. After contaminating the root canals with E. faecalis, they were incubated for 60 days. Then, the teeth were randomly divided into six experimental groups (n=20). Group 1, 2% CHX; group 2, normal saline (NS) with direct current (DC); group 3, normal saline (NS) with high-frequency alternating current (AC); group 4, 2% CHX with DC; group 5, 2% CHX with AC; group 6, control (normal saline). The samples were collected from the root canal walls of 16 teeth in each group and 1:10 serial dilutions were prepared and added to Muller-Hinton agar (MHA) plates and incubated at 37°C for 48 h. The longitudinal sections of the other 4 teeth used to observe under a scanning electron microscope (SEM). A classic colony counting technique was used for counting the vital E. faecalis bacteria in MHA. Two-way ANOVA was used for statistical analysis of the data. The level of significance was set at P<0.05.ResultsThe electric current significantly changed the colony-forming units (CFU) values (P<0.001). According to pair-wise comparisons, the highest CFU difference was observed between the AC group and the group without electric current (P<0.001); furthermore, the difference between the DC group and the group without electric current was not significant (P=0.823).ConclusionsThe highest bioelectric effect occurred with the use of high-frequency alternating electric current in the form of an apex locator with CHX as a canal irrigant. Key words:Biofilm, Chlorhexidine, Direct current, Electric current, Enterococcus faecalis.

Micro-computed tomographic comparative evaluation of efficacy of different rotary instrument systems for removal of gutta-percha/bioceramic sealer from oval root canals (in vitro study)

Aim: This study used micro-computed tomography (CT) to compare the efficacy of three techniques for removing the root canal filling in single oval-shaped root canals after using laterally compacted gutta-percha/bioceramic sealer (BCS). Materials and Methods: Root canals in 30 single-rooted teeth will be instrumented with the ProTaper NEXT (Dentsply Maillefer, Ballaigues, Switzerland) and obturated using lateral condensation technique with gutta-percha and BCS. The teeth were divided randomly into three groups (n = 10). Removal of the root fillings was performed using one of the following techniques: group 1: ProTaper Universal Retreatment System with continuous rotational motion (RM); Group 2: Reciproc files with reciprocating adaptive motion; and Group 3: retreatment was done using Gates Glidden (GG) drills and H files. The teeth were scanned with CT scans. The percentage of remaining filling material was recorded. The data were analyzed statistically using the one-way ANOVA test and Tukey's post hoc test. Two-way ANOVA was used to study the effect of the interaction of file type and root segment, at a 95% confidence level (P

DETECTION OF CRACK FORMATION FOLLOWING CORONAL FLARING WITH THREE DIFFERENT INSTRUMENTS USING TWO EVALUATION METHODS (IN VITRO STUDY)

INTRODUCTION: Coronal flaring is now considered as an essential preparatory step in root canal treatment sequence. OBJECTIVES: To detect crack formation after coronal flaring of root canals with Gates Glidden (GG) drills, ProTaper Universal (PT) SX, and Endoflare (Ef) flaring instruments using cone beam computed tomography (CBCT) and scanning electron microscope (SEM). MATERIALS AND METHODS: Thirty mesiobuccal canals of mandibular first molars were selected. Teeth specimens were classified into three equal groups according to the instrument used for coronal flaring. Group1: Gates Glidden drills, group 2: ProTaper Universal SX and group 3: Endoflare instruments. Preoperative and postoperative (CBCT) imaging was performed and defect formation was detected. All roots were sectioned horizontally at 2,4and 6 mm from the cementoenamel junction. The sections were inspected under SEM, and any defect formations were recorded and compared with CBCT images according to scoring system. Data were collected and then statistically analyzed at an alpha error of 0.05. P≤0.05 were considered significant. RESULTS: The Ef file produced significantly less dentinal defects compared with the GG and PT SX at the three studied sections. Significant differences were found between the 3 groups at 2 and 4 mm with values (P=0.026) & (P=0.050) respectively, while no significant difference was found at 6mm with value of (P=0.217) when using the 2 evaluation methods. There was a significant difference (P=0.049) between the two used evaluation methods. CONCLUSIONS: Although all used coronal flaring instruments caused dentinal defects, Endoflare file showed the least defects. CBCT was not able to detect the smallest defects such as craze lines while SEM showed more capabilities and was considered as a confirmatory method. KEYWORDS: Coronal flaring, cracks, cone beam computed tomography, scanning electron microscope.

Antibiofilm Efficacy of Positively Charged Imidazolium-Based Silver Nanoparticles in Enterococcus faecalis Using Quantitative Real-Time PCR

Background: Nanoparticles are made by different methodologies, which can affect the particle’s features. Recently, imidazolium-coated silver nanoparticles with a positive surface charge (PC Im-based AgNPs) have revealed favorable results as a root canal disinfectant. However, the antibacterial potency of these particles against biofilm form of Enterococcus faecalis, as the most resistant organism to eliminate in endodontic treatment, has not been investigated. It can be noted that removing this microorganism is associated with extremely effective disinfection. Objectives: This study investigated the antibacterial efficacy of PC Im-based AgNPs at 5.7 × 10-8 mol L-1 in comparison with 2.5% sodium hypochlorite (NaOCl) and 2% chlorhexidine as the two broadly used endodontic irrigation solutions against biofilm E. faecalis using quantitative real-time polymerase chain reaction. Methods: In total, 48 premolar teeth with a single root were infected with E. faecalis and then prepared with ProTaper rotary instruments. The samples were randomly allocated into 4 groups of 12 samples. Sterile saline, PC Im-based AgNPs, NaOCl, and chlorhexidine were used as irrigants. Sampling the root canals was implemented with paper points and Gates-Glidden drills. The reduction in E. faecalis counts was calculated and statistically analyzed by means of the Kruskal-Wallis and Mann-Whitney U tests. Results: Irrigation with PC Im-based AgNPs or NaOCl was significantly more effective in bacterial count reduction compared to irrigation with chlorhexidine or sterile saline (P 0.001). Conclusions: The PC Im-based AgNP solution revealed promising results as a root canal irrigant. This solution at 5.7 × 10-8 mol L-1 was effectively able to eliminate biofilm E. faecalis and this was not significantly different from that of 2.5% NaOCl.

Failure analysis of eleven Gates Glidden drills that fractured intraorally during post space preparation. A retrieval analysis study.

The purpose of this study was to determine the failure mechanism of clinically failed Gates Glidden (GG) drills. Eleven retrieved GG drills (sizes #1 to #3) which fractured during root canal preparation were collected and the fracture location was recorded based on macroscopic observation. All fracture surfaces were investigated by a SEM. Then the fractured parts were embedded in acrylic resin and after metallographic preparation, the microstructure and elemental composition was evaluated by SEM and EDS. The Vickers hardness (HV) of all specimens was also determined. Macroscopic examination and SEM analysis showed that the drills failed near the hand piece end by torsional fatigue with fatigue cracks initiating at several locations around the circumference and propagating toward the center. Final fracture followed by a tensile overloading at the central region of cross section. Microstructural analysis, hardness measurements and EDS show that the drills are made of a martensitic stainless steel like AISI 440C. Based on the findings of this study, clinicians should expect fatigue fracture of GG drills that have small size during root canal preparation. Selection of a more fatigue resistant stainless steel alloy and enhancing the instrument design might reduce the incidence of quasi-cleavage fracture on GG drills.

Influence of different surface treatments of fiberglass posts on the bond strength to dentin

Aim: To assess the influence of different fiberglass post surface treatments on the bond strength (BS) to root dentin. Methods: Thirty bovine root canals were endodontically treated and filled with gutta-percha and AH Plus sealer. At 24 h after the endodontic filling, the post spaces were prepared with Gates-Glidden drills and #3 drills of the DC White Post system, maintaining a 4 mm apical seal. The roots were randomly divided into three groups: S (fiberglass posts treated with silane), SA (fiberglass posts treated with silane and a hydrophobic adhesive system) and SHA (fiberglass posts treated with silane, followed by drying with hot air). The posts were cemented with a selfadhesive cement (RelyX U200). The specimens were stored in distilled water at 37 °C for 24 h and subjected to the push-out test (0.5 mm/min). Data were statistically analyzed using one-way ANOVA and Tukey's test (α=0.05) Results: SA and SHA groups showed the highest BS mean values (11.29 and 10.85 MPa, respectively), while the S group presented the lowest BS mean value (7.21 MPa). S group was significantly different from SA and SAH groups. Conclusions: The surface treatment of fiberglass posts influenced BS values.

Influence of Post Space Preparation on the Apical Leakage of Calamus, Single-Cone and Cold Lateral Condensation Obturation Techniques: A Computerized Fluid Filtration Study.

Apical microleakage between the root canal and periapical tissues is considered a common cause of endodontic failure. The aim of this study was to evaluate the apical microleakage of various obturation techniques after immediate post space preparations with different drills. One hundred twenty human single-rooted teeth were selected for this study. The coronal portions were removed to achieve a uniform length of 15 mm. All root canals were instrumented with ProTaper Next rotary files using crown-down technique. The 120 roots were randomly assigned to 3 experimental groups according to obturation technique (n = 40). The root canals were obturated with lateral condensation in group 1, single-cone technique in group 2, and Calamus 3D obturation system in group 3. Each group was divided into two subgroups (n = 20) according to drill types (Gates Glidden and Peeso drills) leaving 5 mm of apical gutta-percha. The apical microleakage was measured using the computerized fluid filtration meter method. The results were evaluated using Kruskal-Wallis test with Bonferroni Corrected Mann-Whitney U multiple comparison post hoc tests. There was no statistically significant difference between obturation techniques after post space preparation with Peeso drills (p > 0.05). In Gates Glidden drill groups, single-cone technique demonstrated higher leakage (0.0051 ± 0.0037 μl x min-1 × cmH2 O-1 ) than Calamus techniques (0.0019 ± 0.0012 μl x min-1 × cmH2 O-1 ) (p < 0.017). Gates Glidden drills caused the highest apical leakage in teeth obturated with single-cone technique.

CBCT Assessment of Root Dentine Removal by Gates-Glidden Drills and Two Engine-Driven Root Preparation Systems.

Introduction:The aim of this study was to compare the dentine removing efficacy of Gates-Glidden drills with hand files, ProTaper and OneShape single-instrument system using cone-beam computed tomography (CBCT). Methods and Materials:A total of 39 extracted bifurcated maxillary first premolars were divided into 3 groups (n=13) and were prepared using either Gates-Glidden drills and hand instruments, ProTaper and OneShape systems. Pre- and post-instrumentation CBCT images were obtained. The dentin thickness of canals was measured at furcation, and 1 and 2 mm from the furcation area in buccal, palatal, mesial and distal walls. Data were analyzed using one-way ANOVA test. Tukey’s post hoc tests were used for two-by-two comparisons. Results:Gates-Glidden drills with hand files removed significantly more (P<0.001) dentine than the engine-driven systems in all canal walls (buccal, palatal, mesial and distal). There were no significant differences between OneShape and ProTaper rotary systems (P>0.05). Conclusion:The total cervical dentine removal during canal instrumentation was significantly less with engine-driven file systems compared to Gates-Glidden drills. There were no significant differences between residual dentine thicknesses left between the various canal walls.

Efficacy of Triple Antibiotic Paste, Moxifloxacin, Calcium Hydroxide And 2% Chlorhexidine Gel In Elimination of E. Faecalis: An In vitro Study.

Root canal treatment is incomplete without usage of intra canal medicaments. They help in the reduction of bacterial count and its by-products, making canals clean and decreasing postoperative pains. The aim of this study was to evaluate and compare the antimicrobial activity of triple antibiotic paste, Moxifloxacin, calcium hydroxide and 2% Chlorhexidine (CHX) gel in elimination of Enterococcous faecalis (E. faecalis). Seventy-five root blocks were obtained from extracted single rooted human teeth. The canal diameter was increased using Gates- Glidden drill up to size 3 and then contaminated with E. faecalis for 21 days. The contaminated samples were then divided into following 5 groups. Group 1: Saline (negative group), Group 2: Calcium hydroxide Ca(OH)2, Group 3: 2% CHX gel, Group 4: Triple Antibiotic Paste (TAP) (50 μg - metronidazole of 400 mg, 50 μg - minocycline of 100 mg, 50 μg - ciprofloxacin of 100 mg) and Group 5: Moxifloxacin (50 μg - moxifloxacin of 400 mg). Dentin debris was obtained at the end of first, 7th, and 10th day using Gates Glidden drill sizes 4 and 5. The bacterial load was assessed by counting the number of Colony Forming Units (CFUs). The data were analyzed with the ANOVA and Post-Hoc tests to assess the differences in antibacterial efficacy between groups (p=<0.001). A 2% CHX gel alone completely inhibited the growth of E. faecalis after one, seven and 10 days. The 2% CHX gel was the most effective medicament against E. faecalis, as it showed significant differences with normal saline, calcium hydroxide, Moxifloxacin or triple antibiotic paste at all time intervals. The triple antibiotic paste group showed a moderate antibacterial effect as its difference with all group was significantly better at all days. Moxifloxacin was more effective than calcium hydroxide on 7th and 10th day. Best antimicrobial efficacy was shown by 2% CHX gel. Moxifloxacin was equally efficient compared to triple antibiotic paste against E. faecalis at longer intervals of time.

The Discoloration effect of White Mineral Trioxide Aggregate (WMTA), Calcium Enriched Mixture (CEM), and Portland Cement (PC) on Human Teeth.

BackgroundThe aim of this study was to evaluate the discoloration induced by CEM cement, Portland cement (PC) and MTA mixed with propylene glycol (MTA-PG) in comparison to White MTA.Material and MethodsNinety extracted premolar and canine teeth were resected 2 mm below the CEJ. The coronal part of crown was prepared with peeso reamer and Gates-Glidden drills, and the specimens were randomly divided into 4 experimental (n=20) and one control (n=10) groups. The tooth crowns in experimental groups 1 to 4 were filled with White MTA, PC, CEM cement and MTA-PG, respectively; and in group 5, the teeth were kept empty. After incubation, digital photographs of teeth were acquired at 4 time points (before, immediately after placing the materials, 3 and 6 months afterwards). Images were transferred to Adobe Photoshop CS4 and CIE L*a*b color space was used for tooth shade assessment. One-Way ANOVA and One-Sample t-test were used to compare discoloration of teeth between groups.ResultsSignificant statistical discoloration was only observed in the cervical one third of all groups at each time points (except between 3 and 6 months). Tooth discoloration was greatest in PC and lower in MTA and MTA-PG at the end of 6 months. The tooth discoloration between immediately and 3 months after placing the materials had significant difference only between MTA and PC; and also the tooth discoloration between immediately and 6 months after placing the materials was observed only between PC and MTA, and PC and MTA-PG.ConclusionsAll of the experimental biomaterials caused tooth discoloration after 6 months, of those, PC had the most and MTA and MTA-PG had the least discoloration effect. Key words:Mineral trioxide aggregate (MTA). Calcium enriched mixture (CEM). Propylene glycol. Portland cement.

Comparative Antimicrobial Efficacy of Eucalyptus Galbie and Myrtus Communis L. Extracts, Chlorhexidine and Sodium Hypochlorite against Enterococcus Faecalis.

Introduction:The aim of this study was to evaluate the antimicrobial effect of Eucalyptus galbie and Myrtus communis L. methanolic extracts, chlorhexidine (CHX) and sodium hypochlorite (NaOCl) on Enterococcus faecalis (E. faecalis) as the predominant species isolated from infected root canals. Methods and Materials:One hundred twenty mandibular premolars were randomly divided into 8 groups: Eucalyptus galbie (E. galbie) 12.5 mg/mL, Myrtus communis L. (M. communis L.) 6.25 mg/mL, 0.2% CHX, %2 CHX, 2.5% NaOCl, 5.25% NaOCl, positive and negative control group. Sampling was performed using paper points (from the root canal space lumen) and Gates-Glidden drills (from the dentinal tubules); then colony forming units (CFU) were counted and analyzed using the Kruskal-Wallis test, followed by Mann Whitney U test. The level of significance was set at 0.05. Results:All irrigants reduced more than 99% of bacteria in root canal. In the presence of M. communis L. and E. galbie, the bacterial count in dentin were significantly more than CHX and NaOCl groups (P<0.05) except 0.2% CHX in 200 µm and 400 µm depths (P>0.05).Conclusion:Although 5.25% NaOCl was the most effective irrigant, all agents exerted acceptable antimicrobial activity against E. faecalis.

Comparative evaluation of apical microleakage in immediate and delayed postspace preparation using four different root canal sealers: An in vitro study.

Background:Endodontically treated teeth often lack sufficient support for a permanent restoration. During post space preparation, it is important not to disturb the integrity of the apical seal.Aim:This study compared the effect of immediate versus delayed post space preparation on the apical seal using four different sealers.Materials and Methods:One hundred and thirty single rooted teeth were biomechanically prepared and obturated with single cone gutta-percha and 4 sealers: Endoflas FS, AH Plus, Gutta flow and MTA. Teeth were divided randomly into eight groups, post spaces were prepared using Gates Glidden drills immediately for group I, III, IV and VII. For groups II, IV, VI and VIII prepared after storage of the specimens in 100% humidity for one week. The samples were kept in methylene blue dye, centrifuged at 3000 rpm for 3 min sectioned and then measured under stereomicroscope for apical leakage.Statistical Analysis:The data was analysed using one way ANOVA and post hoc Tukey test.Results:All the specimens showed dye leakage, and a statistically significant difference was seen among all the groups (P > 0.05) except Gutta flow.Conclusion:Less leakage is seen when post space is prepared immediately.

Efficacy of LA Axxess burs, Gates Glidden drills and Protaper Sx in obtaining straight line access in mesiobuccal roots of mandibular first molars: A cone-beam computed tomography assessment.

Objective:This study aims at cone-beam computed tomography (CBCT) evaluation of the ability of Gates Glidden (GG) drills, Protaper Sx, and LA Axxess burs to produce a straight line access (SLA) in mesiobuccal canals of mandibular first molars.Methodology:Forty-five freshly extracted mandibular teeth with a canal curvature of 10-20° were taken for the study and divided into three groups according to the instruments used for cervical preflaring: Group I (LA Axxess burs), Group II (GG drills), and Group III (Protaper Sx). Pre- and post-instrumentation CBCT images were evaluated for comparing the ability of GG drills, Protaper Sx and LA Axxess burs to produce an SLA in mesiobuccal canals of mandibular first molars.Results:There was no significant change (P = 0.06) in the angle in the preSLA images of LA Axxess Group I (12.37 ± 1.01), GG Group II (13.39 ± 1.74), and Protaper Sx Group III (13.90 ± 1.74). The mean decrease in the angle from preSLA to postSLA was significant for all the three groups (P = 0.0001). However, the mean change was highest in Group I (4.25 ± 1.14), followed by Group II (3.28 ± 1.22) and Group III (2.89 ± 1.53).Conclusion:LA Axxess burs were the most effective in reducing the coronal curvature and produced a straighter access to apical third compared to GG Drills and Protaper Sx.

Efficacy of CM-Wire, M-Wire, and Nickel-Titanium Instruments for Removing Filling Material from Curved Root Canals: A Micro–Computed Tomography Study

IntroductionThe aim of this ex vivo study was to evaluate the removal of filling material after using CM-wire, M-wire, and nickel-titanium instruments in both reciprocating and rotary motions in curved canals. MethodsThirty maxillary lateral incisors were divided into 9 groups according to retreatment procedures: Reciproc R25 followed by Mtwo 40/.04 and ProDesign Logic 50/.01 files; ProDesign R 25/.06 followed by ProDesign Logic 40/.05 and ProDesign Logic 50/.01 files; and Gates-Glidden drills, Hedström files, and K-files up to apical size 30 followed by K-file 40 and K-file 50 up to the working length. Micro–computed tomography scans were performed before and after each reinstrumentation procedure to evaluate root canal filling removal. Statistical analysis was performed with Kruskal-Wallis, Friedman, and Wilcoxon tests (P < .05). ResultsNo significant differences in filling material removal were found in the 3 groups of teeth. The use of Mtwo and ProDesign Logic 40/.05 rotary files did not enhance filling material removal after the use of reciprocating files. The use of ProDesign Logic 50/.01 files significantly reduced the amount of filling material at the apical levels compared with the use of reciprocating files. ConclusionsAssociation of reciprocating and rotary files was capable of removing a large amount of filling material in the retreatment of curved canals, irrespective of the type of alloy of the instruments. The use of a ProDesign Logic 50/.01 file for apical preparation significantly reduced the amount of remnant material in the apical portion when compared with reciprocating instruments.

An in vitro comparison of push-out bond strength of biodentine and mineral trioxide aggregate in the presence of sodium hypochlorite and chlorhexidine gluconate

Aim: The aim of this in vitro study was to compare the push-out bond strength of Biodentine (Septodont, Saint Maur des Fosses, France) and mineral trioxide aggregate (MTA) (Angelus, Londrina, PR, Brazil) when treated with 3% sodium hypochlorite (NaOCl) and 2% chlorhexidine gluconate (CHX). Materials and Methods: Forty-six single canal premolars were selected for this study, and the canal spaces were prepared with #5 Gates glidden drill (1.3 mm diameter). The dentin of these teeth was horizontally sectioned into 1-mm-thick slices at the mid-root level. The samples were divided into two groups (n = 20). Biodentine and MTA were placed into the canal space of dentin slices. The samples were wrapped in wet gauze for 10 min and divided into two subgroups (n = 10) to be immersed into 3% NaOCl and 2% CHX for 30 min. No irrigation was performed in the controls (n = 3). After incubation for 48 h, the dislodgement resistance of the samples was measured using a universal testing machine. The samples were examined under a stereomicroscope to determine the nature of the bond failures. Results: Biodentine showed significantly higher push-out bond strength than MTA (P Conclusion: Push-out bond strength is the force needed for the displacement of the dental material tested. The various irrigants used during the root canal therapy may increase or decrease the push-out bond strength of a material.

An in vitro study to determine fracture resistance of tooth roots after different instrumentation techniques

Aim: The aim was to study the influence of rotary and hand instruments techniques on the susceptibility of the root to fracture. Materials and Methods: Forty extracted human maxillary permanent first and second molars without any defects were selected as sample. Teeth were randomly divided into four groups of ten teeth in each group. Palatal canals were instrumented depending on the instrumentation techniques used in the groups. Group 1: 0.02 taper K-files and Gates Glidden drills (Mani Inc., Japan); group 2: Hand ProTaper (Dentsply-Maillefer, France); group 3: Rotary ProTaper (Dentsply-Maillefer, France); and group 4: Endowave (J. Morita, Japan). After instrumentation, palatal roots were resected and apical 7 mm sectionally obturated. Obturated roots were embedded in putty impression material and mounted on Universal testing machine (Lloyd instruments, UK). Vertical load was applied by means of a spreader inserted into the canal and load at fracture was recorded for each tooth. Fractured roots were embedded in self-cure resin, sectioned horizontally, and viewed under operating microscope to determine the direction of fracture line: Maximum and minimum remaining dentin thickness was measured at coronal, middle, and apical thirds. Statistical analysis of data was accomplished by one-way ANOVA and post-hoc tests with Tukey honest significant difference. Results: Mean fracture loads was 20.6 ± 3.8 kg (group 1), 9.5 ± 2.4 kg (group 2), 8.4 ± 1.4 kg (group 3), and 13.4 ± 3.1 kg (group 4). There was statistical significance in the values between group 1 and groups 2, 3, and 4 (P Conclusion: Preparation of canals with a conventional hand instrumentation technique using 0.02 taper K-files showed highest fracture resistance with least amount of dentin removed at all levels followed by Endowave, ProTaper Hand, and Rotary files.

Efficacy of Different Methods for Removing Root Canal Filling Material in Retreatment - An In-vitro Study.

Although success of endodontic therapy has significantly improved in the last few decades due to the introduction of novel materials and techniques, failures of endodontic therapy requiring re-treatment still comprise a significant percentage of patients requiring root canal treatment. To evaluate and compare the effective removal of gutta percha and sealer, amount of apical debris extrusion and time required for gutta percha removal using various endodontic files. Total 48 extracted mandibular premolars were mounted on acrylic blocks and endodontic procedure was carried out using size 40 K file and obturated using guttapercha and zinc oxide eugenol sealer. After one month storage, samples were decoronated, mounted on screw capped vials and subjected to removal of obturated material by four instruments: H files, safe sided H files, protaper universal retreatment rotary system and ultrasonic retreatment tip, grouped as 1, 2, 3, and 4 respectively. Only 2mm of obturated material from the coronal part was removed using no. 3 Gates Glidden drill, guttapercha was softened with a drop of xylene for 2 mins for each canal and retreatment was performed. The retreatment procedure was said to be complete when no visible debris were observed on the instrument flutes. The samples split into two halves and examined under stereomicroscope, photographed, assessed using AUTOCAD software and percentage of remaining filling material in coronal, middle, apical thirds of the canal was calculated in mm(2). Retreatment time was recorded in seconds and apically extruded debris was assessed by microbalance in grams for each tooth. The data was analyzed by using descriptive statistics, ANOVA and Scheffe's post hoc test through SPSS for windows (v 16.0). The ultrasonic retreatment tip had less percentage of residual guttapercha/sealer, shorter mean operating time and little apical extrusion with a significant difference (p<0.05) between the other groups. All techniques retained guttapercha/sealer remnants within the root canal. The ultrasonic retreatment tip proved to be an efficient method of removing obturated material. It was fastest with least apical debris extrusion.

A comparison of the sealing ability of various temporary restorative materials to seal the access cavity: An in vitro study.

Introduction:In multiple-appointment root canal treatment, a temporary filling material is used to seal the access cavity between visits. The primary function of this material is to prevent the contamination of the root canal system by fluids, organic debris, and bacteria from the oral cavity.Material and Methods:A total of fifty extracted noncarious unrestored human maxillaryanterior teeth with intact crowns and roots were selected The canals were instrumented using stepback technique and sodium hypochlorite (3%) and hydrogen peroxide (3%) were used as irrigants for each specimen alternatively. The coronal two-thirds of each canal were flared using Gates-Glidden drills up to no. 3 size and obturated with Gutta-percha using zinc oxide-eugenol (ZnOE) as sealer. The teeth were then randomly selected and divided into six groups out of which four were experimental groups and two control groups. The teeth were then immersed in 2% methylene blue dye solution for 3 days. All sealing materials and Gutta-percha were gently removed from the walls of the canal, and the entire circumference of the canal wall examined for dye penetration.Results:The lowest mean leakage was in the Fermit-N group followed by Cavit-W, ZnOE, intermediate restorative materials (IRM), and positive control.Conclusion:Fermit-N showed better sealing ability compared to cavit, ZnOE and IRM.

The Antibacterial Efficacy of Photo-Activated Disinfection, Chlorhexidine and Sodium Hypochlorite in Infected Root Canals: An in Vitro Study.

Introduction:This study compared the efficacy of light-activated low-power laser, 2% chlorhexidine (CHX) and 2.5% NaOCl in eliminating Enterococcus faecalis (E. faecalis) from the root canal system. Methods and Materials:The root canals of 60 maxillary central incisors were contaminated with E. faecalis and then the bacteria were incubated for 24 h. All the root canals were instrumented in a crown-down manner with #4 and 3 Gates-Glidden drills, followed by RaCe rotary files (40/0.10, 35/0.08, and 30/0.06). The samples were randomly assigned to three experimental groups and one control group (n=15). In the control group no intervention was made. In the photo-activated disinfection (PAD) group, laser therapy was undertaken with diode laser beams (with an output power of 100 mW/cm2) for 120 sec. For the other two experimental groups, root canals were irrigated either with 5 mL of 2% CHX or 2.5% NaOCl solutions, respectively. The Kruskal-Wallis test was used to compare the CFU values of the bacteria and post-hoc Bonferroni test was used for pairwise comparisons. The level of significance was set at 0.05. Results:The inhibition of bacterial growth in all the experimental groups was significantly superior to the control group (P<0.05). There was no significant difference between the effect of PAD and 2% CHX (P=0.05). The effect of 2.5% NaOCl was significantly better than that of the PAD technique (P<0.001). In addition, 2.5% NaOCl was significantly better than 2% CHX (P=0.007). Conclusion:Photodynamic therapy was effective in reducing the E. faecalis counts in comparison with the control group, but 2.5% NaOCl solution was the most effective protocol.