Gates Glidden Drills Research Articles

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.

Push-out bond strength of a self-adhesive resin cement used as endodontic sealer.

ObjectivesThe aim of the present study was to investigate the bond strength of RelyX Unicem (3M) to root canal dentin when used as an endodontic sealer.Materials and MethodsSamples of 24 single-rooted teeth were prepared with Gates Glidden drills and K3 files. After that, the roots were randomly assigned to three experimental groups (n = 8) according to the filling material, (1) AH Plus (Dentsply De Trey GmbH)/Gutta-Percha cone; (2) Epiphany SE (Pentron)/Resilon cone; (3) RelyX Unicem/Gutta-Percha cone. All roots were filled using a single cone technique associated to vertical condensation. After the filling procedures, each tooth was prepared for a push-out bond strenght test by cutting 1 mm-thick root slices. Loading was performed on a universal testing machine at a speed of 0.5 mm/min. One-way analysis of variance and Tukey test for multiple comparisons were used to compare the results among the experimental groups.ResultsEpiphany SE/Resilon showed significantly lower push-out bond strength than both AH Plus/Gutta-Percha and RelyX Unicem/Gutta-Percha (p < 0.05). There was no significant difference in bond strength between AH Plus/Gutta-Percha and RelyX Unicem/Gutta-Percha (p > 0.05).ConclusionsUnder the present in vitro conditions, bond strength to root dentin promoted by RelyX Unicem was similar to AH Plus. Epiphany SE/Resilon resulted in lower bond strength values when compared to both materials.

Displacement Of Apical Plugs Fabricated From Calcium Hydroxide Paste In Three Root Canal Filling Techniques

Objective: The present study evaluated the displacement of calcium hydroxide apical plugs in the root canals of teeth with enlarged apical foramens subjected to three filling techniques: lateral condensation, a hybrid method, and a thermoplastic technique (Ultrafil). Methods: The root canals of 30 extracted single-rooted human teeth were drilled in reverse order with no. 1-5 Gates-Glidden drills using a crown-down technique until the no. 1 drill passed through the apical foramen. The specimens were prepared with K files, beginning with a 50 K file and progressing until a 90 K file was visible 1 mm beyond the apex. Apical plugs were fabricated from calcium hydroxide paste, and the specimens were stored at 37°C at 100% humidity for 3 days. They were allocated into three experimental groups (n=10) according to the root canal technique. After filling, the specimens were incubated for 48 h at 37°C and longitudinally sectioned to assess apical plug displacement. Data was analysed by Kruskall-Wallis and Dun´s tests. Results: The hybrid method caused the largest average apical plug displacement (1.96 mm), followed by the lateral condensation technique (0.85 mm) and the Ultrafil system (0.59 mm). Conclusions: According to the results obtained in this study, when a 5mm apical plug is fabricated using L & C paste, filling of the remaining root canal can be performed with lateral condensation technique, hybrid method or Ultrafill.

Endodontic filling removal procedure: an ex vivo comparative study between two rotary techniques

In this study, we compared the ex vivo removal capacity of two endodontic rotary techniques and determined whether there was a significant quantitative difference in residual material when comparing root thirds. Forty extracted molars were used. The palatal roots were selected, and the canals were prepared using a step-back technique and filled using a lateral condensation technique with gutta-percha points and Endofill sealer. After two weeks of storage in a 0.9% saline solution at 37 ºC in an oven, the specimens were divided into 2 groups of 20, with group 1 samples subjected to Gates-Glidden drills and group 2 samples subjected to the ProTaper retreatment System. Hedstroem files and eucalyptol solvent were used in both groups to complete the removal procedure. Then, the roots thirds were radiographed and the images were submitted to the NIH ImageJ program to measure the residual filling material in mm. Each root third was related to the total area of the root canals. The data were analyzed using Student's t test. There was a statistically significant difference between the two techniques as more filling material was removed by technique 2 (ProTaper) than technique 1 (Gates-Glidden drills, p < 0.05). The apical third had a greater amount of residual filling material than the cervical and middle thirds, and the difference was statistically significant (p < 0.05). None of the selected techniques removed all filling material, and the material was most difficult to remove from the apical third. The ProTaper files removed more material than the Gates-Glidden drills.

Influência do pré-alargamento na escolha da lima patência e lima apical inicial

The present study evaluated the influence of cervical preflaring in the choice of patency and initial apical files. Forty mesial canals of mandibular molars were divided into two groups. In the first, no cervical preflaring was performed while in the second it was performed with Gates Glidden drills. The measurement of the anatomic diameter of the apical foramen and of the working length was performed by the retrograde method with the aid of a microscope. The choice of patency and initial apical files was determined in the root canal. When the preflaring was not performed, the difference between the diameters of the files and the anatomic diameters was greater. Preflaring was shown to be essential for the determination of patency and initial apical files.

Temperature rise on the external root surface during removal of endodontic fractured instruments

To investigate the temperature rise (TR) on the external root surface while preparing a staging platform, for removing intra-canal fractured instruments, using Gates Glidden (GG) drills. Thirty extracted mandibular incisors were decoronated and 3-3.5 mm of F3 ProTaper files were fractured 3 mm from the most coronal end of the root. Roots were divided into three groups. GG drills were used in a size-2 to size-5 sequence to prepare the staging platform coronal to the fractured segment. They were rotated at three speeds according to the study groups: group A for 2,000 revolutions per minute (rpm); group B for 4,000 rpm; and group C for 8,000 rpm. Temperature changes were recorded at the proximal and buccal or lingual external root surfaces while preparing the staging platform. Data were analyzed using the paired sample T, one- and two-ways ANOVA tests at p ≤ 0.05. Overall, TR at the proximal root surface (5.44 °C) was significantly higher than that at the buccal or lingual surface (3.25 °C) (p < 0.001). Generally, TR increased significantly as the size of GG drills or the revolution speed increased (p < 0.05). GG5 drills rotated at 8,000 rpm produced the highest TR (10.85 °C). There was no interaction effect of the GG drill size and the revolution speed on TR (p = 0.272). The highest TR on the external root surface, associated with preparation of a staging platform and produced by using GG drills size-5 rotating at up to 8,000 rpm, was lower than the damaging threshold. A staging platform can be performed by modified GG drills (no 2 to 5) rotating at 8,000 rpm without generating a hazardous TR.

Residual dentin thickness of bifurcated maxillary premolars following two post space preparation methods.

The aim of this in vitro study was to compare the effect of Gates-Glidden and Peeso reamer drills on residual dentin thickness during post space preparation in order to discover which method has minimum root structure damage. Thirty extracted human maxillary premolars with bifurcations at root middle were horizontally cut 15 mm coronal to the apical end after root canal treatment. The samples were scannedby Cone Beam Computed Tomography (CBCT) before and after preparing the post space. Residual dentin thicknesses were measured at 4-, 6-, and 8-mm levels from the apex. Data were analyzed using repeated measured ANOVA. Endodontic therapy and post space preparations removed more dentin within the bifurcation of both roots compared to outer dentin. The difference in residual dentin thickness was highly significant regarding stage (before and after post space preparation) in all levels and stage × device in coronal and middle levels (P<.05). This in vitro study emphasizes the minimal dentin width in the buccal root of maxillary premolars, especially near the bifurcation. Lack of adequate residual dentin thickness after post space preparation implies that the use of posts in maxillary first premolars should be limited. When mandatory, it is recommended that post space be prepared with Gates-Glidden drill in the palatal root of maxillary first premolars and use of Peeso reamer be avoided.

The sealing ability of MTA apical plugs exposed to a phosphate-buffered saline

The aim of this study was to evaluate the influence of exposure of the mineral trioxide aggregate (MTA) - with and without calcium chloride (CaCl2) - to phosphate-buffered saline (PBS) on the apical microleakage using a glucose leakage system. Sixty root segments were randomly divided into 4 experimental groups (n=15). After resecting the apical segments and enlarging the canals with Gates-Glidden drills, the apical cavities were filled with MTA with or without CaCl2 and the root canals were dressed with a moistened cotton pellet or PBS, as follows: 1) MTA/cotton pellet; 2) MTA/PBS; 3) MTA+10%CaCl2/cotton pellet; 4) MTA+10%CaCl2/PBS. All root segments were introduced in floral foams moistened with PBS. After 2 months, all root segments were prepared to evaluate the glucose leakage along the apical plugs. The amount of glucose leakage was measured following an enzymatic reaction and quantified by a spectrophotometer. Four roots were used as controls. The data were analyzed using Kruskal-Wallis and Mann-Whitney tests (p<0.05). There were no differences between groups 1 and 2 (p>0.05), and 3 and 4 (p>0.05). The addition of CaCl2 to the MTA significantly decreased its sealing ability (p<0.05). The interaction with PBS did not improve the MTA sealing ability. The addition of CaCl2 to the MTA negatively influenced the apical seal.

Effectiveness of an electronic apex locator used after preflaring of cervical and middle third

The electronic method has been studied and improved aiming to add precision, speed and reliability of the measurement technique to determine the exact location of the working length. Currently, the root canal preparation recommends prior to determine the tooth length and consequent perform instrumentation of the apical portion, a previous preflaring of the cervical and middle thirds in various techniques. This procedure may provide a reduction in system impedance, leading to read errors by the apex locators. Objective: Investigate the influence of preflaring of the cervical and middle thirds on the accuracy of measuring the working length by apex locators. Material and methods: Twenty-five mesial roots of molars were used and had their crowns cut at the cemento-enamel junction. The actual measure of each root canal was performed and then the samples were embedded into a mixture of alginate, used as a conducting medium, where electronic measurements were taken with apex locator before and after preflaring of the canals with Gates-Glidden drills in descending order (#4, #3, #2). Measurements obtained by electronic method were then compared with the actual measurement of the root canal. The results were tabulated and submitted to the Student t test Results: The results show that there was no statistical significance (p&lt;0.05) between the readings before and after preflaring. Readings closer to the foraminal ending occurred in the group after preflaring with Gates Glidden. Conclusion: It was concluded that preflaring with Gates Glidden drills were not able to influence significantly the accuracy of apex locator in determining the exact working length.

Effectiveness of different obturation techniques in surpassing the ledge formed in simulated curved canals

AIM: To compare the effectiveness of different obturation techniques in surpassing the ledge formed in simulated curved root canals. METHODS: Eighty acrylic-resin blocks with curved canals were instrumented with Gates-Glidden drills to simulate a ledge formation. Then, a K-File #10 was used for trying to surpass the deviation, and the blocks that permitted surpassing were rejected. The remaining blocks were divided into 4 groups according to the obturation technique: lateral condensation, Tagger's Hybrid technique, Thermafil and System B. The blocks had their images digitalized using a scanner before and after the obturation procedures. The images were analyzed with Image Tool 3.0 software. Statistical analysis was performed by one-way ANOVA at a significant level of 5%. RESULTS: The System B resulted in the highest obturated area (p<0.001). There were no significant differences between the Tagger's Hybrid technique and Thermafil system regarding the effectiveness in surpassing ledge (p>0.05). The lateral condensation resulted in the worst ability in filling the ledge space (p<0.001). CONCLUSIONS: Within the limitations of this study, it was possible to conclude that techniques using heat condensation or gutta-percha thermoplastification were more effective in surpassing the ledge formed in curved canals than the lateral condensation.

The Incidence of Root Microcracks Caused by 3 Different Single-file Systems versus the ProTaper System

IntroductionThe aim of this study was to compare the incidence of root cracks observed at the apical root surface and/or in the canal wall after canal instrumentation with 3 single-file systems and the ProTaper system (Dentsply Maillefer, Ballaigues, Switzerland). MethodsOne hundred mandibular incisors were selected. Twenty control teeth were coronally flared with Gates-Glidden drills (Dentsply Maillefer). No further preparation was made. The other 80 teeth were mounted in resin blocks with simulated periodontal ligaments, and the apex was exposed. They were divided into 4 experimental groups (n = 20); the root canals were first coronally flared with Gates-Glidden drills and then instrumented to the full working length with the ProTaper, OneShape (Micro-Mega, Besancon, France), Reciproc (VDW, Munich, Germany), or the Self-Adjusting File (ReDent-Nova, Ra'anana, Israel). The apical root surface and horizontal sections 2, 4, and 6 mm from the apex were observed under a microscope. The presence of cracks was noted. The chi-square test was performed to compare the appearance of cracked roots between the experimental groups. ResultsNo cracks were found in the control teeth and teeth instrumented with the Self-Adjusting File. Cracks were found in 10 of 20 (50%), 7 of 20 (35%), and 1 of 20 (5%) teeth after canal instrumentation with the ProTaper, OneShape, and Reciproc files, respectively. The difference between the experimental groups was statistically significant (P < .001). ConclusionsNickel-titanium instruments may cause cracks on the apical root surface or in the canal wall; the Self-Adjusting File and Reciproc files caused less cracks than the ProTaper and OneShape files.

Predictive models of pain following root canal treatment: a prospective clinical study

To determine the probability of the incidence, intensity, duration and triggering of post-endodontic pain, considering factors related to the patient (age, gender, medical evaluation) and to the affected tooth (group, location, number of canals, pulp vitality, preoperative pain, periapical radiolucencies, previous emergency access, presence of occlusal contacts with antagonist). A total of 500 one-visit root canal treatments (RCTs) were performed on patients referred to an endodontist. Shaping of root canals was performed manually with Gates-Glidden drills and K-Flexofiles, and apical patency was maintained with a size 10 file. A 5% NaOCl solution was used for irrigation, and canals were filled with lateral compaction and AH-Plus sealer. Independent factors were recorded during the treatment, and characteristics of post-endodontic pain (incidence, intensity, type and duration) were later surveyed through questionnaires. Of the 500 questionnaires, 374 were properly returned and split in two groups for two different statistical purposes: 316 cases were used to adjust the logistic regression models to predict each characteristic of post-endodontic pain using predictive factors, and the remaining 58 cases were used to test the validity of each model. The predictive models showed that the incidence of post-endodontic pain was significantly lower when the treated tooth was not a molar (P=0.003), demonstrated periapical radiolucencies (P=0.003), had no history of previous pain (P=0.006) or emergency endodontic treatment (P=0.045) and had no occlusal contact (P<0.0001). The probability of experiencing moderate or severe pain was higher with increasing age (P=0.09) and in mandibular teeth (P=0.045). The probability of pain lasting more than 2days was increased with age (P=0.1) and decreased in males (P=0.007) and when a radiolucent lesion was present on radiographs (P=0.1). Predictive formulae for the incidence, the intensity and the duration of post-endodontic pain were generated and validated taking account of the interrelation of multiple concomitant clinical factors. A predictive model for triggering post-endodontic pain could not be established.

Influence of the Cervical Enlargement in Determining the Diameter of the First File and Establishing the Working Length

ABSTRACT The objective of this study was to analyze the influence of different methods of cervical prepare in determining the first file of the apical preparation of root canal and working length. Thirty mesiobuccal fully formed roots of upper first permanent molars humans were used and the root canals were initially cleaned with K-file #10. Then, the teeth were randomly divided into three groups according to the type of enlargement: group I: ProTaper S1, SX; group II: K3 Orifice Opener 25.10 and 25.08; and group III: technique with hybrid K-type hand files and gates glidden drills # 3 and # 2. The specimens were taken to a stereomicroscope to evaluate the adaptation of the first file in the dentinal walls at length established. The data were submitted to Kruskal-Wallis and Wilcoxon tests. The reliability of the apex locator methods was performed by Spearman test. All groups showed statistically significant difference in the length of root canals after preparation of the cervical third (p &lt; 0.05). The level of agreement between the measurement and visual electronics was higher (r = 98.07%) before the cervical enlargement, compared to that reported after cervical preparation (r = 96.42%) (p &lt; 0.0001). Based on the methodology, was possible to conclude that cervical and middle thirds prepare were important to determine the first file diameter and it did lead to a decrease in the working length. The electronic apex was effective to determine the working length. How to cite this article Pires LB, Bueno C, Albergaria S, Bandéca MC, Semenoff-Segundo A, Porto AN, Borges; H. Influence of the Cervical Enlargement in Determining the Diameter of the First File and Establishing the Working Length. World J Dent 2013;4(3):164-169.

Comparison of Orange Oil and Chloroform as Gutta- Percha Solvents in Endodontic Retreatment

To compare the efficacy of gutta-percha removal achieved with simple mechanical technique using two different solvents. It was an in vitro experimental study conducted at the Aga Khan University Hospital, Karachi, Pakistan on 27 extracted human molars divided into two groups by alternate sampling technique. The teeth were prepared by manual filing and obturated with gutta-percha and calcium hydroxide sealer. Two drops of the assigned solvent were placed on the orifice of the obturated canal and Gates Glidden drills #1, 2 and 3 were used for removal of coronal gutta-percha. Manual filing was done for removal of remaining gutta-percha and the solvent was used in drops until needed. Postoperative periapical radiographs were taken to visualize the remaining gutta-percha left in the canals. Descriptive statistics (mean and SD) of the variables such as tooth type, obturation length and canal curvatures were determined. Chi-square and independent sample t-tests were applied and level of significance was set at 0.05. There was 5.19 (3.8) mm of remaining gutta-percha in the orange oil group and 5.37 (4.2) mm in the chloroform group (p=0.90). There is no statistically significant difference between the orange oil and chloroform when used as solvent for removing gutta-percha.

Dentinal tubule disinfection with 2% chlorhexidine, garlic extract, and calcium hydroxide against Enterococcus faecalis by using real-time polymerase chain reaction: In vitro study

Aim:To compare the efficacy of garlic extract with 2% chlorhexidine (CHX) and calcium hydroxide Ca(OH)2 in disinfection of dentinal tubules contaminated with Enterococcus faecalis by using real-time polymerase chain reaction (PCR).Materials and Methods:Agar diffusion test was done to evaluate the minimum inhibitory concentration of garlic extract against E. faecalis. Forty human extracted mandibular premolar teeth were selected for this study, access cavity was prepared and cleaning and shaping was done. Middle third of the root was cut using a rotary diamond disc. The teeth specimens were inoculated with E. faecalis for 21 days. Specimens were divided into four groups---Group 1: 2% CHX, Group 2: Garlic extract, Group 3: Ca(OH)2, and Group 4: Saline (negative control). The intracanal medicaments were packed inside the tooth specimens and incubated for 5 days. The dentinal chips were collected at 400 μm depth using a Gates-Glidden drill, following which DNA isolation was done. The specimens were analyzed using real-time PCR. The results were then statistically analyzed using one-way analysis of variance, followed by post hoc Tukey's honestly significant difference (HSD) multiple comparison of means.Results:Threshold cycle (Ct) values of 2% CHX was found to be 32.4, garlic extract to be 27.5, and Ca(OH)2 to be 25.6.Conclusion:A total of 2% CHX showed the maximum efficacy against E. faecalis, followed by garlic extract and Ca(OH)2.

The sealing ability of MTA apical plugs exposed to a phosphate-buffered saline

ObjectiveThe aim of this study was to evaluate the influence of exposure of the mineral trioxide aggregate (MTA) - with and without calcium chloride (CaCl2) - to phosphate-buffered saline (PBS) on the apical microleakage using a glucose leakage system. Material and MethodsSixty root segments were randomly divided into 4 experimental groups (n=15). After resecting the apical segments and enlarging the canals with Gates-Glidden drills, the apical cavities were filled with MTA with or without CaCl2 and the root canals were dressed with a moistened cotton pellet or PBS, as follows: 1) MTA/cotton pellet; 2) MTA/PBS; 3) MTA+10%CaCl2/cotton pellet; 4) MTA+10%CaCl2/PBS. All root segments were introduced in floral foams moistened with PBS. After 2 months, all root segments were prepared to evaluate the glucose leakage along the apical plugs. The amount of glucose leakage was measured following an enzymatic reaction and quantified by a spectrophotometer. Four roots were used as controls. The data were analyzed using Kruskal-Wallis and Mann-Whitney tests (p<0.05). ResultsThere were no differences between groups 1 and 2 (p>0.05), and 3 and 4 (p>0.05). The addition of CaCl2 to the MTA significantly decreased its sealing ability (p<0.05). ConclusionThe interaction with PBS did not improve the MTA sealing ability. The addition of CaCl2 to the MTA negatively influenced the apical seal.

Working length changes in curved canals after coronal flaring by using rotary files and hand file: An in vitro study

Aim:This in vitro investigation examined the effect of early coronal flaring (CF) and late CF on the working length (WL) in curved root canals.Background:The objective of this study was to determine if canal length is altered as a result of CF in curved canals of molar roots.Study Design:The conditions compared were combinations of (a) stainless steel hand files using Gates Glidden (G. G.) drills (SS) versus nickel-titanium rotary files (Ni-Ti); and (b) early CF (flaring completed before WL determination) versus late CF (flaring completed after WL determination). Selected were 90 canals of extracted maxillary or mandibular first molars (mesial root of mandibular molars and the mesiobuccal root of the maxillary molars) from three groups. CF was accomplished for the SS group using G. G. drills and for the Ni-Ti group using rotary ProTaper and Hero Shaper files. WL was determined by a digital vernier caliper before CF, immediately after CF, and again after canal preparation.Statistical Analysis:A repeated measures analysis of variance (ANOVA) test and a Tukey's multiple prosthoc test were used for this study.Results:Results indicated that WL decreased for all canals as a result of canal preparation. The mean decrease in WL was significantly greater for the SS group (−0.77 ± 0.42 mm) than for the Ni-Ti groups (−0.33 mm ± 0.44). Less change in WL occurred in all groups when initial WL was determined after CF.Conclusion:WL in curved canals consistently decreases during the course of instrumentation. Clinician should keep this in mind for better treatment outcome.

Comparison of Apical Sealing of Two Canal Sealers between Immediate Versus Delayed Post Space Preparation

The effect of post space preparation on the sealing ability of a root canal filling is important because the sealer is crucial for preserving the apical seal. The question of how, when, and how much of the gutta-percha should be removed is a debate when preparing a post space. This study is aimed to compare the effect of immediate versus delayed post space preparation on the apical seal using AH Plus and EndoREZ sealers. Forty four single rooted teeth were prepared using the step-back technique and were obturated with combinations of gutta-percha/AH Plus and gutta-percha/EndoREZ using the lateral compaction technique. Four teeth were used as positive/negative controls. After the teeth were divided randomly into six groups, post spaces were prepared either immediately after filling or after storage of the obturated teeth in saline at 37°C for one week. The post space preparation procedure was performed using hot pluggers or Gates Glidden drills leaving a 5 mm of root canal filling in the apical part. Leakage was determined by a computerized fluidfiltration device. Immediate and delayed post space preparation of the gutta-percha/AH Plus groups had mean leakage values of 4.97 µl.cmH2O.min-1.10-4 and 4.94 µl.cmH2O.min-1.10-4, respectively. The respective mean leakage values of immediate and delayed post space preparation of the gutta-percha/EndoREZ groups were 4.97 µl.cmH2O.min-1.10-4 and 5.57 µl.cmH2O.min-1.10-4. The mean leakage value obtained in the positive control group was 398.16 µl.cmH2O.min-1.10-4, whereas there was no fluid filtration in the negative control group. Better sealing was achieved in the guttapercha/AH Plus delayed group in comparison to the other groups. Delayed post space preparation in the gutta-percha/EndoREZ group showed the highest percentage of leakage.

Effect of Different Techniques of Immediate and Delayed Post Space Preparation on Apical Seal

The purpose of this study was to investigate the effect of different post space preparation techniques and times on the apical seal of two types of gutta-percha obturation techniques. Materials and methods: Two hundred extracted human lower premolars were selected for this study. All teeth were decoronated to adjust the working length at 14 mm. The canals were instrumented with ProTaper rotary instruments to size F3. The (200) root canals were randomly divided into two groups (100) of each according to the obturating method. Then each group was sub divided into (10) sub groups (10) of each (2 control groups and 8 experimental groups). Nine mm segment of gutta-percha was removed from the roots in each of the experimental groups either immediately after obturation or 7 days later using either heated pluggers, or Gates-Glidden drills or ProTaper rotary instruments or peeso reamers. The roots in the control groups were left without any post space preparation. The canal orifice of the roots in the experimental groups was sealed with amalgam. The extend of linear dye leakage was measured in mm with a stereomicroscope at (X 20). One-way ANOVA and sheffe statistical analysis were performed to the data collected. Results: The groups with ProTaper rotary instrument prepared the post space immediately after obturation( gps 3,11), showed the lowest mean leakage, but the difference was not statistically significant than the other experimental groups. T-test represented no significant differences existed at either two time interval studied and the type of obturation techniques. Sheffe-test for the post space preparation techniques revealed that there were a significant differences occurred with the use of ProTaper rotary instruments regardless the time interval and the obturation techniques. Conclusions: ProTaper rotary instrument provided less microleakage comparing to the other instruments used to prepare the post space. The post space preparation did not affect the apical seal in comparison with that of the intact filling.

Influence of smear layer removal and application mode of MTA on the marginal adaptation in immature teeth: a SEM analysis

This study was an ex vivo evaluation of the marginal adaptation of mineral trioxide aggregate as an apical barrier using teeth with an open apex and scanning electron microscopy. Eighteen single-rooted human teeth were used. An artificial open apex was created using Gates Glidden drills #6-1 in a crown-down manner until the #1 bur passed through the foramen. A 1.36-mm divergent open apex was created at the foramen by retrograde apical transportation using a #40 Profile 0.6 taper instrument inserted to the length of the cutting blade. The teeth were divided into four groups (n=4), and two teeth served as controls. The GI=mineral trioxide aggregate (MTA) was placed as a 5-mm-thick apical barrier without removal of the smear layer; GII=MTA was placed with indirect ultrasonic activation; GIII=apical plug was placed after removal of the smear layer without indirect ultrasonic activation; and GIV = MTA was placed with indirect ultrasonic activation, but the smear layer had been previously removed. The root apices were visualized with SEM (1000×), and 12 predetermined material/dentine interface points were measured (gaps). One-way anova and Bonferroni's post hoc tests were used to compare the linear measurements of the gaps between the groups. GIV had the lowest gap when compared with other groups, and no statistical differences were found among GI, GII, and GIII. The technique of MTA placement using passive ultrasonic vibration in association with smear layer removal improved the marginal adaptation of the material.