Root Canal Preparation Techniques Research Articles

Canal Preparation and Filling Techniques do not Influence the Fracture Resistance of Extensively Damaged Teeth

The purpose of this study was to assess the fracture resistance of extensively damaged teeth after two root canal preparation techniques (hand and rotary files) and after two filling techniques (active and passive compaction). Sixty-eight maxillary canines roots with an apical diameter equal to that of a #25 K-file were embedded in acrylic resin and the periodontal ligament was simulated by using a polyether impression material. The roots were randomly distributed into four groups (n=17): hand preparation and active compaction (HA), hand preparation and passive compaction (HP), rotary preparation and active compaction (RA), and rotary preparation and passive compaction (RP). All roots were restored with glass fiber post and metallic crown. The specimens were mechanically cycled (500,000 cycles, 45 °, 37 °C, 133 N, 2 Hz) and then subjected to a fracture resistanhe fracture resistance values ranged between 621.15 N (HP) and 785.71 N (HA). However, the Kruskal-Wallis test did not reveal differences in the fracture ce test. A single blinded examiner analyzed the external root surface and classified the failure pattern as favorable or unfavorable. Tresistance values among the four groups (p =0.247). Under the tested conditions, root canal preparation and filling techniques had no influence on the fracture resistance of extensively damaged teeth restored with fiber post and metallic crown.

Evaluation of canal cleanliness and tubular penetration of root canal sealers in extracted primary second molars: a SEM study

Objectives: To evaluate canal surface changes and the remaining debris/smear after canal preparation, and the subsequent penetration of root canal sealers into dentinal tubules in extracted primary second molars, using scanning electron microscopy (SEM). Materials and Methods: The widest roots of 120 recently extracted human primary second molars were used. The roots were randomly distributed into four groups, according to instrumentation techniques [conventional stainless-steel hand files / nickel-titanium (Ni-Ti) rotary files] and irrigation solutions [0.5% sodium hypochlorite (NaOCl) and 0.9% saline solution/0.4% chlorhexidine gluconate (CHX)] employed. Surface change, the debris/smear layer remaining after instrumentation/irrigation, and the tubular penetration of root canal sealers [zinc oxide and eugenol (ZOE)/Apexit Plus (AP)] were evaluated using SEM. All data were analyzed statistically using the Kruskal-Wallis and Mann-Whitney U tests. Results: No significant difference was found between the surface changes and debris/smear layer scores based on root canal preparation technique and irrigant solution (P>0.05). ZOE cement was unable to enter dentinal tubules, while AP-based calcium hydroxide was able to gain limited entry to the tubules of some roots, but not others. Conclusions: No differences in canal cleanliness were noted among the instrumentation and irrigant protocols evaluated. AP was found in this SEM study to penetrate the dentinal tubules of prepared primary molar root canals more effectively than ZOE; though, penetration with AP was not noted in every root canal.

Antimicrobial efficacy of two irrigation techniques in tapered and non-tapered canal preparations. A randomized controlled clinical trial.

The aim of this randomized controlled clinical trial was to investigate the antimicrobial efficacy of traditional positive pressure (PP) irrigation compared with apical negative pressure (ANP) in tapered as well as non-tapered root canal preparation techniques. Patients referred for treatment of mandibular permanent molars with necrotic pulps and apical periodontitis were considered for this study. A total of 32 eligible teeth were evaluated based on strict inclusion and exclusion criteria and randomly assigned as follows: Group 1: LightSpeed LSX 0.02 preparation and A NP irrigation (n = 8). Group 2: LightSpeed LSX 0.02 preparation and PP irrigation (n = 8). Group 3: ProTaper preparation and A NP irrigation (n = 8). Group 4: ProTaper preparation and PP irrigation (n = 8). A ll teeth were sampled immediately upon access (S1), after completion of the chemo- mechanical preparation (S2), and one week later after intracanal medication (S3). All samples were microbiologically processed immediately and plated in duplicates on aerobic plates, anaerobic plates, and chocolate plates and colonies statistically analyzed. No statistically significant differences were found between groups at S1. When comparing colony-forming unit (CFU) levels at S1 and S2 within groups, the reduction was statistically significant in all groups. While no significant difference was found in the proportion of teeth that culture positive at either S2 or S3 by shaping groups, a significant difference was noted when comparing PP irrigation and A NP groups. The percentage of samples in the PP irrigation group with a negative culture at both time points was 67%, compared to 100% among the A NP group. Within the limitations of the present study, taper and apical size failed to demonstrate a difference in microbiological reduction of cultivable bacteria. On the other hand, A NP revealed a significant difference when compared to PP irrigation.

A Survey of Endodontic Practices among Dentists in Nigeria

To investigate the pattern of routine endodontic practices among Nigerian dentists. This study was a questionnaire-based survey of samples of dentists in the Nigerian cities of Enugu and Benin. The self-administered questionnaire contained 25 close-ended questions with multiple choice options. The data collected included demographic details of respondents, root canal preparation techniques, irrigants and intracanal medicaments used, the number of appointments, method of working length determination, root filling techniques, cements used, and the scope of treatment performed. Most respondents used sodium hypochlorite as the irrigant, the step back technique for canal preparation, and lateral condensation with a zinc oxide-eugenol-based sealer for obturation. Most respondents did root canal treatment on all types of teeth and used radiographs to determine the working length 70% of the time. Most respondents followed up their patients for less than 12 months and most treated teeth with periapical areas larger than 10 mm by root canal therapy combined with apical surgery. Most Nigerian dentists use step back technique for canal preparation and lateral condensation for obturation. Endodontic practice by Nigerian dentists differs from some established practice quality guidelines in many other countries, particularly in nonperfusion of modern techniques into practice, popularity of antibiotic use for endodontic emergencies and a high rate of perforations.

Ex vivo evaluation of the effects of several root canal preparation techniques and irrigation regimens on a mixed microbial infection

To assess the ex vivo effectiveness of the alternated use of 1% NaOCl and 15% citric acid in association with two instrumentation techniques for the disinfection of root canals infected with Enterococcus faecalis and Candida albicans. Eighty human mandibular premolars with straight, oval root canals standardized to 15 mm in length were infected with a mixed culture of E. faecalis and C. albicans for 28 days. Five other teeth were used as controls and were neither contaminated nor instrumented. Specimens were divided into two groups (n = 40), according to whether the canal preparation technique used manual (K-type) or rotary (Protaper Universal) instruments. These groups were further divided into four subgroups (n = 10) according to the irrigation solution used: saline, 1% NaOCl, 1% NaOCl with alternated use of 15% citric acid and 5.25% NaOCl. Root canals were prepared with a crown-down technique until a size 50 K-file or with rotary preparation until an F5 instrument. Microbiological sampling was performed before (S1) and after (S2) the chemomechanical preparation, using sterile paper points. The specimens were split, and 0.02 g of dentine chips was collected from the root thirds to verify the presence of microorganisms in root canal walls. Saline and 1% NaOCl were less effective in reducing microorganisms compared with 1% NaOCl with alternated use of 15% citric acid or 5.25% NaOCl alone (P < 0.05). Both manual and rotary preparations significantly reduced microorganisms regardless of the irrigation solution used (P < 0.05). However, there was no significant difference between the canal preparation techniques (P > 0.05). Irrigation with 5.25% NaOCl and 1% NaOCl alternated with 15% citric acid reduced microorganisms in infected root canals significantly more than saline and 1% NaOCl.

Assessment of three root canal preparation techniques on root canal geometry using micro-computed tomography: In vitro study

Aim: To assess the effects of three root canal preparation techniques on canal volume and surface area using three-dimensionally reconstructed root canals in extracted human maxillary molars. Materials and Methods: Thirty extracted Human Maxillary Molars having three separate roots and similar root shape were randomly selected from a pool of extracted teeth for this study and stored in normal saline solution until used. A computed tomography scanner (Philips Brilliance CT 64-slice) was used to analyze root canals in extracted maxillary molars. Specimens were scanned before and after canals were prepared using stainless steel K-Files, Ni-Ti rotary ProTaper and rotary SafeSiders instruments. Differences in dentin volume removed, the surface area, the proportion of unchanged area and canal transportation were calculated using specially developed software. Results: Instrumentation of canals increased volume and surface area. Statistical analysis found a statistically significant difference among the 3 groups in total change in volume (P = 0.001) and total change in surface area (P = 0.13). Significant differences were found when testing both groups with group III (SafeSiders). Significant differences in change of volume were noted when grouping was made with respect to canal type (in MB and DB) (P < 0.05). Conclusion: The current study used computed tomography, an innovative and non destructive technique, to illustrate changes in canal geometry. Overall, there were few statistically significant differences between the three instrumentation techniques used. SafeSiders stainless steel 40/0.02 instruments exhibit a greater cutting efficiency on dentin than K-Files and ProTaper. CT is a new and valuable tool to study root canal geometry and changes after preparation in great details. Further studies with 3D-techniques are required to fully understand the biomechanical aspects of root canal preparation.

Root canal treatment of a mandibular second premolar with atypical canal pattern

To present a unique case of mandibular second premolar with an atypical canal pattern. Thorough knowledge of root canal morphology, appropriate assessment of the pulp chamber floor, and critical interpretation of radiographs are a prerequisite for successful root canal treatment. Mandibular premolars frequently exhibit variable and complex root canal morphology and are one of the most difficult cases to treat endodontically. These teeth may require skillful and special root canal preparation and obturation techniques. This article reports an unusual case of a mandibular second premolar with atypical canal pattern that was successfully treated endodontically.

The effect of working length and root canal preparation technique on crack development in the apical root canal wall

To evaluate the effects of working length and root canal preparation technique on crack development in the apical root canal wall. Seventy extracted mandibular premolars were mounted in a resin block with simulated periodontal ligaments and divided into seven groups according to preparation technique and working length: group A, step-back preparation with stainless steel files with working length set at the apical foramen and defined as root canal length (CL); group B, same as for A, except that the working length was CL-1 mm; group C, crown-down preparation with Profile instruments followed by an apical enlargement sequence with CL as working length and group D, same as for C, except that the working length was CL-1 mm. Groups E, F and G served as controls. Groups E and F were prepared only with the crown-down sequence up to CL and CL-1 mm, respectively. Group G was left unprepared. Digital images of the apical root surface (AS) were recorded before preparation, immediately after instrumentation and after removing the apical 1 mm (AS-1 mm) and 2 mm (AS-2 mm) of the root end. Working length significantly affected crack development at AS (P < 0.05). Preparation technique significantly affected crack development at AS-1 mm (P < 0.05). At AS-2 mm, there was no significant difference between preparation technique and working length in terms of crack development on the canal wall. Root canal preparation alone, regardless of the technique used, can potentially generate cracks on the apical root canal wall as well as the apical surface. Working 1- mm short of the apical foramen might produce fewer cracks in the apical region.

The Effect of Root Preparation Technique and Instrumentation Length on the Development of Apical Root Cracks

The purpose of this study was to compare the effects of root canal preparation techniques and instrumentation length on the development of apical root cracks. Forty extracted mandibular premolars with straight roots were randomly selected and mounted on resin blocks with simulated periodontal ligaments, and the apex was exposed. The teeth were divided into four groups of 10 teeth each for different canal preparation techniques and instrumentation lengths: group A: step-back preparation (SB) with stainless steel files (SF) using root canal length (RCL) to guide instrumentation length; group B: SB using RCL − 1 mm; group C: crown-down preparation (CD) with Profile using RCL; and group D: CD with PF using RCL − 1 mm. Digital images of the instrumentation sequence were compared for each tooth. Statistical analysis revealed a significant effect of instrumentation length (p < 0.05) but no significant effect of preparation technique (p > 0.05) on the development of apical cracks.

Effect of three nickel-titanium rotary file techniques on infected root dentin reduction

This study compared the bacterial reduction of in vitro infected root canals after instrumentation by 3 nickel-titanium (NiTi) rotary files with different taper and diameter versus manual stainless steel files. Sixty-four single-rooted human teeth were infected with a suspension of Streptococcus sanguis measured by optical density. Teeth were divided randomly into 4 groups of 16 and prepared with Flexofiles, GT rotary files, HERO 642, and ProFile. Bacterial samplings were performed before (S1), during (S2-S3), and after (S4) instrumentation. All techniques significantly reduced the number of bacterial cells in the root canals (P < .05). There was no significant difference between NiTi and manual instrumentation at S2, S3, or S4. Concerning bacterial reduction, the results suggest that a manual stainless steel file preparation is as efficient as a NiTi rotary instrumentation. Regardless of the root canal preparation technique, its taper, and diameter, the root dentin remained infected and was not bacteria-free at the end of the experiment.

Root canal preparation technique with FlexMaster system

Root canal preparation technique with FlexMaster system

A comparison of spreader penetration depth and load required during lateral condensation in teeth prepared using various root canal preparation techniques

To compare the influence of various root canal preparation techniques on spreader penetration depth and load required during lateral condensation with gutta-percha and sealer. Eighty extracted human teeth with single and straight canals were used. Twenty teeth were instrumented using one of four root canal preparation techniques. The four preparation techniques were: step-back technique without Gates-Glidden drills, step-back technique with Gates-Glidden drills, crown-down pressureless technique and hybrid technique (step-down/step-back). After root canal preparation had been completed a simulated periodontal ligament was fabricated from a uniform layer of silicone impression material. The roots were then mounted in an acrylic resin to simulate the physical condition found in tooth socket. A standardized stainless steel hand spreader of the same size as the master apical file was mounted in an Instron testing machine and lateral compaction with gutta-percha and sealer was performed. The load value was recorded from the Instron testing machine. The spreader penetration depths were measured with an endodontic ruler. The data obtained were analysed statistically using anova and Student's t-tests. No significant difference in initial spreader load needed to condense the master cone was found amongst the four canal preparation techniques (P > 0.05). The step-back technique with Gates-Glidden drills and the hybrid technique demonstrated the least difference between the initial spreader penetration and the working length (mean 1.925 and 2.25 mm, respectively). The step-back technique without Gates-Glidden drills and the crown-down pressureless technique had the greatest difference between initial spreader penetration and the working length (mean 4.425 and 4.75 mm, respectively). The flare created by canal preparation affected spreader penetration depth, but had no effect on the spreader load.

Anatomic Endodontic Technology (AET) – a crown‐down root canal preparation technique: basic concepts, operative procedure and instruments

To illustrate the conceptual basis and the operative procedure of the Anatomic Endodontic Technology (AET) technique and to illustrate the specific instruments used in each phase. The basic characteristics of the AET technique are reported. The instruments and procedure are described in three phases: coronal access, coronal-middle preparation and apical preparation. In the first phase, correct cavity design is described. In the coronal-middle phase, the use of four stainless steel shaping instruments, powered by a reciprocating handpiece is described, incorporating a brushing-milling action against canal walls. During the apical phase, dedicated apical stainless steel and NiTi hand instruments are used to complete the preparation. The stainless steel apical files are used with a 1/4 turn and withdrawal movement whilst the NiTi are used in 360 degrees rotary motion. Most current canal shaping techniques do not prepare all the canal walls and can result in over-enlargement in some areas. AET defines three regions of the canal: coronal (from the cavo-surface of the access cavity), coronal-middle, and apical. Coronal-middle instrumentation is undertaken with four mechanically driven stainless steel shaping instrument used in brushing-milling action against canal walls. Apical preparation is completed by hand and with the formation of a stop.

Significance of crown-down root canal preparation technique in endodontic therapy by using the hydroxylapatite sealer

To evaluate the crown-down preparation technique, and the use of hydroxylapatite based material for the definitive root canal obturation. The investigation included 20 single-canal roots with chronic periapical inflammatory lesion. Biomechanical medicamentous canal preparation was done using the double-flared technique with balanced force, and the obturation was performed with hydroxylapatite sealer (unicone technique). Clinical and radiographic check-up performed 12 months after the treatment, used the following parameters: pain, swelling, percussion and palpation sensitivity, and the presence of fistula. The obtained results showed a successful treatment in 18 cases, while in the 2 cases the treatment failed. These findings suggested that the crown-down preparation technique efficiently cleaned and shaped the root canal, and that the hydroxylapatite-based material created the homogenous and hermetic root canal obturation, so this methodology could be recommended for the endodontic therapy.

An analysis of endodontic treatment with three nickel‐titanium rotary root canal preparation techniques

To investigate clinical results of root canal treatment performed with the aid of nickel-titanium (NiTi) rotary instruments. A total of 179 patients underwent root canal treatment with either (A) Lightspeed, or (B) ProFile .04 or (C) ProFile .04 and .06 or GT rotary instruments to create tapered preparations. In groups A and B, laterally condensed gutta-percha and AH Plus were used. Canals in group C were obturated with System B, Obtura II and Roth's 801 sealer. Initial and recall radiographs were assessed using the periapical index (PAI). Outcomes were analysed using chi-square tests, event-time analyses and logistic regression models. Two hundred and thirty-three teeth were radiographically assessed after a mean interval of 25.4 +/- 11.8 months. Favourable outcome of treatment, defined as PAI < 3 at recall was 86.7%. Logistic regression analysis and univariate analyses indicated that teeth with preoperative PAI scores >2 and retreated teeth had a significantly lower chance of healing compared with periapically healthy teeth and primary treatments, respectively. Preparation technique, length of fill and the type of sealer did not significantly affect healing rates. Root canal treatment with NiTi root canal instrumentation systems renders favourable outcomes in more than 86% of the cases. Outcome is significantly affected by preoperative diagnoses but not by the specific choice of instrumentation system.

Bactericidal effect of a 980-nm diode laser in the root canal wall dentin of bovine teeth.

The aim of this in vitro study was to investigate the antibacterial depth effect of continuous wave laser irradiation with a wavelength of 980 nm in the root canal wall dentin of bovine teeth. The long-term success of an endodontic therapy often fails due to remaining bacteria in the root canal or dentin tubules, which cannot be sufficiently eliminated through the classical root canal preparation technique nor through rinsing solutions. A total of 102 slices of bovine root dentin of different thicknesses (100, 300 and 500 micro m) were prepared. The samples were inoculated from one side with 5 micro L of an enterococcus faecalis suspension of defined concentration. Four slices per slice thickness served as a control group; the rest of the 30 slices per thickness were subjected to laser irradiation - 10 each of these slices were irradiated with distal outputs of 1.75, 2.3, and 2.8 Watts (W). After drying them for 30 sec, the back of the inoculated dentin slice was irradiated for 32 seconds with a 200- micro m fiber optical waveguide under constant movement of the fibers. The remaining bacteria were then detached in NaCl under vibration. The eluate produced by this was - taking account of the degree of dilution - plated out on sheep blood agar plates. After 24 h of incubation, the grown bacterial colonies were able to be counted out and evaluated. By doing so, they were compared with the non-irradiated, but otherwise identically treated control group. With a slice thickness of 100 micro m, the 980-nm diode laser achieved a maximum bacterial reduction of 95% at 1.75 W, 96% at 2.3 W, and 97% at 2.8 W. With a slice thickness of 300 micro m, a maximum of 77% of the bacteria was destroyed at 1.75 W, 87% at 2.3 W, and 89% at 2.8 W. The maximum bacterial reduction with a slice thickness of 500 micro m was 57% at 1.75 W, 66% at 2.3 W, and 86% at 2.8 W. The results of this research show that the 980-nm diode laser can eliminate bacteria that have immigrated deep into the dentin, thus being able to increase the success rate in endodontic therapy.

Antimicrobial Efficacy of Various Root Canal Preparation Techniques: An In Vitro Comparative Study

In this study, we compared the antimicrobial efficacy of various root canal preparation techniques and instruments in the root canals of 40 human first maxillary premolars extracted for orthodontic reasons. After extirpation of the pulp, teeth were sterilized in an autoclave. Then, the root canals were infected with Enterococcus faecalis suspension and the teeth incubated at 37 degrees C for 24 h. Thereafter, the teeth were divided into five groups: preparation with K-file or K-Nitiflex file (step-back technique; groups 1 and 2), K-reamer (standardization technique; group 3), irrigation only (group 4), and no treatment (group 5). Before and after treatments, samples were taken for culture. Results were evaluated after 24-h incubation in E67 selective culture medium. We observed a considerable reduction in bacterial population after mechanical preparation. No significant differences were seen among the efficacy of the various preparation techniques and files used.

Endodontic teaching in Philippine dental schools.

The aim of this study was to evaluate the pattern of undergraduate endodontic teaching in Philippine dental schools. Data were gathered by sending questionnaires to the deans of the 23 dental schools in the country to determine details of the teaching of root canal treatment in permanent teeth. The covering letter requested that endodontic staff complete the questionnaire. Twenty of 23 dental schools returned completed questionnaires. Similarities were observed in the timing of undergraduate endodontic teaching, working length determination, and root canal preparation technique. Irrigating fluids recommended included one or a combination of the following: sodium hypochlorite, hydrogen peroxide, distilled water and EDTA. The root canal medicaments popularly employed were CMCP and eugenol. Most schools used slow-setting zinc oxide eugenol cement as sealer. Differences between schools were noted in the laboratory component of the course. The time allotted for the laboratory exercises, as well as the number of teeth used, differed greatly between each school. An inadequate tutor to student ratio was noted in the majority of schools. Teaching aids were limited and, in most instances, produced by faculty members. Most faculty members teaching endodontics had no specialist training. The results of this study have demonstrated that there is a need to review endodontic teaching in the majority of the Philippine dental schools to ensure that the course content and curriculum employed by all schools meet specified standards and that appropriate measures should be considered to enhance the learning experience of students.

Step-by-step description of a rotary root canal preparation technique.

CLINICAL TECHNIQUE: Since the introduction of nickel-titanium in endodontics, several canal preparation techniques involving the use of rotary instruments have become popular. Such engine-driven rotary instruments rotate between 150 and 2000 r.p.m. and may be high or low torque orientated. This paper describes one such engine-driven system called the ProFile technique. The instruments are of a different specification to that used for conventional endodontic files and reamers. This paper describes a technique employed by the Division of Endodontology, Zurich Dental School, in a step-by-step procedure using primarily photographs of radiographs. The intention is to give any interested clinician a better idea of the technique using radiographs taken from both the buccolingual (clinical) perspective and the mesiodistal projection. Basically, the technique involves preparing the coronal portion of the root canal using Gates-Glidden burs and the ProFile instruments. Only when any constricting coronal parts of the canals have been removed is the working length established using conventional files. Finally, the apical part of the canal is prepared using only the ProFile instruments. Three clinical cases are also briefly described, in order to illustrate the potential of the technique in cases treated generally by clinicians.

Scanning electron microscope study comparing four root canal preparation techniques in small curved canals

Scanning electron microscope study comparing four root canal preparation techniques in small curved canals