Instrumentation of root canals in molar using the step-down technique

A micro- computed tomographic study of the anatomic danger zone in mesial roots of permanent mandibular first and second molars

BACKGROUND

To investigate the geometric characteristics of the danger zone in the mesial roots of mandibular molars using micro-computed tomography (micro-CT).

METHODS

A total of 75 extracted mandibular first (50 were 2-rooted [2RM1] and 25 were 3-rooted [3RM1]) and 35 2-rooted mandibular second molars (2RM2) were collected and evaluated using micro-CT. The morphological aspects of the mesial roots associated with the danger zone (the canal curvature, minimum mesial [MWT] and distal canal wall thickness [DWT], depth and level of root concavities) were evaluated. One-way analysis of variance (ANOVA) was used for multiple group comparisons. Student's t-test or paired t-test was used to test the means between two groups.

RESULTS

All mesial roots curved severely (81.8%, 90/110) or moderately (18.2%, 20/110) towards the furcation side, and the mean angle was 25.3 ± 7.2 degrees. The presence of a distolingual root only had limited influence on the geometricgeometry of the mesial root. In the majority of cases, the mean DWT was less than the MWT, and statistical significance (all p < 0.05) was detected at 0-3 mm (MB and ML of 3RM1), 0-4 mm (MB of 2RM1, and MB and ML of 2RM2), 0-5 mm (single mesial canals of mandibular first and second molars), and 0-6 mm (ML of 2RM1) below furcation. The mean depth of distal concavities is always greater (all p < 0.05) than the mesial ones at each root level. Generally, the mean depth of distal concavities increased apically in the cervical portion, reaching the maximum value at 2 mm below furcation, and then declined gradually in the apical portion.

CONCLUSIONS

The mesial roots of mandibular first and second molars often exhibit severe distal curvature, with a mean Schneider's angle of 25.3 degrees, and the thinnest dentin wall is typically on the distal side. Distal root concavities are significantly deeper than mesial ones, with the maximum depth generally located 2 mm below the furcation. When identifying the danger zone, factors such as DWT should not be considered in isolation. Canal curvature, distal root concavities, and the type of instrument used are also critical in affecting the likelihood and location of strip perforation, though their precise roles warrant further investigations.

Glide Path in Endodontics: A Literature Review of Current Knowledge

The introduction of nickel-titanium rotary instruments revolutionized shaping procedures as they were able to produce a well-tapered preparation while reducing operator fatigue. The major drawback of rotary instruments was the high risk of fracture due to bending and torsional stress. Thus, the creation of a glide path has been advocated and recommended by most rotary instrument manufacturers. The aim of the present review is to summarize existing knowledge on glide path preparation and identify areas where further research is needed. The primary goal is to provide a comprehensive overview of the techniques and instruments used in glide path preparation, highlighting their advantages and limitations. The secondary goal is to explore the effect of glide path creation on the overall success of endodontic treatment, particularly in terms of reducing procedural errors and improving treatment outcomes. An online search on PubMed, ScienceDirect, UCLA, and Scopus databases was conducted, and 116 articles were identified. Eligible articles were divided into nine categories based on what they researched and compared. The categories included centering ability and/or root canal transportation, cyclic fatigue resistance, glide path and shaping time, tortional stress resistance, apical extrusion of debris and/or bacteria, defects in dentine walls, file separation, postoperative pain assessment, and scouting ability and performance. Establishing a glide path reduces root canal transportation, especially with rotary methods. Reciprocating and heat-treated files offer higher fatigue resistance and shorter preparation time. Instruments with shorter pitch lengths have greater torsional strength. Preparation and coronal preflaring reduce apical debris and bacteria. Glide paths do not affect dentine microcracks, file separation, or defects but reduce immediate postoperative pain and improve cutting ability. Randomized trials are needed to assess their impact on treatment outcomes.

Effect of different apical actions of new integrated endodontic motors on apical debris extrusion: An in vitro study

The new generation endodontic motors can perform different kinematics when they reach a certain predetermined level thanks to the integrated apex locator system. These actions consist of apical reverse, apical slow down and apical stop. The aim of this study is to compare this action's effect on apical debris extrusion. Sixty extracted human lower premolars were selected. Teeth are divided into four random groups (n = 15). Groups are prepared accordance to their group names as continuous rotation, apical slow down, apical reverse and apical stop. Extruded debris is collected into preweighted Eppendorf tubes and then calculated. One-way ANOVA test showed no statistically significant result between experimental groups. Similar debris extrusion values of all motion modes of the integrated endodontic motor can be interpreted that there will be similar debris extrusion and consequently similar postoperative pain on clinical setting. More in vitro and in vivo research is needed to make a conclusion.

Apical Extrusion: Is It an Inherent Occurrence During Every Endodontic Treatment?

The aim of this literature review was to analyze all available scientific data on apical extrusion and to identify and associate the possible factors influencing the occurrence of apical extrusion, ranging from the choice of the canal shaping system, the irrigation technique, to the choice of diameter and the apical limit of preparation. A bibliographic search for relevant articles on apical extrusion of debris, irrigants, and bacteria was performed using the following databases: PubMed, Cochrane Library, and ScienceDirect. This search identified articles published between 2010 and 2023 in two languages (French and English). After selective sorting, 25 relevant documents were included. All the studies retained clearly agree on the inherent nature of apical extrusion during endodontic treatment. At the same time, we also understand that the amount of extrusion can be influenced by a number of parameters throughout endodontic therapy. According to this review, despite the undeniable nature of apical extrusion during endodontic therapy, studies with relatable experimental models that approach in vivo conditions are required to establish exploitable conclusions regarding apical extrusion and its prevention.

Comparison of Er:YAG laser and ultrasonic in root canal disinfection under minimally invasive access cavity

The disinfection of root canal through minimally invasive access cavity remains questionable. This in vitro study compared the effectiveness of three disinfection measures including conventional irrigation, ultrasonic assisted irrigation, and erbium:yttrium-aluminum-garnet (Er:YAG) laser assisted irrigation through conventionally or minimally invasive access. Sixty-six extracted maxillary first molars were randomly divided into group 1 conventionally invasive access group (CIA) and group 2 computer-guided minimally invasive access group (MIA). Each group was further randomly divided into three subgroups, (A) conventional irrigation (CI), (B) passive ultrasonic agitation (PUI), and (C) Er:YAG laser activated irrigation (LAI). Enterococcus faecalis (E. faecalis) infection model was established inside all root canals after instrumentation was performed up to ProTaper Universal F2. After various disinfection methods, microbial samples were collected from root canals by paper tip method and cultured, and colony forming units (CFU) values of each sample were calculated. Then the root canals were enlarged to the size of F3, after which dentin debris was collected from the F3 file. After dilution and culturing, the CFU value was calculated for each group. Two-way analysis of variance (ANOVA) was performed to test the interaction. The results revealed a significant antagonism (F = 3.394, P = 0.043). The bacterial CFU counts of group B and group C were significantly less than that of group A (P < 0.05), and there was no significant difference between group B and C (P > 0.05). Additionally, group 2A was better than group 1A (P < 0.05); there was no significant difference between group 1B and group 2B, group 1C and group 2C (P > 0.05). Comparison of the bacterial CFU counts in dentin debris after disinfection, the results revealed a significant antagonism (F = 7.224, P = 0.002), and group C had the least. The disinfection effect of Er:YAG laser or ultrasonic assisted computer-guided minimally invasive access is similar to conventionally invasive access, and Er:YAG laser is better than ultrasonic in removing bacteria from dentinal tubules and is easy to operate, which is more suitable for minimally invasive root canal treatment.

Present status and future directions -Management of curved and calcified root canals

Root canal curvature and calcification introduce factors that increase the risk of procedural accidents during root canal treatment. The inability to achieve patency to the apical third, asymmetrical dentine removal leading to transportation, perforation and instrument fracture inside the curved trajectories are some of the procedural problems that might jeopardize the management of intraradicular infection and result in poor treatment outcomes. In fact, curved and constricted canals introduce such complexity that total instrumentation concepts and specially designed instruments have been developed to deal with the challenge. This narrative review seeks to provide and consolidate the principles necessary for understanding the dynamics of curved and constricted canal management and to improve the understanding for future developments in this field.

Impact of Contracted Endodontic Access Cavity on Shaping Ability of Hyflex Electrical Discharge Machining Single File Using Cone Beam Computed Tomography: An Ex Vivo Study

AIM: The aim of the study was to evaluate and compare the effect of different access cavity designs, using cone-beam computed tomography (CBCT), on root canal transportation, and centralization performed on two rooted maxillary premolars. METHODS: Twenty maxillary premolars were randomly divided into two groups. In Group 1, traditional endodontic cavities (TECs) were prepared. In Group 2, contracted endodontic cavities (CECs) were prepared. Mechanical preparation was done by HyFlex electrical discharge machining (EDM) single file in both groups. CBCT imaging was performed pre- and post-root canal preparation for calculations of root canal transportation and centering ability. RESULTS: Data were analyzed using Mann–Whitney U test and Kruskal–Wallis test. For transportation, teeth with CECs showed the statistically significantly highest median amount of transportation, while as for centering ability, results showed no significant difference between both groups. CONCLUSION: Under the conditions of this study, HyFlex EDM prepared canals with different access cavity designs without significant shaping errors. TEC showed less transportation than CEC, while both TEC and CEC had no effect on the file centering ability.

Comparative evaluation of apical extrusion of intracanal bacteria using ProTaper Next, Mtwo, and ProTaper rotary systems: An in vitro study

Aim:

The aim of this study was to evaluate the number of intracanal bacteria extruded apically after instrumentation with three different nickel–titanium rotary instruments.

Materials and Methodology:

Forty freshly extracted mandibular premolars were selected, access cavities were prepared, and the teeth were mounted in the bacterial collection apparatus. Root canals were contaminated with a suspension of Enterococcus faecalis and incubated for 24 h at 37°C. The contaminated teeth were divided into four groups of 10 teeth each according to the rotary system used for instrumentation: Group 1: ProTaper universal files, Group 2: MTwo files, Group 3: ProTaper Next files, and Group 4: Control group (no instrumentation). Bacteria extruded after preparations were collected into vials. The number of colony-forming units (CFUs) was determined for each sample.

Statistical Analysis:

The data obtained were analyzed using the one-way analysis of variance followed by post hoc Tukey’s test with a P = 0.05 as the level for statistical significance.

Results:

The results suggested a statistically significant difference in the number of CFUs between four experimental groups (P < 0.001).

Conclusion:

Least amount of bacterial extrusion was seen in ProTaper Next Group while more bacterial extrusion was seen in MTwo Group.

Undergraduate endodontic clinical training in Malaysia: A National survey

AIM

Online survey was conducted to investigate the state of undergraduate endodontic clinical training in Malaysian dental schools.

METHODS

An online questionnaire and a cover letter were emailed to the deans of 13 Malaysian dental schools. The questionnaire covers various aspects of endodontic clinical training including teaching methods, endodontic clinical procedures, minimum requirements, clinical sessions and teaching staff.

RESULTS

The response rate was 69%. Similarities in teaching methods were observed in all responding schools. All schools taught contemporary root canal treatment procedures, including the utilisation of radiograph and electronic apex locator for working length determination, the crown-down approach for canal preparation and the cold lateral compaction for obturation. Sodium hypochlorite solution and non-setting calcium hydroxide medicament were used in most dental schools. Variations were observed in terms of the number of clinical requirements, supervisor: student ratio, and availability of endodontic specialists. The use of engine-driven instruments was observed mainly in government-funded dental schools.

CONCLUSIONS

The majority of dental schools in Malaysia are adopting the European Society Endodontology recommendation for undergraduate endodontic training, particularly in relation to the surveyed aspects. Most of the government-funded dental schools have progressed towards engaging contemporary endodontics with their increasing application of engine-driven Ni-Ti instruments and 3D imaging techniques. Appointments of full-time endodontic specialists would further enhance the quality of endodontic teaching and permit the utilisation of contemporary endodontic materials.

Does the type of endodontic access influence in the cyclic fatigue resistance of reciprocating instruments?

INTRODUCTION

The aim of the present study was to compare the cyclic fatigue resistance of Reciproc R25 (R25) and Reciproc Blue R25 (R25B) instruments, after simulated clinical use in traditional (TradAC) and ultraconservative (UltraAC) endodontic access cavities.

METHODS

Forty mandibular molars were randomly assigned into the following groups, according to the type of access and instrument to be used: TradAC and R25, TradAC and R25B, UltraAC and R25, and UltraAC and R25B. Teeth were accessed accordingly, and the root canals were prepared using "RECIPROC ALL" kinematics. The cyclic fatigue resistance of the forty used instruments was obtained measuring the time to fracture in an artificial stainless-steel canal. Ten brand new R25 and R25B were used as control groups. The fracture surfaces and the side cutting edges of the instruments were examined with a scanning electron microscope. Data were statistically analyzed using one-way ANOVA and post hoc Tukey tests with a significance level of P < 0.05.

RESULTS

R25B instruments showed significantly higher cyclic fatigue resistance than R25, regardless of the access cavity type (P < 0.05). No differences were observed in the cyclic fatigue resistance between instruments without simulated clinical use and used in TradAC (P > 0.05). R25 and R25B used in UltraAC showed significantly lower cyclic fatigue resistance compared with the instruments used in TradAC and without simulated clinical use (P < 0.05).

CONCLUSIONS

R25B files showed improved cyclic fatigue resistance than R25. The use of R25B and R25 files in mandibular molars with UltraACs decreased their cyclic fatigue resistance, compared with TradAC.

CLINICAL RELEVANCE

The use of Reciproc and Reciproc Blue files in mandibular molars with ultra-conservative endodontic access cavities reduced their cyclic fatigue resistance. Clinicians should be aware about the reduced cyclic fatigue resistance of these files when used in mandibular molars with UltraAC, due to the synergistic effect of access angulation and severe curvature induced in the endodontic files.

The efficacy of five different techniques in identifying C-shaped canals in mandibular molars

Information regarding the canal anatomy especially in complex cases such as C-shaped canals is essential for a successful treatment. In this study, five different methods for identification of C-shaped canal configuration were compared. 108 extracted mandibular molars with fused roots were studied. Radiographic evaluation was carried out using periapical radiography and CBCT. After access cavity preparation, all specimens were evaluated by direct visual examination and then under dental operating microscope. Finally, the actual anatomy of each sample was determined by preparing horizontal cross sections of the roots (1 mm thick) and examining them under stereomicroscope as the gold standard. Among the techniques used, high-resolution CBCT manifested the highest accuracy, whereas periapical radiography had the lowest. All approaches can be useful in reaching a correct diagnosis. CBCT, especially the low-resolution modality, is an effective technique in the diagnosis of C-shaped anatomy.

Comparative evaluation of apical bacterial extrusion following root canal instrumentation using different endodontic file systems: An in vitro study

Aim:

This study aims to evaluate the amount of apical extrusion of bacteria during root canal instrumentation using K3XF, Protaper Gold, Edge taper platinum, and Hyflex CM Rotary systems.

Materials and Methods:

Sixty freshly extracted maxillary incisors teeth collected in saline. Access cavity prepared and canals were made free of bacterial and pulp. The teeth were mounted on the bacteria collecting apparatus. Root canals were contaminated with the Fusobacterium Nucleatum (ATCC25586) and dried at 37°C for 24 h. In Group 1 (Control group): No instrumentation was done and biomechanical preparation done in all other groups with Group 2: Hand K-files, Group 3: Protaper gold, Group 4: K3XF, Group 5: Edge taper platinum, and Group 6: Hyflex CM rotary file systems. Then, the extrude was collected, and it is incubated in Mueller-Hinton agar for 24 h and the number of colony forming units were counted and statistical comparison was done using Kruskal–Wallis test and Mann–Whitney U test.

Results:

Hand K-files extruded more bacteria when compared to other four rotary systems, K3XF file system extruded least number of bacteria.

Conclusion:

All instrumentation techniques extruded intracanal bacteria apically. However, engine-driven nickel-titanium instruments extruded less bacteria than the manual technique. The K3XF rotary file system comparatively extruded less bacteria than other rotary file systems.

Comparison of post-operative pain after root canal instrumentation with hand K-files, H-files and rotary Kedo-S files in primary teeth: a randomised clinical trial

PURPOSE

To compare the post-operative pain after root canal instrumentation with hand K-files, H-files and rotary Kedo-S in primary teeth.

METHOD

All 4-6-year-old children were invited and 69 agreed to participate. The participants were randomly divided and distributed for instrumentation with K-file (Group 1), H-file (Group 2) and rotary Kedo-S files (Group 3). After completion of root canal procedure, the post-operative pain was evaluated at intervals of 6, 12, 24, 48, and 72 h using modified Wong-Baker pain scale and compared between the groups.

RESULTS

Post-operative pain between three groups at 6, 12, 24, 48 and 72 h was compared using Chi square test. There was decreased post-operative pain with Kedo-S rotary files as compared to other two groups (P value < 0.001). The post-operative pain decreased after 12 h for all the groups with no pain at 24, 48 and 72 h intervals.

CONCLUSION

Paediatric rotary files Kedo-S showed significantly less post-operative pain as compared to K-file and H-file at 6 h and 12 h intervals. However, follow-up interval of 24, 48 and 72 h showed no significant difference between the rotary and hand file groups.

Comparative evaluation of the effectiveness and fracture rate of three pathfinding nickel-titanium rotary instruments, Mtwo, OneG, and ProGlider, in mechanically negotiating moderately curved molar canals to the full working length

Aim:

To evaluate the scouting ability of three pathfinding nickel-titanium rotary instruments in moderately curved molar canals.

Materials and Methods:

Ninety maxillary and mandibular molars were collected and were divided randomly into three groups each having 15 maxillary and 15 mandibular molars. The teeth were mounted on a specific apparatus for simulation of dento-alveolar socket. After access cavity preparation, the canals were negotiated with 08 K-file. Glide path preparation was performed using Mtwo or ProGlider or OneG instruments. The number of teeth in which the file reached the full working length (RFWL), number of passes required, and number of fractured instruments were recorded and subjected to statistical analysis using Chi-square, Kruskal–Wallis, and Mann–Whitney tests.

Results:

There was a significant difference between the groups (P < 0.05). The RFWL of ProGlider was significantly higher than that of Mtwo (P = 0.005) and OneG (P = 0.037). The percentage of fracture with ProGlider was 6.67% and both Mtwo and OneG had 26.67% frequency. The difference was not statistically significant (P > 0.05). There was significant difference in the number of insertion passes in maxillary distobuccal (P < 0.05), mandibular mesiobuccal (P < 0.01), and distal (P < 0.01) canals. ProGlider was the most effective pathfinding instrument due to its file's design and a progressive taper of 2%–8%. This achieves a greater preflaring of the coronal and middle portions of the root canal, rendering the advance of the instrument toward the apex easier.

Conclusion:

ProGlider performed more efficiently and with less instrument breakage in scouting moderately curved canals of molar teeth.

Endodontic Procedural Errors by Students in Two Saudi Dental Schools

Objective:

To explore endodontic procedural errors committed by undergraduate dental students in King Khalid University (KKU), Abha and AlFarabi dental college, Riyadh.

Methods:

In this cross sectional study, a questionnaire was distributed to 500 dental students from both schools and of both genders in the 5th and 6th levels in the academic year 2016–2017. Participants were asked to record their endodontic procedural error(s) that had occurred during training.

Results:

Returned and eligible questionnaires were 469 (93.8% response rate) and were almost equally distributed by university (KKU and Alfarabi). The participants’ age ranged from 22 to 24 years, and approximately 47% of them were female students and 65% were 6th level students. Almost 56% of the sample reported at least one endodontic procedural error during their training. Female students reported errors (65%) more frequently than the male students (49%; P=0.002). Up to 54% of these errors were in the posterior teeth and 65% were in teeth with curved roots. Most common error during access cavity preparation was gouging (68%) and due to instrumentation was ledge formation (47%), during obturation was voids (41%). There were no differences in the reported endodontic errors between the two universities.

Conclusion:

The frequency of reported endodontic procedural errors by senior dental students in both schools, more specifically those in the 6th year, is high. Ledge formation and voids in the root canal filling are the most frequently reported endodontic errors.

Shaping of the Root Canal System: A Multistep Technique

AIM

The aim of this scientific work is to illustrate the technique of shaping the root canal system using the multistep technique.

BACKGROUND

Over time, various endodontic instrumentation techniques have been put forward, from the "step-back" technique (apical-coronal) to the "crown-down" technique (coronal-apical), the "double-flared" technique, and the most recent "single-length" technique.

TECHNIQUE

The multistep technique involves six steps, one of the main objectives of these being the safety of the use of mechanical instruments with a reduction in the risk that they fracture. This technique ("mixed") provides for the use of both manual instruments in stainless steel and mechanical instruments in nickel titanium (Ni-Ti).

CONCLUSION

The multistep technique is based on a standardized, flexible, and clinical protocol, which can provide for a reduction in the number of endodontic passages and instruments used and, therefore, a simplification of the operating procedure depending on both the difficulty of the root canals and the competence of the operator.

CLINICAL SIGNIFICANCE

This technique is a technique for shaping the endodontic space that allows the set objectives of endodontic therapy to be reached in a predictable way with a reduced risk of iatrogenic complications.

Evaluation of conventional, protaper hand and protaper rotary instrumentation system for apical extrusion of debris, irrigants and bacteria- An in vitro randomized trial

BACKGROUND

Endodontic instrumentation carries the risk of over extrusion of debris and bacteria. The technique used and the type of instrumentation influences this risk.

AIM

The purpose of this study was to evaluate and compare the K-file, ProTaper hand and ProTaper rotary instrumentation systems for the amount of apically extruded debris, irrigant solution and intracanal bacteria.

DESIGN

Experimental single blinded randomized type of in vitro study with sample of 30 single rooted teeth. Endodontic access cavities were prepared and the root canals were filled with the suspension of E. faecalis. Myers and Montogomery Model was used to collect apically extruded debris and irrigant. Canals were prepared using K files, Hand protapers and Protaper rotary files.

STATISTICAL ANALYSIS

Non Parametric test like Kruskal-Wallis and Mann-Whitney U test were applied to determine the significant differences among the group.

RESULTS

Tests revealed statistically significant difference between the amount of debris and number of bacteria extruded by the ProTaper hand and the K-files. No statistically significant difference was observed between the amounts of irrigant extruded by the ProTaper hand and the K-file system. Statistically significant differences were observed between the amounts of bacteria and irrigant extruded by the ProTaper rotary and the Protaper hand. No statistically significant difference was observed between the amounts of debris extruded by the ProTaper hand and the K-file system.

CONCLUSIONS

Amount of apical extrusion of irrigant solution, bacteria and debris are significantly greater with K File instruments and least with Protaper rotary instruments. Key words:Protaper, rotary, periapical extrusion.

Comparison of apical centring ability between incisal-shifted access and traditional lingual access for maxillary anterior teeth

The aim of this study was to compare the apical centring ability of incisal-shifted access (ISA) with that of traditional lingual access (TLA). Fifteen three-dimensional printed resin models were prepared from the computed tomography data for a human maxillary central incisor and divided into ISA (n = 7), TLA (n = 7) and control (n = 1) groups. After access preparation, these models were shaped to the working length using K-files up to #40, followed by step-back procedures. An apical portion of the model was removed at 0.5 mm coronal to the working length. Microscopic images of each cutting surface were taken to measure the preparation area and the distance of transportation. TLA created a larger preparation area than ISA (P < 0.05). The distance of transportation (mean ± standard deviation) was 0.4 ± 0.1 mm for ISA and 0.7 ± 0.1 mm for TLA (P < 0.05). Access cavity preparation has a significant effect on apical centring ability. ISA is beneficial to maintaining apical configuration.

The dentin thickness remaining in the risk zone of mandibular molars after cervical preflaring with four methods

Abstract Introduction Cervical preflaring is an important step of the canal system instrumentation, but can lead to excessive enlargement or root perforation. Objective Evaluate the remaining dentin thickness in the mandibular molars of mesial roots using cone beam computed tomography: Gates-Glidden (crown-down); Gates-Glidden (step-back); LA Axxess and Easy Pro-Design. Material and method Were selected 40 lower molars mesial roots, which were scanned in a cone beam CT scanner before and after preparation. Were obtained five sections of the CT images with an interval of 1 mm from the furcation, and measured the thickness variation between the root canal to the root external portion in analysis software. Result The evaluation of the different levels showed no significance within the same group for the Gates-Glidden group. On the other hand, were observed difference for LA Axxess (p=0.002) and Easy Pro-Design (p=0.005). In the intergroup analysis, were observed difference in all levels, especially for Gates-Glidden in the ascendant order (ANOVA and Tukey). Conclusion Within the limitations of these study, is possible to conclude that the protocol with greater wear in the cervical risk area was the Gates-Glidden in step-back sequence, as the other groups were equivalent (p>0.05).

Apical Extrusion of Intracanal Bacteria following use of Two Engine-driven Instrumentation Techniques: An in vitro Study

AIM

The aim of the present study was to compare in vitro the amount of debris extruded apically from extracted teeth, using Twisted files and ProTaper rotary during two different instrumentation systems.

MATERIALS AND METHODS

Forty-five human single-rooted mandibular premolar teeth were randomly divided into three groups and contaminated with Enterococcus faecalis. The teeth in experimental groups were instrumented until reaching the working length with ProTaper rotary instruments and Twisted files with XSmart and XSmart Dual groups. Debris extruded from the apical foramen was collected into glass vials and the amount of bacteria was calculated. The data obtained were analyzed using Kruskal-Wallis one-way analysis of variance and Mann-Whitney U tests, with p = 0.05 as the level for statistical significance.

RESULTS

The XSmart Dual group extruded comparatively lesser bacteria compared to the XSmart group. Lesser amount of bacterial extrusion was seen when Twisted files were used compared to the ProTaper files (p < 0.05).

CONCLUSION

Under the circumstances of this in vitro study, it can be concluded that all instrumentation techniques produced measurable apical extrusion of debris. So, it is upon the practitioner to decide which system best fits their individual needs and their level of skill and experience that will provide the best possible endodontic care for our patients.

CLINICAL SIGNIFICANCE

The newer instrument designs, including noncutting tips, different cross sections, radial lands, and variable tapers, are better for the clinicians to improve working safety, to reduce the working time, and to create a greater flare within the preparations.

A Comparison of Apical Bacterial Extrusion in Manual, ProTaper Rotary, and One Shape Rotary Instrumentation Techniques

INTRODUCTION

Apical extrusion of irrigants and debris is an inherent limitation associated with cleaning and shaping of root canals and has been studied extensively because of its clinical relevance as a cause of flare-ups. Many factors affect the amount of extruded intracanal materials. The purpose of this study was to assess the bacterial extrusion by using manual, multiple-file continuous rotary system (ProTaper) and single-file continuous rotary system (One Shape).

METHODS

Forty-two human mandibular premolars were inoculated with Enterococcus faecalis by using a bacterial extrusion model. The teeth were divided into 3 experimental groups (n = 12) and 1 control group (n = 6). The root canals of experimental groups were instrumented according to the manufacturers' instructions by using manual technique, ProTaper rotary system, or One Shape rotary system. Sterilized saline was used as an irrigant, and bacterial extrusion was quantified as colony-forming units/milliliter. The results obtained were statistically analyzed by using one-way analysis of variance for intergroup comparison and post hoc Tukey test for pair-wise comparison. The level for accepting statistical significance was set at P < .05.

RESULTS

All the instrumentation techniques resulted in bacterial extrusion, with manual step-back technique exhibiting significantly more bacterial extrusion than the engine-driven systems. Of the 2 engine-driven systems, ProTaper rotary extruded significantly more bacteria than One Shape rotary system (P < .05).

CONCLUSIONS

The engine-driven nickel-titanium systems were associated with less apical extrusion. The instrument design may play a role in amount of extrusion.

A Comparative SEM Investigation of Smear Layer Remaining on Dentinal Walls by Three Rotary NiTi Files with Different Cross Sectional Designs in Moderately Curved Canals

OBJECTIVE

The objective of this study was to compare the smear layer formed on root canal walls during canal preparation of extracted human teeth by Twisted, Mtwo, and ProTaper rotary nickel titanium instruments.

MATERIALS AND METHODS

Sixty single rooted human premolar teeth with root curvature <25(0) were selected and randomly divided into three Groups (n= 20 teeth per Group). Three types of rotary nickel titanium instruments were used, Twisted (SybronEndo, Orange, CA, USA), Mtwo (VDW, Munich, Germany) and ProTaper (Dentsply Maillefer, Ballaigues, Switzerland) according to manufacturer's instructions to instrument the root canals. Irrigation for all groups was performed after each instrument change with 3ml of 3% sodium hypochlorite followed by Glyde (File Prep, Dentsply, Maillefer, Ballaigues, Switzerland) as chelator paste and lubricant. Three different areas (coronal, middle and apical thirds) of the root canal were evaluated using scanning electron microscopy (SEM). The canal wall of each sample was assessed and compared using a predefined scale for the presence or absence of smear layer. Data were analysed statistically using ANOVA and Tukey HSD test Results: All three groups showed statistically significant more smear layer in the apical thirds of the canal as compared to the coronal and middle thirds (p<0.001). Mtwo rotary file system produced significantly less smear layer (p<0.001) compared to Twisted and ProTaper rotary instruments in the apical portion. Twisted Files resulted in less smear layer formation in the apical thirds of the canal compared to ProTaper rotary instruments but were statistically insignificant.

CONCLUSION

Completely clean root canals were not found after instrumentation with any of the three instruments. Under the confines of this study Mtwo instruments produced significantly cleaner dentin wall surfaces throughout the canal length in comparison to Twisted and ProTaper rotary files. Twisted Files proved to be comparable to ProTaper rotary instruments with respect to canal cleanliness in the apical thirds of the root canal.

Comparative evaluation of apically extruded debris during root canal preparation using ProTaper™, Hyflex™ and Waveone™ rotary systems

BACKGROUND AND AIMS

Extrusion of any debris during endodontic treatment may potentially cause post-operative complications such as flare-ups. The purpose of this in vitro study was to assess the amount of apically extruded debris during the root canal preparation using rotary and reciprocating nickel-titanium instrumentation systems.

MATERIALS AND METHODS

In this study, 60 human mandibular first premolars were randomly assigned to 3 groups (n = 20 teeth/group). The root canals were instrumented according to the manufacturers' instructions using the Reciprocating single-file system WaveOne™ (Dentsply Maillefer, Ballaigues, Switzerland) and full-sequence rotary Hyflex CM™ (Coltene Whaledent, Allstetten, Switzerland) and ProTaper™ (Dentsply Maillefer, Ballaigues, Switzerland) instruments. The canals were then irrigated using bidistilled water. The debris that was extruded apically was collected in preweighed eppendorf tubes and assessed with an electronic balance and compared.

STATISTICAL ANALYSIS USED

The debris extrusion was compared and statistically analyzed using analysis of variance and the post hoc Student-Newman-Keuls test.

RESULTS

The WaveOne™ and ProTaper™ rotary instruments produced significantly more debris compared with Hyflex CM™ rotary instruments (P < 0.05).

CONCLUSIONS

Under the conditions of this study, all systems that were used resulted in extrusion of apical debris. Full-sequence rotary instrumentation was associated with less debris extrusion compared with the use of reciprocating single-file systems.

Comparative assessment of the effects of Gates-Glidden, Largo, LA-Axxess, and New Brazilian Drill CPdrill on coronal pre-enlargement: cone-beam computed tomographic analysis

INTRODUCTION

The removal of dentin interferences from the cervical third of root canals is essential for their correct cleaning and shaping and to facilitate access of endodontic instruments to the critical apical region. In mandibular molars, the concavity observed in the furcation area reduces dentin thickness, making this region more susceptible to perforation. The present ex vivo study used cone-beam computed tomographic imaging to compare 3 rotary burs with a new rotary bur recently launched in Brazil (ie, CPdrill; Helse Industry and Commerce Ltda, Santa Rosa, São Paulo, Brazil) regarding the amount of dentin removal from the distal wall of the mesial root of mandibular first molars.

METHODS

A total of 40 root canals were selected and randomly divided into 4 groups for cervical preparation: Gates-Glidden burs #2 and #3 (Dentsply Maillefer, Ballaigues, Switzerland), Largo burs #1 and #2 (Dentsply Maillefer), LA-Axxess burs #1 and #2 (SybronEndo, Glendora, CA), and CPdrill burs (1-size only). Dentin thickness in the distal wall of mesial canals at 2 mm from the furcation was measured using I-CATvision software before and after cervical preparation.

RESULTS

There was no statistically significant difference between groups regarding residual dentin thickness after instrumentation with the drills (P = .684).

CONCLUSIONS

It was concluded that CPdrill is safe for use in cervical preparation of the mesial root of mandibular first molars because it did not promote excessive dentin removal on distal walls.

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.

Quantitative evaluation of apical extrusion of intracanal bacteria using K3, Mtwo, RaCe and protaper rotary systems: An in vitro study

Aim:

This aim of this study was to evaluate the number of bacteria extruded apically during root canal preparation using Four Rotary instrumentation techniques.

Materials and Methods:

A total of 50 extracted mandibular premolars were selected, access cavities prepared and inserted in to rubber stoppers of 10 mL glass vial. Root canals were contaminated with a suspension of Enterococcus faecalis (E. faecalis) American Type Culture Collection (ATCC) 29212 and incubated for 24 h at 37°C. Debris extruded from the apical foramen during instrumentation was collected into vials. The numbers of Colony-forming units were determined for each sample.

Statistical Analysis:

The data obtained were analyzed using the one-way ANOVA followed by post-hoc tukey's test with a P = 0.05 as the level for statistical significance.

Results:

Results suggested a statistically significant difference in the number of colony forming units between four experimental rotary Nickel-Titanium instrumentation groups (P < 0.001).

Conclusion:

Although, extrusion of bacteria was found in all the experimental groups. There was less bacterial extrusion in K3 Group while more bacterial extrusion was seen in Mtwo Group.

Weight of apically extruded debris following use of two canal instrumentation techniques and two designs of irrigation needles

AIM

To compare the weight of apically extruded debris associated with canal shaping using K-files, and the Revo-S system using two different needle tips, open-ended and side-vented.

METHODOLOGY

Forty freshly extracted mandibular premolar teeth were divided into four groups as follows; Group 1a: Hand instrumentation of root canal with open-ended needle used to provide irrigation, Group 1b: Hand instrumentation with a two side-port needle, Group 2a: Revo-S preparation with open-ended needle, Group 2b: Revo-S preparation with a two side-port needle. One Eppendorf tube for each tooth was weighed with a 0.0001 electronic weighing machine before instrumentation procedures. During instrumentation, irrigation was performed after every instrument with 1 mL distilled water. On completion of the preparation, teeth were removed from the Eppendorf tubes. All of the tubes were incubated at 37 °C for 15 days, to evaporate the irrigant. After the incubation period, tubes were weighed again. The difference between pre-and post-debris weights was calculated, and statistical evaluation was performed using analysis of variance at 0.05 level of significance.

RESULTS

No statistically significant difference was observed between K-files and the RevoS system. A significant difference was observed between needles (P < 0.05). Open-ended needles were associated with significantly more debris than side-vented needles (P < 0.05).

CONCLUSIONS

Both hand and rotary canal instrumentation resulted in extrusion of debris beyond the apical foramen. No significant difference was observed between K-files and Revo-S system. Open-ended needles were associated with significantly more extruded debris than two side-port needles.

Apical extrusion of debris and irrigants using hand and three rotary instrumentation systems − An in vitro study

Introduction:

Sterilization of the root canal is a prime aim of successful endodontics. The cleaning and shaping of the canal is directed as achieving this goal. The extrusion of apical debris has a deleterious effect on the prognosis of root canal treatment. Several instrument designs and instrumentation techniques have been developed to prevent this.

Materials and Methods:

Forty caries free single rooted human mandibular premolar teeth were divided in four groups of ten teeth each. Teeth in each group were instrumented until the working length with rotary ProTaper, K3, Mtwo systems, and hand K-type stainless steel files. Debris and irrigant extruded from the apical foramen were collected into vials and the amounts were quantitatively determined. The data obtained were analyzed using Kruskal-Wallis one-way analysis of variance and Mann-Whitney U tests.

Results:

The results show that all instrumentation techniques produced significant amount of extruded debris and irrigant. The engine-driven nickel-titanium systems showed less apical extrusion of debris and irrigant than manual technique. No statistically significant difference was found between the groups at [P > 0.05]. Maximum apical debris and irrigant extrusion was seen with K-file group and least in the Mtwo group.

Conclusions:

The use of rotary files and techniques to perform instrumentation does show less extrusion of the debris and irrigant from the apex. This can contribute to more successful endodontic therapy.

Thickness of dentine in mesial roots of mandibular molars with different lengths

AIM

To measure the minimum thickness of the distal (furcal) root dentine associated with the buccal and lingual canals of the mesial roots of mandibular first molars with different lengths.

METHODOLOGY

The mesial roots of 285 mandibular first molars were allocated into three groups according to their length: group I - long (24.14 mm +/- 0.85), group II - medium (22.10 mm +/- 0.65) and group III - short (19.97 mm +/- 0.75). The minimum thickness of the distal (furcal) root dentine associated with the buccal and lingual canals of the mesial roots 2 mm below the furcation was measured. The distance between the buccal and lingual canals, and the depth of concavity in the distal surface of the mesial roots were also measured. anova and Tukey-Kramer were used to test for significant differences among the groups.

RESULTS

The minimum thickness of the distal wall of the mesiobuccal canal was significantly different (P < 0.05) between group I (long) and III (short), with long teeth having the smallest mean values. No significant difference was found in the thickness of the distal wall of the mesiolingual canal among the groups studied (P > 0.05). The shortest distance between the mesiobuccal and the mesiolingual canals was observed in group III (P < 0.05). The distal (furcal) concavity was deeper in group I (P < 0.05) when compared with the other groups.

CONCLUSION

There was a significant difference in the minimum thickness of the distal (furcal) root wall of the mesiobuccal canal of mandibular first molars 2 mm below the furcation between group I (long) and group III (short) teeth. The thinnest walls were found in the longest teeth. The deepest concavities in the distal (furcal) walls of the mesial roots were found in the longest roots.

Micro-computed tomographic comparison of nickel-titanium rotary versus traditional instruments in C-shaped root canal system

INTRODUCTION

The purpose of this study was to assess the efficacy of instrumentation of C-shaped canals with ProTaper rotary system and traditional instruments by using micro-computed tomography (micro-CT).

METHODS

Twenty-four mandibular molars with C-shaped canals were selected in pairs and sorted equally into 2 groups, which were assigned for instrumentation by ProTaper rotary system (ProTaper group) or by K-files and Gates-Glidden burs (Hand Instrument group). Three-dimensional images were constructed by micro-CT. The volume of dentin removed, uninstrumented canal area, time taken for instrumentation, and iatrogenic error of instrumentation were investigated.

RESULTS

Hand Instrument group showed greater amount of volumetric dentin removal and left less uninstrumented canal area than ProTaper group (P < .01). The time needed for instrumentation was shorter for ProTaper group than for Hand Instrument group (P < .05). No instrument breakage occurred in both groups, but more conspicuous procedural errors were detected in Hand Instrument group than for ProTaper group.

CONCLUSIONS

It was concluded that ProTaper rotary system maintained the canal curvature with speediness and few procedural errors, whereas traditional instrumentation can clean more canal surface.

Evaluation of surface preparation and maintenance of canal curvature following instrumentation with hand 'K' file and three different Ni-Ti rotary systems: A radiographic and SEM study

Aim:

To determine the shaping ability and cleaning efficiency of hand K-flexofiles, ProTaper, LightSpeed and Mtwo instruments during the preparation of curved root canals in extracted human teeth.

Materials and Methods:

A total of 120 root canals of mandibular and maxillary molars with curvature more than 20° were divided into four groups of 30 each. In group A, canals were prepared using hand K-flexofiles following the crown down technique. In group B LightSpeed, in group C ProTaper, and in group D Mtwo rotary instruments were used to prepare the root canals. Using pre- and post-instrumentation radiographs, straightening of the canal curvature was determined with Corel Draw 9.0 software tools. The amount of debris and smear layer were quantified at three different areas (coronal, middle, and apical thirds) of root canal using SEM. The collected data were analyzed statistically using Student's paired ‘t’ test.

Results:

The mean change in curvature for hand K-files was 7.71°, for ProTaper files 6.03°, for Mtwo 5.43°, and for LightSpeed instruments were found to be 4.57°. The percentage change in the curvature for all the four groups was statistically highly significant (P< 0.01). LightSpeed instruments maintained the original canal curvature significantly (P< 0.01) better than the other instruments. For leftover debris, the minimum percentage was found to be associated with ProTaper (65.48%) followed by Mtwo (66.22%), LightSpeed (71.67%) and the maximum with hand K-files (74.16%). However, the difference in mean leftover debris between ProTaper and Mtwo was not significant.

Conclusion:

ProTaper and Mtwo resulted in good cleaning, and LightSpeed maintained the original canal curvature better than the ProTaper, Mtwo, or Hand K-files.

Cleaning ability of chlorhexidine gel and sodium hypochlorite associated or not with EDTA as root canal irrigants: a scanning electron microscopy study

The aim of this study was to evaluate the cleaning efficacy of 2% chlorhexidine gluconate gel (CHX) compared to 2.5% sodium hypochlorite solution (NaOCl) associated or not with 17% EDTA used as irrigants during the biomechanical preparation. Fifty freshly extracted single-rooted human teeth with complete apex formation were randomly divided into five groups: G1 - sterile saline, G2 - 2.5% NaOCl, G3 - 2% CHX, G4 - 2.5% NaOCl + EDTA and G5 - 2% CHX + EDTA. The specimens of G1 were subdivided into two control groups. The teeth were decoronated and the coronal and middle root thirds were prepared with Gates-Glidden burs, and the apical third was reserved to manual instrumentation. All procedures were performed by a single operator. In all groups, 2 mL of irrigant was delivered between each file change. The teeth were sectioned and prepared for analyses under scanning electron microscopy (SEM). SEM micrographs were graded according to a score scale by two examiners. Data were analyzed statistically by Kruskal-Wallis and Dunn tests at 1% significance level. The best results were obtained in the groups in which the irrigant was used followed by the chelating agent. No statistically significant difference was observed among G4, G5 and the positive control group (p<0.01). The groups G2 and G3 were significantly different from the others, presenting the worst cleaning capacity. In conclusion, the use of the chelating agent is necessary to obtain clean canal walls, with open tubules and no heavy debris. The use of 2% chlorhexidine gluconate gel alone is not able to remove the smear layer.

Evaluation of apical deviation in root canals instrumented with K3 and ProTaper systems

Objectives:

this study evaluated the apical deviation of curved root canals instrumented with K3 and ProTaper systems.

Material and methods:

twenty root canals of human maxillary and mandibular first molars were employed, which were divided into 2 groups: group A (10 teeth) was instrumented with the K3 system, and group B (10 teeth) with the ProTaper system. Evaluation of deviation was performed by double radiographic exposure. Radiographs were achieved before and after instrumentation, with 0.3-second, thus allowing superimposition of images. Three-dimensional computerized tomograph was performed in 3 specimens in each group, as an additional means to evaluate the apical deviation.

Results:

were evaluated by the parametric test Student-Newman-Keuls at 5%, which did not reveal significance between groups concerning the apical deviation. The results of computerized tomograph images demonstrated that the larger deviation of the root canal occurred at the distolingual area for both systems.

Conclusions:

both techniques produced a mild apical deviation. Computerized microtomography was shown to be accurate for experimental endodontics studies.