Assessment of Smear Layer Removal and Penetration Depth of Root Canal Irrigant Using Different Irrigation Activation Systems: A Comparative Study.

AIM: The aim of the current study was to evaluate the penetration depth and smear layer removal of root canal irrigant using various irrigation activation techniques. MATERIALS AND METHODS: In this investigation, sixty single-rooted premolars extracted for orthodontic purposes were chosen. Diamond burs were used to create an access cavity, and #10 K-file was used to determine the patency. About sixty samples were divided into the following three groups (20 samples in each group), group I: Irrigation with conventional needle, group II: Activation of EndoVac system, group III: Passive ultrasonic irrigation (PUI). The efficacy of the smear layer was assessed using a scanning electron microscopy at a ×2000 magnification. One-way ANOVA was used to record and analyze the data. All statistical analyses were performed with a significance level of p < 0.05. RESULTS: At coronal third, the maximum smear layer was removed in group II (1.26 ± 0.02) followed by group III (1.84 ± 0.16) and group I (2.89 ± 0.21). At middle third, smear layer removal was maximum in group I (1.18 ± 0.10) followed by group III (1.72 ± 0.09) and group I (2.66 ± 0.18). At apical third, the more smear layer was removed in group II (1.02 ± 0.01) followed by group III (1.58 ± 0.08) and group I (2.38 ± 0.06). There was a highly significant difference found between the three different irrigation systems at all three levels (p < 0.001). CONCLUSION: In conclusion, every irrigation device that was evaluated was successful in removing the smear layer from the root canal. However, the EndoVac system group removed a greater amount of smear layer compared with PUI and conventional needle group. CLINICAL SIGNIFICANCE: With the goal of promoting cleaning that is beyond the ability of mechanical devices, irrigation is a crucial part of root canal therapy. If an efficient irrigation delivery system is used, the irrigants can reach the working length (WL). This type of distribution system needs to provide a suitable amount of irrigants up to the WL, as well as have enough flow and be effective at debriding the entire canal system. How to cite this article: Pujari MD, Das M, Das A, et al. Assessment of Smear Layer Removal and Penetration Depth of Root Canal Irrigant Using Different Irrigation Activation Systems: A Comparative Study. J Contemp Dent Pract 2024;25(4):331-334.

Comparative assessment of cleaning efficacy of two exclusive paediatric rotary files in root canals of primary teeth: An in vitro study.

BACKGROUND: Paediatric rotary file systems have recently been developed for primary teeth use. AIM: To study the cleaning efficacies of two paediatric rotary endodontic files, the Prime PedoTM, and the Kedo-SG BlueTM against the standard H files. DESIGN: This in vitro study included 54 freshly extracted primary molars, which were randomised into three groups (n = 18 each) and were prepared using either Kedo-SG BlueTM, Prime PedoTM or hand H files after injecting methylene blue dye into the canals. Pre- and post-operative cone beam computerised tomography (CBCT) was performed to assess change in root canal volumes. Methylene blue dye removal from canals was assessed using stereomicroscopy, and canal cleanliness was examined by scanning electron microscopy (SEM). RESULTS: Both Prime PedoTM and Kedo-SG BlueTM files reduced significantly less dentine when compared with conventional hand filing with Prime PedoTM removing the least amount of dentine. No significant difference was found in median SEM scores among the groups in the cervical, middle and apical thirds of the roots. Stereomicroscopic assessment of root canal cleanliness using dye removal technique shows a statistically significant difference existing between Kedo-SG BlueTM and hand H files groups. CONCLUSION: Prime PedoTM removed the least amount of dentine. Kedo-SG BlueTM performed significantly better than conventional hand filing with H files when the root canal cleanliness was assessed.

Assessment of the apically extruded debris between a rotary system, a reciprocating system and hand files during the root canal instrumentation of the deciduous molars.

BACKGROUND: One of the factors that most negatively affect the endodontic instrumentation process in primary teeth is the presence of extruded debris in the periapical region. Therefore, different techniques have been evaluated to reach an answer to the question regarding which root canal preparation method produces the least amount of debris extrusion. OBJECTIVES: The main objective of this study was to assess the amount of debris extrusion as well as irrigation associated with 3 different instrumentation techniques: a rotary system (PROTAPER NEXT® - PTN), a reciprocating system (WaveOne® - WO) and hand K-files. MATERIAL AND METHODS: Forty-eight primary mandibular molars with a single distal canal were selected and randomly divided into 3 groups (n = 16). Three different techniques were used for the canal instrumentation of each group, comprising PTN, WO and hand K-files. Pre-weighed Eppendorf tubes were used for the collection of debris extrusion, then stored in an incubator at 70°C for 5 days. A one-way analysis of variance (ANOVA) test was used for data analysis, followed by Tukey's post hoc test. RESULTS: Statistically significant differences were found while comparing the PTN and WO systems with the hand files. Both PTN and WO showed less debris extrusion toward the periapical tissues than the hand files. Still, no statistically significant differences were seen between the PTN and WO groups. CONCLUSIONS: Generally, debris extrusion occurred in all of the 3 experimental groups. The PTN and WO systems showed the least debris extrusion as compared to the hand files during the root canal instrumentation of the primary teeth, and for these reasons along with the shorter operating time, it may be concluded that using rotary and reciprocating systems rather than manual files is highly advisable. However, a clinical assessment is suggested.

Comparative assessment of dentin removal following hand and rotary instrumentation in primary molars using cone-beam computed tomography.

OBJECTIVE: Pediatric endodontics has witnessed many advances in recent years, thus facilitating a faster and efficient treatment option in root canal therapy in children. This in vitro evaluation aims to determine the amount of dentin removal in primary mandibular first and second molars instrumented with hand and rotary files using cone-beam computed tomography (CBCT). MATERIALS AND METHOD: Sixty primary mandibular molars were divided into two groups: Group I was prepared by manual instrumentation using K-type files and Group II was prepared with rotary instrumentation using 0.04 Hero Shaper Classics. Both these groups were further divided into two subgroups, namely (a) primary mandibular first molar and (b) primary mandibular second molar. All the root canals were prepared up to size 30 using the stepback technique. They were mounted on silicone-based impression material and subjected to CBCT scans for the evaluation of dentin removal before and after instrumentation. Dentin removal was calculated by superimposing images using the InVivo 5.1 Anatomage software. Data were statistically analyzed using independent samples t- test. RESULTS: An average amount of dentin removed was found to be significantly higher in manual instrumentation compared to rotary instrumentation in both primary mandibular first and second molars (P < 0.001). CONCLUSIONS: Rotary technique serves as an efficient alternative to the traditional manual instrumentation by overcoming its shortcomings in terms of conservation of the remaining dentin thickness and the time required for its preparation.

Micro-computed Tomography Shaping Ability Assessment of the New Blue Thermal Treated Reciproc Instrument.

INTRODUCTION: The present study aimed to assess canal preparation outcomes achieved by the new Reciproc Blue instrument using micro-computed tomography technology. M-Wire Reciproc was used as a reference instrument for comparison. METHODS: Seven pair-matched mesial roots of mandibular molars presenting similar anatomic features of the canal (length, volume, surface area, and configuration) were selected after scanning procedures and assigned to 1 of the 2 groups according to the instrument used, M-Wire Reciproc and Reciproc Blue. After canal instrumentation, the specimens were rescanned, and the registered preoperative and postoperative datasets were examined to evaluate the percentages of removed dentin, untouched canal walls, and degree of canal transportation. Comparisons regarding the above outcomes between the 2 groups were done by using paired t test with the alpha-type set at 5%. RESULTS: Root canals prepared with conventional M-Wire Reciproc or Reciproc Blue were found to present similar shaping properties with no significant differences in the tested parameters. CONCLUSIONS: M-Wire Reciproc and Blue Reciproc presented similar shaping outcomes.

Assessment of apical transportation caused by nickel-titanium rotary systems with full rotation and reciprocating movements using extracted teeth and resin blocks with simulated root canals: A comparative study.

OBJECTIVES: : We compared apical transportation in the WaveOne and ProTaper Next systems, which are rotary nickel-titanium systems with reciprocating and continuous rotation movements, respectively, using manual measurements obtained from resin blocks with simulated root canals and double digital radiographs of extracted teeth. MATERIALS AND METHODS: : We used 30 resin blocks with simulated root canals and 30 extracted teeth for this study. The same endodontist performed root canal shaping using the WaveOne or ProTaper Next system. We assessed apical transportation by measuring the amounts (in mm) of material lost 1 mm from the apical foramen in the resin blocks and by using double digital radiography for the extracted teeth. Significant differences between groups were assessed using t-tests. P < 0.05 was considered statistically significant. RESULTS: : The amount of apical transportation differed significantly between the two systems when resin blocks were used for assessment (P < 0.05), but there were no significant differences when extracted teeth were used (P < 0.05). CONCLUSIONS: In the current study, there was no significant difference in apical transportation between natural teeth prepared using WaveOne and those prepared using ProTaper Next. However, significant differences were observed between the two systems with resin blocks. These findings indicate that the use of resin blocks is not an accurate method for apical transportation evaluation.

Rotary Versus Reciprocation Root Canal Preparation: Initial Clinical Quality Assessment in a Novice Clinician Cohort.

INTRODUCTION: Reports comparing clinical outcomes using nickel-titanium (NiTi) reciprocating instruments with other instrumentation modalities are scarce. This study examined initial shaping outcomes after an instrumentation change of root canal instrumentation technique in a doctor of dental surgery educational program. Student characteristics, faculty/student ratio, facility, and overall endodontic treatment guidelines remained unchanged. METHODS: A total of 200 nonsurgical initial molar root canal treatments completed by third-year dental students were evaluated. The cases were examined regarding the number of treatment appointments, access cavity preparation, canal taper, canal transportation, perforations, missed canals, presence of ledges, fractured instruments, obturation length, obturation quality, and sealer extrusion. Two independent evaluators determined the number of appointments per case; 4 independent and blinded evaluators analyzed radiographs at 4 treatment stages: preoperative situation, working length, cone fit, and obturation. RESULTS: The following factors were significantly different between the 2 cohorts: the number of appointments, preparation length, taper, and occurrence of ledges. The WaveOne (Dentsply Sirona, York, PA) cohort had a significantly reduced treatment time compared with hand/GT rotary instrumentation (Dentsply Tulsa Dental, Tulsa, OK) (average of 3.3 vs 4.3 appointments). Appropriate length control and adequate taper were significantly more frequent in the WaveOne group. The frequency of ledges was significantly larger in the hybrid group. Other variables, such as access cavity preparation, canal transportation, perforations, missed canals, fractured instruments, obturation quality, and sealer extrusion, were statistically similar between the 2 groups. CONCLUSIONS: NiTi reciprocation instrumentation was superior to hybrid hand/NiTi rotary instrumentation in reducing both patient appointments and the incidence of ledging and in improving obturation length and taper in a dental student clinic setting.

Quantitative Assessment of apically Extruded Bacteria using different Instrumentation Techniques and Preparation Taper.

BACKGROUND: Cleaning and shaping of the pulp canal is one of the most important steps of endodontic therapy. Serious complications occur by the apical extrusion of bacteria during the instrumentation procedures. Both crown-down (CD) and full-length linear motion (FM) techniques are routinely used as a component of taper rotary instrument procedures for achievement of thorough cleaning and shaping of the pulp canal space. Hence, we aimed for this study to assess the change in the amount of apically extruded bacteria using CD and FM instrumentation techniques produced by differences in taper between the instruments used during biomechanical preparation of root canals. MATERIALS AND METHODS: The present study included assessments of 132 extracted maxillary central incisor teeth. To achieve a uniform teeth length of 21 mm, the height of the tooth crown was reduced for preserving the coronal portion of teeth. A modified glass vial model was constructed for the estimation of amount of bacterial extrusion through the apical region. For filling of each pulp canal specimen, 20 mL of Enterococcus faecalis suspension was used followed by the use of a number 10 K-file for carrying the bacteria down the lengths of pulp canals. All the contaminated teeth specimens were divided into six study groups with groups I to III containing specimens prepared in the CD manner, while groups IV to VI contained specimens prepared in the FM manner. Six teeth were taken as negative control with three specimens with each technique, and another six specimens were taken as positive controls. Cultivable bacterial counts were determined by evaluating 100 mL saline solution from each vial followed by its inoculation on blood agar. All the colony-forming unit (CFU) values were log-transformed (base 10), and the results were analyzed by Statistical Package for the Social Sciences software. RESULTS: A significantly lower quantity of CFU values was observed during CD instrumentation procedures with 0.02 files in comparison with all other study groups. However, while comparing both the instrumentation procedures when different taper files, other than 0.02 taper, were used for biomechanical preparation of root canal, nonsignificant results were obtained. CONCLUSION: With 0.02 taper preparations, significantly less amount of extrusion of bacteria is associated when done with CD technique. CLINICAL SIGNIFICANCE: No change in the amount of apical extrusion of bacteria will be seen by changing the type of instrumentation procedures. Amount of bacteria extruded can be minimized using 0.02 taper. Key words: Bacteria, Instrumentation, Taper.

Safety Assessment of Two Hybrid Instrumentation Techniques in a Dental Student Endodontic Clinic: A Retrospective Study.

The aim of this study was to retrospectively assess the safety potential of a hybrid technique combining nickel-titanium (NiTi) reciprocating and rotary instruments by third- and fourth-year dental students in the predoctoral endodontics clinic at one U.S. dental school. For the study, 3,194 root canal treatments performed by 317 dental students from 2012 through 2015 were evaluated for incidence of ledge creation and instrument separation. The hybrid reciprocating and rotary technique (RRT) consisted of a glide path creation with stainless steel hand files up to size 15/02, a crown down preparation with a NiTi reciprocating instrument, and an apical preparation with NiTi rotary instruments. The control was a traditional rotary and hand technique (RHT) that consisted of the same glide path procedure followed by a crown down preparation with NiTi rotary instruments and an apical preparation with NiTi hand instruments. The results showed that the RHT technique presented a rate of ledge creation of 1.4% per root and the RRT technique was 0.5% per root (p<0.05). Three stainless steel hand files separated: two in the RHT group and one in the RRT group. There was no separation of any NiTi file in any of the techniques. The use of the reciprocating and rotary technique for root canal instrumentation by these dental students provided good safety. This hybrid technique offered a low rate of ledge creation along with no NiTi instrument separation.

Micro-computed Tomography Assessment of Dentinal Micro-cracks after Root Canal Preparation with TRUShape and Self-adjusting File Systems.

INTRODUCTION: The aim of the present study was to evaluate the percentage frequency of dentinal micro-cracks observed after root canal preparation with TRUShape and Self-Adjusting File (SAF) systems by means of micro-computed tomography imaging analysis. A conventional full-sequence rotary system (BioRace) and a single-file reciprocation system (Reciproc) were used as reference techniques for comparison because of their known assertive cutting efficiency. METHODS: Forty anatomically matched mandibular incisors were selected, scanned at a resolution of 14.25 µm, and assigned to 4 experimental groups (n = 10), according to the preparation protocol: TRUShape, SAF, BioRace, and Reciproc systems. After the experimental procedures, the specimens were scanned again, and the registered preoperative and postoperative cross-section images of the roots (n = 70,030) were screened to identify the presence of dentinal micro-cracks. RESULTS: Overall, dentinal defects were observed in 28,790 cross-section images (41.11%). In the TRUShape, SAF, BioRace, and Reciproc groups, dentinal micro-cracks were visualized in 56.47% (n = 9842), 42.38% (n = 7450), 32.90% (n = 5826), and 32.77% (n = 5672) of the slices, respectively. All dentinal defects observed in the postoperative data sets were already present in the corresponding preoperative images. CONCLUSIONS: None of the preparation systems induced the formation of new dentinal micro-cracks.

Assessment of rotary and reciprocating movements in root canal filling material removal / Análise dos sistemas rotatórios e reciprocante com diferentes ligas na desobturação em retratamento endodônticos

The aim of this study was to evaluate the effects of preparation, filling removal material, reinstrumentation and reobturation of root canals with different Ni-Ti alloys in endodontic retreatment. Firstly, the selection and pairing of mesial root canals of mandibular molars (n = 45) were performed by computerized micro-tomography (micro-CT). After pairing, the specimens were divided into three groups (n = 15), instrumented with the Mtwo® (up to file 25.06), ProDesign Logic (25.06) and ProDesign R (25.06) systems. After this, the specimens were scanned again for root canal deviation analysis at 2, 4, 6, 8 and 10 mm from the apex and the volume increase of these root canals was evaluated through CTan Then, the root canals were filled with Endofill® with 0.1% rhodamine B and scanned in micro-CT once again. For the retreatment of the specimens, 3 groups were established according to the system used (Reciproc®, Hyflex® and ProDesign Duo Hybrid®). During the retreatment, the specimens were scanned in micro-CT in two more phases, after removal of filling material and after reinstrumentation of the root canals. All the images obtained previous and post-retreatment were compared to evaluate the capacity of removal filling material of each system through the volume of material remaining at 3mm in the apical third. Possible deviation of the root canal was assessed at 2, 4, 6, 8 and 10 mm from the apex. In addition, the times of preparation, removal filling material and reinstrumentation of these files were also evaluated. After the removal filling material and reinstrumentation of the root canals, they were refilled with AH Plus with 0.1% fluorescein. The specimens were sectioned crosswise into 2 mm slices to be analyzed by a confocal laser scanning microscope (CLSM) at 1, 3 and 5 mm from the apex, where the volume of material was evaluated through LAS X 3D and 2D software. The time of preparation, removal filling material and reinstrumentation of the root canals between the different systems was measured by a digital timer. The evaluation of canal volumetric increase and preparation time between Mtwo and ProDesign Logic systems were conducted using Student t-test analysis. Non-parametric Wilcoxon test was used to the intragroup comparison at the 2, 4, 6, 8 and 10 mm levels and non-parametric Mann-Whitney test was used to the comparison between groups in the root canal transportation in all sections of the root canal. The intra-group comparison regarding the presence or absence of root canal deviation after removal of root canal filling material and re-instrumentation was submitted to the parametric T-paired statistical test, since it had a normal distribution. The working time with the different alloys used to removal filling material an reinstrumentation was analyzed through parametric ANOVA e Tukey statistical test. The analysis of the remaining material present in the root canals was performed with nonparametric Kruskal-Wallis and Dunn tests. For the intra-group comparison between the different slices (1, 3 and 5 mm), the data were submitted to nonparametric Friedman and Dunn tests. The level of significance was established at 5% in all analysis. After the initial preparation of the root canals, the ProDesign Logic system proved to be faster than Mtwo system, with statistical difference between them (P <0.05). There was no statistical difference in root canal deviation after initial preparation and after retreatment (P> 0.05). In addition, the groups did not present a significant statistical difference to the volume increase of the root canals after the initial preparation or to the volume of filling material remaining after the retreatment (P> 0.05). The Reciproc system proved to be the fastest system for the removal filling material and reinstrumentation of the root canals (P <0.05). The present study demonstrated that the Prodesign Logic and Mtwo systems presented similar capacity of preparation of mesial root canals. The Reciproc, Hyflex and ProDesign Duo Hybrid systems are similar in the removal of filling material, preserving the original root canal shape in endodontic retreatment. However, Reciproc was the fastest compared to the other groups.(AU)

O presente trabalho teve como objetivo avaliar os efeitos decorrentes do preparo inicial, desobturação, reinstrumentação e reobturação de canais radiculares com diferentes ligas de Ni-Ti em casos de retratamento endodôntico. Primeiramente, foi realizado a seleção e o pareamento da anatomia de canais mesiais de primeiros molares inferiores (n=45) através de micro-tomografia computadorizada (micro-CT). Após o pareamento dos espécimes, os mesmos foram divididos em três grupos (n =15), instrumentados com os sistemas Mtwo® (até a lima 25.06), ProDesign Logic (25.06) e ProDesign R (25.06) sendo escaneados novamente para análise de desvio do canal radicular a 2, 4, 6, 8 e 10 mm, além do aumento de volume desses canais, avaliados através do CTan. Em seguida, os canais radiculares foram obturados com o cimento Endofill® acrescido de 0,1% de rodamina B e escaneados em micro-CT mais uma vez. Para o retratamento dos espécimes, foram estabelecidos 3 grupos, de acordo com o sistema utilizado (Reciproc®, Hyflex® e ProDesign Duo Híbrido®). Durante o retratamento, os espécimes foram escaneados em micro-CT em mais duas etapas, após a desobturação e a após a reinstrumentação dos canais. Todas as imagens obtidas referentes ao pré e pós retratamento foram confrontadas com o intuito de avaliar a capacidade de remoção de material obturador de cada sistema através do volume de material remanescente nos 3 mm apicais, além de avaliar possíveis desvios dos canais a 2, 4, 6, 8 e 10 mm do ápice. Foram avaliados também, o tempo efetivo de preparo, desobturação e de reinstrumentação desses instrumentos. Após a desobturação e reinstrumentação dos canais, os mesmos foram reobturados com cimento AH Plus acrescido de 0,1% de fluoresceína. Os espécimes foram seccionados transversalmente em fatias de 2 mm para serem analisados em microscópio confocal de varredura a laser (MCVL) a 1, 3 e 5 mm do ápice, onde foi avaliado, através do software LAS X 3D e 2D, o volume de material obturador antigo. O tempo de preparo, desobturação e reinstrumentação dos canais entre os diferentes sistemas foi marcado através de um cronômetro digital. A análise do aumento volumétrico e tempo de preparo entre os sistemas Mtwo e ProDesign Logic foi feita através do teste estatístico Student t. Para a análise do desvio do canal radicular após o preparo inicial, o teste não-paramétrico Wilcoxon foi utilizado para a comparação intra-grupos nos níveis a 2, 4, 6, 8 e 10 mm do ápice, enquanto o teste não-paramétrico Mann-Whitney foi utilizado para comparação entre os grupos nos mesmos níveis. Para a análise do desvio do canal radicular após a desobturação e reinstrumentação dos canais, os dados foram submetidos ao teste paramétrico T-pareado. O tempo de desobturação e reinstrumentação com os diferentes sistemas foi analisado através do teste ANOVA e Tukey. Os dados referentes ao remanescente de material obturador foram analisados através dos testes não-paramétrico Kruskal-Wallis e Dunn. Para a comparação intra-grupos entre os diferentes níveis (1, 3 e 5 mm) foram utilizados os testes não-paramétricos Friedman e Dunn. O nível de significância foi estabelecido a 5% em todas as análises. Após o preparo inicial dos canais, o sistema ProDesign Logic demonstrou ser mais rápido que o sistema Mtwo, havendo diferença estatística entre eles (P < 0.05). Não houve diferença estatística quanto ao desvio do canal radicular tanto após o preparo inicial quanto após o retratamento (P > 0.05). Além disso, os grupos também não apresentaram diferença estatística significante quanto ao aumento do volume dos canais após o preparo inicial, nem em relação ao volume de remanescente de material obturador após o retratamento (P > 0.05). O sistema Reciproc demonstrou ser o mais rápido dentre os sistemas quanto à desobturação e reinstrumentação dos canais (P < 0.05). O presente trabalho demonstrou que os sistemas Prodesign Logic and Mtwo apresentaram capacidade similar de preparo dos canais mesiais de molares inferiores. Os sistemas Reciproc, Hyflex e ProDesign Duo Híbrido são parecidos quanto à remoção de material obturador, preservando o formato original do canal em casos de retratamentos entodônticos. Entretanto, Reciproc foi o mais rápido comparado aos outros grupos.(AU)

Light-emitting Diode Assessment of Dentinal Defects after Root Canal Preparation with Profile, TRUShape, and WaveOne Gold Systems.

INTRODUCTION: The objective of this study was to use light-emitting diode (LED) transillumination to assess the presence of dentinal defects in roots instrumented with 3 different root canal preparation systems: ProFile (Dentsply Tulsa Dental Specialties, Tulsa, OK), TRUShape (Dentsply Tulsa Dental Specialties), and WaveOne Gold (Dentsply Tulsa Dental Specialties). METHODS: Eighty mesial roots of mandibular molars presenting 2 canals were randomly divided into 4 different groups (n = 20) as follows: the control group, no root canal preparation was performed; the ProFile group, root canals were prepared with nickel-titanium ProFile sizes 20.06 and 25.06; the TRUShape group, root canals were prepared with nickel-titanium rotary TRUShape instrument sizes 20.06 and 25.06; and the WaveOne Gold group, root canals were prepared with the reciprocating WaveOne Gold instrument #25.07. The specimens were sliced at 3, 6, and 9 mm from the apex with a low-speed saw under water cooling. Microscopic pictures of the specimens were taken with the aid of LED; the root canal space was masked, and 2 independent evaluators assessed the images for the assessment of dentinal defects. The number of dentinal defects was recorded, and the chi-square test was used for statistical analysis (P < .05). RESULTS: The number of specimens presenting dentinal defects was as follows: the control group = 10, the ProFile group = 10, the TRUShape group = 13, and the WaveOne Gold group = 10. CONCLUSIONS: Using the novel LED method, no difference in the visualization of dentinal defects was found among the ProFile, TRUShape, and WaveOne systems and the control group. Previous studies using the traditional sectioning method lack proper control and should be evaluated with caution.

A Micro-Computed Tomographic Assessment of the Influence of Operator's Experience on the Quality of WaveOne Instrumentation.

INTRODUCTION: Micro-computed tomographic scanning was used to evaluate the influence of operator's experience on the time and quality of instrumentation of the mesial root canals of mandibular molars using WaveOne Primary files (Dentsply Maillefer, Ballaigues, Switzerland). METHODS: Thirty mandibular molars with 2 separate mesial canals were submitted to preoperative micro-CT scans. Teeth were randomly allocated to 3 groups: and experienced operator group and inexperienced groups before and after training with WaveOne files. Second scans were obtained after instrumentation. The volume of the untreated canal, the volume of dentin removed after preparation; the amount of the uninstrumented area; and transportation to the coronal, middle, and apical thirds of canals were measured. The preparation time was also recorded. RESULTS: Instrumentation of canals increased their volume and surface area in all groups. No significant differences between experienced and inexperienced (with and without training) groups in the apical, middle, and coronal sections were detected although coronal transportation was slightly larger in both inexperienced groups than in the experienced group. The inexperienced operator without training used significantly more time for instrumentation than the experienced operator (P < .05); after training for 1 month, the instrumentation time by the same inexperienced operator was reduced (P < .05) to close to the time of the experienced operator (P > .05). CONCLUSIONS: The WaveOne instrumentation technique required a short learning curve for the inexperienced user in order to master this technology.

Reasons for Apical Surgery Treatment in an Underserved New York City Population.

Endodontic retreatment often involves remaking restorations. The total cost may steer the treatment towards surgery. The aim of this study was to retrospectively record the reasons for performing apical surgery in an economically deprived patient population. The clinical reasons (59%) for apical surgery were most common, but the nonclinical (financial) reasons (41%) emerged as a major cause. The finding that 41% of the apicoectomies were performed because of nonclinical constraints is a high figure and may not reflect the situation generally. Still, economic factors potentially play a major role in the selection of surgical versus nonsurgical endodontic retreatment.

Histologic Assessment of Debridement of the Root Canal Isthmus of Mandibular Molars by Irrigant Activation Techniques Ex Vivo.

INTRODUCTION: This study aimed to evaluate the efficacy of a new irrigation system (EndoIrrigator Plus; Innovations Endo, Nasik, India) using a histologic method ex vivo. METHODS: Mandibular molars with a normal pulp extracted for periodontal reasons (N = 68) were assessed for the presence of an isthmus using cone-beam computed tomographic imaging. Root canals of the included molars (n = 40) were instrumented up to a ProTaper F2 instrument (Dentsply Maillefer, Baillagues, Switzerland) using 3% sodium hypochlorite as irrigant in a closed apical design. Final irrigation delivery/activation was performed as follows (n = 10): group 1, syringe irrigation; group 2, apical negative pressure delivery with continuous warm activated irrigation and evacuation system (CWAIS); group 3, manual dynamic agitation (MDA); and group 4, passive ultrasonic irrigation (PUI). Untreated teeth (n = 5) served as histologic controls. The isthmus regions (1, 3, and 5 mm from the apex) were analyzed by hematoxylin-eosin stain to calculate the percentage of remaining pulp tissue (RPT) relative to the area of the isthmus. Results were analyzed using the Mann-Whitney U test (P = .05). RESULTS: CWAIS showed significantly less RPT than the other groups at all 3 root levels (P < .05). MDA showed significantly less RPT at 1 and 3 mm from the apex compared with PUI and syringe irrigation (P < .05). There was no significant difference between PUI and MDA at the 5-mm level (P > .05). CONCLUSIONS: None of the methods could completely clean the isthmus. CWAIS left behind the least amount of RPT.

Quantitative transportation assessment in curved canals prepared with an off-centered rectangular design system.

The purpose of this study was to assess the ability of an off-centered rectangular design system [ProTaper Next (PTN)] to maintain the original profile of the root canal anatomy. To this end, ProTaper Universal (PTU), Reciproc (R) and WaveOne (WO) systems were used as reference techniques for comparison. Forty clear resin blocks with simulated curved root canals were randomly assigned to 4 groups (n = 10) according to the instrumentation system used: PTN, PTU, R and WO. Color stereomicroscopic images of each block were taken before and after instrumentation. All image processing and data analysis were performed with an open source program (Fiji v.1.47n). Evaluation of canal transportation was obtained for two independent regions: straight and curved portions. Univariate analysis of variance and Tukey's Honestly Significant Difference test were performed, and a cut-off for significance was set at α = 5%. Instrumentation systems significantly influenced canal transportation (p = 0.000). Overall, R induced significantly lower canal transportation compared with WO, PTN and PTU (p = 0.000). The curved portion displayed superior canal transportation compared to the straight one (p = 0.000). The significance of the difference among instrumentation systems varied according to the canal level evaluated (p = 0.000). In its straight portion, R and WO exhibited significantly lower transportation than PTN; whereas in the curved portion, R produced the lowest deviation. PTU exhibited the highest canal transportation at both levels. It can be concluded that PTN produced less canal transportation than PTU and WO; however, R exhibited better centering ability than PTN.

Assessment of Apical Extrusion during Root Canal Irrigation with the Novel GentleWave System in a Simulated Apical Environment.

INTRODUCTION: This study assessed apical extrusion during treatment with GentleWave (GW; Sonendo Inc, Laguna Hills, CA), a conventional open-ended 30-G needle (CN), or Endovac (EV; SybronEndo, Orange, CA) in root canals enlarged to different dimensions with and without apical constriction. METHODS: Sixteen mandibular molars were mounted in an in vitro apparatus. Roots were immersed in a pressure-regulated chamber containing distilled water with pressure kept at 5.88 ± 0.15 mm Hg to simulate periapical back pressure. Mesiobuccal (curved ≤30°) and distal (straight) canals were instrumented to the working length (WL) as follows: minimal instrumentation (MI, #15/.04), traditional instrumentation (#35/.06), or overinstrumentation (OI, #35/.06, to the WL + 1 mm). Canals were tested 5 times each with distilled water using GW, CN (at WL-3 mm), or EV and the mass (g) of extruded water recorded. Extrusion frequency and mean extruded mass were compared for each canal, irrigation group, and canal instrumentation mode (Wilcoxon t test, P < .05). RESULTS: No extrusion occurred with GW and EV, whereas the frequency of extrusion with CN was 33%. Mean extruded water mass using CN ranged in mesial canals from 0.000 ± 0.000 g (OI) to 0.047 ± 0.098 g (MI) and in distal canals from 0.123 ± 0.191 g (MI) to 0.505 ± 0.490 g (OI). With traditional instrumentation and OI instrumentation, extruded mass in distal canals was significantly higher than in mesial canals (P < .002) and distal canals with MI (P < .020). CONCLUSIONS: Within this study's limitations, root canal treatment with GW and irrigation with EV was not associated with extrusion. Extruded irrigation mass using the open-ended 30-G needle depended on the canal type and enlargement. These results have to be interpreted with caution, and further investigations are warranted to evaluate the possibility of extrusion using GW in different tooth types and clinical situations.

Assessment of postoperative pain after reciprocating or rotary NiTi instrumentation of root canals: a randomized, controlled clinical trial.

OBJECTIVES: The aim of this study was to assess postoperative pain in a prospective randomized clinical trial comparing two groups, using the Reciproc® system in one group and the ProTaper® rotary system in the other. MATERIAL AND METHODS: The study included 78 male patients, aged 18-64 years (mean age of 26 years), with asymptomatic pulp necrosis in mandibular molar teeth (n = 78). The single-session endodontic treatment was performed by a single operator specialized in Endodontics. Mechanical preparation of the root canals was performed using the ProTaper® and Reciproc® instrumentation techniques. Postoperative pain was recorded using a verbal rating scale (VRS) and verbal description with well-defined categories at the three following time intervals: 24 h, 72 h, and 7 days after the endodontic procedure. The assessment of postoperative pain was recorded as no pain, mild pain, moderate pain, and severe pain or flare-up. Data were analyzed using the nonparametric Mann-Whitney test with the aid of the STATA® software. RESULTS: The incidence of postoperative pain in the ProTaper group (PT) 24 h after the endodontic procedure was 17.9 and 5.1 % after 72 h. In the Reciproc group (RP), the incidence after 24 h was 15.3 and 2.5 % after 72 h. No patients presented severe pain at the time intervals assessed. CONCLUSIONS: No significant difference (p > 0.05) in postoperative pain was found between the ProTaper® and Reciproc® instrumentation technique during endodontic treatment in this study. CLINICAL RELEVANCE: According to our findings and the results of the clinical trial, the occurrence of postoperative pain was low and similar between the reciprocating and rotary techniques during the time intervals assessed. These results are different from basic laboratory studies that affirm that the reciprocating techniques tend to promote more postoperative pain since extrusion of debris is greater.

Quantitative transportation assessment in curved canals prepared with an off-centered rectangular design system

Abstract The purpose of this study was to assess the ability of an off-centered rectangular design system [ProTaper Next (PTN)] to maintain the original profile of the root canal anatomy. To this end, ProTaper Universal (PTU), Reciproc (R) and WaveOne (WO) systems were used as reference techniques for comparison. Forty clear resin blocks with simulated curved root canals were randomly assigned to 4 groups (n = 10) according to the instrumentation system used: PTN, PTU, R and WO. Color stereomicroscopic images of each block were taken before and after instrumentation. All image processing and data analysis were performed with an open source program (Fiji v.1.47n). Evaluation of canal transportation was obtained for two independent regions: straight and curved portions. Univariate analysis of variance and Tukey's Honestly Significant Difference test were performed, and a cut-off for significance was set at α = 5%. Instrumentation systems significantly influenced canal transportation (p = 0.000). Overall, R induced significantly lower canal transportation compared with WO, PTN and PTU (p = 0.000). The curved portion displayed superior canal transportation compared to the straight one (p = 0.000). The significance of the difference among instrumentation systems varied according to the canal level evaluated (p = 0.000). In its straight portion, R and WO exhibited significantly lower transportation than PTN; whereas in the curved portion, R produced the lowest deviation. PTU exhibited the highest canal transportation at both levels. It can be concluded that PTN produced less canal transportation than PTU and WO; however, R exhibited better centering ability than PTN.

Current Assessment of Reciprocation in Endodontic Preparation: A Comprehensive Review--Part II: Properties and Effectiveness.

INTRODUCTION: Many reciprocating file systems (RFs) have recently been introduced. This article reviews the properties, effectiveness, and clinical outcomes of the RFs. METHODS: A PubMed electronic search was conducted by using appropriate key words to identify investigations on RFs. After retrieving the full-text relevant articles, the cross citations were also identified. RESULTS: This review summarizes the mechanical properties, shaping ability, preservation of the root canal anatomy, shaping time, cleaning effectiveness, microcrack formation, bacterial reduction, extrusion of debris, and removal of root canal filling materials of RFs. CONCLUSIONS: The favorable results of RFs indicate their potential application as viable alternatives to rotary file systems, yet no filing system is able to entirely prepare the dentin of canals, totally eliminate sessile and planktonic microorganisms, or remove the filling material completely from the root canal system.