Maxillary First Molars with 2 Distobuccal Canals: A Case Series.

An appreciation of the anatomic complexity of the root canal system is essential at every step of endodontic treatment. Endodontic treatment of teeth with unusual root canal anatomy presents a unique challenge. Eight patients underwent nonsurgical root canal treatment of 3-rooted maxillary first molars in a specialty endodontic private practice. Four cases of Weine type II and 4 cases of Weine type III canal configurations in the distobuccal root of maxillary first molars were presented.This article highlighted an uncommon anatomic variation of 2 canals in the distobuccal root of the maxillary first molar.

Influence of Passive Ultrasonic Irrigation on the Removal of Root Canal Filling Material in Straight Root Canals.

OBJECTIVE: This study evaluates the efficacy of passive ultrasonic irrigation (PUI) in removing root canal filling material from endodontically treated teeth after using one of two reciprocating systems, Reciproc (VDW, Munich, Germany) or WaveOne (Dentsply Maillefer, Ballaigues, Switzerland), or one nickel-titanium (NiTi) rotary system, ProTaper Universal Retreatment (Dentsply Maillefer). METHODS: One hundred and twenty straight root canals of extracted human maxillary incisors were instrumented and then obturated. The specimens were divided into six groups (n=20) as follows: Group R, Reciproc R25 instrument without PUI; Group W, WaveOne Primary instrument without PUI; Group PT, ProTaper Universal Retreatment system without PUI; Group R-PUI, Reciproc R25 with PUI; Group W-PUI, WaveOne Primary with PUI and Group PT-PUI, ProTaper Universal Retreatment system with PUI. After removing the filling material, the teeth were cleaved longitudinally and photographed. The total canal space and remaining material were quantified with the aid of an imaging software tool. The Kruskal-Wallis test was used to identify significant differences between the groups. RESULTS: No statistically significant differences (P>0.05) in residual filling material were observed between the groups. CONCLUSION: The use of PUI did not improve the removal of filling material from the root canals, regardless of the previously used instrumentation system.

Comparative Analysis of Dentinal Erosion after Passive Ultrasonic Irrigation versus Irrigation with Reciprocating Activation: An Environmental Scanning Electron Study.

INTRODUCTION: The aim of this study was to assess ex vivo the erosive effects of passive ultrasonic irrigation versus irrigation with reciprocating activation on the dentinal surface of the root canal at 3 predetermined levels using environmental scanning electron microscopy. METHODS: Ten roots of mandibular premolars were prepared using the ProTaper Universal system (Dentsply Maillefer, Ballaigues, Switzerland). The specimens were embedded in flasks cleaved longitudinally, and indentations were made 3.0, 6.0, and 9.0 mm from the apex. The specimens in the control group (n = 10) were cleaned in an ultrasonic bath containing 2.5% sodium hypochlorite and 17% EDTA and then dried. Then, environmental scanning electron microscopic images were obtained at magnification × 800. The specimens were then reassembled in their flasks, and the NaOCl and EDTA solutions were activated according to the conditions established for the experimental groups (ie, the passive ultrasonic irrigation group [n = 5] and the EasyClean (Easy Equipamentos Odontológicos, Belo Horizonte, MG, Brazil) group, irrigation with reciprocating activation with the EasyClean instrument [n = 5]). The specimens of both experimental groups were analyzed in the same manner as in the control group. Analysis of the dentinal surface topography was conducted using the 3D Roughness Reconstruction program (Phenom-World BV, Eindhoven, the Netherlands) as a means for assessing erosion. The data were evaluated by means of the Kruskal-Wallis, Student-Newman-Keuls, and Mann-Whitney tests. RESULTS: In the EasyClean group, the degree of dentinal erosion at 3.0 mm was significantly higher than at 9.0 mm. In the other comparisons, there was no statistically significant difference (P < .05). CONCLUSIONS: The final irrigation techniques tested were equivalent in relation to the degree of erosion caused to the dentinal surface.

Avaliação do sistema WaveOne Gold e ProTaper retratamento para remoção de guta-percha clínico / Evaluation of WaveOne Gold system and ProTaper retreatment for gutta-percha removal

Objetivo: avaliar ex vivo a quantidade de guta-percha remanescente no retratamento de canal de dentes pré-molares inferiores com único canal utilizando o sistema WaveOne Gold em comparação com o sistema de retratamento ProTaper R. Materiais e métodos: foram selecionados 52 pré-molares inferiores humanos extraídos, distribuídos aleatoriamente em 2 grupos (n=26), em função das técnicas de retratamento: sistema WaveOne Gold (grupo 1) e sistema de retratamento ProTaper R (grupo 2). Após os canais radiculares serem instrumentados e obturados com guta--percha, foram submetidos à de sobturação e ao procedimento de retratamento. Os dentes foram seccionados confeccionando uma canaleta nas faces proximais dos dentes obtendo-se duas hemi--secções radiculares, expondo, portanto, a luz do canal preparado. Todas as amostras foram codificada se fotografadas por máquina Cânon A640 acoplada ao microscópio Zeiss, com aumento de 5 vezes. As fotos foram transportadas para o programa de software Image Tool 3.0. Foi feita medição das áreas de remanescentes de material obturador no interior do canal e a medição da área total do interior do canal através das imagens da secção no computador. As medidas foram comparadas em relação a cada sistema utilizando o programa BioEstat 4.0 (teste de Mann-Whitney). Resultados:A menor porcentagem de material obturador remanescente ocorreu no sistema ProTaper Rcom diferenças significantes em relação ao sistema WaveOne Gold (p<0.01). Conclusão: o sistemaProTaper R foi mais eficaz na remoção de guta-percha em comparação com o sistema WaveOne Gold, entretanto nenhum dos sistemas removeram totalmente o material obturador do canal.

Objective: This ex vivo research study aims to evaluate ex vivo the amount of remaining gutta -perchaduring canal retreatment of lower premolars single-rooted using WaveOne Gold system compared with Protaper R system. Materials and methods: 52 mandibular premolars were selected and randoml y divided into 2 groups (n = 26), according to the retreatment techniques, which are: WaveOne Gold system(group 1) and ProTaper R system (group 2). After the root canals were instrumented and filled withgutta-percha, they underwent removal procedure. After retreatment procedure, the teeth were sectioned in the proximal surfaces resulting in two hemi-sections exposing the interior of the root canal. Allsamples were coded and photographed by A640 Canon machine attached to the microscope Zeiss withzoom in 5 times, and the photos were transported to the Image Tool 3.0. software. The evaluation wasdone by measurement of areas of remaining filling material and the total area of the interior of root canal through the images on the computer. The measurements were compared for each system using Bio-Estat 4.0 program and Mann-Whitney test. Results: The smallest percentage of remaining gutta-perchaoccurred in ProTaper Retreatment system with significant differences from the WaveOne Gold system(p <0.01).Conclusion: ProTaper R system was more effective in removing gutta-percha compared withWaveOne Gold system. However none of the both systems completely removed the filling material.

Assessing the Impact of Voice-Over Screen-Captured Presentations Delivered Online on Dental Students' Learning.

The traditional lecturing method is still one of the most common forms of delivering content to students in dental education, but innovative learning technologies have the potential to improve the effectiveness and quality of teaching dental students. What challenges instructors is the extent to which these learning tools have a direct impact on student learning outcomes. The aim of this study was to assess the impact of a voice-over screen-captured learning tool by identifying a positive, nil, or negative impact on student learning as well as student engagement (affective, behavioral, and cognitive) when compared to the traditional face-to-face lecture. Extraneous variables thought to impact student learning were controlled by the use of baseline measures as well as random assignment of second-year dental students to one of two teaching conditions: voice-over screen-captured presentation delivered online and the traditional classroom lecture. A total of 28 students enrolled in the preclinical course in endodontics at a Canadian dental school participated in the study, 14 in each of the two teaching conditions. The results showed that, in most cases, the students who experienced the online lecture had somewhat higher posttest scores and perceived satisfaction levels than those in the face-to-face lecture group, but the differences did not achieve statistical significance except for their long-term recognition test scores. This study found that the students had comparable learning outcomes whether they experienced the face-to-face or the online lecture, but that the online lecture had a more positive impact on their long-term learning. The controls for extraneous variables used in this study suggest ways to improve research into the comparative impact of traditional and innovative teaching methods on student learning outcomes.

Investigation of the Efficacy of Passive Ultrasonic Irrigation Versus Irrigation with Reciprocating Activation: An Environmental Scanning Electron Microscopic Study.

INTRODUCTION: The objective of this ex vivo study was to compare the efficacy of passive ultrasonic irrigation (PUI) versus a new activation system using reciprocating motion (EasyClean [EC]; Easy Equipamentos Odontológicos, Belo Horizonte, Brazil) to remove debris from the root canal walls at 6 predetermined apical levels using environmental scanning electron microscopy. METHODS: Mesiobuccal root canals of 10 mandibular molars were prepared with a 30/.05 final instrument. The specimens were embedded in flasks containing heavy body silicone, cleaved longitudinally, and 6 round indentations were made into the apical region of the buccal half at 1-mm intervals. The same specimens were used to prepare a blank control group (no debris), a negative control group (completely covered by debris), and 2 experimental groups: PUI and irrigation with reciprocating activation. Standardized images of the indentations were obtained under environmental scanning electron microscopy and assessed by 2 examiners. The amount of debris was then classified using a 4-category scoring system. The kappa test was applied to determine interexaminer agreement, whereas the Kruskal-Wallis, Dunn, and Friedman tests were used to compare scores. RESULTS: The EC group had results statistically similar to those of the blank control group for all 6 root levels examined. The PUI group had results statistically similar to those of the negative control group for the 3 most apical levels and similar to those of the blank control group for the 3 most cervical levels. CONCLUSIONS: Activating the irrigant with a reciprocating system (EC) promoted more effective debris removal from the more apical regions of the root canal when compared with PUI.

The impact of endodontic irrigating solutions on the push-out shear bond strength of glass fiber posts luted with resin cements.

Resin-based restorative materials, widely used to cement posts, may be influenced by irrigants used during endodontic chemical-mechanical preparation. This study evaluated the impact of endodontic irrigating solutions and adhesive cement systems on the push-out shear bond strength of glass fiber posts to root dentin. Ninety-six bovine incisors were divided into 12 groups (4 irrigants × 3 resin cements; n = 8). Prepared canals were irrigated with saline solution, 2.5% sodium hypochlorite (NaOCl), 5.25% NaOCl, or 2% chlorhexidine gel, and posts were cemented with RelyX ARC, Panavia F, or RelyX U100. The bond strength was evaluated by means of the push-out test, and results were subjected to analysis of variance. The mean bond strength observed for the combination of 5.25% NaOCl irrigant and RelyX U100 cement was significantly lower (8.82 MPa) than the values found for the other groups (P < 0.05). The other combinations of irrigating solution and resin cement had no adverse effect on the bond strength of the glass fiber posts to dentin.

Comparison of the Incidence of Postoperative Pain after Using 2 Reciprocating Systems and a Continuous Rotary System: A Prospective Randomized Clinical Trial.

INTRODUCTION: The objective of the present study was to clinically compare the incidence of postoperative pain and the intake of analgesic medication (frequency and quantity) after endodontic treatment of posterior teeth using 2 reciprocating systems and a continuous rotary system. METHODS: In a prospective randomized clinical study, 210 patients with vital teeth indicated for conventional endodontic treatment were treated by 5 specialists according to a pre-established protocol. The teeth were randomly assigned to 1 of 3 groups (n = 70) according to the instrumentation system used: ProTaper Next (Dentsply Tulsa Dental Specialties, Johnson City, TN), WaveOne (Dentsply Tulsa Dental Specialties), or Reciproc (VDW, Munich, Germany). Treatments were performed in a single visit. After the visit, the patients were given a prescription for ibuprofen 400 mg to be taken every 6 hours if they experienced pain. Participants were asked to rate the intensity of the postoperative pain on a visual analog scale according to 4 classes (no pain, mild pain, moderate pain, and severe pain) after 24 hours, 48 hours, 72 hours, and 7 days. Patients were also asked to record the number of prescribed analgesic medication tablets taken at these time points. RESULTS: No statistically significant difference was found among the 3 groups in relation to postoperative pain or analgesic medication intake at the 4 time points assessed (P > .05, Kruskal-Wallis test). CONCLUSIONS: The reciprocating systems and the continuous rotary system were found to be equivalent in regard to the incidence of postoperative pain and intake of analgesic medication at the time points assessed.

Evaluation of the Efficacy of TRUShape and Reciproc File Systems in the Removal of Root Filling Material: An Ex Vivo Micro-Computed Tomographic Study.

INTRODUCTION: The purpose of this study was to evaluate the efficacy of TRUShape (Dentsply Tulsa Dental Specialties, Tulsa, OK) compared with the Reciproc file (VDW, Munich, Germany) in the removal of filling material from oval canals filled with 2 different sealers and differences in the working time. METHODS: Sixty-four mandibular canines with oval canals were prepared and divided into 4 groups (n = 16). Half of the specimens were filled with gutta-percha and pulp canal sealer (PCS), and the remainders were filled with gutta-percha and bioceramic sealer (BCS). The specimens were retreated using either the Reciproc or TRUShape files. A micro-computed tomographic scanner was used to assess filling material removal, and the time taken for removal was also recorded. Data were analyzed using the Kruskal-Wallis and Mann-Whitney U tests. RESULTS: The mean volume of the remaining filling material was similar when comparing both files (P ≥ .05). However, in the groups filled with BCS, the percentage of remaining filling material was higher than in the groups filled with PCS (P < .05). The reciprocating file allowed for faster filling removal than the TRUShape files (P < .05). Retreatment was faster in the groups that were filled with PCS compared with those filled with BCS (P < .05). CONCLUSIONS: There was no difference regarding the percentage of remaining filling material when comparing both files system; however, Reciproc was faster than TRUShape. BCS groups exhibited significantly more remaining filling material in the canals and required more time for retreatment. Remaining filling material was observed in all samples regardless of the technique or sealer used.

IS GUTTACORE MORE EASILY REMOVED FROM THE ROOT CANAL THAN THERMAFIL? AN EX-VIVO STUDY.

GuttaCore is a new cross-linked gutta-percha carrier. Its handling time and ease of removal were compared with those of a plastic carrier (Thermafil) and the continuous wave of condensation technique (control). Forty-five maxillary central incisors were randomly divided 3 groups according to filling technique and retreatment was carried out in all samples with NiTi rotary files, hand files and ultrasonic inserts. Time required for filling removal was recorded. Roots were then split longitudinally and photographed under 5x magnification, and residual filling material was quantified. Removal time was significantly longer for Thermafil (7.10 minutes) than GuttaCore (2.91 minutes) and the control group (1.93 minutes) (p < 0.001). The amount of residual filling material did not differ among the groups: Thermafil 8.31%, GuttaCore 6.27 and control 8.68% (p > 0.05). In conclusion, replacing plastic core with cross-linked gutta-percha allows easier removal of carrier from the root canal. The remnants of filling material in all samples illustrate that retreatment remains a challenge in endodontics.

Glide Path Management with Single- and Multiple-instrument Rotary Systems in Curved Canals: A Micro-Computed Tomographic Study.

INTRODUCTION: Securing a reproducible glide path before instrumentation is recommended to maintain the original geometry of the root canal system and to prevent file separation. Mechanical glide path management systems have been introduced to expedite this step. The aim of this study was to compare apical transportation, canal volume increase, and working time during glide path management with ProGlider (PG; Dentsply Tulsa Dental Specialties, Tulsa, OK) and PathFiles (PF, Dentsply Tulsa Dental Specialties). METHODS: Forty curved mesial canals of mandibular molars were randomly allocated into 2 experimental groups (n = 20) according to the glide path management system: PG or PF. A glide path was achieved according to the manufacturers' protocol. Micro-computed tomographic analysis was performed to assess apical transportation at 1, 3, and 5 mm and volume increase. The time required to achieve the glide path was measured. RESULTS: The overall apical transportation mean values (± standard error) were 13.33 ± 3.37 µm for PG and 19.21 ± 4.4 µm for PF (P > .05). The mean (± standard error) volume increase values were 0.49 ± 0.06 mm(3) for PG and 0.48 ± 0.06 mm(3) for PF (P > .05). A statistically significant difference in the working time was found between the groups (P < .0001) where the mean (± standard error) values for time were 7.38 ± 1.73 seconds for PG and 20.61 ± 5.54 seconds for PF. CONCLUSIONS: Similar apical transportation and volume increase occurred during glide path management with PG single-file and PF multi-file systems; however, PG achieved glide path faster than PF.

Antibacterial Potential of 2.5% Sodium Hypochlorite in Distinct Irrigation Protocols on Enterococcus faecalis Biofilm.

OBJECTIVE: The aim of this study was to evaluate the effect of irrigation methods on antibacterial potential of 2.5% NaOCl on Enterococcus faecalis biofilm. MATERIALS AND METHODS: Enterococcus faecalis biofilms were prepared during 60 days on 48 human root canals and randomized into control and experimental groups using positive and negative pressure irrigation. Bacterial growth was analyzed using turbidity of culture medium followed by UV spectrophotometry, and scanning electron microscopy (SEM) analyses were performed. Mean and standard deviations were used for evaluate the mean optical densities associated to the number of bacteria present culture, and Scheirer-Ray-Hare (an extension of the Kruskal-Wallis test) and Tamhane test to analyze the SEM images in the groups and thirds. Significance was set at 5%. RESULTS: Enterococcus faecalis was still present after root canal cleaning regardless of irrigation methods or bacterial identification methods. CONCLUSION: Positive and negative pressure irrigation protocols using 2.5% NaOCl show a similar capacity to reduce E. faecalis in infected root canals.

Micro-Computed Tomographic Evaluation of Hard Tissue Debris Removal after Different Irrigation Methods and Its Influence on the Filling of Curved Canals.

INTRODUCTION: The aim of this study was to compare the efficacy of passive ultrasonic irrigation (PUI) and the EndoVac (EV) System (Discus Dental, Culver City, CA) in hard tissue debris removal and its influence on the quality of the root canal filling with the aid of micro-computed tomographic scanner. METHODS: Twenty-four mandibular molars were subjected to 4 microtomographic scannings (ie, before and after instrumentation, after final irrigation, and after obturation) using the SkyScan 1176 X-ray microtomograph (Bruker microCT, Kontich, Belgium) at a resolution of 17.42 µm. Mesial canals were prepared using R25 Reciproc instruments (VDW GmbH, Munich, Germany) and divided into 2 groups according to the final irrigation method: the PUI group (n = 12) and the EV group (n = 12). All specimens were filled with the continuous wave of condensation technique. CTAn and CTvol software (Bruker microCT) were used for volumetric analysis and 3-dimensional model reconstruction of the root canals, hard tissue debris, and the filling material. Data were statistically analyzed using the Student t test. RESULTS: Analysis of the micro-computed tomographic scans revealed debris accumulated inside the root canals, occupying an average of 3.4% of the canal's volume. Irrigation with PUI and the EV system reduced the volume of hard tissue debris in 55.55% and 53.65%, respectively, with no statistical difference between them (P > .05). Also, there was no difference among the groups with regard to the volume of filling material and voids (P > .05). CONCLUSIONS: PUI and the EV system were equally efficient in the removal of hard tissue debris and the quality of root canal filling was similar in both groups, with no influence from the irrigation method.

Unilateral fusion of a supernumerary tooth to a maxillary permanent lateral incisor: a report of a rare case.

A supernumerary tooth is an additional entity to the normal series of teeth that may occur in isolation or may be fused to a normal counterpart. Diagnosis and delineation of an accurate treatment plan in cases involving supernumerary teeth are often a challenge. This report describes a case of unilateral fusion of a supernumerary tooth to a maxillary permanent lateral incisor in which a conservative approach was used to reach a favorable outcome.

Efficiency and effectiveness evaluation of three glass fiber post removal techniques using dental structure wear assessment method.

AIM: This study evaluated the efficiency and effectiveness of three glass fiber post removal techniques. MATERIALS AND METHODS: Forty-five extracted maxillary teeth were endodontically treated and cross-sectioned in thirds. Presence of cementing agent and dental structure wear were assessed by analyzing images taken before luting of glass fiber post and after removal procedure. Teeth were divided into 3 groups: Group 1 - diamond bur + Largo reamer; Group 2 - ultrasonic insert; Group 3 - carbide bur + ultrasonic insert. Time spent on removal procedures, dental structure wear and amount of remaining cement agent were recorded and results submitted to ANOVA, Kruskal Wallis and Tukey-Kramer tests. RESULTS: Group 1 - 16'46", 33.33% and 6.99%; Group 2 - 12'31", 40% and 7.86%; and Group 3 - 10'24", 80% and 8.14%. Group 3 presented the most effective removal of glass fiber posts. CONCLUSION: There was no significant difference in efficiency among the evaluated techniques.

Analysis of the effect of ultrasonic agitation on the cleaning of root canals using different periods during the final irrigation

Introduction: The ultrasonic agitation was introduced as an adjuvant to conventional chemo-mechanical debridement during endodontic treatment to overcome the persistence of biofilms. Objective: To verify the cleaning of root canals irrigated with sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA), with or without an ultrasonic agitation, using different time periods and images obtained by scanning electron microscope (SEM). Material and methods: Forty mandibular incisors were cleaned, shaped and randomly divided into five groups according to the final irrigation protocol: SH10 group (ultrasonic agitation with NaOCl for 10 s), SH30 group (ultrasonic agitation with NaOCl for 30 s), SHE30 group (ultrasonic agitation with NaOCl and EDTA for 10 s), SHE90 group (ultrasonic agitation with NaOCl and EDTA for 30 s), and control group (NaOCl and EDTA without ultrasonic agitation). The teeth were prepared and analyzed by SEM at ×2000. The Kruskal-Wallis test was used with a 5% level of significance. Results: For the cervical and medial thirds, there was no statistically significant difference in cleaning among the protocols used (p > 0.05). For the cleaning of the apical third, SHE90 group demonstrated a significant difference (p < 0.05), as compared to the control and SH10 groups. Conclusion: For the final irrigation, an ultrasonic agitation with NaOCl and EDTA for 30 s allowed a better cleaning of the debris in the apical third of the root canal.

Assessment of smear layer removal protocols in curved root canals.

This study sought to assess if the final rinse protocol interferes with the smear layer removal in the apical area of curved canals. Sixty-four extracted human mandibular molars with curved mesial roots were instrumented with rotary files and divided into six experimental groups for final rinse: 1EDTA (syringe irrigation with 1 mL of 17% ethylenediaminetetraacetic acid (EDTA) ), 5EDTA (syringe irrigation with 5 mL of 17% EDTA), 1EDTA-P (syringe irrigation with 1 mL of 17% EDTA + pumping with gutta-percha point), 5EDTA-P (syringe irrigation with 5 mL of 17% EDTA + pumping with gutta-percha point), 1EDTA-EA (syringe irrigation with 1 mL of 17% EDTA + EndoActivator) and 5EDTA-EA (syringe irrigation with 5 mL of 17% EDTA + EndoActivator). Final rinsing was carried out over 3 min. The specimens were split lengthwise and observed under a scanning electron microscope using a score criterion. Comparison among the groups showed statistically significant difference only between the 5EDTA-EA group and the other groups (Kruskal-Wallis and Dunn's post-hoc tests, P < 0.05). The combination of 5 mL of 17% EDTA and 3 mL of 2.5% sodium hypochlorite (NaOCl) with the EndoActivator removed smear layer from the apical area of curved root canals more effectively than the other protocols used.

Influência do tratamento e do retratamento endodóntico na resistência adesiva de pinos de fibra de vidro / Influence of endodontic treatment and retreatment on the bond strength of fiber-glass post

O espaço preparado para pino após um retratamento endodôntico pode estar sujeito a maior quantidade de smear layer, em comparação com a quantidade de resíduos produzidos no tratamento inicial, já que nenhum protocolo de retratamento é capaz de garantir completa remoção de guta-percha e cimento obturador das paredes dos canais radiculares. Este estudo avaliou a resistência adesiva in vitro de pinos de fibra de vidro cimentados em dentes submetidos ao retratamento endodôntico, em comparação aos cimentados em dentes tratados endodonticamente. Quarenta canais de raízes bovinas foram instrumentados e obturados. As amostras foram divididas aleatoriamente em 2 grupos, sendo que as raízes do Grupo I foram preparadas para pino imediatamente depois de obturadas. As raízes do Grupo II tiveram as embocaduras dos canais seladas com o cimento restaurador temporário por um período de 30 dias, com posterior retratamento endodôntico e preparo para pino imediato. Pinos de fibra de vidro foram cimentados com cimento resinoso RelyX U100 nas raízes dos dois grupos, que permaneceram armazenadas por 7 dias para posterior realização do teste push-out, com resultados submetidos à análise de variância e ao teste de Tukey. A comparação das médias de força entre os grupos testados revelou que a média de força do Grupo I foi significativamente maior que a do Grupo II (p<0,01). O padrão de fratura foi predominantemente adesivo (interface dentina-cimento resinoso) em ambos os grupos. Pode-se concluir que há diminuição na resistência adesiva de pinos de fibra de vidro cimentados em dentes submetidos ao retratamento endodôntico.

The space prepared for a post after endodontic retreatment could be subject to a greater amount of debris compared to that produced during initial treatment because no retreatment protocol is capable of ensuring complete removal of gutta-percha and sealer from the root canal walls. This study assessed the in vitro bond strength of glass fiber posts cemented in teeth submitted to endodontic treatment, in comparison to posts cemented in teeth submitted to endodontic retreatment. Fourty roots of bovine teeth were instrumented, obturated and then randomly divided into two groups. In Group I, the gutta-percha was partially removed and the roots were prepared for post placement immediately after obturation. In Group II, the roots were sealed with temporary restorative cement and stored for a period of 30 days, after which they were endodontically retreated and immediately prepared for post preparation. Glass fiber posts were cemented with RelyX U100 resin cement in the roots of both groups, which remained stored during 7 days for subsequent push-out testing a and Tukey’s test. Comparison between groups revealed that the mean bond strength for Group I was significantly higher than that for Group II (p < 0.01). The pattern of bond failure was predominantly adhesive (dentin-resin cement interface) for both groups. It could be concluded that there was a reduction in the bond strength of glass fiber posts cemented in teeth submitted to endodontic retreatment

Assessment of the separation incidence of reciprocating WaveOne files: a prospective clinical study.

INTRODUCTION: Despite metallurgical advancements in the nickel-titanium file manufacturing process, file separation remains a concern. The purpose of this prospective clinical study was to assess the separation incidence of the reciprocating WaveOne file (Dentsply Tulsa Dental Specialties, Tulsa, OK) when used to prepare root canals of posterior teeth. METHODS: File separation incidence was assessed over an 18-month period in which 4 experienced and calibrated endodontists performed conventional endodontic treatment on posterior teeth using the WaveOne file system. The separation incidence was determined based on both the number of teeth and the number of canals instrumented during this time period. RESULTS: A total of 2,215 canals (711 teeth) were treated. Three instruments (two 21.06 and one 25.08) separated during use and were deemed to be irretrievable. The overall instrument separation incidence in relation to the number of canals shaped was found to be 0.13% (0.42% teeth). CONCLUSIONS: Based on the results of this study, the incidence of endodontic instrument separation when using the WaveOne reciprocating file was considerably low.

Influence of single-file endodontics on apical transportation in curved root canals: an ex vivo micro-computed tomographic study.

INTRODUCTION: More information regarding the ability of single files to maintain the original canal position is required before adopting a single-file approach to cleaning and shaping. This study compares apical transportation in curved root canals when instrumenting with a single WaveOne (WO) file (Dentsply Tulsa Dental Specialties, Tulsa, OK) in a reciprocating motion with that incurred when using a sequence of Twisted Files (TFs; SybronEndo, Orange, CA) in a continuous rotating motion. METHODS: Forty mesial canals of mandibular molars were evenly allocated into 2 balanced groups (n = 20) with a 17-mm average canal length and 20° average curvature. Canals were accessed in a conventional manner and instrumentation was completed with a single WO file or a series of TFs. The canals were instrumented according to the manufacturers' protocol. Apical transportation was assessed on a comparison of the pre- and postinstrumentation micro-computed tomographic scans at 1-, 2-, 3-, 4-, and 5-mm sections. One-way analysis of variance was performed to assess if a significant difference between systems exists. RESULTS: No significant difference (P > .05) was found between the WO and TF groups. Transportation in the mesial direction was of greater magnitude than distal transportation for both files systems. The mean transportation in the mesial direction was 100.1 ± 8.8 µm (WO group) and 101.0 ± 10.9 µm (TF group) (P = .5), whereas distal transportation was found to be 80.9 ± 14.6 µm (WO group) and 60.3 ± 11.0 µm (TF group) (P = .3). CONCLUSIONS: The results suggest that no difference exists between the WO file system and the conventional multifile TF system when considering apical transportation in curved canals.