Root canal dentin wear during final irrigation in endodontic retreatment with passive ultrasonic irrigation and easy clean instruments.

Context: Complementary procedures have been proposed to improve the endodontic retreatments. Aim: The aim of this study was to evaluate, by microcomputed tomography (micro-CT), the dentin wear caused by passive ultrasonic irrigation (PUI) and easy clean (EC) instruments, when used for the final removal of filling material during endodontic retreatment. Methods: Thirty-six mesial roots of the lower first molars were divided into four groups (n = 9), according to the final irrigation and sealer: PUI/AH Plus, EC/AH Plus, PUI/Total Fill (TF), and EC/TF. Canal volume was evaluated, both before and after the final irrigation, by micro-CT analysis. The Kruskal-Wallis test was used to compare the volumes among groups and the paired Wilcoxon test was used to compare the volume values before and after the final irrigation within each group. Results: Both complementary cleaning procedures promoted dentin wear that was observed only when the volume was analyzed for each third of the root canal. In the apical third, both instruments showed significant wear, where the use of the EC instrument resulted in greater wear than the PUI, in teeth filled with both AH Plus and TF BC Sealers (P < 0.05). Conclusion: Both complementary cleaning procedures promoted dentin wear and must be used cautiously.

Intraradicular Dentinal Changes Following Fiber Postremoval: Micro-computed Tomography Analysis.

Context: Excessive dentine wear during postremoval can occur due to the adhesion between the cement and the post. Aim: The aim is to evaluate dentine wear and microcrack occurrence following the removal of intraradicular fiberglass posts that were previously cemented with two types of resin cement. Methods: Distal roots (n = 38) of lower molars were instrumented, filled, prepared for intraradicular postinstallation, and divided into two groups according to the cement used for the posts: RelyX ARC or RelyX U200. The posts were removed through abrasion using ultrasonic diamond tips, after which the degrees of dentine wear (volume/mm3) and microcrack formation were assessed using microcomputed tomographic imaging. Statistical Analysis Used: The Mann-Whitney U (P ≤ 0.05) and Chi-squared tests (P ≤ 0.05) were used. Results: After the removal of the posts, no statistically significant difference in root canal volume or microcrack occurrence was observed between the groups (P > 0.05). The procedure produced significant dentine wear regardless of the type of cement used (P < 0.05). Conclusions: The removal of fiberglass posts caused extensive dentine wear but did not influence microcrack occurrence. The type of resin cement used did not affect the dentine loss or microcrack appearance that resulted from fiberglass postremoval.

Ionic concentration in periradicular medium after dissolution of endodontic file fragments: an in vitro study.

The aim of this study was to obtain ionic quantification in periradicular medium after diffusion tests of the solution used inside root canals during the electrochemical dissolution of endodontic file fragments and the NiTi-containing dissolution product via an apical foramen. Thirty single-rooted extracted human teeth had root canals prepared and were attached to Eppendorf tubes filled with sterile saline. The samples were divided into 3 groups (n = 10) according to the solution used inside the root canal during the diffusion tests: Group 1: [NaF 12 g/L + NaCl 1 g/L]; Group 2: [NaF 12 g/L + NaCl 1 g/L + NiTi 0.50 g/L]; Group 3: [NaF 6 g/L + NaCl 0.5 g/L + NiTi 0.25 g/L]. The sample in each Eppendorf tube was then analyzed to assay the ionic quantification in periradicular medium. The groups were compared in relation to ionic quantifications (Kruskal-Wallis and Dunn's tests, p ≤ 0.05). Group 2 showed significantly higher F-, Ni and Ti quantities than groups 1 and 3 (p < 0.05). Group 3 showed significantly higher Ti and Ni quantities than group 1, where no measurable quantities of Ti and Ni were observed (p < 0.05). The conclusions were that a 50% dilution of the NiTi-containing dissolution product resulted in significantly lower F-, Ni and Ti quantities compared to the undiluted product. The quantifications observed here suggest that irrigation is recommendable during the electrochemical dissolution process to reduce the resultant ion concentrations in both the root canal and the periradicular medium.

Ionic concentration in periradicular medium after dissolution of endodontic file fragments: an in vitro study

Abstract The aim of this study was to obtain ionic quantification in periradicular medium after diffusion tests of the solution used inside root canals during the electrochemical dissolution of endodontic file fragments and the NiTi-containing dissolution product via an apical foramen. Thirty single-rooted extracted human teeth had root canals prepared and were attached to Eppendorf tubes filled with sterile saline. The samples were divided into 3 groups (n = 10) according to the solution used inside the root canal during the diffusion tests: Group 1: [NaF 12 g/L + NaCl 1 g/L]; Group 2: [NaF 12 g/L + NaCl 1 g/L + NiTi 0.50 g/L]; Group 3: [NaF 6 g/L + NaCl 0.5 g/L + NiTi 0.25 g/L]. The sample in each Eppendorf tube was then analyzed to assay the ionic quantification in periradicular medium. The groups were compared in relation to ionic quantifications (Kruskal-Wallis and Dunn's tests, p ≤ 0.05). Group 2 showed significantly higher F-, Ni and Ti quantities than groups 1 and 3 (p < 0.05). Group 3 showed significantly higher Ti and Ni quantities than group 1, where no measurable quantities of Ti and Ni were observed (p < 0.05). The conclusions were that a 50% dilution of the NiTi-containing dissolution product resulted in significantly lower F-, Ni and Ti quantities compared to the undiluted product. The quantifications observed here suggest that irrigation is recommendable during the electrochemical dissolution process to reduce the resultant ion concentrations in both the root canal and the periradicular medium.

Retreatment of mesial roots of mandibular molars filled with resin-based and bioceramic sealers

Aim: The aim of this study was to evaluate, by micro-computed tomography (micro-CT) analysis, the remaining filling material during endodontic retreatment performed with Protaper retreatment without solvent. Methods: Forty mandibular molars were divided into two groups (n = 20) according to the sealer used in the obturation: the bioceramic TotalFill BC (TF) or the resin-based AH Plus (AHP). The specimens were scanned before instrumentation, after obturation and after filling removal. Only the mesial roots were analysed. The filling volumes and the remaining filling material were calculated in the entire root canal and in the cervical, middle and apical thirds. Results: The volume of obturation and the volume of remaining filling material in the entire root canal and in the cervical, middle and apical thirds of the canal between the groups were not statistically different (independent t-test, p > 0.05). In the AHP group, there was a higher percentage of remaining filling material in the middle third than in the cervical third (p < 0.05). Conclusion: The filling material could not be entirely removed from any specimen

The effectiveness of passive ultrasonic irrigation and the easy-clean instrument for removing remnants of filling material.

OBJECTIVE: This study aimed to evaluate the efficacy of passive ultrasonic irrigation (PUI) and the easy clean instrument by micro-computed tomography (CT) for removing remnant filling materials during endodontic retreatment. MATERIALS AND METHODS: Forty mesial roots of mandibular molars were divided into four groups (n = 10) according to the agitation system and sealer used: Group 1: PUI/AH Plus; Group 2: PUI/TotalFill; Group 3: Easy Clean/AH Plus; and Group 4: Easy Clean/TotalFill. The groups were compared by micro-CT analysis according to the volumes of the obturation and the remaining material before and after the agitation systems were used. RESULTS: There was no difference between the groups for total filling volume and initial and final remaining filling volume (P > 0.05). CONCLUSIONS: Both the PUI and easy-clean instrument are effective for removing remnants of filling material with no difference between the groups.

Accuracy of the initial diameter of finishing files and Gutta-Percha cones of the protaper Universal System

Objective: to assess the accuracy of the nominal initial diameter of ProTaper Universal® finishing files and their respective gutta-percha cones. Method : ProTaper Universal® finishing files, F1, F2, F3, F4 and F5 and corresponding ProTaper cones were used (10 of each). A Profile Projector was used to evaluate the initial diameter of files and cones. All measurements were repeated twice and performed by a single trained operator. A descriptive analysis of the files' initial diameters was performed considering the tolerance limit established by the ADA number 101. According to this standard, the files F1, F2 and F3 have a tolerance limit of ± 0.025 mm and the files F4 and F5 ± 0.05 mm. The same tolerance limit was used to evaluate the cones. The initial diameters of the instruments and cones studied were compared with the nominal values given by the manufacturer through Student's T test (pd"0.05). Results: No finishing file group showed adequate accuracy (pd"0.05). Accuracy was verified only from the F5 ProTaper cone group (p> 0.05). It was verified that 30% (n=15) of the finishing files and 20% (n = 10) of the cones exceeded the tolerance limits. Conclusion : Accuracy was not observed for any file and it was identified only in the F5 ProTaper Universal® cone. Most files and cones were within the tolerance limits established by the ADA.

Objetivo: Analisar a acurácia do diâmetro inicial dos instrumentos de acabamento do sistema ProTaper Universal® e seus respectivos cones de guta-percha. Método: Foram utilizados instrumentos de acabamento do sistema ProTaper Universal® F1, F2, F3, F4 e F5 e cones de guta-percha ProTaper correspondentes (10 de cada). O projetor de perfil foi usado para avaliar o diâmetro inicial dos instrumentos e cones. Todas as medições foram feitas duas vezes por um único operador treinado. Uma análise descritiva do diâmetro inicial dos instrumentos foi realizada considerando o limite de tolerância proposto pela ADA número 101. De acordo com essa norma, os instrumentos F1, F2 e F3 tem um limite de tolerância de ± 0.025 mm e os instrumentos F4 e F5 ± 0.05 mm. O mesmo limite de tolerância foi utilizado para avaliar os cones. Os diâmetros iniciais dos instrumentos e cones estudados foram comparados com os valores nominais dados pelo fabricante através do teste T (pd"0.05). Resultados: Foi verificada acurácia somente do cone de guta-percha ProTaper do grupo F5 (p>0,05). Nenhum grupo de instrumento de acabamento apresentou acurácia (pd"0,05). Foi verificado que 30% (n=15) dos instrumentos de acabamento e 20% (n=10) dos cones excederam o limite de tolerância. Conclusão: Acurácia não foi verificada em nenhum instrumento ProTaper Universal® e somente o cone F5 apresentou acurácia. A maioria dos instrumentos e cones estavam dentro do limite de tolerância proposto pela ADA.

Effectiveness of three methods for evaluating root canal anatomy of mandibular incisors.

This study compared the effectiveness of clinical observation, clinical microscopic observation, and tooth-clearing technique in determining the number of canals in mandibular incisors. Root canal ramifications were also analyzed. Using clinical and microscopic analyses, we determined the number of canal entrances in 277 mandibular incisors. In addition, tooth-clearing technique was used to determine the number of canals and frequency of ramifications in the samples. The kappa coefficient was used to compare the different methods with regard to frequency of canals. Most teeth had one canal entrance. The proportion of teeth with two canals was 23.5% by tooth-clearing analysis, 5.8% by clinical microscopy, and 1.1% by clinical analysis. A large number of samples had some type of ramification (40.1%), and most ramifications were present in teeth with two canals. The most frequent ramification was lateral canals (8.3%). Clinical microscopy improved identification of a second canal in mandibular incisors. However, it did not identify second canals in all teeth with two canals. (J Oral Sci 58, 347-351, 2016).

Obliteração pulpar cronica após traumatismo dentário e tratamento ortodôntico: relato de caso / Chronic pulp canal obliteration after dental trauma and orthodontic treatment: a case report

Introdução: descrever o tratamento endodôntico de incisivos inferiores com obliteração pulpar crônica (OPC) e periodontite apical após trauma dentário e tratamento ortodôntico prolongado. Relato de caso: paciente do sexo feminino, 22 anos de idade, procurou atendimento em uma clínica de Pós-graduação em Endodontia, relatando ter sofrido trauma dentário na região anteroinferior, seguido por tratamento ortodôntico por cinco anos. Dois nos após o nal do tratamento ortodôntico, lesões radiolúcidas associadas aos incisivos centrais inferiores foram observadas e o tratamento endodôntico foi iniciado por um clínico geral, sem sucesso na localização dos canais, devido à OPC. O tratamento endodôntico foi proposto e, com o auxílio de magni cação por microscopia óptica (25X), a localização dos canais foi feita. Movimentos de inserção, retração e rotação de 1/4 de volta nos sentidos horário e anti-horário com uma lima K #10 pré-curvada foram feitos até a patência apical. A intrumentação dos canais foi feita com a técnica do pré-alargamento e a medicação intracanal foi à base de pasta de hidróxido de cálcio, paramonoclorofenol e glicerina, por 15 dias, seguida pela obturação termoplasti cada e restauração com resina fotopolimerizável. Resultados: após 12 meses, a paciente não apresentou sinais e sintomas, e ocorreu o completo reparo das lesões perirradiculares dos incisivos centrais inferiores. Conclusão: a OPC causada pela associação do trauma dentário ao tratamento ortodôntico prolongado pode ter evoluído para a necrose pulpar e, consequentemente, para a periodontite apical. O protocolo de localização, exploração, limpeza, modelagem, medicação intracanal e preenchimento dos canais radiculares evitou as complicações por iatrogenia e permitiu o sucesso do caso.

Ability of Three Endodontic Sealers to Fill the Root Canal System in Association with Gutta-Percha.

INTRODUCTION: The present study compared the ability of the endodontic sealers AH Plus, Pulp Canal Sealer and EndoREZ to fill the root canal system in association with gutta-percha. METHODS: Ninety mandibular premolars were accessed, prepared and divided into three groups of 30 teeth each, according to the sealer used to fill the canals: AH Plus, Pulp Canal Sealer and EndoREZ. All the teeth were filled using the continuous wave of condensation technique. The specimens were then decalcified, dehydrated, rendered transparent, and analyzed by three independent evaluators with 8x magnification. Chi-squared test (χ(2), p < 0.05) was used to compare the groups in relation to the totally filled, the partially filled and the non filled ramifications. The same test was used to compare the directions of filled ramifications and the number of ramifications among the three thirds of the roots. RESULTS: EndoREZ filled a significantly higher number of ramifications than AH Plus and Pulp Canal Sealer (χ(2), p < 0.05). All the groups showed higher number of totally filled ramifications than partially filled and unfilled ramifications. The ramifications were more frequently detected in the apical third, followed by medium and coronal thirds, respectively (χ(2), p < 0.05). The ramifications were more frequently detected towards lingual direction (χ(2), p < 0.05). CONCLUSION: EndoREZ presented higher ability to fill the root canal system in association with gutta-percha when compared to AH Plus and Pulp Canal Sealer. The ramifications were more frequently detected in the apical third, running in a lingual direction.

Influence of Heat Treatment of Nickel-Titanium Rotary Endodontic Instruments on Apical Preparation: A Micro-Computed Tomographic Study.

INTRODUCTION: The aim of this study was to make a 3-dimensional comparison of the canal transportation and changes in apical geometry using micro-computed tomographic imaging after canal preparation with K3 (SybronEndo, Orange, CA) and K3XF (SybronEndo) file systems. METHODS: Twenty-eight mandibular molars were randomly divided into 2 groups according to the rotary system used in instrumentation: K3 or K3XF. The specimens were scanned by micro-computed tomographic imaging before and after instrumentation. Images before and after instrumentation from each group were compared with regard to canal volume, surface area, and structure model index (SMI) (paired t test, P < .05). After instrumentation, the canals from each group were compared regarding the changes in volume, surface area, SMI, and canal transportation in the last 4 apical mm (t test, P < .05). RESULTS: Instrumentation with the 2 rotary systems significantly changed the canal volume, surface area, and SMI (P < .05). There were no significant differences between instrument types concerning these parameters (P > .05). There were no significant differences between the 2 groups with regard to canal transportation in the last 4 apical mm (P > .05). CONCLUSIONS: Both rotary systems showed adequate canal preparations with reduced values of canal transportation. Heat treatment did not influence changes in root canal geometry in the apical region.

Influence of electrochemical polishing on the mechanical behaviour of nickel-titanium rotary files.

The purpose of this study was to evaluate the influence of electrochemical polishing on the cyclic fatigue, cutting efficiency and surface topography of Miltex nickel-titanium rotary files. A group of files were submitted to electrochemical polishing. New files and polished files were tested for flexural fatigue and for cutting efficiency. Scanning electron microscopy observations of all files were carried out to compare the surface morphologies of polished and new files. The t-test was used to compare the groups for cutting efficiency. Scanning electron microscopy analysis indicated that the polishing resulted in more regular surfaces in relation to the new files. Electropolished files attained a significantly higher number of cycles to fracture than new unpolished files. No statistical difference exists between the groups in relation to the cutting efficiency (t-test, P < 0.05). The polished files keep their integrity for a significantly higher number of cycles to fracture than the new files, without compromising cutting efficiency.

An initial investigation of the electrochemical dissolution of fragments of nickel-titanium endodontic files.

INTRODUCTION: A recent study presented the concept of an electrochemical-induced dissolution technique of fractured instruments. The purpose of this study was to test the ability to dissolve embedded fragments of K3 nickel-titanium (NiTi) files. The surface of the fragment exposed to the electrolytic solution was the main parameter evaluated as an interfering factor on the dissolution process. METHODS: Three types of K3 NiTi 30.06 file fragments were produced, resulting in different exposed cross-section areas. Anodic current was recorded and used as a reference to evaluate the dissolution process of the fragments. Analysis of variance (P < .05) was used to compare the total electrical charge obtained from current versus time records among the fragments of the 3 groups. Radiographic analysis was carried out before and after the tests to observe the extension of dissolution achieved. RESULTS: The total electrical charge values generated during the tests evidence a statistical difference among the 3 groups of fragments (analysis of variance, P < .05). The larger is the diameter of the exposed surface cross section, the higher is the total value of electrical charge. The radiographic images obtained before and after the tests showed a significant reduction of the fragment length as a result of the polarization imposed. CONCLUSIONS: The results presented here showed that it is possible to obtain a significant dissolution of K3 NiTi endodontic instrument fragments. The diameter of the surface of fragment exposed to the medium affects the current levels used to promote the dissolution.

Dissolution of nickel-titanium endodontic files via an electrochemical process: a new concept for future retrieval of fractured files in root canals.

INTRODUCTION: The retrieval of fractured instruments from root canals has been largely reported in the literature. However, a less complex retrieval method that causes minimum damage to the dental structures is needed. The aim of this article is to introduce a new concept of retrieval of fractured instruments from root canals based on an electrochemical process. METHODS: Current register tests were used to evaluate the dissolution process of 25.04 nickel-titanium (NiTi) K3 rotary files. A constant anodic potential was applied to the NiTi files, whereas the Potentiostat registered the anodic current. After the tests, all files were observed by using an optical microscope. RESULTS: The current attained initial values of approximately 55 mA that declined during the entire test. A good reproducibility of results was observed. The optical microscopy analysis evidenced a progressive consumption of the files with increasing polarization time. CONCLUSIONS: The results presented here show that the concept of fractured file retrieval by an electrochemical process is feasible. This concept resulted in a consistent basis for the development of a method to remove fractured instruments from root canals.