Academic literature on the topic 'Curved root canal'

The objective of this study was to analyse the effectiveness of some parameters which characterise the change in morphology in human root canals subjected to ProTaper rotary enlargement with the help of an X-ray microfocus computed tomography (MCT) and to introduce a novel parameter that is effective in quantifying changes in root canal morphology. Ten each straight and curved root canals with mature apices chosen from extracted human upper incisor and canine teeth were scanned with MCT before and after canal shaping using ProTaper rotary instruments in order to facilitate three-dimensional digital reconstruction and quantitative gauging of relevant instrumental parameters and changes therein (surface area and volume). Root canal geometry change and the effectiveness of shaping were quantified with Structure Model Index change (ΔSMI) and surface area change to volume change ratio (ΔSA/ΔV). These two parameters were also tested on simulated canals. Postinstrumentation cross-sectional changes were also analysed, but only on the plastic blocks. Statistical analysis of parameters was carried out to verify the significance of results. Analysis of cross-sectional shape of postinstrumented resin simulated canals showed statistically significant decrease in Form Factor (p<0.05) and statistically significant increase in Eccentricity (p<0.005). ΔSMI did not show significant difference between straight and curved canals. SMI values showed bidirectional change during root enlargement which questions the reliability of this metric in analysing instrumentation. Statistically significant (p<0.005) deviations in ΔSA/ΔV were quantified as 1.92 and 3.22 for straight and curved human canals, respectively. Instrumentation-induced canal geometry change was determined to be more pronounced in curved canals using the novel parameter ΔSA/ΔV. This has been proven as being a statistically accurate and reproducible parameter for quantitative characterisation of root canal geometry change and differentiation of preparational efficacy for both straight and curved root canals.

In this study, curved maxillary molar root canals were instrumented with RaCe rotary system to evaluate: 1. the occurrence of canal transportation using a radiographic platform; 2. the action of the instruments on the dentin walls, centering ability and canal enlargement by analysis of digital images; and the percentage of regular dentin surfaces and debris within the canal by histological analysis. Ten mesiobuccal roots of extracted human maxillary molars were embedded in acrylic resin and sectioned at the middle and apical thirds. Root canal shaping was performed using the RaCe rotary system at 250 rpm and 1 Ncm torque. Each instrument set was used five times according to a crown-down technique in the following sequence: 40/0.10, 35/0.08, 25/0.06, 25/0.04, 25/0.02 (working length - WL), 30/0.02 (WL) and 35/0.02 (WL). Each instrument was inserted until resistance was felt and then pulled back, followed by brushing movements towards all canal walls. Each specimen was assessed by three study methods: radiographic platform, digitized image assessment and histological analysis. The radiographic platform showed lack of apical transportation. No statistically significant difference (Wilcoxon test, p>0.05) was found between the middle and apical thirds regarding instrument action on dentin walls, centering ability, area of root canal enlargement, percentage of regular dentin surfaces and debris within the root canal. It may be concluded that RaCe system is a suitable method for the preparation of curved root canals, regarding the maintenance of root canal original path, action on dentin walls, canal enlargement and removal of debris from the root canal lumen.

The obturation quality of GuttaFlow Bioseal in curved root canals is not commonly investigated although there has been a current approach toward utilizing this material in extracted molars in recent years. This study assessed the obturated surface area, extrusion of root filling material beyond the apical foramen and duration of obturation procedure in curved root canals using monocone obturation technique. Access cavity was prepared in 20 human mandibular molars. Root canals with curvature of more than 10 as determined according to Schneider’s method were included. Samples were prepared using Hyflex CM rotary files and divided into two groups (n=10): Group 1 [gutta-percha cone and GuttaFlow Bioseal] and Group 2 [gutta-percha cone and RoekoSeal Automix root canal sealer]. The duration of obturation procedure was recorded and obturation radiographs were taken. Samples were bisected and the mesial roots were sectioned horizontally to obtain 3 root segments; apical, middle and coronal. All resected roots were mounted on brass stubs, sputter-coated with thin platinum coating and observed under scanning electron microscope (SEM) at 70x magnification. The SEM images were transferred to the SketchAndCalc Area Calculator software. No statistically significant differences in the obturated surface area and extrusion of root filling material were observed between Group 1 and 2, irrespective of the status of root canal curvature. Duration for obturation in severe root canal curvatures between Group 1 and 2 were statistically significant. Obturated surface area and extrusion of root filling material were not affected by the root canal curvature, however duration for obturation using GuttaFlow Bioseal in severe root canal curvatures was slightly longer.

Objective: this study evaluated the ability of rotary (ProTaper-Retreatment and Mtwo-Retreatment) and reciprocating (Reciproc and WaveOne) systems in maintaining the original shape of the canal after root canal retreatment. Material and Methods: forty curved resin blocks with simulated root canals were prepared and filled. After that, each block was randomly assigned to 4 groups (n = 10) according to the retreatment system used. Stereomicroscopic images from each block were taken before and after retreatment procedures. Evaluation of canal transportation was obtained for all canal length and for 2 independent canal regions: straight and curved parts. ANOVA followed by Tukey’s test was used (P<0.05). Results: for all canal length ProTaper-Retreatment system showed lowest transportation values followed by Reciproc, MTwo-Retreatment and WaveOne systems (P <0.01). At the straight part, ProTaper-Retreatment system produced the lowest canal transportation followed by Reciproc and MTwo-Retreatment systems (P < 0.05); at the curved part, ProTaper-Retreatment and Reciproc systems produced the lowest canal transportation followed by MTwo-Retreatment system (P < 0.05). The WaveOne system resulted in the highest transportation values at both canal parts (P < 0.05). Conclusion: overall, ProTaper-Retreatment system produced less canal transportation in both portions of the simulated canals than the others systems tested after retreatment procedures.

The use of nickel-titanium instruments have become an important part of the root canal treatment, in order to facilitate the cleaning and shaping of root canals, because the incorrect utilization of the endodontic files during endodontic treatment may produce unwanted procedural errors. The aim of this study was to evaluate on simulated curved root canal models the cleaning efficiency and the apical transportation in three reference areas of the root canal files, ProTaper (Dentsply Maillefer), K3XF (Sybron Endo) and HyFlex (Coltene Endo) systems, compared to the hand K-files (DentsplyMaillefer). According to our results, rotary file systems are more efficient than the hand files, in cleaning the root canal.

This study evaluated the effectiveness of NiTi ultrasonic tips for Enterococcus faecalis (E. faecalis) biofilm removal in simulated complex root canals. Sixty root canal models consisting of a 30-degree curved main canal and two lateral canals were constructed from polydimethylsiloxane and incubated with E. faecalis. Irrigants in root canals were activated using a manual syringe (SI), a stainless steel (SS) instrument, a nickel-titanium (Ni-Ti) ultrasonic instrument, or a sonic instrument (EA). Instruments of SI, SS, and NiTi-9 groups were placed 9 mm from the apex, whereas those in NiTi-2 and EA groups were placed 2 mm from the apex. The efficacy of each method was determined as the ratio of fluorescence concentration before and after activation. In the apical curved canal, the highest efficacy was found in the NiTi-2 group (99.40%), followed by SI (84.25%), EA (80.38%), SS (76.93%), and NiTi-9 (67.29%) groups. In lateral canals 1 and 2, the efficacy was the highest in the NiTi-2 group and the lowest in the SI group. The NiTi ultrasonic instrument could effectively remove biofilms in the curved canal and lateral canals. This instrument should be introduced close to the working length. An up-and-down motion of the activation instrument is recommended.

Introduction: More detailed acquaintance with specialist endodontic literature and treating complicated endodontic cases have revealed that the palatal root canal in maxillary first molars has different features from generally accepted simplicity. Aim: The aim of this study was to investigate the number, orientation and shape of the curvature of the palatal root canal in maxillary first molars, characteristics that may have great influence on the procedure and outcome of endodontic therapy. Materials and methods: Material consisted of 100 left and 100 right extracted human first maxillary molars. Extended access cavity was prepared, and canal orifices were detected using an endodontic probe. K-flex file no 15 or 20 was then introduced into the palatal root canal until the tip appeared at the apical foramen. The tooth was radiographed from buccal-oral (clinical) and mesial-distal (proximal) aspect under standardized conditions. On magnified images, the number and character of canal, orientation and shape of the curvature were determined. Results: One palatal root canal was found in each of 200 teeth. From the clinical projection, 60% of the palatal canals appeared curved and from the proximal 93.5% (p<0.05). Out of 120 curved canals from the clinical aspect, 66.7% were oriented distally and 33.3% mesially. From the proximal projection, of 187 curved canals 68,4% were oriented buccally, and 31,6% palatally. From the clinical projection, 49.2% were C-shaped, and 32.5 % with the J-shaped curvature. Only 18.3% of the palatal canals were with the S-shaped curvature (p<0.05). Conclusions: Upon presented results, practitioners may predict with high significance the character, orientation and curvature shape of the palatal root canal in maxillary first molars in the buccal-oral dimension which is not visible on clinical radiographs and, therefore, perform more successful endodontic treatment.

Abstract Objective: The aim of the study was to compare the canal transportation and centering ability of Rotary ProTaper Next, Hyflex CM and Wave One primary systems using cone beam computed tomography (CBCT) in curved root canals. Materials and Methods: Total 30 freshly extracted maxillary first molars having root canals with curvature between 10°- 20° were divided into three groups of 10 teeth each. All teeth were scanned by CBCT to determine the root canal shape before instrumentation. In Group 1, the canals were prepared with ProTaper Next files, in Group 2 with Hyflex CM files and in Group 3 with Wave One files. After preparation, post-instrumentation scan was performed. Pre-instrumentation and post-instrumentation images were obtained at 3 mm and 6 mm above the apical foramen and were compared using CBCT software. The amount of canal transportation and centering ability were assessed and statistically compared with one way analysis of variance and Tukey honestly significant test. (p<0.05). Results: All instrumentation systems used resulted in some amount of canal transportation. Data obtained suggested that Wave One files caused significantly lesser transportation and remained better centered in the canal than Hyflex CM and Rotary ProTaper Next files. Conclusion: The canal preparation with Wave One files results in lesser transportation and better centering ability than Hyflex CM and ProTaper Next rotary files in curved root canals.

Abstract Objectives The aim of this study was to compare the volume variation and maintenance of the root canal position when using the ProGlider 16.02 (PG) and the WaveOne Gold Glider 15.02 (WOGG) file systems for glide path preparation. Materials and Methods Twenty-four moderately curved mesiobuccal canals of maxil-lary first molars were selected and randomly divided into two groups: PG and WOGG. The selected teeth were scanned using microtomography before and after root canal preparation to assess centralization and linear transport at 1, 3, 5, and 7 mm from the apical foramen. Statistical Analysis The data were analyzed with the Mann–Whitney U test. The level of significance was 5%. Results There were no significant differences in volume variation or root canal transport (p > 0.05). There was a significant difference in the centralization of the root canal at 3 mm from the foramen (p < 0.05). Conclusions WOGG and PG instruments presented similar results regarding the root canal volume increase and transport. WOGG caused higher decentralization at 3 mm from the apical foramen.

Preservation of the original anatomical shape following instrumentation of root canals is essential for endodontic success. Procedural errors created during glide path enlargement might be exacerbated or initiated during subsequent shaping. The aims of this study were to: (1) compare canal centering ability and transportation of pre-curved Senseus K-FlexoFiles (stainless steel), ProGlider file (M-Wire) and One G file(NiTi alloy) after glide path enlargement in curved root canals micro-computed tomography (micro-CT) scanning; (2) compare canal centering ability and transportation of OneShape (NiTi alloy), ProTaper NEXT (M-Wire alloy) and WaveOne Gold (Gold wire) instrumentation techniques in the same canals; (3) compare the change in root canal volume between uninstrumented canals, canals after glide path preparation, and canals after root canal preparation. One hundred and thirty-five curved mesio-buccal root canals of human maxillary molars were randomly divided into three groups. These groups were (1) glide path enlarged using pre-curved size 10, 15 and 20 stainless steel Senseus K-FlexoFiles (n=45); (2) manual glide path enlargement with a size 10 K-File followed by One G (n=45); and (3) manual glide path enlargement with a size 10 K-File followed by the ProGlider (n=45). Micro-CT was used to scan teeth before and after glide path preparation. Each glide path specimen group was randomly assigned to three equal groups (n=15) resulting in nine glide path/shaping groups of fifteen canals each: Group 1 (K-FlexoFile + OneShape)(K/OS); Group 2 (K-FlexoFile + ProTaper NEXT)(K/PTN); Group 3 (K-FlexoFile + WaveOne Gold)(K/WOG); Group 4 (One G + OneShape)(OG/OS); Group 5 (One G + ProTaper NEXT)(OG/PTN); Group 6 (One G + WaveOne Gold)(OG/WOG); Group 7 (ProGlider + OneShape)(PG/OS); Group 8 (ProGlider + ProTaper NEXT)(PG/PTN); and Group 9 (ProGlider + WaveOne Gold)(PG/WOG). After canal preparation with the shaping instruments, all the specimens were scanned again by means of micro-CT. The three-dimensional images obtained before instrumentation, after glide path preparation, and again after final canal preparation were reconstructed and interpreted. Centering ratio values, canal transportation and change in root canal volume were recorded and compared between the three glide path- and nine root canal preparation groups. Canal transportation and centering ability were evaluated over the apical, midroot, and coronal levels (2 mm, 5 mm and 9 mm from the root apex). The results were statistically analysed using a one-way ANOVA for parametric and Kruskal-Wallis H test for non-parametric comparisons. Statistical significance was set at p< 0.05. One G and ProGlider displayed statistically significantly better mean centering ratios than stainless steel K-FlexoFiles at each level examined and for the combined results of the three levels (p<0.05). Apical canal transportation ratio values after glide path enlargement were significantly higher for the K-File group compared to One G and ProGlider (p<0.05). At the midroot and coronal levels and for the combined results of the three levels, the canal transportation results were statistically similar for all glide path groups (p>0.05). The volume of dentine removed by the three glide path groups was statistically significantly similar for K-FlexoFiles, One G and ProGlider (p<0.05). No statistically significant difference was found in the mean centering ratios at the apical and midroot levels of the various glide path groups in combination with the shaping instruments (p>0.05). However, at the coronal level, centering ratio results following glide path preparation with K-FlexoFiles appeared to affect shaping outcomes for both PTN and OS groups. One Shape performed poorly following all glide path techniques with OG/OS and significantly displayed the worst centering ratio at this level. The results for the combined centering ratio values of the various glide path/shaping groups displayed no statistically significant differences between the different combination groups (p>0.05). Apical canal transportation after shaping was significantly highest for K/OS followed by K/PTN. At the midroot level canal transportation was significantly higher for K/PTN than K/OS and OG/OS, which were statistically similar to each other. Coronal canal transportation after canal shaping was significantly highest for K/PTN followed by K/OS. The most favourable mean combined transportation ratio values of the various glide path/shaping groups were observed in OG/WOG and in PG/WOG groups and the least favourable for the K/OS and the K/PTN groups. The three groups shaped with ProTaper NEXT exhibited the highest volume of dentine removed with the highest displayed by the PG/PTN group. Statistically, the lowest mean volume of removed dentine was by the PG/WOG group. In general, results were more favourable after canal preparation with the WaveOne Gold Primary file following any of the three glide path preparation techniques.
Thesis (PhD)--University of Pretoria, 2017.
Community Dentistry
PhD
Unrestricted

A proposta desse estudo in vitro foi avaliar a influência do pré-alargamento cervical no desgaste apical de canais simulados curvos preparados com instrumentos rotatórios de níquel-titânio. Foram confeccionados 30 blocos de resina com canais simulados de 20 graus de curvatura que foram divididos aleatoriamente em três grupos distintos (n=10) de acordo com o tipo de alargamento cervical realizado: Grupo I - sem alargamento cervical; Grupo II - alargamento cervical realizado com brocas CP Drill®; Grupo III - alargamento cervical realizado com brocas LA Axxess®. Previamente ao alargamento cervical os canais foram preenchidos com tinta nanquim em toda sua extensão e realizaram-se as fotografias iniciais com auxílio de máquina digital posicionada em estativa. Para o preparo apical utilizaram-se instrumentos rotatórios K3® na seqüência de 20.02 até 45.02, sendo que, entre o intervalo do uso de cada instrumento o canal foi preenchido, novamente, com tinta nanquim e realizada a fotografia final para cada instrumento. As fotografias pré e pós-operatórias foram sobrepostas e procedeu-se a mensuração do desgaste linear da parede interna e externa do canal simulado no ápice da curvatura e no ápice do canal proporcionado por cada instrumento, com auxílio do software Image Tool. A diferença entre esses valores, de acordo com cada área do canal avaliada, foi submetida à análise estatística. O teste de Regressão Linear permitiu estabelecer uma correlação entre o calibre do instrumento e o desgaste do canal, que pode ser traduzida em uma equação matemática, indicando que é diretamente proporcional. O teste de Kruskal-Wallis (complementado com pós-teste de Dunn) permitiu a comparação do desgaste entre os diferentes grupos experimentais. Por meio desses testes pode-se observar que grupo onde não foi realizado o pré-alargamento cervical apresentou padrões de desgastes diferentes daqueles onde o preparo foi executado. O grupo sem pré-alargamento provocou o desgaste acentuado do lado externo da curvatura, enquanto os grupos preparados com CP Drill® e LA Axxess® mostraram padrões de desgaste semelhantes, denotando a maior centralização do instrumento no canal em ambas as regiões analisadas (ápice da curva e ápice do canal). Pode-se concluir que o pré-alargamento cervical influenciou de forma positiva no preparo da região apical de canais simulados curvos, proporcionando preparos mais centralizados dessa região.
The purpose of this in vitro study was to evaluate the influence of cervical preflaring on prepared canal shape in simulated curved root canals prepared with nickel-titanium rotary systems. Thirty resin blocks with simulated canals with 20º curvature were fabricated and randomly assigned to three groups (n=10) according to the type of cervical preflaring: Group I - no cervical preflaring; Group II - cervical preflaring with CP Drill® burs; Group III - cervical preflaring with LA Axxess® burs. Previously cervical preflaring, the canals were thoroughly filled with India ink and the initial photographs were taken using a digital camera fixed in a static position. Right after, apical preparation was performed using 20.02 to 45.02 K3® rotary instruments. At each change of file, the canals were refilled with India ink and the final photographs were taken for each instrument. The initial and final photographs were superimposed and linear dentin removal produced by each type of rotary instrument was measured with specific software at the internal and external portions of the curvature apex and at the canal apex. The difference between the initial and final values was analyzed statistically, according to each canal region. Statistical analysis by linear regression established a correlation between instrument size and canal transportation, which can be expressed by a mathematical equation. This correlation is directly proportional, which means that the greater instrument, the more accentuated the canal transportation. Additionally, Kruskal- Wallis test (complemented by the Dunn\' post-test) allowed comparing dentin removal among the different experimental groups. These tests revealed that the non-flared group presented different dentin removal patterns, as compared to the groups where cervical preflaring was undertaken. The group without preflaring presented a significantly greater dentin removal on the external side of curvature, while the groups preflared with CP Drill® and LA Axxess® exhibited similar dentin removal patterns, demonstrating a greater centralization of the instrument inside the canal, for both analyzed regions (curvature apex and canal apex). It may be concluded that cervical preflaring influenced positively the apical preparation of simulated curved canals, producing more centralized preparations in this region.

The aim of this in vitro study was to investigate various glide path preparation instruments followed by root canal preparation with the reciprocating Primary WaveOne Gold instrument in curved mesial root canals of extracted human mandibular molars. Micro Computed Tomography (micro-CT) was used. Canal transportation, centering ability and effect on remaining dentine thickness were evaluated over the apical, midroot and coronal levels (3 mm, 5 mm and 7 mm from the root apex). In addition, preparation times for glide path preparation and final canal preparation with the Primary WaveOne Gold instrument were also recorded and compared. Sixty curved mesio-buccal root canals were randomly divided into four groups. These groups were Group 1: no further glide path preparation (n=15); Group 2: glide path enlarged with the use of pre-curved size 10,15 and 20 stainless steel K-files (n=15); Group 3: manual glide path enlargement with a size 10 K-file and further preparation with rotary PathFiles no.1-3 (n=15); and Group 4: manual glide path enlargement with a size 10 K-file and further preparation with the reciprocating WaveOne Gold Glider (n=15). Micro-CT was used to scan teeth before and after glide path preparation. The final canal preparation was done with the Primary WaveOne Gold instrument after which all 60 specimens were scanned again by means of micro-CT. The three-dimensional images obtained before instrumentation, after glide path preparation and again after final canal preparation with the Primary WaveOne Gold instrument were reconstructed and interpreted. Centering ratio values, canal transportation, remaining dentine thickness as well as glide path and final canal preparation times were recorded and compared between the four glide path groups with the use of a one-way analysis of variance (ANOVA) for parametric and Kruskal-Wallis H test for non-parametric comparisons. Statistical significance was set at p< 0.05. PathFiles performed most favourably when mean centering ratios were compared over all three levels from the root apex. However, no statistically significant difference in the mean centering ratios was found after glide path preparation when K-files, PathFiles and the WaveOne Gold Glider were compared. Mean combined transportation over the apical, midroot and coronal levels after glide path preparation was statistically significantly higher in the K-file preparation groups compared to the PathFile and WaveOne Gold Glider groups. There was no statistically significant difference in the mean combined centering ratios or transportation values of the various glide path groups in combination with the Primary WaveOne Gold instrument over the apical, midroot and coronal levels. Although not statistically significant, the highest mean transportation values were seen in the group where no glide path was prepared prior to final canal preparation with the Primary WaveOne Gold Instrument. All glide path groups performed similarly in evaluation of preservation of dentine when they were used in combination with the Primary WaveOne Gold instrument. Not having a prior glide path resulted in the most dentine thickness reduction after final canal instrumentation with the Primary WaveOne Gold instrument. Glide path preparation was statistically significantly fastest with the use of the WaveOne Gold Glider (p<0.0001). Having no prior glide path preparation resulted in statistically slower final canal preparation in combination with the Primary WaveOne Gold instrument compared to the other three glide path preparation groups (K-files, PathFiles and WaveOne Gold Glider) (p<0.0001).
Dissertation (MSc Dentistry)--University of Pretoria, 2017.
Odontology
MSc Dentistry
Unrestricted

Endodontic retreatments are time-consuming and difficult to perform. Removing the root canal filling material of the original treatment with maximum efficiency and safety is a complex task that requires a good technique, patience and perseverance. This filling material is often contaminated and prevents access to areas of the canal harboring bacteria and remnants of necrotic tissue, especially in the isthmus region and in dentinal tubules. The aim of this study was to use micro-computed tomography to evaluate two protocols for the removal of root canal filling material from curved root canals of the mesial roots of mandibular molars using a reciprocating instrument followed by two different rotary instruments manufactured with different nickel-titanium alloys. The reduction in the volume of the filling material inside the root canals was evaluated. Assessments were also made of the influence of the glide path extension on root canal obturation, the extrusion of filling material after the use of the reciprocating instrument, the volume of filling material after retreatment and its presence in isthmus areas. In addition, the use of a solvent and the agitation of a 2% sodium hypochlorite solution using either passive ultrasonic irrigation (PUI) or a plastic instrument in reciprocating motion were evaluated. A total of 40 mesial roots of mandibular molars with a mean curvature of 25 degrees were selected. The teeth were radiographed digitally in the buccolingual and mesiodistal directions, with a digital Xray system (Schick CDR; Schick Technologies, Long Island, NY), using an exposure time of 0.16 s. This was done in order to select the teeth and then compose two groups with similar characteristics to ensure their anatomic homogeneity. Group homogeneity in terms of anatomy, root canal length, curvature angle, and Vertucci classification type II and IV were confirmed and showed that the study groups were well balanced. Two groups were defined according to the retreatment protocol adopted, namely RHPui (Reciproc + Hyflex + PUI) and RMEasy (Reciproc + Mtwo + EasyClean). The teeth were instrumented with the Reciproc R25 instrument and filled using the single-cone technique and AHPlus cement. Prior to the use of this instrument, canal patency was achieved by creating a glide path with PathFile instruments, throughout the entire extension of the canal in Group RHPui, and up to 1 mm short of the total canal length in Group RMEasy. In both groups, the original filling material was removed with the Reciproc R25 instrument. Xylene was used as a solvent in Group RHPui up to the middle third, but not in the apical area, in the later steps of instrumentation with Reciproc R25. In Group RHPui, the Hyflex 40.04 instrument, made with a CM nickeltitanium alloy, was used. After that, xylene solvent was applied for one minute in the pulp chamber, followed by passive ultrasonic irrigation (PUI) with 2% sodium hypochlorite using an irrisonic instrument, applied up to 2 mm short of the working length. In Group RMEasy, the Mtwo 40.04 instrument, made with a conventional nickeltitanium alloy, was used. Xylene solvent was also used in the pulp chamber for one minute, followed by application of a 2% sodium hypochlorite solution agitated mechanically with an EasyClean plastic instrument in reciprocating motion up to the full working length. The two groups were re-obturated using the warm vertical condensation technique, with a gutta-percha cone corresponding to the final instrument, and with AHPus cement. Micro-CT scans were performed after each procedure to evaluate the volume of the remaining material, the extrusion after the use of the reciprocating instruments, the final volume of the obturation at the end of the retreatment and the filling material volume in the isthmus area, both after the original obturation and after re-obturation. The results showed that the initial filling was significantly closer to the apical foramen in Group RHPui than in Group RMEasy, after the initial treatment. After performing the retreatment protocols, the complete removal of filling material from inside the root canals was not achieved in either study group, with no statistically significant difference (P > 0.05) between groups regarding this variable. In the intra-group evaluation, a statistically significant difference (P < 0.05) was found between the procedural steps regarding the reduction in filling material volume, both in the total canal length and at its different levels, except for the middle third after HyFlex, the cervical third after Mtwo, and the middle third after EasyClean. The volume of the final filling material was significantly higher (P < 0.05) than the volume of the original filling material in both study groups. The volume of filling material in the isthmus region was significantly higher after re-obturation in both groups (P < 0.05), and this increase was greater in the RMEasy Group. There was no statistically significant difference (P > 0.05) between groups regarding the total amount of time expended in the removal of filling material (P > 0.05), namely 209.40 s for the RHPui Group and 227.40 s for the RMEasy Group. There was also no statistically significant difference (P > 0.05) between groups regarding the volume of extruded filling material, namely 0.0258 mm3 (0 0.954) in the RHPui Group and 0.0037 mm3 (0 0.565) in the RMEasy Group. The Shapiro-Wilks, Mann-Whitney, Wilcoxon, Friedman and Dunn tests were used in the data analysis.
Os retratamentos endodônticos demandam tempo e são difíceis de serem executados. Remover o material de obturação do tratamento original com a máxima eficiência e segurança é uma tarefa complexa que necessita de técnica, paciência e perseverança. Esse material de obturação muitas vezes está contaminado, e impede o acesso às áreas do canal onde permaneceram restos de tecido necrótico e microrganismos, especialmente na região do istmo e nos túbulos dentinários. O objetivo deste trabalho foi avaliar, por meio da microtomografia computadorizada, dois protocolos de desobturação de canais radiculares curvos de raízes mesiais de molares inferiores utilizando um instrumento reciprocante seguido de dois diferentes instrumentos rotatórios fabricados com diferentes ligas metálicas de níquel-titânio. Além da redução dos volumes de material obturador no interior dos canais, foram avaliados a influência do comprimento da patência do canal radicular (glide path) na obturação, extrusão de material obturador após o uso do instrumento reciprocante Reciproc R25, o volume do material de obturação após o retratamento e a presença deste em áreas de istmo. Também foi avaliado o uso de um solvente seguido da agitação do hipoclorito de sódio a 2% com ultrassom (PUI) e com um instrumento plástico acionado em movimento reciprocante. Foram selecionadas 40 raízes mesiais de molares inferiores com curvatura média de 25 graus que foram divididos em dois grupos de forma homogênea quanto ao comprimento, à curvatura e à anatomia (classes II e IV de acordo com a classificação de Vertucci) dos canais radiculares. Os dentes foram instrumentados com o instrumento Reciproc R25 e obturados com a técnica do cone único e com cimento AHPlus. Previamente ao uso do instrumento Reciproc R25, obteve-se a patência inicial do canal, ou seja, criou-se um glide path, com os instrumentos PathFile em toda a extensão do canal no Grupo RHPui e 1 mm aquém do comprimento total do canal no Grupo RMEasy. Os dois grupos foram definidos de acordo com o protocolo de retratamento adotado, a saber, RHPui (Reciproc + Hyflex + PUI) e RMEasy (Reciproc + Mtwo + EasyClean). Nos dois grupos, a remoção do material obturador original foi realizada com o instrumento Reciproc R25, sendo que no grupo RHPui foi utilizado o solvente xilol até a proximidade do terço médio, não sendo utilizado solvente no terço apical. No Grupo RHPui, utilizouse, então, o instrumento Hyflex 40.04 feito com liga de niquel-titânio CM (control memory ou de memória controlada) e, por último, utilizou-se o solvente xilol por um minuto na câmara pulpar, seguido de irrigação ultrassônica passiva (PUI) com solução de hipoclorito de sódio a 2% utilizando o instrumento Irrisonic, até o limite de 2 mm aquém do comprimento de trabalho. No Grupo RMEasy, foi utilizado o instrumento Mtwo 40.04 fabricado com liga de níquel-titânio convencional e, a seguir, também se utilizou o solvente xilol por um minuto na câmara pulpar seguido de uma agitação mecânica do hipoclorito de sódio a 2% com o instrumento plástico EasyClean em movimento reciprocante até o limite do comprimento total de trabalho. Os dois grupos foram re-obturados com a técnica de condensação vertical aquecida com cone de guta-percha correspondente ao instrumento final e com cimento AHPus. Foram realizadas microtomografias após cada procedimento para avaliar o volume de material remanescente, a extrusão após o uso dos instrumentos reciprocantes, o volume final da obturação ao final do retratamento e o volume na área de istmo, tanto após a obturação original quanto após a re-obturação. Os resultados obtidos mostraram que, no tratamento inicial, a patência do canal (ou glidepath) realizado com instrumentos Pathfile previamente ao uso dos instrumentos Reciproc R25 possibilitou que a obturação dos canais atingisse um limite significativamente (P < 0,05) mais próximo ao forame apical no grupo RHPui, onde o glidepath foi realizado em toda a extensão do canal. Em relação aos diferentes protocolos de retratamento, não houve remoção completa do material obturador do interior dos canais nos dois grupos estudados em todos os níveis avaliados, sem diferença estatisticamente significativa (P > 0,05) entre os grupos com relação a essa variável. Na avaliação intragrupo, houve uma diferença estatisticamente significativa (P < 0,05) entre os passos do procedimento em relação à redução do volume de material obturador, tanto na extensão total do canal, quanto nos seus diferentes níveis, com exceção do terço médio após o Hyflex, no terço cervical após o Mtwo e no terço médio após o EasyClean. O volume do material obturador final foi significativamente maior (P < 0,05) do que o volume do material obturador original, nos dois grupos estudados. O volume de material obturador na região do istmo foi significativamente maior (P < 0,05) após a re-obturação nos dois grupos, sendo significativamente maior (P < 0,05) no grupo RMEasy do que no grupo RHPui. Não houve diferença estatística (P > 0,05) entre os grupos com relação ao tempo total despendido na remoção do material obturador (P > 0,05), sendo 209,40 s para o Grupo RHPui e 227,40 s para o Grupo RMEasy. Não houve diferença estatística (P > 0,05) entre os grupos com relação ao volume da extrusão de material obturador, sendo 0,0258 mm3 (0 0,954) no Grupo RHPui e 0,0037 mm3 (0 0,565) no Grupo RMEasy. Os testes de Shapiro-Wilks, Mann- Whitney, Wilcoxon, Friedman e Dunn foram utilizados na análise dos dados.

The purpose of this study was to compare the density of gutta percha following three different obturation techniques using two split-tooth models. One split-tooth model was constructed with a straight rooted maxillary incisor and the other with the curved palatal root of a maxillary molar. Each tooth was obturated using single cone, cold lateral, and warm vertical obturation techniques without sealer. Each obturation technique was performed 20 times for each of the root systems. The weights of the gutta percha were recorded for each root type and obturation technique by subtracting the post-fill weight from the pre-fill weight of the two split-tooth models. Results show that in the straight canal, the three obturation techniques are significantly different (p < 0.0001). The warm vertical technique had the largest weight of gutta percha, followed by the single cone, and lastly by the cold lateral condensation group. In the curved canal, the three fill types were also significantly different (p < 0.0001). The warm vertical and single cone obturation techniques were not significantly different from one another but were significantly greater in gutta percha weight than the cold lateral technique. In conclusion, within curved canals, warm vertical and single cone techniques were more dense than cold lateral condensation. In the straight canal, the warm vertical was more dense than the single cone which was more dense than the cold lateral technique.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Este estudo avaliou o preparo apical, em canais curvos de raízes mesiais de molares inferiores humanos, sobre três diferentes aspectos: a área, o perímetro e o deslocamento, a partir da utilização do Sistema Protaper Universal empregando-se três diferentes cinemáticas: instrumentação manual e mecanização rotatória e oscilatória. Para isso, trinta e nove canais de raízes mesiais de molares inferiores humanos foram previamente selecionados. Todos eles apresentavam-se viáveis e não tratados endodonticamente, apresentando curvatura entre 30 e 40 graus e raio de 8 a 10 mm. As amostras foram preparadas, inseridas em blocos de resina, seccionadas transversalmente, na região apical e, em seguida, fotografadas com o auxílio de um microscópio digital (Olimpus Mic-D), para que posteriormente, fosse possível mensurar a variação dos aspectos propostos, pré e pós-instrumentação. Com a análise dos resultados obtidos, pode-se concluir que não foi encontrada nenhuma diferença estatística entre as três cinemáticas: instrumentação manual e mecanização rotatória e oscilatória, empregadas aos instrumentos do Sistema Protaper Universal. O único dado estatisticamente relevante é que o instrumento de acabamento F3, quando empregada a cinemática oscilatória, promoveu um deslocamento maior do que quando a ele foi empregada a cinemática manual. Além disso, recomendamos o emprego da cinemática manual com os instrumentos do Sistema Protaper Universal, visto que sem incidências estatiísticas, foi a que obteve um maior aumento de área e perímetro, promovendo um menor deslocamento apical durante a fase de preparo biomecânico de canais radiculares com curvatura severa.
This study evaluated the apical preparation, in curved mesial root canals of human mandibular molars, through three different features: area, perimeter and displacement (transportation), applying to it three different kinematics to Protaper Universal System: manual instrumentation, mecanically rotatory and oscilatory. Thirty-nine mesial root canals of human mandibular molars were previously selected. All of them were viables and without endodontic treatment, presenting angles of curvature between 30 degrees and 40 degrees, beyond the radius of 8 to 10 mm . The samples were prepared, invested into resin blocks and transversally seccioned in apical region. Afterwards, a digital microscope (Olimpus Mic-D) was used to take pictures, pre and post-instrumentation, for subsequently measurement of the proposed features variation. All results were analysed and there was no statistically difference between three kinematics (manual instrumentation and mecanical rotatory and oscilatory) applyed to the Protaper Universal System´s instruments. Data statistically relevant which should be considered is that the finishing file F3 applyed the oscilatory kinematic, promoved a bigger transportation when compared to this file applyed the manual kinematic. Moreover, the manual kinematic applyed to the instruments of Protaper Universal system is recommended, since there is no statistical evidences it was the one which had a greater increase of area and perimeter, promoving a least apical displacement during the biomecanical prepare in root canal with several curvature.