Dissertations / Theses on the topic 'Curved root canal'

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.

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Foram avaliadas comparativamente as técnicas Quantec LX, Pow-R, Profile e Profile série 29, em blocos de resina com canais radiculares simulados, as deformações produzidas nas paredes côncavas e convexas, através da editoração de imagens com a utilização do programa AutoCAD. Os resultados nos permitiram concluir que o sistema que mais provocou a ampliação foi o sistema Quantec LX seguido respectivamente pelo sistema Profile série 29, sistema Profile e sistema Pow-R. Permitiu também fazer uma análise matemática de qual a quantidade e local do desgaste nos níveis 1, 3, 5, 7, 12 e 16 milímetros.
It was comparatively evaluated the Quantec LX, Pow-R, Profile and Profile series 29 techniques, utilizing resin blocks, with simulated canals. The evaluation was done with the AutoCAD program after image editoration. The results led us to conclude that, the Quantec LX system promoted the greater amplification of the root canal, folowed by Profile series 29, Profile and Pow-R systems. This kind of analysis, alowed us to concluse also, where and the quantity of wear in different levels.

Orientador: Idomeo Bonetti Filho
Banca: Renato de Toledo Leonardo
Banca: Fabio Luiz Camargo Villela Berbert
Banca: Luciana Arantes Porto Carvalho
Banca: Eloi Dezan Junior
Resumo: 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.
Abstract: 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.
Doutor

O preparo do canal radicular ideal relaciona-se ao processo de sanificação em conjunto com a modelagem que resulta em condições especificas para a obturação dos sistemas de canais radiculares. Com a evolução constante dos sistemas de preparo, a microtomografia computadorizada (micro-CT) se apresenta como método de pesquisa confiável que possibilita uma avaliação completa e detalhada do canal radicular. Para tanto, o objetivo deste estudo foi comparar a capacidade de modelagem do sistema ProTaper Gold (PTG) em relação ao ProTaper Next (PTN) com glide path realizado com lima K #15 ou sistema ProGlider (PG), analisando o transporte da curvatura original do canal, desgaste de dentina, aumento no volume e na superfície do canal radicular e a quantificação das superfícies não tocadas após o preparo do canal radicular em canais mesiais de molares inferiores com curvatura acentuada. A média de curvatura de todos os dentes foi de 54o. Vinte e quatro molares inferiores foram divididos em dois grupos (n=12) de acordo com o glide path realizado (com PG ou com lima K #15). A seguir, o sistema PTG foi utilizado no canal mésio-vestibular e o sistema PTN no canal mésio-lingual, criando mais dois subgrupos. Os dentes foram escaneados por meio da micro-CT antes e após o preparo. Os dados obtidos foram comparados utilizando teste ANOVA para análise de variância de dois fatores e teste Tukey para combinações múltiplas. Nos resultados, em toda extensão do canal radicular, assim como para as análises nos terços cervical, médio e apical, não houve diferença estatisticamente significativa entre os grupos quanto ao transporte do canal. Quanto à quantidade de dentina removida, o sistema PTN combinado com a lima K #15 apresentou porcentagem significativamente menor do que nos outros grupos apenas no terço médio. O percentual de aumento do volume do canal foi maior nos grupos onde o glide path foi realizado com lima K #15 em relação aos grupos com glide path realizado com PG e significativo na totalidade do canal e nas análises individualizadas para os terços cervical e médio. O percentual do aumento da área de superfície foi significativamente maior na análise da totalidade do canal e na análise individualizando o terço médio nos grupos onde o glide path foi realizado com lima K#15. Ocorreu diferença significativa e maior quantidade de paredes não tocadas no terço apical nos grupos onde foi realizado glide path com lima K#15. Diante dos resultados, é possível concluir que em todos os grupos o glide path realizado com lima K #15 ou PG, não apresentou interferência sobre o desvio da curvatura original do canal radicular, no entanto, nos grupos que o PG foi usado, houve maior quantidade de paredes tocadas na região apical.
The ideal root canal preparation is related to the process of cleaning and shaping that results in specific conditions for the filling of root canal systems. Due the constant evolution of preparation systems, microcomputed tomography (micro-CT) has been presented as a reliable method of research that possibilite a complete and detailed appraisal of the root canal. Few studies have been performed on instrumentation systems with this methodology. Therefore, the aim of this study was to compare the shaping ability of the ProTaper Gold (PTG) system and the ProTaper Next (PTN) with glide path done with K #15 file or ProGlider (PG) system, analyzing the canal transportation, quantity of dentine removed, increase in volume and surface of the root canal and the quantification of uninstrumented root canal surface after the its prepare into mesial canals of mandibular molars with severely curvature. Twenty-four mandibular molars were divided in two groups (n=12) according to the glide path accomplished (with PG or with K #15 file). After, the PTG system was used on the mesiobuccal canal and the PTN system on the mesiolingual, creating two more subgroups. The teeth were scanned by a micro-CT before and after the preparation. The obtained data were compared using ANOVA test for the variance analyzes of two factors and Tukey test for multiple combinations. In the results, on all of the root canal extension, as well as to the analysis on the cervical, middle and apical thirds, there was no statistically significant difference between the groups about the canal transportation. In terms of the quantity of dentine removed, the PTN system combined with K #15 file showed significant lower percentage than the other groups just in the middle third. The increase on percentage of the canal volume was bigger in the groups where the glide path was done with K #15 file in relation to the groups with glide path accomplished with PG and significant on the totality of the canal and on the individualized analyzes for the cervical and middle thirds. The percentage of the surface increase was significantly greater on the totality analyzes of the canal and on the one individualizing the middle third on the groups where the glide path was performed with K #15 file. There was meaningful difference and greater amount of walls uninstrumented in the apical third on the groups where glide path with K #15 file was used. In front of the results, is possible to conclude that the glide path, done with K #15 file or PG, didn\'t present interference on the deviation of the root canal original curvature to all groups; however, when PG was used, there was a greater number of walls instrumented on the apical region to both systems tested.

Orientador: Roberto Miranda Esberard
Banca: Renato de Toledo Leonardo
Banca: Giulio Gavini
Resumo: Foram avaliadas comparativamente as técnicas Quantec LX, Pow-R, Profile e Profile série 29, em blocos de resina com canais radiculares simulados, as deformações produzidas nas paredes côncavas e convexas, através da editoração de imagens com a utilização do programa AutoCAD. Os resultados nos permitiram concluir que o sistema que mais provocou a ampliação foi o sistema Quantec LX seguido respectivamente pelo sistema Profile série 29, sistema Profile e sistema Pow-R. Permitiu também fazer uma análise matemática de qual a quantidade e local do desgaste nos níveis 1, 3, 5, 7, 12 e 16 milímetros.
Abstract: It was comparatively evaluated the Quantec LX, Pow-R, Profile and Profile series 29 techniques, utilizing resin blocks, with simulated canals. The evaluation was done with the AutoCAD program after image editoration. The results led us to conclude that, the Quantec LX system promoted the greater amplification of the root canal, folowed by Profile series 29, Profile and Pow-R systems. This kind of analysis, alowed us to concluse also, where and the quantity of wear in different levels.
Mestre

O preparo químico-mecânico tem sido essencial no sucesso do tratamento endodôntico. No entanto, atualmente não existe instrumento ou técnica com capacidade de proporcionar a limpeza e a desinfecção dos sistemas de canais em sua totalidade. O objetivo desse estudo foi avaliar a limpeza, tempo, transporte e centralização de preparos de canais radiculares curvos utilizando os sistemas de rotação contínua ProTaper®, de rotação alternada WaveOne® e uma sugestão de técnica híbrida de preparo. Foram selecionadas raízes mesiais de primeiros molares inferiores humanos permanentes extraídos. Após a definição dos ângulos de curvatura e raio, os canais (n=60) foram divididos em três grupos experimentais, conforme sistemas de preparo (ProTaper, WaveOne, WaveOne Técnica Híbrida). O diâmetro apical final foi padronizado em #25. As quantidades de debris e smear layer remanescentes foram analisadas em microscopia eletrônica de varredura, através de escores, e avaliadas estatisticamente por meio do teste de Kruskal–Wallis. Fraturas ou deformações nos instrumentos foram registradas. O tempo de preparo foi cronometrado e analisado através de ANOVA e Tukey. Tomografia computadorizada de feixe cônico pré e pós-operatória foram feitas para mensuração do transporte e centralização dos canais e os resultados obtidos foram avaliados estatisticamente através de ANOVA. Em relação à capacidade de limpeza, os três grupos apresentaram semelhante capacidade em remover debris e formar smear layer, sem diferenças estatísticas (P>0,05) em todas as porções dos canais. O preparo com apenas um instrumento foi significativamente mais rápido do que com sequências de instrumentos (P<0,05). Durante a instrumentação, não ocorreram fraturas, apenas três instrumentos deformaram. Não foram encontradas diferenças no transporte e centralização dos canais entre os sistemas. Sob as condições deste estudo, todos os instrumentos apresentaram uma capacidade de limpeza similar, sendo o instrumento único semelhante aos demais sistemas de sequências de instrumentos, contudo, reduzindo o tempo de preparo de forma significativa. Nenhum instrumento forneceu um debridamento completo. Todos os grupos mostraram-se similares em relação à capacidade de manter a curvatura original do canal.
The chemo-mechanical preparation is essential for successful endodontic treatment. However, currently no instrument can predictably clean the entire root canal system. The aim of this investigation was to assess the cleanliness, preparation time and shaping ability of curved root canals in extracted human molar teeth using rotary full-sequence ProTaper, single-file system WaveOne and a protocol using both systems. Sixty canals had the degree and the radius of curvature determined and were divided into three groups according with preparation systems. Canals were prepared until #25 apical sizes and the shaping ability and the cleaning efficacy were evaluated. The amounts of debris and smear layer were quantified on the basis of a numerical evaluation scale by scanning electron microscope and were analyzed statistically using the Kruskal–Wallis test. Instrument failures were recorded. Preparation time was analyzed statistically using ANOVA and Tukey. Teeth were scanned pre- and post-operatively using computed tomography to measure shaping changes and the obtained results were statistically analyzed using ANOVA. For debris removal and smear layer remaining, the results for three groups were similar and not significantly different for the all parts of the canals (P> 0.05). Instrumentation with WaveOne was significantly faster than with other instruments (P< 0.05). During preparation, no file fractured, three suffered deformations. No difference in the transportation and centering ratio was found between the systems. Under the conditions of this study, all instruments maintained the original canal curvature well and were safe to use. A single-file system presented as good cleanliness capacity as others, reducing the preparation time significantly, although none could provide a complete debridement.

O presente estudo teve por objetivo avaliar in vitro a eficiência dos sistemas de irrigação (convencional, ultrassônica e EndoSafe), na remoção do magma dentinário de canais mesiais curvos de molares inferiores, por meio de microscopia eletrônica de varredura. Foram utilizados canais mesiais com curvatura entre 200 e 400, de 47 molares inferiores, preparados com Reciproc (instrumento R25). Destes, dois condutos foram utilizados como controle negativo, e os outros foram divididos aleatoriamente em três grupos experimentais conforme a sua irrigação final: IC irrigação convencional com seringa e agulha; PUI irrigação ultrassônica passiva; EndoSafe irrigação com o sistema EndoSafe. Em todos os grupos foram utilizados 5mL de EDTA e 5mL de NaOCl por 30 segundos cada. A observação da região apical, após clivagem, foi realizada através de microscopia eletrônica de varredura em aumento de 1000X. Posteriormente, as imagens obtidas foram avaliadas por 3 examinadores calibrados pelo sistema de três pontos. Da análise dos resultados, pelo teste de Kruskal-Wallis, pode-se observar que o grupo ultrassônico e o EndoSafe apresentaram melhores resultados quando comparados ao grupo convencional, com diferença estatística entre os grupos (PIU: 40%; EndoSafe: 26,7% e IC: 6,7%; sem magma dentinário). Concluiu-se que a irrigação ultrassônica apresenta melhores resultados em comparação aos outros grupos, aumentando a remoção do magma dentinário no terço apical de raízes curvas.
The present study aimed to evaluate in vitro the efficiency of irrigation systems (conventional, ultrasound and EndoSafe system), on removing the smear layer of curved mesial root canals of mandibular molars by means of scanning electron microscopy to evaluate. Fourty seven mesial canals were used with curvature degree between 200 and 400, and were shaped with rotary system Reciproc (R25 instrument). Two of these were used as negative control, and the others were randomly divided into three groups according to their final irrigation: IC - irrigation with conventional syringe and needle; PUI - passive ultrasonic irrigation; EndoSafe - EndoSafe irrigation system. In all groups, 5mL of EDTA, and 5 mL of NaOCl was used for 30 seconds each. Root canals were split longitudinally and subjected to scanning electron microscopic at a magnification of 1000X. The presence of smear layer was evaluated by three calibrated observers using a three-score scale. Analyzing the results, using Kruskal-Wallis test, it could be observed that ultrasonic group and EndoSafe system showed better results when compared to the conventional group, statistical significance between groups (PIU: 40%; EndoSafe: 26.7% and CI: 6.7%; without smear layer). It was concluded that ultrasonic irrigation performs better compared to the other groups, increasing the removal of the smear layer in the apical third of curved roots.

Um dos objetivos da terapêutica endodôntica radical e a conformação e limpeza do sistema de canais radiculares. Nos últimos anos têm surgido múltiplos sistemas de instrumentação e variações em suas dinâmicas, sendo fundamental a manutenção da forma original do canal depois do preparo. O objetivo desse estudo foi avaliar a centralização e transporte de canais radiculares curvos, nos terços cervical e apical, utilizando os sistemas de rotação contínua ProTaper® e Mtwo®, de rotação alternada Reciproc® e uma técnica coroa-ápice de instrumentação manual. Foram selecionadas raízes mesio vestibulares de primeiros molares superiores humanos permanentes extraídos. Após a definição dos comprimentos, ângulos e raios de curvatura, os canais (n=60) foram divididos em quatro grupos experimentais, conforme os sistemas de preparo. O diâmetro apical final foi padronizado em #25. Tomografias computadorizadas antes e após o preparo foram feitas para mensuração do transporte e centralização dos canais e os resultados obtidos foram avaliados estatísticamente através de ANOVA e Tukey. Quando se utilizou diâmetro apical 25 nos preparos radiculares, não foram encontradas diferenças estatísticas no transporte dos canais entre os sistemas (p˃0.05). Na análise de centralização, diferença signficativa ocorreu na avaliação apical (p˂0.05) entre o sistema Reciproc e ProTaper, sendo que o sistema Reciproc apresentou o pior resultado.
One of the purposes of the radical endodontic therapy consists of cleaning and shaping of the root canal system. In recent years there have been multiple instrumentation systems and variations in their dynamics, being fundamental the fact of maintaining the original shape of the canal after mechanical preparation. The aim of this study was to evaluate the centering ability and transportation in curved root canals at the cervical and apical thirds, using systems with continuous motion, ProTaper ® and MTwo ®, reciprocating motion, Reciproc®, and a step-down manual instrumentation technique. Mesial buccal roots of human extracted first maxillary permanent molars were selected. After having determined the lengths, angles and radius of curvature, the canals (n = 60) were divided into four groups according with preparation systems. The final apical diameter was standardized in # 25. Computed tomographies were made to measure centering ability and transportation of the canals. The results were statistically analyzed by ANOVA and Tukey. When used apical preparation # 25, no statistical differences were found in the transportation between the systems (p ˃ 0,05). In the analysis of centering ratio, significantly difference occurred in the apical evaluation (p ˂ 0,05) between Reciproc and ProTaper systems, the Reciproc system showed the worst result.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Foram analisadas, comparativamente, a ação e a presença de deformações proporcionadas pela instrumentação com limas manuais Flexofile e dois Sistemas Rotatórios de Limas Endodônticas de Níquel e Titânio: o Sistema K3 (SDS Kerr) e o Sistema Race (FKG), sobre as paredes dos canais radiculares curvos simulados em blocos de resina. Foram utilizadasa as técnicas manual e ultra-sônica de irrigação. Após a instrumentação, os blocos de resina foram digitalizados, analisados e estabelecido escores de acordo com a qualidade do preparo biomecânico obtido em cada uma das técnicas. Concluímos que os melhores resultados foram obtidos com as duas técnicas de instrumentação rotatória associadas à irrigação manual.
It were comparatively analyzed the action and aberrations provided by the instrumentation using manual files Flexofile and two Rotary Systems of Endodontic Nickel-Titanium files, the K3 (SDS Kerr) System and the Race (FKG) System, in the curved root canal walls simulated in resin blocks, with two irrigations techniques: a manual and an ultrasonic technique. Thereafter the instrumentation, the resin blocks were digitalized, analysed and scores were set according to the preparation's quality achieved in each technique. It was ended that the best results were obtained with the two techniques of rotary instrumentation associated to the manual irrigation.

No presente estudo foi realizado a análise qualitativa da remoção do magma dentinário do terço apical de raízes curvas, quando submetidos a irrigação convencional, irrigação ultrassônica passiva e irrigação sônica. Como corpos de prova, foram utilizados 62 canais mésio-vestibulares com curvatura entre 20° e 40° de molares inferiores. Todos os condutos, após odontometria, foram instrumentados com o sistema rotatório até a lima F2. Destes, dois condutos foram utilizados como controle negativo, e os outros sessenta foram divididos aleatoriamente em três grupos experimentais conforme sua irrigação final: G1- irrigação convencional com seringa e agulha; G2- irrigação ultrassônica passiva; G3- irrigação sônica com sistema EndoActivator®. Em todos os grupos experimentais, foram utilizados 5mL de EDTA 17% por 1 minuto e 5mL de NaOCl 2,5% por 30 segundos. A observação da região apical, após clivagem, foi realizada através de microscopia eletrônica de varredura em aumento de 1000X. Isto posto, as imagens obtidas foram avaliadas por 3 examinadores calibrados pelo sistema de 3 pontos. Da análise dos resultados, pelo teste de Kruskal-Wallis, pode-se observar que os sistemas sônico e ultrassônico removeram significativamente o magma dentinário, sem diferença estatística entre os grupos. Quando comparados estes sistemas com a irrigação convencional, ambos mostraram-se mais eficientes, sendo os dois grupos estatisticamente diferentes do grupo convencional. Conclui-se que a irrigação sônica e irrigação ultrassônica passiva apresentam resultados semelhantes, aumentando a remoção do magma dentinário no terço apical de raízes curvas.
The aim of this study is to qualitative evaluate, the smear layer removal in the apical third of curved canals, after sonic, ultrasonic and conventional irrigation. Sixty two mesiobuccal root canals of mandibular molar with curvature degree between 20 and 40 degrees, were shaped with rotary system ProTaper® until file F2, and occasionally divided into three experimental groups (n=20) and one control group (n=2). The control group received no final irrigation after fitting of the master cone. The experimental groups received those final irrigations: G1- conventional irrigation with no agitation of the irrigant; G2- passive ultrasonic irrigation; G3- sonic irrigation with EndoActivator® system. In all groups, a final irrigation with 5mL EDTA 17% for 1 minute and 5mL NaOCl 2,5% for 30 seconds was procedure. Root canals were split longitudinally and subjected to scanning electron microscopy at a magnification of 1000X. The presence of smear layer was evaluated by three calibrated observers using a three-score scale. The differences in smear layer scores between the experimental groups were analyzed with Kruskal-Wallis test. Concerning the activations groups, both removed significantly smear layer, with no statistical significant difference. There were statistical significant differences when comparing this systems with conventional irrigation, the activation systems removed significantly more smear layer. The sonic and ultrasonic irrigation, in a similar way, enhance the removal of the smear layer, in the apical third of curved canals.

Localized irregularities in the canal walls are sities which concentrate stresses and make the stresses distribution occurs asymmetrically in the root structure during the filling phase. This asymmetric distribution of stresses may contribute to the generation of defects in the dentin, which can propagate in vertical root fracture (VRF). Thus, this study evaluated the influence of enlargement in the apical stress distribution in curved canals when a spreader digital was inserted against the canal walls using Finite Element Analysis (FEA). A basic three-dimensional geometric model of the mesiobuccal root (MV) of a Maxillary First Molar (1ºMM) with root canal curved and anatomical diameter 0.25 mm was confectioned with the program SolidWorks Simulation (Dassault Systèmes SolidWorks Corporation, France). Based on this basic model, four post-instrumentation geometric models were established to accommodate canal preparation performed with HERO 642 (Micromega, Besançon, France) instruments 30/.02 (IAF +1); 35/.02 (IAF +2); 40/.02 (IAF +3) and 45/.02 (IAF +4). In the program SolidWorks Simulation, the models were discretized in a finite number of elements united by their nodal points. To the models were attributed to mechanical properties of dentin that characterized their mechanical behavior. The models were fixed to the outer surface to limit the rotational and translational movements in all directions during the simulation. A load of 13 N was applied along the canal walls (mesial, distal, buccal and palatal) up to 3 mm of the apical foramen simulating the action of a spreader digital Nickel-Titanium (NiTi) B Dentsply Maillefer, Ballaigues, Switzerland). The results of AEF showed a better distribution of stresses as further enlargement was performed. The highest stress decreased distal and palatal walls of the canal because of the increased apical enlargement. The location of the highest value of stress changed in the buccal and palatal walls due to increased apical enlargement. Thus, it can be concluded that the enlargement apical improve the distribution of stresses in curved canals when a digital spreader is inserted against the walls of the canal.
Irregularidades presentes nas paredes do canal radicular são sítios que concentram tensões, e fazem com que a distribuição de tensão ocorra de maneira assimétrica na estrutura radicular durante a etapa obturadora. Essa distribuição assimétrica de tensões talvez contribua para a geração de defeitos na dentina radicular, os quais podem propagar-se em Fratura Vertical da Raiz (FVR). Diante disso, este estudo avaliou a influência do alargamento apical na distribuição de tensões em canais radiculares curvos quando um espaçador digital foi inserido contra as paredes do canal utilizando a Análise de Elementos Finitos (AEF). Um modelo geométrico tridimensional básico da raiz Mésio-Vestibular (MV) de um Primeiro Molar Superior (1ºMS) com canal radicular curvo e diâmetro anatômico 0,25 mm foi confeccionado com o programa SolidWorks Simulation (Dassault Systèmes SolidWorks Corporation, França). Baseado nesse modelo básico, quatro modelos geométricos pós-instrumentação foram estabelecidos para acomodar o preparo do canal realizado com instrumentos HERO 642 (Micromega, Besançon, França) 30/.02 (IAI+1); 35/.02 (IAI+2); 40/.02 (IAI+3) e 45/.02 (IAI+4). No programa SolidWorks Simulation, os modelos foram discretizados em um número finitos de elementos unidos por seus pontos nodais. Aos modelos foram atribuídas propriedades da dentina (módulo de elasticidade, coeficiente de Poisson e densidade) a fim de caracterizar o seu comportamento mecânico. Então, os modelos foram fixados na superfície externa para limitar os movimentos de rotação e translação em todas as direções durante a simulação. Uma força de 13 N foi aplicada ao longo das paredes do canal radicular (mesial, distal, vestibular e palatina) até 3 mm do forame apical simulando a ação de um espaçador digital B de Níquel-Titânio (NiTi) (Dentsply Maillefer, Ballaigues, Suíça). Os resultados da AEF mostraram que houve uma melhor distribuição de tensões à medida que um maior alargamento foi realizado. O maior valor de tensão diminuiu nas paredes distal e palatina do canal em virtude do maior alargamento apical. O local aonde a tensão foi maior, mudou nas paredes vestibular e palatina, de 6 mm para 3 mm, em decorrência do maior alargamento apical. Dessa forma, pode-se concluir que o alargamento apical melhora a distribuição de tensões em canais radiculares curvos quando um espaçador digital é inserido contra as paredes do canal.

O presente estudo avaliou a interferência de operadores com diferentes proficiências no preparo de canais radiculares curvos, simulados em blocos de resina transparente. Os grupos, com 10 indivíduos cada um, foram: Grupo 1 – professores de Endodontia; Grupo 2 - alunos de especialização; Grupo 3 – alunos de odontologia Monitores de Endodontia e o Grupo 4 – alunos de graduação no início do curso de Endodontia. Cada operador instrumentou dois canais com 20 graus de curvatura, o primeiro canal era visualizado para treinamento e o segundo não. O sistema mecanizado com instrumentos rotatórios de níquel-titânio empregado foi o RaCe®. Os parâmetros de avaliação foram: tempo de instrumentação, quantidade de material removido, desvio apical e deformação dos instrumentos. Os resultados encontrados (ANOVA e Teste de Tuckey a= 0,05%), foram: Para o tempo de instrumentação, no primeiro canal, houve diferença estatística entre o grupo 1 e os grupos 3 e 4, o grupo 2 diferiu somente do grupo 4. Já, no segundo canal, não houve diferença estatística entre os grupos. Para a quantidade de material removido do primeiro canal houve diferença estatística entre os graduados (grupos 1 e 2) em relação aos graduandos (grupos 3 e 4), porém, no segundo canal, houve diferença somente entre os grupos 1 e 2. O desvio apical não apresentou diferença estatística entre os grupos em nenhuma das condições experimentais. Após a aplicação do teste do Qui-quadrado (a=0,01%), observou-se que o grupo 1 foi o que produziu as menores deformações nos instrumentos. Conclui-se que: Os desvios apicais promovidos foram semelhantes entre os grupos experimentais. Houve diminuição no tempo de instrumentação do segundo canal em relação ao primeiro, com diferença estatística nos grupos dos monitores e acadêmicos e que não houve diferença estatística entre os grupos, em relação ao tempo de instrumentação do segundo canal. Os grupos dos graduados (professores e alunos de especialização) excisaram maior quantidade de material do primeiro canal, quando comparados aos dos graduandos (monitores e acadêmicos), não havendo diferença estatística entre os grupos em relação à quantidade de material removido do segundo canal, excetuando a comparação entre os professores e os alunos de especialização, onde os primeiros desgastaram significativamente mais que os últimos. Comparados aos demais grupos, os professores produziram menores deformações aos instrumentos.
This study evaluated the interference of operators with different proficiencies in the preparation of curved canals , simulated transparent resin blocks. The groups, with 10 individuals each, were: Group 1 - professors of Endodontics; Group 2 – students of specialization; Group 3 – undergraduate dental students who had concluded the Endodontics course and Group 4 - undergraduate dental students in the beginning of the Endodontics course. Each operator prepared two canals with 20 degrees of bending, the first canal was visualized for training and second no. The rotary instrumentation used was the RaCe®. The parameters of evaluation were: time of instrumentation, amount of removed material, apical transportation and deformation of the instruments. The results (ANOVA and Test of Tuckey = 0.05%): In relation to the instrumentation time, when of the execution of the first canal, it had statistics difference between group 1 and groups 3 and 4, group 2 only differed from group 4. When of the execution of the second canal it did not have difference statistics between the groups. For the amount of material removed of the first canal it had difference statistics between the graduated (groups 1 and 2) relation to the undegraduated (groups 3 and 4). After the second canal instrumentation, only had difference between groups 1 and 2. The apical transportation did not present statistics difference enters the groups in no ne of the experimental conditions. After the application ?2 test (a=0,01%), was observed that group 1 produced lesser deformations in the instruments. Conclusions: The apical transportation was similar between the different groups. It had reduction in the time of instrumentation of the second canal in relation to the first one, with statistics difference in the groups of the monitors and academics. It did not have difference statistics between the groups, in relation to the time of instrumentation of the second canal. The groups of the graduated ones (professors and students of specialization) removed bigger amount of material of the first canal, when compared with the ones of the undergraduate (monitorial and academic). It did not have statistics difference enters the groups in relation to the amount of material removed of the second canal, excepting the comparison between the professors and the students of specialization, where the first ones had consumed significantly more than the last ones. Compared with all groups, the professors had produced minors deformations to the instruments.

Introdução: Os objetivos deste estudo foram comparar a extrusão apical de debris durante a desobturação com WaveOne Gold, ProTaper retratamento, D-RaCe ou limas manuais; descrever as falhas e/ou fraturas ocorridas nos instrumentos de NiTi; e comparar o WaveOne Gold com os sistemas ProTaper e RaCe em relação à quantidade de material obturador remanescente, transporte apical (TA) e tempo de trabalho após a desobturação e após o repreparo de canais radiculares curvos. Materiais e Métodos: Quarenta canais mésiovestibulares de molares superiores foram preparados, obturados e divididos em 4 grupos (n=10): WOG) WaveOne Gold Primary e Medium; PTG) ProTaper Retreatmento e ProTaper Next; RCG) D-RaCe e RaCe; e LM) Limas manuais. A extrusão de debris foi determinada subtraindo-se o peso final do peso inicial dos Eppendorfs. Os instrumentos de NiTi (n=18) foram analisados em MEV antes e após a desobturação. A quantidade de material obturador remanescente e o TA foram avaliados em micro-TC. O tempo de trabalho foi anotado e comparado. Os dados foram estatisticamente analisados (α=.05). Resultados: WOG extruiu menos debris do que LM e RCG (P<.05), e foi similar ao PTG (P>.05). Não houve diferença entre LM, PTG e RCG (P>.05). A análise em MEV mostrou, dos 18 instrumentos avaliados, 3 fraturas e 10 deformações. Nas duas etapas avaliadas, WOG apresentou similar (P>.05) e menor (P<.05) quantidade de material obturador remanescente do que PTG e RCG, respectivamente. A quantidade de material no WOG e RCG foi menor após o repreparo (P<.05). Na desobturação, WOG teve maior TA em 4mm do que em 2mm (P<.05). Em 2mm, o TA do WOG foi menor do que RCG (P<.05), e em 4mm foi igual ao PTG e RCG (P>.05). Na desobturação, o tempo de trabalho no grupo LM foi maior que nos demais (P<.05). No repreparo, WOG foi mais rápido do que PTG e RCG (P<.05). Conclusões: Todos os instrumentos causaram extrusão de debris, sendo que o WOG apresentou os menores valores. Nenhum sistema removeu completamente o material obturador de raízes mésiovestibulares de molares superiores. Considerando os baixos valores de TA obtidos, os instrumentos avaliados foram considerados seguros para desobturação e repreparo de canais curvos. A desobturação com LM foi mais lenta do que com os instrumentos de NiTi. O sistema reciprocante foi mais rápido do que os rotatórios no reprepro.
Introduction: The aims of this study were to assess the amount of apically extruded debris during filling removal with WaveOne Gold, ProTaper Retreatment, D-RaCe or hand files; to describe failures of NiTi instruments; and to compare WaveOne Gold with ProTaper and RaCe systems regarding remaining filling material, apical transportation (AT) and working time after filling removal and after shaping of curved root canals. Methods: Forty mesiobuccal canals of maxillary molars were prepared, filled, and assigned into 4 groups (n=10): WOG) WaveOne Gold Primary and Medium; PTG) ProTaper Retreatment and ProTaper Next; RCG) D-RaCe and RaCe; HF) Hand files. The amount of extruded debris was determined by subtracting the final from the initial Eppendorfs weight. The NiTi instruments (n=18) used for filling removal were analyzed pre and post-operatively by SEM. Micro-CT analysis assessed the residual filling material and AT. Working time was recorded and compared. Data were statistically analyzed (α=.05). Results: WOG produced less debris compared with HF and RCG (P<.05), and similar to PTG (P>.05). HF, PTG and RCG showed no difference (P>.05). SEM analyses after filling removal showed, from the 18 instruments evaluated, 3 fractures and 10 deformations. In both evaluated steps, WOG had similar (P>.05) and less (P<.05) amount of filling material as PTG and RCG, respectively. The remaining material in WOG and RCG was lower after shaping (P<.05). In filling removal, WOG had higher AT at 4mm than at 2mm (P<.05). At 2mm, AT of WOG was lower than RCG (P<.05), and at 4mm, was equal to PTG and RCG (P>.05). In filling removal, working time in HF group was significantly higher than others (P<.05). In shaping step WOG was faster than PTG and RCG (P<.05). Conclusions: All instruments tested caused debris extrusion, with WOG presenting the lowest values. Neither system could completely remove the filling material of mesiobuccal canals of maxillary molars. Considering the low AT values obtained, the instruments evaluated were safe for filling removal and shaping of curved canals. Filling removal with HF was slower than with the NiTi files. The reciprocating system was faster than the rotary in shaping the root canals.

Orientador: Roberto Miranda Esberard
Banca: Renato de Toledo Leonardo
Banca: Giulio Gavini
Resumo: Foram analisadas, comparativamente, a ação e a presença de deformações proporcionadas pela instrumentação com limas manuais Flexofile e dois Sistemas Rotatórios de Limas Endodônticas de Níquel e Titânio: o Sistema K3 (SDS Kerr) e o Sistema Race (FKG), sobre as paredes dos canais radiculares curvos simulados em blocos de resina. Foram utilizadasa as técnicas manual e ultra-sônica de irrigação. Após a instrumentação, os blocos de resina foram digitalizados, analisados e estabelecido escores de acordo com a qualidade do preparo biomecânico obtido em cada uma das técnicas. Concluímos que os melhores resultados foram obtidos com as duas técnicas de instrumentação rotatória associadas à irrigação manual.
Abstract: It were comparatively analyzed the action and aberrations provided by the instrumentation using manual files Flexofile and two Rotary Systems of Endodontic Nickel-Titanium files, the K3 (SDS Kerr) System and the Race (FKG) System, in the curved root canal walls simulated in resin blocks, with two irrigations techniques: a manual and an ultrasonic technique. Thereafter the instrumentation, the resin blocks were digitalized, analysed and scores were set according to the preparation's quality achieved in each technique. It was ended that the best results were obtained with the two techniques of rotary instrumentation associated to the manual irrigation.
Mestre

Introdução: Os objetivos do presente estudo foram comparar a extrusão apical de detritos durante o preparo apical #25 com os sistemas Twisted File Adaptive (TFA), WaveOne Gold (WOG) e técnica manual (TM), registrar o tempo de preparo; e comparar WOG com TFA em relação ao transporte do canal radicular (TCR) e centralização (CR) com diâmetros apicais #25 e #35. Metodologia: Quarenta e cinco canais mésio-vestibulares de molares inferiores foram preparados e divididos em 3 grupos (n=15) para avaliar extrusão apical. A extrusão de detritos foi quantificada subtraindo-se o peso final do peso inicial dos tubos Eppendorf. TCR e CR foram avaliados em micro-TC com os sistemas TFA e WOG (n=15). A normalidade dos valores obtidos para cada grupo foi verificada usando teste de Kolmogorov-Smirnov. Para quantificar detritos extruídos e tempo de preparo, os dados foram paramétricos, sendo utilizado o Teste ANOVA de 1 via e post hoc de Tukey’s. Para avaliar TCR e CR, o teste estatístico foi Mann Whitney e Wilcoxon (α=.05). Resultados: Em relação aos detritos, o sistema WOG foi associado com menos extrusão em comparação com TM (P<0,05) ou com o sistema TFA (P> 0,05). O tempo de preparo exigido pela TM foi significativamente maior do que o exigido pelas outras técnicas (P<0,05). Não foram encontradas diferenças estatisticamente significantes entre WOG e TFA em relação à centralização em todos os níveis, quando usado diâmetro apical #25 ou #35 (P> 0,05). Para TCR, diferença significativa foi encontrada entre TFA e WOG a 1 e 7mm com diâmetro apical #25 e #35 (P<0,05). Foi encontrada diferença significante para TFA em 4mm, quando os diâmetros apicais #25 e #35 foram avaliados no mesmo sistema (P <0,05). Conclusões: Todos os sistemas de instrumentação causaram extrusão de detritos apicais em algum grau. TFA e WOG podem ser usados em canais radiculares curvos com segurança com diâmetros apicais# 25 ou 35.
Introduction: The aims of this study were to assess the amount of apically debris during root canal preparation with apical size #25 with the Twisted File Adaptive system (TFA), WaveOne Gold system (WOG) and manual technique (MT), and recorded working time; and to assess WOG with TFA in relation to root canal transportation (RCT) and centering ratio (CR) with apical diameters # 25 and # 35. Methods: Forty-five mesiobuccal root canals of mandibular molars were prepared and assigned into 3 groups (n = 15) to evaluate apical extrusion. Debris extrusion was quantified by subtracting the final from the initial weight of the Eppendorf tubes. RCT and CR were evaluated in Micro-TC with the TFA and WOG systems (n = 15). The normality values obtained for each group were tested using the Kolmogorov-Smirnov test. To quantify extruded debris and preparation time, the data were parametric, using the Tukey's 1-way and post-hoc ANOVA test. To evaluate RCT and CR, the statistical test was Mann Whitney (α =.05). Results: The WaveOne Gold reciprocating single-file system was associated with less extrusion of debris compared with hand files (P < 0.05) or with the Twisted File Adaptive system (P > 0.05). The preparation time required by hand files was significantly longer than that required by the other techniques (P < 0.05). No significant differences were found between WOG and TFA regarding CR for all levels when used #25 or #35 apical size preparation (p>0.05). For RCT, significant difference was found among TFA and WOG at 1 mm and 7 mm with diameter apical #25 and #35. (p<0.05). Statistically different for the TFA in 4 mm was observed when the apical diameters # 25 and # 35 was evaluated in the same system (P <0,05). Conclusions: All of the instrumentation systems caused apical debris extrusion to some degrees. TFA and WOG can be used in curved root canals with safety with #25 or 35 apical diameters.

O objetivo do trabalho foi avaliar as alterações morfológicas bi, tridimensionais, e o transporte em canais mesiais de molares inferiores com curvatura acentuada. Selecionou-se molares inferiores com dois canais e forames independentes, livres de nódulos pulpares, reabsorção interna, tratamento endodôntico prévio, fratura radicular e dentro do padrão de raio e ângulo de curvatura, avaliados pelos exames radiográficos, tomográficos cone bean e microtomográficos. Partiu-se de 393 dentes para selecionar 15 dentro deste padrão morfológico. Esses dentes foram submetidos à microtomografia antes da instrumentação, após o preparo com instrumento Reciproc® R25 e após o preparo por cada lima dos sistemas de complementação (Mtwo e K3). Os dados morfométricos foram analisados pelo programa CTAn e as análises estatísticas foram realizadas utilizando o programa SPSS onde observou-se os seguintes resultados: a análise morfométrica bidimensional mostrou que a área e o perímetro apresentaram aumento gradual a cada milímetro avaliado, partindo do primeiro milímetro apical; houve também aumento gradual de área e de perímetro a cada troca de instrumento de acordo com o que se realizou o preparo biomecânico dentro dos conjuntos de grupos; houve diferença estatisticamente significante de área e de perímetro dos canais radiculares apenas após o preparo com os instrumentos #40 taper 04 e taper 02 (P<0,05). Em relação à distância do ápice, houve diferença estatística de área entre todos os milímetros avaliados (P<0,05). Em relação ao perímetro, não houve diferença entre os milímetros 1 e 2; e, 4 e 5 (P>0,05), entretanto com diferença entre o terceiro milímetro e os demais (P<0,05). As análises morfológicas tridimensionais de volume, área de superfície e SMI (Índice de Modelo Estrutural) do canal radicular, tiveram comportamento semelhante entre os grupos. Os espécimes submetidos à complementação, com instrumentos taper 04 e taper 02, não apresentaram diferença estatística após os preparos (P>0,05), com diferença entre os canais preparados com a R25 e os canais originais (P<0,05). Quando comparados os conjuntos de grupos, nenhum grupo análogo apresentou diferença estatística (P>0,05). Foi analisado o transporte por terços (cervical, médio e apical) e por todo o canal, não sendo detectada diferença estatisticamente significante (P>0,05) entre os terços, nem do canal todo entre a complementação pelos instrumentos taper 04 (Mtwo) e taper 02 (K3).
The purpose of this study was to evaluate the two- and three-dimensional morphological changes, and the transportation that occurs in the mesial canals of mandibular molars with severe curvature. Molars were selected with two independent canals and foramina, no pulpal nodules, internal resorptions, previous endodontic treatment or root fracture and within the standard radius and angle of curvature evaluated by radiographs, cone-beam tomography and microtomography. From the 393 teeth initially selected, 15 fulfilled the selected parameters. The teeth were subjected to microtomography before instrumentation, after instrumentation with Reciproc® R25 and after preparation with each file of the complementary systems (MTwo and K3). The morphometric data were analyzed by CTAn software and the statistical analysis was performed using the SPSS software where the following results were observed. The two-dimensional morphometric analysis showed that the area and the perimeter presented a gradual increase for every evaluated millimeter, starting from the first apical millimeter. There was also a gradual increase in area and perimeter with each change of instrument according to the biomechanical within the sets of groups. There was a statistically significant difference in area and perimeter of root canals after the preparation with the instruments #40 taper 04 and taper 02 (P <0.05). Regarding the distance from the apex area, there was statistically difference among all evaluated millimeters (P <0.05). Regarding the perimeter, there was no difference between 1 and 2 mm, and 4 or 5 (P> 0.05), however with a difference between the third millimeter and the others (P <0.05). The three-dimensional morphological analyses of volume, surface area and root canal SMI (Structural Model Index) of the root canal showed a similar behavior among the groups. The specimens subjected to complementation to the instrumentation with instruments of tapers 04 and 02 showed no statistically significant difference after preparation (P> 0.05), with significant difference between the original and prepared canals (P <0.05). When comparing the sets of groups, no analogue group presented a statistically significant difference (P> 0.05). Transport was analyzed by thirds (cervical, middle and apical) and throughout the canal there, without statistically difference (P> 0.05) among the thirds or between groups with complementation with taper 04 (MTwo) and taper 02 (K3) instruments.

O presente estudo teve por objetivo avaliar ex vivo a eficiência de sistemas para retratamento (ProTaper Universal Retratamento, Mtwo Retratamento e D-Race), na desobturação de canais mésio vestibulares curvos de molares superiores, por meio de tomografia computadorizada por feixe cônico. Foram utilizados canais mésio vestibulares com curvatura entre 20° e 40°, de 36 molares superiores, preparados com Protaper Universal (até instrumento F2), obturados com cone ProTaper F2 e cimento AH Plus, pela técnica de condensação lateral. Para a desobturação, os dentes foram divididos em grupos (I: ProTaper Universal Retratamento, II: Mtwo Retratamento e III: D-Race). A captura das imagens foi realizada após a obturação e após a desobturação dos canais radiculares, por meio de tomografia computadorizada por feixe cônico de pequeno volume (Prexion 3D XTrillion Inc). As imagens foram segmentadas utilizando o programa InVesalius, para verificar o material obturador remanescente. O tempo para desobturação também foi analisado. De posse dos valores, iniciais e finais, de volume de material obturador e de estrutura dentinária, a proporção dos volumes foi calculada. Para a análise estatística, os resultados foram avaliados pelos testes de ANOVA e de Múltiplas Comparações de Bonferroni. Os grupos ProTaper Universal Retratamento (13,97%) e D-Race (9,87%), apresentaram os menores volumes percentuais médios de material obturador remanescente, não havendo diferença estatística significante entre eles; porém, apresentaram diferença estatística significante (p 0,05) do grupo Mtwo Retratamento (33,88%). Os três sistemas provocaram desgaste semelhante de dentina após a desobturação. O grupo D-Race apresentou menor tempo para desobturação, estatisticamente diferente em relação aos demais sistemas. As características dos sistemas de retratamento podem interferir na eficiência de desobturação quanto ao tempo e volume de material remanescente.
The present study aimed to evaluate, ex vivo, the efficiency of systems for retreatment (ProTaper Universal Retreatment, Mtwo Retreatment and D-Race), in removal filling material of curved mesiobuccal canals of maxillary molars, using cone beam computed tomography. Were used mesiobuccal canals with curvature between 20 ° and 40 °, of 36 molars prepared with ProTaper Universal (until instrument F2), filled with cone F2 ProTaper and AH Plus sealer by lateral condensation. For the removal procedure of filling material, the teeth were divided into groups (I: Protaper Universal Retreatment, II: Mtwo Retreatment and III: D-Race). The capture of images was performed after filling and after the removal procedure of root canal through cone beam computed tomography of small volume (Prexion 3D - XTrillion Inc). The images were segmented using the software InVesalius to check the remaining filling material. The time for removal procedure was also analyzed. Possession of values, initial and final, of volume filling material and dentin structure, the ratio of the volumes was calculated. For statistical analysis, the results were evaluated by ANOVA and Bonferroni\'s Multiple Comparisons. ProTaper Universal Retreatment (13.97 %) and D-Race (9.87 %) groups had the lowest average percent volume remaining filling material, with no statistically significant difference between them, but showed a statistically significant difference (p 0.05) group Mtwo Retreatment (33.88 %). The three systems caused similar wear dentin after removal procedure. The group D-Race had less time for removal procedure, statistically different compared to the other systems. The characteristics of retreatment systems may interfere with the efficiency of removal procedure on the time and volume remaining material.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
O objetivo deste estudo foi avaliar a espessura mínima radicular remanescente e o desgaste porcentual do terço cervical em raízes mesiais de molares inferiores, após a instrumentação com as técnicas ProTaper Universal e Lima única F2. Foram obtidos 100 primeiros molares inferiores com raízes completamente separadas. Desse total, foram selecionados e incluídos no estudo somente 22 que possuíam dois canais distintos na raiz mesial, comprimento entre 20 e 22 mm e grau de curvatura da raiz mesial com angulação variando entre 10 e 20. Destes, 8 foram eliminados por possuírem uma anatomia muito discrepante, o que limitava o processamento e análise digital das imagens (PADI). Os dentes foram acessados e a patência apical foi realizada em todos os canais determinando o comprimento de trabalho. Em cada dente, cada canal mesial foi instrumentado por uma técnica diferente. As amostras foram posicionadas em um dispositivo de montagem e digitalizadas através de microtomografia computadorizada antes e depois de serem completamente instrumentadas. O volume de interesse, correspondente à região de zona de risco, com uma grande margem de tolerância, tanto em direção apical quanto em direção cervical, foi determinado por 234 fatias, totalizando um comprimento vertical de 3,5 mm, para avaliação quantitativa comparativa. Através de PADI mediu-se, de forma automática, a espessura mínima radicular nos dois canais mesiais, antes e após a instrumentação, para todas as fatias de todos os dentes. A partir destes dados foi calculado o desgaste porcentual. Após o tratamento estatístico das mais de 6500 medidas obtidas, pôde-se concluir que não existiu diferença no desgaste da zona de risco produzido pelas duas técnicas de instrumentação testadas. Em todos os casos a espessura radicular remanescente permaneceu dentro de uma margem de segurança, não havendo, portanto, nenhum caso de rasgo ou perfuração. Dessa forma, ambas as técnicas estudadas foram consideradas seguras quanto ao desgaste da zona de risco da raiz mesial dos molares inferiores.
The aim of the present study was to evaluate the minimal remaining root canal thickness and percentage of dentin removed of the cervical third of the mesial roots mandibular molars after instrumentation with the ProTaper Universal and Single File F2 Techniques. From a total of 100 teeth, only 22 were selected and included in the study by having two distinct canals in the mesial root with length between 20 and 22 mm and degree of curvature presenting angle between 10 and 20. Eight specimens were eliminated because they have a very disparate anatomy that limited the digital processing and analysis of the images (PADI). The teeth were accessed and patency was performed in all canals determining the working length. In each tooth, each mesial canal was instrumented by a different technique. The samples were placed in a mounting device and scanned by microcomputed tomography before and after instrumentation. The corresponding volume of interest to the region of the risk zone was determined by 234 slices, with a total vertical length of 3.5 mm, for quantitative comparative evaluation with a high degree of tolerance. The PADI performed the measures automatically of the minimal thickness of root in both mesial canals, before and after instrumentation for all slices of each tooth. From these data, the percentage of dentin removed was calculated. After statistical analysis of more than 6500 measurements, it was concluded that there was no difference in the wear of the risk zone produced by the two instrumentation techniques tested. In all instrumented specimens, the root thickness remained within a security margin, thus, no case of strip perforation was observed. Therefore, both techniques were considered safe to be used in mesial root of mandibular molars.

碩士
高雄醫學大學
牙醫學研究所
98
Purpose：The objectives of modern root canal therapy was to proper clean and shape the root canal system and complete removing the intracanal infection substance and sealing the system with a permanent sealing. Studies shows the sealer provides the seal and the percentage of the sealer should be as lower as possible in order to increase the long term sealing ability. Although it is difficult to use cold lateral compaction technique in curved canal, but the most clinical dentist still use it . The purpose of this study was to use two different tapered root canal enlargement and two different tapered master cone in curved canal obturation using cold lateral compaction technique, in order to find the effect of the taper of the root canal enlargement and the taper of the master cone on the percentage of GP filling using cold lateral compaction technique in curved canal. Material and Method: 40 simulated canals in resin blocks with 16.5mm in length and a 32 degrees curve were divided to two groups in this study. In the first group, root canal was prepared by using Gates-Glidden drills and K Flexo file files to an apical size 35 and the 0.1 tapered. In the secondary groupe, root canal was enlargement by using SystemGP® (Dentsply France SAS) NiTi rotary instruments to an apical size 30 and the 0.06 tapered. Every group were divided into two subgroups (subgroup A and B)，and filled the canal by using 0.02-tapered and 0.06-tapered gutta-percha master cone. Type C NiTi finger spreader (Dentsply,Ballaigues,SWISS) was used for lateral compaction technique, and the compaction force was controlled at 2 Kg. All samples were sectioned at 2mm and 4 mm from the canal terminus by using low speed saw after stewing one week. The horizontal cutting surface was examined under microscope with 50 times magnifying power. The percentages of gutta-percha, sealer or voids to the total root canal area were calculated using software JMP 8.0.The data was to test the significant differences .Among the effect of the taper of the root canal enlargement and the taper of the master cone on the percentage of GP filling with ANOVA and Tukey-Kramer HSD test using JMP6.0 software package. Result：Between the four groups which were cross-section at 2 mm from the canal terminus, the percentage of the area filled with gutta-percha were significant difference than the other groups (p&lt;0.001).From the result of Tukey-Kramer HSD test, the group IIB was grater than the other three groups, and the group IIA was grater than the group IB. There was no significant different between other gropes. In the groups which was cross-section at 4 mm from the canal terminus, the percentage of GP filling was significant difference between etch groups(p&lt;0.001).The result of Tukey-Kramer HSD test showed group IIB was grater than the others. There was no significant different in other groups. About the percentage of void, there was no significant different between the four groups which were cross-section at 2mm from the canal terminus, but the IIA group in the group which were cross-section at 4mm from the canal terminus was higher than IIB group(p=0.03). Conclusion: When filling the curved canal by using lateral compaction technique, we could get the best percentage of GP filling if preparing the canal to 0.06-tapered and using 0.06-tapered master cone. It showed the batter percentages no mater the cross-section at either 2 mm or 4 mm at canal terminus. If we prepared the canals to 0.01-tapered, the tapered sizes of master cons were no influences to the percentages of GP. ge of GP was no influence by using the 0.02 tapered master cones filling curve canal by later compaction technique if we increased the canal tapered. But if we used 0.06 tapered master cones, the percentages of GP would be significantly decrease. We also found, if we enlarged the root canal to 0.06-tapered and filled with 0.02-tapered master cones, we have larger percentages of voids than using 0.06-tapered master cones at the cross-section at 4 mm of canal terminus

One of the desired outcomes of root canal instrumentation is to stay centered in the root canal and avoid stripping of the walls which could lead to perforation. Previous studies have shown that nickel titanium (NiTi) instruments stayed centered in the root canal system to a greater degree than stainless steel instruments. However, in cases such as mesial roots of mandibular molars, where root canals lie closer to the furcation side or the inner part of curved roots (danger zone), root canal instrumentation should be directed away from this region. This type of instrumentation, anticurvature filing technique, has not been reported utilizing rotary NiTi files to determine if removal of dentin during instrumentation can be directed away from the danger zone. It is of clinical significance to determine if rotary NiTi files can be directed away from the danger zone in order to avoid perforation and canal stripping which can lead to endodontic failure. The aim of this study was to investigate whether rotary NiTi Orifice Shapers™ (ProfileR, Tulsa Dental, Dentsply, USA) can be directed away from the danger zone, into the bulky or safety zone of the root dentin during instrumentation of the coronal portion of mesial canals of mandibular molars. For studying the anatomical morphology of root canals before and after instrumentation teeth were mounted in a modified muffle block. The modified muffle block allowed for removal and exact repositioning of the complete tooth block after tooth sectioning. Teeth modified muffle blocks were sectioned at 3 different levels, around furcation and orifice. The mesial canals were divided into 2 groups. Group A (Force group) where force was applied 90 degree to the long axis of the root while instrumenting with NiTi Orifice Shapers™ (Profile[sup R]). Group B (no force group) functioned as control where no lateral force was applied during the instrumentation. Prior to instrumentation using NiTi rotary Orifice Shapers™ (Profile[sup R]), the canals in both groups were enlarged with K-files hand-instruments (Union Broach) up to size 25 as a pre-rotary instrumentation step. The first rotary instrumentation of canals was done using NiTi Orifice shapers™ (Profile[sup R]) according to the manufacturers suggested sequence sizes 30, 50, 40. The second rotary instrumentation of canals involved size 40 Orifice Shapers™ (Profile[sup R]) only. The third instrumentation of canals was done with Gates- Glidden bur #2 (Dentsply, Oklahoma, USA) as a positive control. The modified muffle block sections were scanned before and after each instrumentation. The images were superimposed in Corel Photopaint™ (Corel, Ottowa, CA) and transferred to Scion NIH image 1.62 (Scion Corp, Maryland, USA). Utilizing this software the X -Y centre point coordinates and the area of each canal space were computed. The X -Y centre point movement was calculated after the first rotary instrumentation, after the second rotary instrumentation and finally after Gates-Glidden instrumentation. The lateral force was applied 90 degrees to the long axis of the tooth, and was measured with an Instron Universal Testing Machine (Instron, Massachuset, USA), at all times. No significant difference in canal centre movement was found between force and no force groups after first and second rotary instrumentation. However, a significant difference (p=0.007) was seen in canal centre movement between force and no force groups after Gates-Glidden instrumentation (positive control). It was concluded that with the amount of force (3-5.5N) and the time period (12-16sec) under which the force was applied, it is not possible to direct NiTi Orifice Shapers™ away from the danger area in the coronal root third of the mesial root of mandibular molars.

Ziel der Studie: Das Ziel der Studie war es, verschiedene Applikationsmethoden und Medikamente auf die erzielbare Homogenität der Füllung bei der Einbringung einer Kalziumhydroxid-Paste in den Wurzelkanal zu untersuchen. Weiterhin sollte die Untersuchung für zwei verschiedene Präparationsgrößen des Wurzelkanals erfolgen. Material und Methode: Für die Versuche wurden 160 konfektionierte Wurzelkanalmodelle verwendet, die vor ihrer Verwendung auf die apikale Gängigkeit überprüft wurden. Anschließend erfolgte die randomisierte Aufteilung der Proben gemäß den Präparationsgrößen 35 und 45 in zwei Hauptgruppen (n = 80), die wiederum in jeweils vier Untergruppen (n = 20) aufgeteilt wurden. Die jeweils 80 künstlichen Wurzelkanäle der beiden Hauptgruppen wurden standardisiert bis zur Größe 35 und bis zur Größe 45 präpariert. Die so präparierten Wurzelkanalmodelle wurden mit verschiedenen Medikamenten und Methoden jeweils für die Größe 35 und 45 gefüllt. Die erste Untergruppe wurde mit Hypocal gefüllt und anschließend mit einem Wattepellet verdichtet. Die zweite Untergruppe wurde mit Hypocal gefüllt, das anschließend mit einer Papierspitze im Kanal verteilt wurde, mit Hypocal nachappliziert und abschließend mit einem Wattepellet verdichtet. Die Applikationsmethode der dritten Untergruppe entspricht der Methode der ersten Gruppe, jedoch wurde Ultracal als Medikament genutzt. Die vierte Untergruppe wurde äquivalent zur zweiten Untergruppe mit Ultracal gefüllt. Die Wurzelkanalmodelle wurden geröntgt und mit Hilfe eines Score-Systems von zwei kalibrierten Untersuchern ausgewertet. Die Ergebnisse wurden nach einem nichtparametrischen Rangverfahren für longitudinale Daten für die Kriterien „Vollständigkeit der Füllung“, „Qualität im apikalen Bereich“, „Überpressung“, „Blasengröße“ und „Füllung des Apex“ ausgewertet. Weiterhin wurden Paarvergleiche der Applikationsmethoden „Hypocal/Wattepellet“, „Ultracal/Wattepellet“, „Hypocal mit Verdichtung durch eine Papierspitze“ und „Ultracal mit Verdichtung durch eine Papierspitze“ für multiples Testen adjustiert nach Tukey angestellt. Die Untersuchungen wurden getrennt für die Größen 35 und 45 durchgeführt. Ergebnis: Es konnte nachgewiesen werden, dass keine Medikament-Applikations-Kombination in allen Kriterien generell eine vollständige, nicht-überpresste und blasenfreie Füllung gewährleistet. Weiterhin wurde aufgezeigt, dass die signifikant beste Füllqualität durch eine 3-malige Applikation der Kalziumhydroxid-Paste mit anschließender Verdichtung mit einem Wattepellet erreicht wurde. Es lag kein signifikanter Unterschied zwischen den beiden Kalziumhydroxid-Medikamenten hinsichtlich der Füllqualität vor. Schlussfolgerung: Die beste Füllqualität wurde unabhängig vom Medikament nach 3-maliger Applikation des Kalziumhydroxids und anschließender Verdichtung mit einem Wattepellet erzielt.