The effectiveness of rotary and reciprocating techniques in curved root canals retreatment: a micro- CT analysis

Introduction: Different NiTi rotary systems have been developed to improve efficiency and retreatment success rates. Aim: To evaluate the Protaper Universal retreatment system and WaveOne instrument in removing the filling material from curved canals during retreatment. Materials and Methods: Thirty mesial root canals of extracted human mandibular molar teeth were randomly allocated into 2 groups (n=15). In the PT group, retreatment was performed with ProTaper Universal Retreatment according to the manufacturer's instructions. In the WO group, was used WaveOne Primary. ProTaper Universal F2 and F3 were used to achieve the apical diameter in both groups. The samples were scanned by micro-computed tomography pre and postoperatively to evaluate the filling material remaining. The percentage of material filling was compared between groups using Student's T test and in the same group among thirds was compared using Kruskal-Wallis followed by Dunn's post hoc test. Results: The filling material remaining was not statistically different between the groups (p≥0.05). The apical third presented a greater amount of remaining filling material when compared with the cervical third for both groups (p<0.05). Conclusion: Rotary and reciprocating techniques can effectively, but not completely, remove the filling materials from the root canal system. The apical third presented a more significant amount of remaining filling material.

Experimental study on central location ability and clearance rate of three nickel-titanium instruments for root canal retreatment / 口腔疾病防治

Objective@# Comparision of the central location ability and clearance rate of ProTaper retreatment, Fengdu O-file and M3-RT three kinds of nickel-titanium instruments and hand stainless instruments K-file, H-file. Observe the form of the root canal wall. To provide experimental basis and reference for the clinical application of nickel-titanium instruments for root canal retreatment.@*Methods @#40 simulated resin blocks with the same specification were randomly divided into four groups (n=10). Each group was separately prepared with hand stainless instruments K-file and H-file (group A1), ProTaper retreatment (group B1), Fengdu O-file (group C1), and M3-RT (group D1). Using scanner to obtain the pre- and post-operative images and overlapping the images through Photoshop. Measuring the root canal inner and outer wall resin removal with Image J, compared the central location ability of the four group. A total of 60 mandibular single canal premolars extracted due to orthodontics were collected. The teeth were randomly divided into four groups (n=15) after filling the root canal. Use hand stainless instruments K-file,H-file(group A2), ProTaper retreatment (group B2), Fengdu O-file(group C2) , M3-RT(group D2) to remove the filling materials. The roots were longitudinally sectioned, and the image of the root surface was photographed under the 10 × magnification microscope. The software was used to trace the area of the root canal wall and residual root filling, and the root filling clearance rate of each group was calculated. Two teeth were randomly selected in each group and observed under scanning electron microscope.@*Results@#Within 9 mm from the root tip hole, the central location ability of group B1, C1, D1 was better than that of group A1(P ＜ 0.05). At 4 mm from the root tip hole, group D1 has the best central location ability(P ＜ 0.05). There was no difference of the four instruments at a distance of 10 mm from the root tip hole（P ＞ 0.05）. There were various degree of filling material remained in the root canal after the four groups of instruments for retreatment canal preparation. There was no significant difference between group B2, C2, D2（P ＞ 0.05）, and both were higher than group A2(P ＜ 0.05). Scanning electron microscope observation results shown that the root canal wall prepared by group B2, C2, D2 was more smooth and continuous than group A2, and the residual filling material was less. @*Conclusion @#The central location ability of three kinds of nickel-titanium root canal retreatment instruments were significantly better than that of hand stainless instruments. ProTaper retreatment, Fengdu O-file and M3-RT three kinds of nickel-titanium root canal retreatment instruments showed good performance, the central location ability of M3-RT was slightly better. Nickel-titanium root canal retreatment instruments are more efficient than traditional hand stainless instruments in removing root fillings and the root canal wall after preparation is smoother and has good continuity.

Management of an elderly patient with orthostatic hypotension in endodontic retreatment: A case report

@#Orthostatic hypotension occurs when cardiovascular adaptive mechanisms fail to compensate the reduction in venous return that normally occurs on the upright position. A patient with orthostatic hypotension can be a challenging case for a dentist. A 78-year-old male came with idiopatic orthostatic hypotension and felt uncomfortable with his old crown restoration and discoloration on his upper teeth. Management of orthostatic hypotension can be handled by manipulating the dental chair interval movement position.

The application of three-dimensional reconstruction-based Micro-CT in the research of root canal treatment / 口腔疾病防治

@#Important guarantees of the success of root canal therapy include being familiar with the anatomical features of root canal system, good root canal preparation and complete root canal filling. With the development of medical imaging technology, three-dimensional reconstruction technology has been widely applied in root canal morphology, root canal preparation, root canal filling quality, root canal retreatment efficiency, three-dimensional finite elements and other related research. The reconstructed 3D images can be observed qualitatively and quantitatively from different angles and levels, which aid in the understanding of root canal anatomy and evaluation of the operation effect on all aspects of root canal therapy, providing important guiding significance for clinical operation. The application of 3D reconstruction technology based on micro-CT in the research of root canal anatomy, root canal preparation, root canal filling, root canal retreatment efficiency and three-dimensional finite element analysis are reviewed. The results of a literature review showed that the resolution of micro-CT is high. Furthermore, three-dimensional reconstruction can accurately display the fine anatomical morphology of a root canal, accurately measure the volume and morphological changes of root canal before and after root canal preparation, accurately measure the incidence and volume of the void after root canal filling and accurately calculate the volume changes of the root canal filling materials before and after root canal retreatment. Micro-CT is the gold standard for the morphological study of the root canal system and quality analysis of root canal preparation and filling. After three-dimensional reconstruction with micro-CT scans, a three-dimensional finite element model can be established to simulate the process of root canal therapy and stress analysis. This method can be used to analyze the stress distribution of root canal preparation instruments and the influence of root canal preparation on the stress distribution of tooth tissue and the root canal wall in the process of root canal filling. Then, suitable operation methods can be selected to prevent instrument breakage and root fracture. The application of three-dimensional reconstruction-based micro-CT is of great value in the evaluation of root canal morphology and treatment.

In vitro evaluation of retreatment efficacy of Mtwo rotary instruments / 口腔疾病防治

Objective@# To evaluate the efficacy of Mtwo rotary instruments during root canal retreatment. @*Methods @#Thirty mandibular premolars with oval root canal were prepared with ProTaper rotary instruments and obturated with lateral condensation method. The samples were divided into 2 groups. In Mtwo group, the filling materials were removed with Mtwo retreatment system and Mtwo basic instruments. Inmanual stainless group, the filling material were removed with manual instruments. The percentage of residual filling material was measured with image proplus software and the operating time was recorded. @*Results@#The percentage of residual filling material in Mtwo group was significantly lower than manual group in middle third, but the opposite result can be found in the coronal third. In the whole canal, no significant difference was found between the two groups. The mean operating time in Mtwo group was significantly shorter than manual group. @*Conclusion @#Mtwo rotary instruments can shorten the time of retreatment, neither of the groups can remove the filling material in oval root canal completely.

Removal of gutta percha in root canal therapy with Pro Taper nickel titanium system / 局解手术学杂志

Objective To evaluate the results of different methods in removing the root canal gutta percha.Methods Select 60 man-dibular premolars with step-back techinique during root canal prepartion,and the mandibular premolars were stored for 2 weeks after AH-plus paste and gutta percha cold lateral condensation.And then they were randomly divided into 3 groups to remove the root canal filling.Group A were given manually cleaning and shaping with stainless steel instruments combined with chloroform.Group B were given Pro Taper nickel ti-tanium system.Group C were given Pro Taper nickel titanium system combined with microscopic ultrasound technology.The completion time of the 3 groups were recorded and the root canal wall cleanliness of the 3 groups were carefully observed.Results The competition time and amount of debris of apical foramen in group C were both significantly less than those of group A and group B,with statistically significant difference (P <0.05).And the cleanliness of root canal wall of group A was significantly better than that of group A and group B (P <0.05). Conclusion During the root canal retreatment,mechanically use Pro Taper nickel titanium system combined with microscopic ultrasound technology can improve the work efficiency and the cleanliness of root canal wall.

Análise das propriedades químicas, biológicas e antimicrobianas de solventes endodônticos / Analysis of chemical, biological and antimicrobial properties of endodontic solvents

O objetivo deste estudo foi avaliar as propriedades químicas, biológicas e antimicrobianas dos solventes endodônticos, Citrol, Eucaliptol, d-Limoneno, Xilol e Endosolv E. Dentre os testes químicos, foram avaliados a microdureza dentinária, onde utilizamos blocos de dentina bovina que foram expostos aos solventes por 2 períodos, 5 e 15 min e submetidos ao teste de microdureza. Outro teste químico foi a capacidade de dissolução dos materiais obturadores pelo teste de imersão nos solventes em 3 períodos, 2, 5 e 15 min. Para essa avaliação foram, confeccionados corpos de prova dos cimentos, AH Plus, Acroseal, Sealer 26, Endofill, MTA Fillapex e RealSeal SE e dos cones de guta-percha estandardizado Dentsply (DP), ProTaper e Resilon. Um terceiro teste, foi realizado para avaliar a capacidade de desobturação dos canais radiculares e o efeito da agitação ultrassônica dos solventes endodônticos após a desobturação. Sessenta incisivos centrais superiores foram divididos em 6 grupos sendo um para cada solvente (n=10) mais um grupo controle (solução fisiológica). Todos dentes foram instrumentados e obturados pela mesma técnica e escaneados no Micro-CT. Os dentes foram então desobturados utilizando ProTaper Retratamento/ProTaper Universal como técnica para todos grupos, associada a um dos solventes e foram escaneados novamente para a avaliação do volume de material remanescente após a desobturação. Cada um dos dentes foi desobturado e preenchido com o mesmo solvente utilizado na desobturação. Cada solvente foi agitado pelo ultrassom por 1 min e novamente foram escaneados e avaliados os volumes restantes dos materiais nos canais radiculares. Na avaliação biológica, utilizamos o teste de citotoxicidade com células de camundongo NIH-3T3 pelo ensaio MTT. As culturas celulares foram plaqueadas e submetidas aos solventes diluídos nas concentrações de 0.5 a 2.5%, e avaliados quanto à viabilidade celular. Por fim o último teste foi o antimicrobiano, avaliado pelo teste de...

The aim of this study was to evaluate the chemical, biological and antimicrobial properties of the Endodontic solvents, Citrol, Eucalyptol, d-Limonene, Xylene and Endosolv E. First chemical properties analysis were evaluated by dentin microhardness, where we used bovine dentin blocks that were exposed to the solvents in 2 periods, 5 and 15 min and subjected to the microhardness test. Second test was to evaluate the ability of endodontic solvents to dissolve root-filling materials by immersion test in, 2, 5 and 15 minutes. Specimens of sealers, AH Plus, Acroseal, Sealer 26, Endofill, MTA Fillapex an RealSeal SE and guttapercha Dentsply (DP), ProTaper and Resilon points were prepared and evaluated in the three periods. Next test was conducted to evaluate the ability of solvents to desobturate root canals filled and analyse the effect of the ultrasonic passive agitation of solvents after canal unfill procedure. Sixty maxillary central incisors were prepared and obturated by same technique and randomly divided into 6 groups, one for each solvent (n=10) and a control group (saline solution). Teeth were scanned in Microcomputed Tomography (Micro-CT), unfilled with ProTaper Retratament/Protaper Universal with one of the solvents and scanned again. The residual root-fillings volumes were analysed and all teeth root canal were filled with the same solvent used in unfilling process and were passive-ultrasonically agitated (PUl) for 1 min. All teeth were scanned again in Micro-CT and data were analysed. Biological properties assessments were evaluated by cytotoxicity test with NIH-3T3 mouse cells by MTT assay. Cell cultures were subjected to diluted solvents at concentrations of 0.5 to 2.5%, and cell viability were analysed. Last evaluation in our study was the antimicrobial test. A total of 60 bovine dentin specimens infected intraorally were exposed for 5 min in direct contact to one of the solvents evaluated. After that, the dentin blocks with biofilms were...

Análise das propriedades químicas, biológicas e antimicrobianas de solventes endodônticos / Analysis of chemical, biological and antimicrobial properties of endodontic solvents

O objetivo deste estudo foi avaliar as propriedades químicas, biológicas e antimicrobianas dos solventes endodônticos, Citrol, Eucaliptol, d-Limoneno, Xilol e Endosolv E. Dentre os testes químicos, foram avaliados a microdureza dentinária, onde utilizamos blocos de dentina bovina que foram expostos aos solventes por 2 períodos, 5 e 15 min e submetidos ao teste de microdureza. Outro teste químico foi a capacidade de dissolução dos materiais obturadores pelo teste de imersão nos solventes em 3 períodos, 2, 5 e 15 min. Para essa avaliação foram, confeccionados corpos de prova dos cimentos, AH Plus, Acroseal, Sealer 26, Endofill, MTA Fillapex e RealSeal SE e dos cones de guta-percha estandardizado Dentsply (DP), ProTaper e Resilon. Um terceiro teste, foi realizado para avaliar a capacidade de desobturação dos canais radiculares e o efeito da agitação ultrassônica dos solventes endodônticos após a desobturação. Sessenta incisivos centrais superiores foram divididos em 6 grupos sendo um para cada solvente (n=10) mais um grupo controle (solução fisiológica). Todos dentes foram instrumentados e obturados pela mesma técnica e escaneados no Micro-CT. Os dentes foram então desobturados utilizando ProTaper Retratamento/ProTaper Universal como técnica para todos grupos, associada a um dos solventes e foram escaneados novamente para a avaliação do volume de material remanescente após a desobturação. Cada um dos dentes foi desobturado e preenchido com o mesmo solvente utilizado na desobturação. Cada solvente foi agitado pelo ultrassom por 1 min e novamente foram escaneados e avaliados os volumes restantes dos materiais nos canais radiculares. Na avaliação biológica, utilizamos o teste de citotoxicidade com células de camundongo NIH-3T3 pelo ensaio MTT. As culturas celulares foram plaqueadas e submetidas aos solventes diluídos nas concentrações de 0.5 a 2.5%, e avaliados quanto à viabilidade celular. Por fim o último teste foi o antimicrobiano, avaliado pelo teste de...

The aim of this study was to evaluate the chemical, biological and antimicrobial properties of the Endodontic solvents, Citrol, Eucalyptol, d-Limonene, Xylene and Endosolv E. First chemical properties analysis were evaluated by dentin microhardness, where we used bovine dentin blocks that were exposed to the solvents in 2 periods, 5 and 15 min and subjected to the microhardness test. Second test was to evaluate the ability of endodontic solvents to dissolve root-filling materials by immersion test in, 2, 5 and 15 minutes. Specimens of sealers, AH Plus, Acroseal, Sealer 26, Endofill, MTA Fillapex an RealSeal SE and guttapercha Dentsply (DP), ProTaper and Resilon points were prepared and evaluated in the three periods. Next test was conducted to evaluate the ability of solvents to desobturate root canals filled and analyse the effect of the ultrasonic passive agitation of solvents after canal unfill procedure. Sixty maxillary central incisors were prepared and obturated by same technique and randomly divided into 6 groups, one for each solvent (n=10) and a control group (saline solution). Teeth were scanned in Microcomputed Tomography (Micro-CT), unfilled with ProTaper Retratament/Protaper Universal with one of the solvents and scanned again. The residual root-fillings volumes were analysed and all teeth root canal were filled with the same solvent used in unfilling process and were passive-ultrasonically agitated (PUl) for 1 min. All teeth were scanned again in Micro-CT and data were analysed. Biological properties assessments were evaluated by cytotoxicity test with NIH-3T3 mouse cells by MTT assay. Cell cultures were subjected to diluted solvents at concentrations of 0.5 to 2.5%, and cell viability were analysed. Last evaluation in our study was the antimicrobial test. A total of 60 bovine dentin specimens infected intraorally were exposed for 5 min in direct contact to one of the solvents evaluated. After that, the dentin blocks with biofilms were...

Efficacy of five rotary systems versus manual instrumentation during endodontic retreatment

The purpose of this study was to evaluate the efficiency of ProFile, GT, ProTaper, Race and K3 rotary instruments compared with hand K-files for removal of gutta-percha during retreatment. Sixty mandibular premolars were instrumented with GT rotary files and filled by thermomechanical compaction of gutta-percha and AH Plus sealer. The teeth are randomly divided into 6 groups of 10 specimens each. The roots were split longitudinally, digital images were created using a flatbed scanner, and the areas with remaining filling material were demarcated using Image Tool 1.21 software. The results indicate that GT left significantly less (p<0.05) remaining filling material (1.18 ± 1.47) than hand (3.70 ± 3.16) and Hero instruments (2.99 ± 2.58). There was no statistically significant difference (p<0.05) among the others techniques: ProFile (1.99 ± 2.66), ProTaper (2.00 ± 1.99) and K3 (2.71 ± 2.87) when compared with GT. In conclusion, GT, ProFile, ProTaper and K3 were more effective in removing gutta-percha than manual and Hero instruments.

O propósito deste estudo foi avaliar a eficiência dos instrumentos rotatórios ProFile, GT, ProTaper, Race e K3 comparados com limas K para a remoção do material obturador durante o retratamento. Sessenta pré-molares inferiores foram instrumentados com o sistema rotatório GT e obturados usando a técnica de compactação termomecânica de guta-percha com cimento AH Plus. Os dentes foram divididos aleatoriamente em seis grupos de dez espécimes cada. As raízes foram seccionadas longitudinalmente, imagens digitais foram criadas através de um scanner, e as áreas de remanescentes de material foram medidas usando o programa Image Tool 1.21. Os resultados indicaram que o GT deixou significantemente menos material remanescente (1,18 ± 1,47) do que os instrumentos manuais (3,70 ± 3,16) e os instrumentos Hero (2,99 ± 2,58) (p<0,05). Não houve diferença estatisticamente significante entre as outras técnicas ProFile (1,99 ± 2,66), ProTaper (2,00 ± 1,99) e K3 (2,71 ± 2,87) quando comparadas com o GT. Como conclusão, GT, ProFile, ProTaper e K3 foram revelados como mais efetivos em remover a guta-percha do que os instrumentos manuais e os instrumentos Hero.

Avaliação radiográfica da eficiência dediferentes instrumentos rotatórios no retratamento endodôntico / Assessment of the effectiveness of differentrotary instruments in endodontic retreatment

Objetivo: O objetivo deste estudo foi comparar in vitro a eficiência da remoção da guta-percha dos canais radiculares por meio de diferentes instrumentos rotatórios. Material e métodos: Foram utilizados 60 prémolares inferiores humanos extraídos, os quais foram manejados com os instrumentos GT até o #30 taper .04 e obturados pela técnica híbrida de Tagger. O retratamento foi realizado de acordo com os seguintes instrumentos: ProFile (grupo I), ProTaper (grupo II), GT (grupo III), manual controle (grupo IV), K3 (grupo V) e Hero (grupo VI). Radiografias no sentido vestibulolingual foram realizadas, escaneadas a uma resolução de 480 DPI e analisadas em computador de acordo com o remanescente de material obturador após o retratamento. As raízes foram divididas em terço cervical, médio e apical, e atribuíram-se escores numa escala de: 0 (sem material remanescente), 1 (até 25%), 2 (até 50%) e 3 (mais de 50%). Os escores de remanescente de material obturador para os diferentes instrumentos testados foram analisados estatisticamente por meio do teste Kruskal- Wallis. Resultados: Existiu diferença estatística entre os instrumentos (p < 0,01). O grupo instrumentado com o sistema Hero e K3 diferiram dos demais grupos, que obtiveram os melhores resultados. O grupo controle (manual), apesar de ter baixos valores juntamente com os demais, quando avaliado por terços, apresentou a maior quantidade de remanescente de material no terço apical. Conclusão: Os grupos ProFile, ProTaper, GT e manual alcançaram os melhores resultados, porém não houve diferença estatística significante entre eles.

Objective: The purpose of this study was to compare in vitro the effectiveness of removing guta-percha from root canals using differents rotatory instruments. Material and methods: Sixty human inferior premolars have been used, which were instrumented with GT hand files up to #30 taper .04 and obturated using Tagger’s hybrid technique. The retreatment has been based in the following instruments: ProFile (group I), ProTaper (group II), GT (group III), Manual-Control (group IV), K3 (group V), and Hero (group VI). Radiographies were taken in vestibular orientation, scanned at resolution 480DPI and analyzed by computer for the observation of the remnant parts of obturation materials after retreatment. The roots have been divided in 1/3 cervical, medium and apical, and scores were attributed as per the following scale: 0 (absence of remnant materials), 1 (up to 25%), 2 (up to 50%), and 3 (over 50%). The scores of obturation remnant materials for the differents tested instruments were statistically assessed by means of the Krusckal-Wallis’ method. Results: There was statistical difference among the instruments (p < 0.01). The group instrumented using Hero and K3 differed from the remaining groups, which presented best results. The control group (manual), in spite of presenting low values, as well as the remaining groups, when appraised by thirds has shown a greater quantity of remaining material at the apical third. Conclusion: The ProFile, ProTaper, GT, and Manual groups have presented more outstanding results, notwithstanding the absence of meaningful statistical difference among them.

Retreatment of Thermafill fillings with the ProFile 04 system at 350 or 2000 rpm

This study aimed at determining the quality of removal of the thermafill systemin endodontic retreatment with utilization of the 0.04 ProFile system at two different speeds. Thirty single-rooted mandibular canines were divided into two groups. The canals were prepared with the crown-down technique and obturated with the thermafill system with a carrier #40 and Ah-plus sealer. Fillings were removed two weeks after obturation, as follows: Group I - 0.04 ProFile following the size sequence 90, 60, 45, 40 and 45, without solvent, at a speed of 350rpm; Group II - same technique at 2000rpm. The specimens were longitudinally sectioned and were scanned and analyzed by a software (ImageTool) that measured the area of remaining filling material and removal of the plastic carrier. The mean of remnants of filling material was 24.86% at Group I, 24.91% at Group II and the area was not statistically different (Student- test) between the two groups and all plastic carriers wereremoved. It was concluded that the quality of removal of the filling material at both speeds (350 or 2000rpm) was similar; and all plastic carriers were removed with success by ProFile .04 system.

O objetivo deste estudo foi determinar a qualidade de remoção do sistemaThermafill durante o retratamento endodôntico com a utilização do sistemaProFile .04 em duas diferentes velocidades. Trinta caninos com raízes únicas foram preparados pela técnica coroa-ápice e obturados com um carregador número 40 do sistema Thermafill, sendo utilizado como cimento obturadoro Ah-plus. Duas semanas após as obturações, a remoção do material obturador foi iniciada da seguinte forma: GRUPO I - sistema ProFile .04 na seqüência 90, 60, 45, 40, 45, sem solvente e na velocidade de 350 rpm; GRUPO II - a mesma técnica, porém em 2.000 rpm. Os espécimes foramentão seccionados longitudinalmente e escaneados para a análise por intermédio de um software específico (ImageTool), o qual mediu a área de remanescentes obturadores, assim como a presença do carregador plástico do Thermafill. A média de remanescentes de material obturador foi de 24,86% para o Grupo I e 24,91% para o Grupo II, e após a aplicação do teste T-student verificou-se que não houve diferença estatisticamente significante entre os grupos estudados, havendo a remoção dos carregadores plásticos do Thermafill em todos os espécimes. Conclui-se que a qualidade de remoção do material obturador foi similar para ambas as velocidades empregadas e que os carregadores plásticos foram removidos com sucesso pelo sistema ProFile .04.

Retratamento de obturações com o sistema Thermafill por meio do sistema ProFile. 04 em 350 ou 2.000 rpm / Retreatment of Thermafill fillings with the ProFile. 04 system at 350 or 2000rpm

O objetivo deste estudo foi determinar a qualidade de remoção do sistema Thermafill durante o retratamento endodôntico com a utilização do sistema ProFile .04 em duas diferentes velocidades. Trinta caninos com raízes únicas foram preparados pela técnica coroa-ápice e obturados com um carregador número 40 do sistema Thermafill, sendo utilizado como cimento obturador o Ah-plus. Duas semanas após as obturações, a remoção do material obturador foi iniciada da seguinte forma: GRUPO I-sistema ProFile .04 na sequência 90,60,45,40,45, sem solvente e na velocidade de 350 rpm; GRUPO II-a mesma técnica, porém em 2.000 rpm. Os espécimes foram então seccionados longitudinalmente e escaneados para a análise por intermédio de um software específico (ImageTool), o qual mediu a área de remanescentes obturadores, assim como a presença do carregador plástico do Thermafill. A média de remanescentes de material obturador foi de 24,86% para o Grupo I e 24,91% para o Grupo II, e após a aplicação do teste T-student verificou-se que não houve diferença estatisticamente significante entre os grupos estudados, havendo a remoção dos carregadores plásticos do Thermafill em todos os espécimes. Conclui-se que a qualidade de remoção do material obturador foi similar para ambas as velocidades empregadas e que os carregadores plásticos foram removidos com sucesso pelo sistema ProFile .04

This study aimed at determining the quality of removal of the thermafill systemin endodontic retreatment with utilization of the 0.04 ProFile system at twodifferent speeds. Thirty single-rooted mandibular canines were divided intotwo groups. The canals were prepared with the crown-down technique andobturated with the thermafill system with a carrier #40 and Ah-plus sealer.Fillings were removed two weeks after obturation, as follows: Group I ­ 0.04ProFile following the size sequence 90, 60, 45, 40 and 45, without solvent, ata speed of 350rpm; Group II ­ same technique at 2000rpm. The specimenswere longitudinally sectioned and were scanned and analyzed by a software(ImageTool) that measured the area of remaining filling material and removalof the plastic carrier. The mean of remnants of filling material was 24.86% at Group I, 24.91% at Group II and the area was not statistically different(Student's "t" test) between the two groups and all plastic carriers wereremoved. It was concluded that the quality of removal of the filling materialat both speeds (350 or 2000rpm) was similar; and all plastic carrierswere removed with success by ProFile .04 system

Avaliação de duas velocidades aplicadas no Profile. 04 no tempo de retratamento endodôntico do sistema Thermafil / Evaluation of two speeds applied to the Profile.04 in the endodontic retreatment time of Thermafille system

O objetivo deste trabalho foi comparar o tempo gasto pelo sistema ProFile.04 na remoção do material obturador do canal radicular em dentes obturados com o sistema Thermafil. Foram utilizados 30 caninos, divididos em dois grupos. Os espécimes foram preparados e então obturados com o sistema Thermafil. Duas semanas após a obturação, iniciou-se o retratamento com o sistema ProFile.04, sendo a velocidade no grupo I de 350 rpm e 2.000 rpm no grupo II. Os tempos de remoção foram submetidos à análise estatística, e houve diferença estatisticamente significante entre os dois grupos experimentais, sendo o grupo II mais rápido

The aim of this study was to compare the time spent through the 0.04 ProFile system in the removal of the root fillings of the root canal in teeth obturated with the thermafill system. 30 tooths, divided in two groups have been used. The specimens have been prepared and then obturated with the thermafill system. Two weeks after obturation, the fillings were removed using 0.04 ProFile instruments, being the speed in group I of 350 rpm and 2000 rpm in group II. The times of the removal have been submitted to the statistical analysis, showing significant statistical difference between the two experimental groups, being Group II faster.