Rotary Versus Reciprocation Root Canal Preparation: Initial Clinical Quality Assessment in a Novice Clinician Cohort.

INTRODUCTION: Reports comparing clinical outcomes using nickel-titanium (NiTi) reciprocating instruments with other instrumentation modalities are scarce. This study examined initial shaping outcomes after an instrumentation change of root canal instrumentation technique in a doctor of dental surgery educational program. Student characteristics, faculty/student ratio, facility, and overall endodontic treatment guidelines remained unchanged. METHODS: A total of 200 nonsurgical initial molar root canal treatments completed by third-year dental students were evaluated. The cases were examined regarding the number of treatment appointments, access cavity preparation, canal taper, canal transportation, perforations, missed canals, presence of ledges, fractured instruments, obturation length, obturation quality, and sealer extrusion. Two independent evaluators determined the number of appointments per case; 4 independent and blinded evaluators analyzed radiographs at 4 treatment stages: preoperative situation, working length, cone fit, and obturation. RESULTS: The following factors were significantly different between the 2 cohorts: the number of appointments, preparation length, taper, and occurrence of ledges. The WaveOne (Dentsply Sirona, York, PA) cohort had a significantly reduced treatment time compared with hand/GT rotary instrumentation (Dentsply Tulsa Dental, Tulsa, OK) (average of 3.3 vs 4.3 appointments). Appropriate length control and adequate taper were significantly more frequent in the WaveOne group. The frequency of ledges was significantly larger in the hybrid group. Other variables, such as access cavity preparation, canal transportation, perforations, missed canals, fractured instruments, obturation quality, and sealer extrusion, were statistically similar between the 2 groups. CONCLUSIONS: NiTi reciprocation instrumentation was superior to hybrid hand/NiTi rotary instrumentation in reducing both patient appointments and the incidence of ledging and in improving obturation length and taper in a dental student clinic setting.

Canal Aberration Assessment in Simulated Root Canals: a Comparative Study.

AIM: The aim of this study was to compare time of preparation and canal aberrations in a simulated root canals after using three different rotary systems: Endostar E5, Endostar E3 and T One File Gold. MATERIALS AND METHODS: A total of 90 endodontic training blocks were used in this study and divided into three groups consisting of 30 each (n = 30). Blocks processing was performed by thirty dentists without any prior experience in rotary instrumentation techniques. In the first group blocks were prepared using Endostar E5, in second one with Endostar E3 and in third one with T One File Gold system. The preparation time was measured. The postoperative image of each block was taken by stereomicroscope and canal aberrations (ledge and instrument fracture) was recorded. Statistical analysis was done by SPSS software. RESULTS: Instrumentation with T One File Gold system is significantly faster compared to instrumentation with Endostar E5 and Endostar E3 systems (p <0.05). There are no statistically significant differences in the type and number of procedural errors between Endostar E5, Endostar E3 and T One File Gold systems when the operators have no previous experience in rotary instrumentation techniques. CONCLUSION: Under the conditions of this study, the incidence of examined canal aberrations were similar for all tested systems. The preparation time was significantly shorter with single file system.

Impact of nickel-titanium instrumentation of the root canal on clinical outcomes: a focused review.

Nickel-titanium (NiTi) root canal instruments have improved the technical quality of enlarging and shaping. These instruments have been shown to prepare even severely curved root canal with fewer procedural errors than traditional stainless steel hand instruments. While it would appear that these instruments might enhance clinical outcomes, very few studies have assessed their impact when used in primary root canal treatment. Clinical studies investigating the outcome of primary root canal treatment using nickel-titanium hand or rotary instruments were identified (MEDLINE database) using appropriate key words in an attempt to determine if there have been enhanced outcomes with these instruments. Evidence from one clinical trial suggests that (i) better maintenance of the original canal curvature and shape results in increased success rates and (ii) that ledging of root canals results in reduced success rates. Evidence from two studies indicates that the use of NiTi-either hand or rotary-instruments significantly increases success rates of primary nonsurgical root canal treatment compared with the use of stainless steel hand instruments, while three investigations failed to show any significant differences.

A prospective cohort study of endodontic treatments of 1,369 root canals: results after 5 years.

OBJECTIVE: The purpose of this prospective study was: 1) to follow-up a large number of endodontic treatments performed by a single operator, periodically checked over a 5-year period; and 2) to correlate outcome to a number of clinical variables. STUDY DESIGN: This prospective study included all consecutive cases during the selected time period. All cases were followed regularly for a 5-year period. At the 5-year end point of the study, 470 patients with 816 treated teeth and with 1,369 treated root canals were available for evaluation. RESULTS: The overall rate of success among the 816 teeth/1,369 root canals available for evaluation was 88.6%/90.3%. The success rate for 435 teeth/793 root canals undergoing vital pulp therapy was 91.5%/93.1%. Teeth/root canals with necrotic pulp but without detectable periapical bone lesion were successfully treated in 89.5%/92.3%. If the pulp necrosis was complicated by apical periodontitis, the success rate fell to 82.7% for the teeth and 84.1% for the root canals (P = .037). Teeth with periapical lesion <5 mm had a success rate of 86.6%, and in cases where the lesion was ≥ 5 mm the rate of success was 78.2%. CONCLUSIONS: More severe disease conditions negatively affects outcome. An optimal working length was identified. Excess of root canal filling material decreases success. Infected pulp space should be treated with an effective intracanal dressing. The quality of the coronal restoration or the placement of intracanal post retentions does not affect treatment outcome.

Microscopic computerized tomographic evaluation of root canal transportation prepared with twisted or ground nickel-titanium rotary instruments.

OBJECTIVE: The aim of this study was to evaluate, ex vivo, canal transportation and the centering ability of nickel-titanium rotary instruments manufactured by twisting and by traditional grinding, with the use of microscopic computerized tomography (µCT). STUDY DESIGN: Fifteen mandibular molars were embedded in a rubber-based impression material and submitted to µCT before and after instrumentation. Images were reconstructed, and cross-sections corresponding to distances 1, 2, 3, 4, 5, 6, and 7 mm from the anatomic apex were selected for analysis. Statistical analysis was performed with Mann-Whitney test. RESULTS: Canal transportation and centering ability results were similar for both instruments. Statistically significant differences (P < .05) were observed only at the 3 and 4 mm cross-sections, with lower levels of apical transportation and a better centering ratio associated with twisted instruments than with ground instruments. CONCLUSIONS: Our findings showed that twisted and ground instruments behaved similarly, allowing the preparation of curved canals with little transportation, which occurred in both mesial and distal directions.

Endodoncia en odontogeriatría: parte II / Endodontics in geriatric dentistry: part II

El odontólogo debe considerar las condiciones biológicas, sistémicas, psicológicas, socioeconómicas y culturales que presentan los adultos mayores para poder ofrecerles las mejores estrategias para su atención. La terapia endodóntica de este grupo etario presenta algunas diferencias con el tratamiento de los pacientes jóvenes. Como ejemplo de esas diferencias se puede señalar que su sintomatología es menos severa, atípica y vaga. Del mismo modo, en cada etapa del tratamiento se producen diferencias específicas que se deben conocer, para poder orecer a estas personas una terapia endodóntica adecuada.

Surface finishing of unused rotary endodontic instruments: a SEM study

During endodontic therapy, cleaning of root canals is performed using endodontic files and auxiliary chemical substances, and it is important that the endodontist be familiar with the instruments used in daily practice. This study evaluated, under scanning electron microscopy (SEM), the quality of the surface finishing of unused rotary endodontic instruments. Fifty sizes 20, 25 and 30 rotary files from different commercial brands (ProFile, Protaper, Race, Hero and K3 Endo) were removed directly from their packages and had their final 3 mm examined with a scanning electron microscope at x190 magnification with no previous preparation. The images were evaluated by 3 skillful, calibrated, blinded observers according to the following criteria: cutting edge, debris, grooves, microcavities, tip shape, tip position, scraping and transition angle. Data were recorded in worksheets designed for the study. Irregular edges were observed in 50-100 percent of the files. Except for ProFile, all commercial brands presented surface debris in 100 percent of samples. Only Race files showed no grooves or microcavities. K3 Endo files presented the best tip centralization. Excetp for ProTaper files, all commercial brands presented blunt-cutting edges in 100 percent of samples. All types of files presented surface scraping. K3 Endo files and Protaper had a high percentage of transition angle. Based on the evaluation criteria used in the present study, most samples presented a minimum of 2 alterations and a maximum of 7 alterations per instrument. Under the tested conditions, the quality of the surface finishing of the examined instruments was not as expected, given that no instrument was free of imperfections and most of them presented at least 2 and up to 7 types of surface defects. These results suggest that the manufacturing process and the packaging conditions of rotary endodontic instruments are far from ideal.

Durante a terapia endodôntica, a ação de limpeza é realizada com os instrumentos endodônticos auxiliada por substâncias químicas. Sendo assim, é importante que o endodontista conheça como são os instrumentos. Este trabalho visou avaliar a qualidade do acabamento de superfície de instrumentos endodônticos rotatórios por meio de microscopia eletrônica de varredura. Foram selecionados, 50 instrumentos endodônticos rotatórios nos números de 20, 25 e 30, das marcas Profile, Protaper, Race, Hero e K3 Endo, da forma como são encontradas no mercado e sem nenhum preparo prévio. Os instrumentos tiveram seus 3 milímetros finais fotomicrografados em microscópio eletrônico de varredura com ampliação de x190. As imagens foram avaliadas por três profissionais especialistas, e os resultados anotados em planilhas. A metodologia aplicada permitiu concluir que todos os instrumentos das marcas comerciais avaliadas apresentaram inadequações no acabamento da superfície. Cabe aclarar que, observando os critérios selecionados utilizados para avaliação a maioria das amostras apresentaram o mínimo de duas alterações e o máximo de sete por instrumento avaliado.

Study of the areas and thicknesses of mesiobucal root canals prepared by three endodontic techniques.

The purpose of this study was to compare, in vitro, by means of computerized analysis of digital radiographic images, the anatomic alterations produced in the mandibular molar tooth dentinal walls of mesiobucal canals with severe curvature by three different endodontic techniques: Progressive Preparation, Staged and Serial Preparation. A selection was made of 45 extracted, human, mandibular molars, with root curvatures greater than 25 degrees. They were divided into three groups for every technique studied, which were then sub-divided into three sub-groups in accordance with the position of the curvature along the root: cervical, median or apical. After access surgery and tooth length determination, the canals were filled with 100% Barium Sulphate radiological contrast and the teeth were then radiographed with a direct digital radiography system, using a special apparatus capable of keeping the samples in the same spatial position during the different radiographic takes. After the above-mentioned endodontic techniques had been performed, the teeth were again filled with Barium sulphate and were also radiographed under the same previously mentioned conditions. The pre- and post-operative digital images were then analyzed in two computerized programs, AutoCAD 2004 and CorelDraw 10, to assess, respectively, the areas and the horizontal alterations which occurred in the internal and external walls of the root canals. The results indicated that although no significant differences among the techniques were shown in the statistical analysis, in a descriptive analysis the Progressive Preparation technique was shown to be more regular, uniform and effective.

Radiographic prevalence of root canal ramifications in a sample of root canal treatments in a Brazilian Dental School

The aim of this study was to radiographically investigate the presence of root canal ramifications found after endodontic treatment, and to determine any relationship between their presence and the type of the auxiliary chemical substance used. The study evaluated 1,470 endodontic treatments performed by final year undergraduate students at the Dental School of Piracicaba, State University of Campinas (UNICAMP), SP, Brazil, during the period from 1998 to 2000. The X-rays taken during treatment were evaluated in order to establish the presence of ramifications of the root canal system. The initial X-ray did not show the presence of any canal ramifications. After filling, X-rays showed only 3 ramification types: 3.06 percent of lateral canals, 2.99 percent of apical deltas, and 0.1 percent of interradicular canals. The maxillary premolars showed the highest number of lateral canals (n = 13), followed by mandibular premolars (n = 10) and maxillary incisors (n = 10). Apical deltas were mostly found in mandibular molars (n = 14), followed by maxillary incisors (n = 9). Only mandibular molars had interradicular canals. The detection of ramifications increased with the use of EDTA. However, no statistically significant relationship was found between the type of auxiliary chemical substance used and the number of root canal ramifications detected after root canal filling. It was concluded that the frequency of root canal ramifications found radiographically was low in treatments performed by undergraduate students.

O objetivo deste estudo foi investigar radiograficamente a presença de ramificações do canal radicular encontrada depois do tratamento endodôntico, e determinar qualquer relação entre a presença destas e do tipo de substância química auxiliar usada. O estudo avaliou 1.470 tratamentos endodônticos executados pelos estudantes do último ano da Faculdade de Odontologia de Piracicaba, Universidade Estadual de Campinas (UNICAMP), SP, Brasil, no período de 1998 a 2000. Foram avaliadas as radiografias feitas durante o tratamento para verificar a presença das ramificações dos sistemas de canais radiculares. A radiografia inicial não mostrou a presença de qualquer ramificação. Depois da obturação as radiografias mostraram apenas 3 tipos de ramificação: 3,06 por cento de canais laterais, 2,99 por cento de deltas apicais e 0,1 por cento de canais interradiculares. Os pré-molares superiores mostraram o maior número de canais laterais (n = 13), seguidos pelos pré-molares inferiores (n = 10) e incisivos superiores (n = 10). Deltas apicais foram encontrados principalmente em molares inferiores (n = 14), seguidos por incisivos superiores (n = 9). Apenas molares inferiores apresentaram canais interradiculares. A detecção de ramificações aumentou com o uso do EDTA. Entretanto, nenhuma relação estatisticamente significante foi encontrada entre o tipo de substância química auxiliar usada e o número de ramificações visualizadas após a obturação dos canais radiculares. Foi concluído que a freqüência de ramificações do canal radicular encontrada radiograficamente é baixa em tratamentos executados por estudantes universitários.

Study of the areas and thicknesses of mesiobucal root canals prepared by three endodontic techniques

The purpose of this study was to compare, in vitro, by means of computerized analysis of digital radiographic images, the anatomic alterations produced in the mandibular molar tooth dentinal walls of mesiobucal canals with severe curvature by three different endodontic techniques: Progressive Preparation, Staged and Serial Preparation. A selection was made of 45 extracted, human, mandibular molars, with root curvatures greater than 25°. They were divided into three groups for every technique studied, which were then sub-divided into three sub-groups in accordance with the position of the curvature along the root: cervical, median or apical. After access surgery and tooth length determination, the canals were filled with 100 percent Barium Sulphate radiological contrast and the teeth were then radiographed with a direct digital radiography system, using a special apparatus capable of keeping the samples in the same spatial position during the different radiographic takes. After the above-mentioned endodontic techniques had been performed, the teeth were again filled with Barium sulphate and were also radiographed under the same previously mentioned conditions. The pre- and post-operative digital images were then analyzed in two computerized programs, AutoCAD 2004 and CorelDraw 10, to assess, respectively, the areas and the horizontal alterations which occurred in the internal and external walls of the root canals. The results indicated that although no significant differences among the techniques were shown in the statistical analysis, in a descriptive analysis the Progressive Preparation technique was shown to be more regular, uniform and effective.

Objetivou-se comparar, in vitro, através de análise computadorizada de imagens radiográficas digitais, as alterações anatômicas promovidas nas paredes dentinárias de canais mésio-vestibulares com curvatura severa de molares inferiores por três técnicas endodônticas diferentes: Preparo Progressivo, Escalonada e Seriada. Foram selecionados 45 molares inferiores humanos extraídos, com curvaturas radiculares superiores a 25°, que foram divididos em três grupos para cada técnica estudada e subdivididos em três subgrupos de acordo com a posição da curvatura ao longo da raiz: cervical, mediana ou apical. Após cirurgia de acesso e odontometria, os canais foram preenchidos com contraste radiológico de sulfato de Bário a 100 por cento e os dentes então foram radiografados por um sistema de radiografia digital direta, utilizando-se um aparato capaz de manter as amostras na mesma posição espacial nas diferentes tomadas radiográficas. Após a realização das técnicas endodônticas supracitadas, os dentes foram novamente preenchidos com o sulfato de Bário e radiografados nas mesmas condições anteriores. As imagens digitais pré e pós-operatórias foram então analisadas em dois programas computadorizados, o AutoCAD 2004 e o CorelDraw 10, para verificar, respectivamente, as áreas e as alterações horizontais ocorridas nas paredes internas e externas dos canais radiculares. Apesar de não ter havido diferenças significantes entre as técnicas na análise estatística, em uma análise descritiva a técnica do Preparo Progressivo mostrou-se mais regular, uniforme e eficaz.

Evaluation of the apical seal after intraradicular retainer removal with ultrasound or carbide bur

There are situations in which intraradicular retainers have to be removed and replaced. The objective of this research was to evaluate the apical seal after the removal of a custom cast post and core with a carbide bur or with an ultrasound apparatus. Twenty five roots of extracted human incisors were used. They were endodontically treated and prepared to receive the posts. The posts and cores were cast with 2 types of dental alloys, CuAlZn and PdAg, and were cemented with zinc phosphate cement. After 24 hours, they were removed using the two above mentioned techniques. Then, the roots had their external surface made impermeable by two layers of cyanoacrylate adhesive, leaving only the cervical area for dye penetration. The teeth were immersed in rhodamine for 24 hours. They were then cut and observed under an optical microscope and analyzed with appropriate software (Imagelab). The results were submitted to ANOVA, and they evidenced that, regarding the alloy factor, PdAg posts presented a larger mean infiltration value (2.23 ± 0.48 mm) as compared to the posts made of CuAlZn (1.39 ± 0.48 mm) (p = 0.025). Regarding the technique factor, there was no significant difference (p = 0.9) between the removal of the intraradicular retainer using ultrasound (1.99 ± 0.62 mm) or using a rotating cutting instrument (1.62 ± 0.62 mm). Under these experimental conditions, it was possible to conclude that the degree of apical leakage was directly related to the alloy type, and it was present in both techniques used.

Há situações que exigem a remoção ou substituição de retentores intra-radiculares. O objetivo deste trabalho foi avaliar o selamento apical do material obturador após a remoção de pino intra-radicular metálico fundido com instrumento cortante rotatório ou com aparelho de ultra-som. Utilizaram-se 25 raízes de incisivos humanos extraídos, que foram endodonticamente tratadas e preparadas para receberem os pinos. Os retentores intra-radiculares foram fundidos com 2 tipos de ligas odontológicas, CuAlZn e PdAg, e foram cimentados com cimento de fosfato de zinco. Após 24 horas, foram removidos com as 2 técnicas citadas. Em seguida, os dentes foram impermeabilizados com cianoacrilato de etila, permitindo a entrada do corante apenas por via cervical. Os dentes foram imersos em rodamina por 24 horas, depois foram clivados e observados em microscópio óptico de luz e analisados em "software" próprio (Imagelab). Os resultados foram submetidos à análise de variância e mostraram que, para o fator liga, os pinos de PdAg geraram uma média de infiltração maior (2,23 ± 0,48 mm) do que os pinos de CuAlZn (1,39 ± 0,48 mm), com p = 0,025; para o fator técnica, não houve diferença significante, com p = 0,9, entre a remoção com ultra-som (1,99 ± 0,62 mm) e a remoção com instrumento cortante rotatório (1,62 ± 0,62 mm). Nestas condições experimentais, foi possível concluir que o grau de infiltração apical está relacionado com o tipo de liga, e a infiltração esteve presente em ambas as técnicas utilizadas.

Retention of radicular posts varying the application technique of the adhesive system and luting agent

This study evaluated in vitro the retention of intracanal cast posts cemented with dual-cure resin varying the application method of the primer/adhesive solution and luting agent in the prosthetic space prepared to receive the posts. Sixty endodontically treated maxillary canines had their crowns discarded, and their roots were embedded in acrylic resin. The prosthetic spaces were prepared with Largo burs mounted on a low-speed handpiece coupled to a parallelometer in order to maintain length and diameter of intraradicular posts constant and to guarantee that the preparations were parallel after casting. Two groups (n = 30) were randomly formed according to the device used to apply the adhesive system: microbrush or standard bristle brush (control). Each group was divided into 3 subgroups (n = 10) according to the technique used to place the luting agent into the root canal: using only a lentulo spiral before setting the post, applying it onto the post surface, or combining both methods. After 72 hours, the tensile force required to dislodge each post was determined by a universal testing machine (Instron 4444) set at a speed of 1 mm/min. The results indicated that the use of the microbrush yielded higher bond strength values (0.1740 ± 0.04 kN) than those recorded for the bristle brush tip (0.1369 ± 0.04 kN, p < 0.001). Bonferroni's test demonstrated a higher retention (p < 0.001) in radicular post cemented with the technique that combined both methods (lentulo + post: 0.1787 ± 0.03 kN) than that obtained with lentulo (0.1461 ± 0.065 kN) or post (0.1416 ± 0.03 kN) alone. The interactions between the adhesive system and luting agent application techniques presented statistical difference (p < 0.001). It was concluded that the best performance in terms of tensile strength among the tested conditions was obtained when the adhesive system was applied with a microbrush and the luting agent was taken into the root canal with lentulo...

O objetivo deste trabalho foi avaliar in vitro a retenção de pinos intra-radiculares variando-se a técnica de aplicação do agente adesivo e do cimento resinoso dual no espaço protético preparado para a recepção do pino. Sessenta caninos superiores tratados endodonticamente tiveram as coroas descartadas e as raízes incluídas em resina acrílica. Os espaços protéticos foram preparados com broca de Largo acionada por micromotor acoplado a um paralelômetro, a fim de manter constantes o comprimento e diâmetro dos pinos intra-radiculares e o paralelismo dos preparos após a fundição. Os pinos foram divididos aleatoriamente em 2 grupos (n = 30) conforme a técnica de aplicação do agente adesivo: com "microbrush" ou com pincel (controle). Cada grupo foi subdividido em três subgrupos (n = 10) segundo a técnica de aplicação do agente cimentante: com o próprio pino, com broca de lentulo previamente ao posicionamento do pino ou associação dos dois modos. Após 72 horas do processo de cimentação, os pinos foram tracionados pela Máquina Universal de Ensaios (Instron 4444) à velocidade de 1 mm/min. Os resultados mostraram diferença estatística significante (p < 0,001) entre as técnicas de aplicação do agente adesivo com "microbrush" (0,1740 ± 0,04 kN) e pincel (0,1369 ± 0,04 kN). Em relação à técnica de aplicação do cimento no interior do espaço protético, a da associação entre lentulo e pino (0,1787 ± 0,03 kN) foi estatisticamente diferente (p < 0,001) das do lentulo (0,1461 ± 0,065 kN) e do pino (0,1416 ± 0,03 kN) isoladamente. As interações entre as técnicas de aplicação do agente adesivo e do agente cimentante apresentaram diferença estatística (p < 0,001). Concluiu-se que as interações entre as técnicas de aplicação do agente adesivo com "microbrush" e aplicação do agente cimentante com lentulo (0,1961 ± 0,04 kN) e com lentulo e pino associados (0,1911 ± 0,02 kN) propiciaram os maiores valores da força de tração.

A scanning electron microscopic evaluation of different root canal irrigation regimens / Avaliação por microscopia eletrônica de varredura de diferentes regimes irrigantes no canal radicular

The purpose of this study was to assess the effectiveness of endodontic irrigants in removing the smear layer from instrumented root canal walls using Scanning Electron Microscopy (SEM). The endodontic irrigants used were: 1 percent sodium hypochlorite (NaOCl); 1 percent NaOCl mixed to 17 percent EDTAC; 2 percent chlorhexidine gel; and Ricinus communis gel. Photomicrographs of the middle and apical thirds were evaluated with the aid of the Fotoscore - v. 2.0 software. The results indicated that the mixture of sodium hypochlorite and EDTAC completely removed the smear layer from dentinal walls. The other endodontic irrigants were not as efficient in cleansing the root canals.

A proposta deste estudo foi avaliar, por meio de microscopia eletrônica de varredura (MEV), a efetividade dos irrigantes endodônticos na remoção da "smear layer" das paredes dos canais radiculares instrumentados. Os irrigantes endodônticos utilizados foram: solução de hipoclorito de sódio a 1 por cento; solução de hipoclorito de sódio a 1 por cento misturado ao EDTAC a 17 por cento, gel de clorexidina a 2 por cento e gel de Ricinus communis. Fotomicrografias dos terços médio e apical foram avaliadas com o auxílio do software Fotoscore - versão 2.0. Os resultados indicaram que a mistura da solução de hipoclorito de sódio e EDTAC removeu eficientemente a "smear layer" das paredes dentinárias. Os demais irrigantes endodônticos não foram tão eficientes na limpeza dos canais.

Root canal transportation with a Ni-Ti rotary file system and stainless steel hand files in simulated root canals.

OBJECTIVE: The purpose of this study was to compare the root canal transportation of the crown-down technique performed with the Ni-Ti rotary ProFile system (Dentsply/Maillefer), with the step-back technique using stainless steel K-Flexofiles (Dentsply/Maillefer). METHOD AND MATERIALS: Thirty simulated root canals in resin blocks were equally divided into 2 groups. The first group was instrumented with the ProFile system in a crown-down technique and the second group with hand K-Flexofiles in a step-back technique. After instrumentation, resin blocks of both groups were scanned by a transparency scanner, and the derived images were superimposed with the scanned image of an uninstrumented block. Transportation was digitally calculated by a computer software, and results were statistically evaluated by Student t test. RESULTS: Statistically significant differences (P < .05) were found among the 2 groups at 1, 2, 4, 5, and 6 mm from the apical foramen. No statistically significant difference was detected at 3 mm from the apical foramen. CONCLUSION: ProFile caused less transportation at 1 and 2 mm from the apex, whereas at 3 mm, both instrumentation techniques caused the same transportation. Standard deviation was less in the ProFile group than in the hand file group, indicating a more standardized preparation.

Analysis of the sealing ability of different obturation techniques in oval-shaped canals: a study using a bacterial leakage model

O objetivo deste estudo foi avaliar a qualidade do selamento obtido por 3 técnicas de obturação em canais ovais, através de um modelo de infiltração bacteriano. Setenta incisivos inferiores com canais ovais foram selecionados após radiografias bucolinguais e mésio-distais, e divididos em 3 grupos. Após a instrumentação, os dentes foram obturados respectivamente pela condensação lateral (G1), condensação vertical da guta-percha aquecida (G2) e pelo Thermafil (G3). Cinco canais radiculares que não foram obturados serviram como grupo controle positivo, e cinco com as coroas intactas serviram como grupo controle negativo. Todos os dentes foram montados em um aparato de 2 câmaras e expostos à saliva humana. O número de dias necessário à total contaminação do canal radicular foi verificado, através da observação do turvamento do BHI, por um período de 100 dias. Não apresentaram contaminação ao término do estudo 84,21% das amostras do grupo da condensação lateral (G1); 84,21% das amostras do grupo da condensação vertical da guta-percha aquecida (G2); e 89,47% das amostras do grupo do Thermafil. Não houve diferença estatisticamente significativa entre as 3 técnicas. A qualidade do selamento apical nas 3 técnicas testadas foi similar.

Hand and nickel-titanium root canal instrumentation performed by dental students: a micro-computed tomographic study.

The aim of this study was to evaluate root canals instrumented by dental students using the modified double-flared technique, nickel-titanium (NiTi) rotary System GT files and NiTi rotary ProTaper files by micro-computed tomography (MCT). A total of 36 root canals from 18 mesial roots of mandibular molar teeth were prepared; 12 canals were prepared with the modified double-flared technique, using K-flexofiles and Gates-Glidden burs; 12 canals were prepared using System GT and 12 using ProTaper rotary files. Each root was scanned using MCT preoperatively and postoperatively. At the coronal and mid-root sections, System GT and ProTaper files produced significantly less enlarged canal cross-sectional area, volume and perimeter than the modified double-flared technique (P < 0.05). In the mid-root sections there was significantly less thinning of the root structure towards the furcation with System GT and ProTaper (P < 0.05). The rotary techniques were both three times faster than the modified double-flared technique (P < 0.05). Qualitative evaluation of the preparations showed that both ProTaper and System GT were able to prepare root canals with little or no procedural error compared with the modified double-flared technique. Under the conditions of this study, inexperienced dental students were able to prepare curved root canals with rotary files with greater preservation of tooth structure, low risk of procedural errors and much quicker than with hand instruments.

Nickel-titanium: options and challenges.

The introduction of nickel-titanium (NiTi) as material for endodontic instruments about 15 years ago opened many new perspectives. Many dentists and scientists see a benefit in using NiFi files. Initial problems such as frequent fractures and the uncertainty of the best way to use them have been solved. Other challenges such as enhancing the cutting ability or optimizing the speed, torque, and fatigue are currently being addressed. Some clinicians are skeptical because they see this approach as too mechanical. Nevertheless, the combination of anatomic, biologic, and pathophysiologic knowledge with the use of NiTi instruments is a large step forward in optimizing the quality of root canal treatment worldwide.

Fratura e tempo de uso de instrumentos rotatórios de NiTi no preparo / Fracture and time of use of rotary engine-drive NiTi endodontic instruments in the preparation of curved canals

Foi comparado o número de fraturas e tempo de uso de instrumentos rotatórios ProFile no preparo de canais curvos com duas técnicas de instrumentação. Foram utilizadas a técnica rotatória convencional e a associação das técnicas oscilatória e rotatória no preparo de canais mesiais de molares inferiores com média de grau de curvatura de 28,82°. Apesar de não apresentar diferença estatística, os resultados mostraram que a técnica rotatória fraturou ou distorceu o dobro de instrumentos em relação à combinação das técnicas oscilatória e rotatória e com diferença significante, no tempo de uso dos instrumentos ProFile

Efeito da frequência da rotação alternativa na fratura de instrumentos tipo K de NiTi / Influence of rotational speed on the time and point of frature of NiTi instruments using a quarter-turn endodontic handpiece

O objetivo deste estudo foi avaliar a influência da frequência da rotação alternada no tempo e ponto de fratura de instrumentos tipo K de NiTi. Foram utilizadas 20 limas Nitiflex n° 35 de 25mm de comprimento (Maillefer, Suiça). Os instrumentos foram divididos em 2 grupos e avaliados em um canal simulado curvo em duas frequências obtidas por meio de um contra-ângulo redutor de 10:1, acoplado em motor elétrico nas velocidades nominais de 8.000 e 30.000 rpm. Os resultado foram submetidos à análise estatística concluindo-se que a frequência de rotação alternada influenciou na vida útil dos instrumentos analisados. O ponto de fratura localizou-se próximo ao centro da parte curva do instrumento. A localização do ponto de fratura não foi alterada com a mudança da frequência de rotação alternada

Effect of experience on quality of canal preparation with rotary nickel-titanium files.

OBJECTIVE: The purpose of this study was to compare inexperienced third-year dental students and experienced dentists with respect to their ability to use rotary nickel-titanium files, specifically with respect to root canal shape and instrument fracture. STUDY DESIGN: A total of 102 simulated endodontic plastic blocks were used. Twelve untrained dental students and 12 practitioners prepared 3 blocks each, and an endodontist and a trained student completed 15 blocks each. Blocks were filmed before instrumentation and then prepared to ISO 35; they were filmed again after canal preparation. Before-preparation images and after-preparation images were then superimposed. The canal deviation during preparation was measured at 9 levels, beginning at the apex. RESULTS: In total, 16 of 170 instruments fractured (9.4%). Nearly all preparations (98%) exhibited good taper, smooth walls, and definite apical stops. Material removal on the outer aspect of the canal was greatest near the apex (levels 1-4: 0.11-0.24 mm). The inner aspect of the canal was most instrumented at level 6 (0.23-0.27 mm). CONCLUSIONS: These findings show that both students lacking endodontic experience and experienced dentists used the rotary nickel-titanium files with success and achieved good root canal geometry.