Continuous Wave of Condensation Improves the Filling of Curved Canals: a Micro-CT Study / La condensación de onda contínua mejora el selle de canales curvos: un estudio de micro-CT

Abstract The aim of this study was to compare the filling capacity in curved root canal using a new continuous wave of condensation technique (Termo Pack II, Easy Dental Equipments, Brazil) or lateral compaction. The percentage of voids in the filling of mesial root canals of mandibular molars was assessed by micro-computed tomography (micro-CT). Mesial root canals (n=24) of mandibular molars with a degree of curvature between 20° and 40° were prepared using rotary system (ProDesign Logic, Easy, Brazil) up to #35, .05 taper. The root canals were filled by using the continuous wave of condensation system or lateral compaction and AH Plus sealer (n=12). Scanning at 9 µm was performed after preparation and after filling by using micro-CT SkyScan 1176. The volumetric percentage of filling material and voids (total length and in each root canal third) were calculated. Data were analyzed using ANOVA/ Tukey and Student's t tests (α=0.05). Before the filling techniques, the root canals volume after preparation was similar (p>0.05). The root canals filled by the continuous wave of condensation technique presented the lowest percentage of voids, and the greatest percentage of filling material in total length and thirds (cervical, middle and apical) (p<0.05). Both techniques were not able of completely filling the root canals. The continuous wave of condensation technique Termo Pack II promoted better root canal filling in curved root canals, when compared with lateral compaction.

Resumen El objetivo de este estudio fue comparar la capacidad de obturación en conductos radiculares curvos utilizando una nueva técnica de condensación de onda continua (Termo Pack II, Easy Dental Equipments, Brasil) vs compactación lateral. El porcentaje de brechas en la obturación de los conductos radiculares mesiales de los molares mandibulares se evaluó mediante microtomografía computarizada (micro-CT). Se prepararon conductos radiculares mesiales (n=24) de molares mandibulares con un grado de curvatura entre 20° y 40° utilizando un sistema rotatorio (ProDesign Logic, Easy, Brasil) al #35, conicidad 0,05. Los conductos radiculares se obturaron utilizando un sistema de condensación de onda contínua o compactación lateral y cemento AH Plus (n=12). Se realizó un escaneo de 9 µm después de la preparación y después de la obturación usando el micro-CT SkyScan 1176. Se calculó el porcentaje volumétrico de material de obturación y vacíos (longitud total y en cada tercio del conducto radicular). Los datos se analizaron utilizando las pruebas ANOVA/Tukey y t de Student (α=0,05). Antes de las técnicas de obturación, el volumen de los conductos radiculares después de la preparación fue similar (p>0,05). Los conductos radiculares obturados con la técnica de condensación por onda contínua presentaron el menor porcentaje de vacíos y el mayor porcentaje de material de obturación en longitud total y en tercios (cervical, medio y apical) (p<0,05). Ambas técnicas no fueron capaces de llenar completamente los conductos radiculares. La técnica de condensación de onda contínua Termo Pack II promovió un mejor relleno del conducto radicular en conductos radiculares curvos en comparación con la compactación lateral.

Effect of Endo-Z bur or Bladesonic ultrasonic tip on the adaptation of filling material. A micro-CT study

Abstract This study aimed to evaluate the effect of apicoectomy performed with a bur or an ultrasonic tip on the adaptation of the filling material to root canal dentin. Twenty human mandibular incisors were selected and prepared with a ProDesign Logic system up to diameter 40/.05. The root canals were filled with Bio-C Sealer (Angelus, PR, Brazil) using the single cone technique and were stored at 37ºC and 95% relative humidity for 7 days. After this period, the apicoectomy of the 3 millimeters of the root apex was performed using Endo-Z bur (Dentsply Sirona) or Bladesonic ultrasonic tip (Helse Ultrasonic, Santa Rosa de Viterbo, Brazil) (n=10). The specimens were scanned by micro-computed tomography (micro-CT; SkyScan 1176) with a voxel size of 8.74 µm after obturation and after apicoectomy. The percentage of voids at the interface between the filling material and the root canal wall was evaluated in the apical 4 mm of the root after apicoectomy, besides the time cutting to both devices. The data obtained were submitted to paired and unpaired t-tests (α = 0.05). Endo-Z and Bladesonic increased the percentage of voids between the filling material and the dentin after apicectomy (p<0.05), and they were similar (p>0.05). Endo-Z has a shorter time to perform apicoectomy compared to Bladesonic (p<0.05). Apicectomies with Endo-Z or Bladesonic could harm the material/dentin interface, while the Endo-Z bur was faster than the Bladesonic ultrasonic tip.

Resumo O objetivo deste estudo foi avaliar o efeito da apicectomia realizada com broca ou inserto ultrassônico na adaptação do material obturador á dentina do canal radicular. Vinte incisivos inferiores humanos extraídos foram selecionados e preparados com o sistema ProDesign Logic até o diâmetro 40/.05. Os canais radiculares foram obturados com Bio-C Sealer (Angelus, PR, Brasil) por meio da técnica de cone único e foram armazenados em estufa a 37ºC e umidade relativa de 95% por 7 dias. Após esse período, foi realizada apicectomia dos 3 milímetros apicais utilizando broca Endo-Z (Maillefer - Dentsply) ou inserto ultrassônico BladeSonic (Helse Ultrasonic, Santa Rosa de Viterbo, Brasil) (n=10). Os espécimes foram escaneados por meio de microtomografia computadorizada (micro-CT; SkyScan 1176) com tamanho de voxel de 8,74 µm após obturação e após apicectomia. Please, correct this sentece to O percentual de falhas na interface entre o material obturador e a parede dentinaria foi avaliado nos 4 mm apicais da raiz apos apicectomia, alem do tempo de corte para ambos dispositivos. Os dados obtidos foram submetidos aos testes t pareado e não pareado (α = 0,05). Endo-Z e Bladesonic aumentaram o percentual de vazios entre o material obturador e a parede da dentina após apicectomia (p<0.05), sendo semelhantes entre si (p>0.05). Endo-Z demonstrou menor tempo para realizar apicectomia em comparação com Bladesonic (p<0.05). Apicectomias com Endo-Z ou Bladesonic podem prejudicar a interface material obturador/dentina, sendo a broca Endo-Z mais rápida que a ponta ultrassônica Bladesonic.

Effect of voxel size of Micro-CT on the assessment of root canal preparation

The aim of this study was to assess the influence of micro-computed tomography (micro-CT) voxel size on evaluation of root canal preparation using rotary heat-treated nickel-titanium files. Curved mesial root canals of mandibular molars were prepared using ProDesign Logic 30/.05 (PDL) or HyFlex EDM 25/.08 (HEDM) (n=12). The specimens were scanned using micro-CT with 5μm of voxel size before and after root canal preparation. Images with sub-resolution of 10 and 20μm voxel sizes were obtained. The percentage of volume increase, debris and uninstrumented root canal surface were analyzed in the different voxel sizes. Data were compared using unpaired Student's t-test and ANOVA statistical tests (α=0.05). No differences were observed for percentage of volume increase, debris and instrumented surface between the root canals prepared by PDL and HEDM (p>0.05). Both systems promoted higher percentage of debris in the apical third compared to the middle third (p0.05). PDL and HEDM had similar root canal preparation capacity. Micro-CT images using different voxel sizes did not influence the results of volume increase and debris evaluation. However, images at 5µm showed greater accuracy to evaluate the percentage of uninstrumented surfaces.

El objetivo de este estudio fue evaluar la influencia del tamaño de vóxel de la microtomografía computarizada (micro-CT) en la evaluación de la preparación del conducto radicular utilizando limas rotatorias de níquel-titanio tratadas térmicamente. Se prepararon conductos radiculares mesiales curvos de molares mandibulares usando ProDesign Logic 30/.05 (PDL) o HyFlex EDM 25/.08 (HEDM) (n=12). Las muestras se escanearon usando micro-CT con un tamaño de vóxel de 5μm antes y después de la preparación del conducto radicular. Se obtuvieron imágenes con subresolución de vóxeles de 10 y 20μm. Se analizó el porcentaje de aumento de volumen, residuos y superficie del conducto radicular no instrumentado en diferentes tamaños de vóxel. Los datos se compararon usando la prueba t de Student no pareada y las pruebas estadísticas ANOVA (α=0,05). No se observaron diferencias en el porcentaje de aumento de volumen, detritus y superficie instrumentada entre los conductos radiculares preparados por PDL y HEDM (p>0,05). Ambos sistemas promovieron un mayor porcentaje de detritos en el tercio apical en comparación con el tercio medio (p0,05). PDL y HEDM tenían una capacidad de preparación del conducto radicular similar. Las imágenes de micro-CT que utilizan diferentes tamaños de vóxel no influyeron en los resultados de la evaluación del volumen y los desechos. Sin embargo, las imágenes de 5µm mostraron una mayor precisión al evaluar el porcentaje de superficies no instrumentadas.

How does nano-focus computed tomography impact the quantification of debris within the root canal system?

Abstract The aim of this study was to compare the quantification of hard-tissue debris by using micro-computed tomography (micro-CT) and nano-focus computed tomography (nano-CT) after root canal instrumentation. Ten mandibular molars containing an isthmus in the mesial root were scanned in a SkyScan 1172 micro-CT device with a voxel size of 12.8 µm and in a NanoTom nano-CT device with 5.5 µm. The mesial root canals were irrigated with 5 mL of saline solution at the orifice level, instrumented with Reciproc R25 files and a second scanning was performed by micro-CT and nano-CT devices for post-instrumentation images. DataViewer software was used for registering the pre- and post-operative micro-CT and nano-CT images. The root canal and the debris were segmented for quantitative analysis of the volume of the canal and volume of debris using CTAn software. Statistical analysis was performed using the T test for comparison between volume of the canal after instrumentation and volume of debris in both image modalities. The level of significance was set at p < 0.05. Nano-CT images showed higher values of debris when compared with micro-CT (p < 0.05) after root canal instrumentation. No difference was observed between the volume of the root canal after instrumentation in the two imaging methods used (p > 0.05). Nano-CT technology can be recommended as a more precise method for quantitative analysis of hard-tissue debris. Moreover, in Endodontic research it is a promising method, as it is capable of providing higher spatial and contrast resolution, faster scanning and higher image quality.

Diamond-coated ultrasonic tip decreases debris and uninstrumented surface after preparation of curved canals with isthmus

Abstract The aim of this study was to evaluate root canal preparation with nickel titanium rotary instruments and complementary preparation with ultrasonic tip in curved canals of mandibular molars with isthmus. Twenty-eight mesial roots of mandibular molars with curvature between 20° and 40° and presence of isthmus throughout the entire extension of the root canals were prepared using ProDesign Logic CM (PDL) up to size 40.05, or HyFlex EDM (HFEDM) up to size 40.04. Complementary preparation was performed in the isthmus region using the ultrasonic insert E18D (Helse, Istmo Diamantada). The root canals were scanned using micro-CT (SkyScan 1176) at 9 µm voxel size before and after each preparation step. Transportation, percentage of increase in volume, debris and uninstrumented surface (UNS) were evaluated. Mann Whitney, Wilcoxon, paired and non-paired t-tests were used for statistical analysis (α = 0.05). The canals prepared with PDL and HFEDM obtained similar results for all the variables assessed before using E18D (p > 0.05). E18D significantly decreased the percentage of debris and UNS values in both Groups (p < 0.05). The complementary preparations with E18D caused a smaller quantity of debris in the isthmus of the canals previously prepared with PDL in comparison with HFEDM (p < 0.05). PDL and HFEDM provided similar root canal preparation. PDL promoted a smaller quantity of Debris in the isthmus than HFEDM after using E18D. E18D significantly improved cleaning, and reduced Debris and UNS.

Análise de metodologias para avaliação da solubilidade do cimento à base de silicato de cálcio Bio-C Sealer / Analysis of methodologies for evaluating the solubility of calcium silicate-based sealer Bio-C Sealer

Introdução: Cimentos endodônticos à base de silicato de cálcio demonstram maior solubilidade em água destilada. Emprego de metodologias alternativas pode auxiliar em melhor compreensão sobre a solubilidade desses materiais. Objetivo: Avaliar o efeito da solução de imersão e do tipo de modelo experimental na solubilidade de cimento pronto para uso Bio-C Sealer. Material e método: Modelos circulares de polietileno ou dentina bovina (n = 16) foram confeccionados. Após inserção do cimento, os espécimes foram mantidos em estufa a 37 °C por 48 horas. Posteriormente, as amostras foram pesadas em balança de precisão para determinação da massa inicial. Na sequência, os espécimes foram imersos em 7,5 mL de água destilada (pH 6,5) ou PBS (pH 7,0) (n = 8) por 28 dias. Após isso, as amostras foram removidas das soluções e pesadas a cada 24 horas até a estabilização da massa final (0,001g). Corpos de prova confeccionados com Bio-C Sealer foram empregados como controle. A solubilidade foi avaliada de acordo com a diferença entre a massa inicial e final em porcentagem. Teste ANOVA Two-Way e teste post-hoc de Tukey foram realizados (α = 0,05). Resultado: Imersão em água destilada proporcionou maior solubilidade em comparação com PBS, independentemente do modelo experimental (p < 0,05). Corpos de prova apresentaram maior solubilidade, seguidos dos modelos de polietileno e dentina imersos em água destilada (p < 0,05). Não houve diferença entre os modelos experimentais imersos em PBS (p > 0,05). Conclusão: Bio-C Sealer apresenta solubilidade significativamente maior em água destilada do que em PBS em todas condições. Modelo experimental empregando dentina bovina e PBS como solução de imersão demonstra diminuir a perda de massa de Bio-C Sealer e pode ser uma alternativa valiosa para avaliar a solubilidade de cimentos biocerâmicos

Introduction: Calcium silicate-based sealers demonstrate greater solubility in distilled water. The use of alternative methodologies can help at better understanding the solubility of these materials. Objective: To evaluate the effect of the immersion solution and the type of experimental model on the solubility of readyto-use Bio-C Sealer. Material and method: Circular models of polyethylene or bovine dentin (n = 16) were made. After insertion of the sealer, the specimens were kept in an oven at 37°C and 95% humidity for 48h. Subsequently, the samples were weighed on a precision balance to determine the initial mass. Next, the specimens were immersed in 7.5 mL of distilled water (pH 6.5) or PBS (pH 7.0) (n = 8) for 28 days. After that, the samples were removed from the solutions and weighed every 24 hours until the final mass stabilized (0.001g). Test specimens made with Bio-C Sealer were used as a control. Solubility was evaluated according to the difference between the initial and final mass in percentage. Two-Way ANOVA test and Tukey post-hoc tests were performed (α=0.05). Result: Immersion in distilled water provided greater solubility compared to PBS regardless of the experimental model (p<0.05). The test specimens showed greater solubility, followed by polyethylene and dentin models immersed in distilled water (p<0.05). There was no difference between the experimental models immersed in PBS (p>0.05). Conclusion: Bio-C Sealer presents significantly greater solubility in distilled water than in PBS under all conditions. Experimental model using bovine dentin and PBS as an immersion solution demonstrates reduction in the mass loss of Bio-C Sealer and can be a valuable alternative for evaluating the solubility of bioceramic sealers

A new proposal for evaluating of the solubility of bioceramic materials in dentin tubes after immersion in PBS: a laboratory investigation / Nova proposta para avaliação da solubilidade de materiais biocerâmicos em tubos de dentina após imersão em PBS: um estudo laboratorial

Introdução: Materiais reparadores devem apresentar baixa solubilidade. Solução salina tamponada com fosfato (PBS) permite simular condição clínica e interação com dentina pode ser importante para correta avaliação da perda de massa de cimentos biocerâmicos. Objetivo: Avaliou o efeito da imersão em água destilada (AD) ou PBS na solubilidade de Bio-C Repair (BCR, Angelus) ou MTA Repair HP (MTAHP, Angelus) usando modelo de tubo de dentina. Material e método: Tubos de dentina bovina foram confeccionados com 4 mm de comprimento, 1,5 mm de diâmetro interno e 1 mm aproximadamente de espessura de parede. Os espécimes foram imersos em AD por 24h, posteriormente preenchidos com BCR ou MTAHP (n = 14) e armazenados em estufa a 37°C e umidade 95% por 24h. Após serem pesados em balança de precisão para determinação da massa inicial, os corpos de prova foram imersos em AD (pH 6,5) ou PBS (pH 7,0) (n = 7) por 28 dias. Tubos vazios também foram utilizados para o cálculo de perda de massa da dentina (n=4). Após esse período, os espécimes foram pesados até a estabilização da massa final (0,001g). A solubilidade de cada material foi avaliada. Testes estatísticos ANOVA e Tukey foram realizados (α=0,05). Resultado: BCR e MTAHP apresentaram ganho de massa em AD e perda de massa em PBS (p<0,05). Conclusão: A solução de imersão influencia a solubilidade de BCR e MTAHP usando modelo de tubo de dentina. Nova proposta metodológica poderá ser uma alternativa às normas ISO para testar a solubilidade de cimentos biocerâmicos

Introduction: Repair materials must have low solubility. Phosphate buffered saline (PBS) allows simulating clinical condition and interaction with dentin may be important for the correct evaluate of mass loss of bioceramic cements. Objective: To evaluate the effect of distilled water (DW), or PBS immersion on the solubility of Bio-C Repair (BCR, Angelus) or MTA Repair HP (MTAHP, Angelus) using a dentin tube model. Material and method: Bovine dentin tubes with a length of 4 mm, an internal diameter of 1.5 mm and walls thickness of approximately 1 mm were made. The specimens were immersed in DW for 24h, then filled with BCR or MTAHP (n = 14) and stored in an oven at 37°C and 95% humidity for 24h. After being weighed on a precision balance to determine the initial mass, the specimens were immersed in DW (pH 6.5) or PBS (pH 7.0) (n = 7) for 28 days. Empty tubes also were used for calculating the mass loss of the dentin (n=4). After this period, the specimens were weighed until stabilization of the final mass occurred (0.001g). The solubility of each material was evaluated. ANOVA and Tukey statistical tests were performed (α=0.05). Result: BCR and MTAHP showing gain of mass in DW and mass loss in PBS (p<0.05). Conclusion: The immersion solution influenced the solubility of BCR and MTAHP using dentin tube model. The new methodological proposal could be an alternative to ISO standards for testing the solubility of bioceramic cement

Influence of voxel size on dentinal microcrack detection by micro-CT after root canal preparation

Abstract The aim of this study was to assess the influence of micro-computed tomography (micro-CT) voxel size on dentinal microcrack detection after root canal preparation using rotary heat-treated nickel-titanium files. Curved mesial root canals (n = 24) of mandibular molars were prepared using ProDesign Logic 30/.05 (PDL) or HyFlex EDM 25/.08 (HEDM). The specimens were scanned by micro-CT at 5 μm voxel size before and after root canal preparation. The percentage of microcracks was evaluated in images at 5, 10 and 20 μm voxel size, by two examiners at two moments. The Kappa and McNemar tests (α = 0.05) were used. The percentage of dentinal microcracks was similar before and after PDL and HEDM preparations, at 10 and 20 μm (p > 0.05). HEDM showed a higher percentage of dentinal microcracks in the middle third at 5 μm after preparation (p < 0.05). The detection of dentinal microcracks before and after instrumentation using PDL was more accurate at 5 μm than at 20 μm, in all thirds (p < 0.05). Within the limitations of this ex vivo study, as expected, the results showed that different resolutions influence the micro-CT analysis of microcracks. The highest accuracy in detecting microcracks was observed for analyses performed at 5 μm voxel size. HyFlex EDM caused even more microcracks to develop in the middle third, detectable only by visualization of images made at 5 μm voxel size.

Evaluation of flow and filling of root canal sealers using different methodologies / Avaliação do escoamento e preenchimento de cimentos obturadores utilizando diferentes metodologias

Abstract Introduction Flow and filling ability of root canal sealers are indispensable for hermetic sealing of the root canal. Micro-computed tomography (micro-CT) can be used as a complementary methodology to evaluate such properties. Objective To evaluate the flow and filling ability of AH Plus, Endofill and Sealapex by conventional methodology and micro-CT. Material and method The flow of the sealers was analyzed according to ISO 6876/2012 and complemented by the area evaluation. Glass plates were manufactured with diameters of 1×1×2 mm and 1×1×1 mm (length, width and height), with a central cavity and four grooves in the horizontal and vertical directions. Each material was placed in the central cavity. Another glass plate and a metal weight were placed on the cement and kept for 10 minutes. The glass plate/sealer set was scanned using micro-CT. The flow was calculated by linear measurement of the material in the grooves. The central filling (mm3) was calculated in the central cavity and the lateral filling was measured up to 2 mm from the central cavity. Data were submitted to ANOVA/Tukey tests (α=0.05). Result All evaluated sealers presented flow according to ISO 6876 standards. The materials showed central cavity filling capacity higher than 80% and lateral filling greater than 75%. There was no difference in flow (mm and mm2) and in the filling ability (mm3) provided by the materials (p>0.05). Conclusion All evaluated root canal sealers showed adequate flow and filling capacity, suggesting their clinical application.

Resumo Introdução Escoamento e capacidade de preenchimento de cimentos obturadores são indispensáveis para um selamento hermético do canal radicular. Microtomografia computadorizada (micro-CT) pode ser utilizada como uma metodologia complementar para avaliação de tais propriedades. Objetivo Avaliar escoamento e capacidade de preenchimento de AH Plus, Endofill e Sealapex, por meio de metodologia convencional e micro-CT. Material e método O escoamento dos cimentos foi analisado de acordo com as normas ISO 6876/2012 e complementado pela avaliação em área. Placas de vidro foram confeccionadas nos diâmetros de 1×1×2 mm e 1×1×1 mm (comprimento, largura e altura), com uma cavidade central e quatro canaletas nas direções horizontal e vertical. Cada material foi colocado na cavidade central. Outra placa de vidro e um peso de metal foram colocados sobre o cimento e mantidos por 10 minutos. O conjunto placa de vidro/cimento foi escaneado usando micro-CT. O escoamento foi calculado por medição linear do material nas canaletas. O preenchimento (mm3) central foi calculado na cavidade central e o preenchimento lateral foi medido até 2 mm a partir da cavidade central. Os dados foram submetidos aos testes ANOVA/Tukey (α=0.05). Resultado Todos os cimentos avaliados apresentaram escoamento de acordo com as normas ISO 6876. Os materiais mostraram capacidade de preenchimento da cavidade central superior a 80% e preenchimento lateral superior a 75%. Não houve diferença no escoamento (mm e mm2) e na capacidade de preenchimento (mm3) proporcionada pelos materiais (p>0.05). Conclusão Todos os cimentos obturadores avaliados mostraram adequado escoamento e capacidade de preenchimento, sugerindo a aplicação clínica dos mesmos.

Micro-CT evaluation of apical enlargement of molar root canals using rotary or reciprocating heat-treated NiTi instruments

Abstract Objective The aim of this study was to evaluate the root canal preparation and apical enlargement of molar root canals with rotary or reciprocating heat-treated nickel-titanium (NiTi) instruments, by using micro-computed tomography (micro-CT). Methodology Mesial root canals (n=48) of mandibular molars, with a curvature between 20° and 40°, were prepared with ProDesign Logic (PDL) 25.01 and 25.06 in rotary motion, or ProDesign R (PDR) 25.06 in reciprocating motion (PDR). Apical enlargement was performed with PDL35.01 and PDL35.05 or PDR35.05. Scanning with 9 µm resolution was performed before and after preparation, and, after apical enlargement, by using micro-CT. The percentage of volume increase, debris and untouched root canal surface, transportation, centralization and preparation time were analyzed. ANOVA and Tukey or Kruskall-Wallis and Dunn statistical tests were conducted (α=.05). Results PDL promoted a higher apical percentage of volume increase, and lower percentage of debris and untouched root canal surface than PDR 25.06 preparation in entire canal and in all thirds (P<.05). Apical enlargement with PDL 35.05 and PDR 35.05 produced a higher percentage of volume increase in the apical region in relation to the initial preparation (P<.05). PDR 35.05 and PDL 35.05 showed similar results in relation to percentage of debris and untouched root canal surface in entire canal and in all thirds (P>.05). Centralization and transportation showed no difference (P>.05). PDR required less time to perform preparation and apical enlargement (P<.05). Conclusions The apical enlargement 35.05 with CM heat-treatment instruments using reciprocating and rotary motion reduced the percentage of debris and untouched root canal surface, without causing deviations or procedural errors. The protocol of greater apical enlargement favors the cleaning of the root canals in both kinematics. Preparation by the reciprocating system was faster than by the rotary system.