Effect of different dimensions of test samples on the volumetric change assessment of endodontic materials

Abstract New methodologies using micro-CT to evaluate solubility besides dimensional and morphological changes of endodontic materials are proposed. However, there is no standardization in the methods. The aim of this study was to assess the effect of different dimensions of test samples on volumetric change evaluation of different endodontic materials. AH Plus, FillCanal and Sealapex root canal sealers, Biodentine, IRM and MTA root-end filling cements were used in the tests. Samples of each material with a thickness of 1.5 mm and different diameters were manufactured: 6.3, 7.75, and 9.0 mm. The samples were scanned in micro-computed tomography (micro-CT) after setting and after 7 days of immersion in distilled water. The volumetric change was evaluated by means of the difference in the total volume of the specimens before and after immersion. Data were submitted to ANOVA and Tukey tests (p<0.05). The size of the samples did not affect the percentage of volumetric change of the materials (p>0.05). All sample sizes had greater volume loss for Sealapex among the sealers and Biodentine for the cements (p<0.05). In conclusion, Biodentine and Sealapex had the highest volume loss after immersion. Samples with 1.5 mm thickness, and diameters ranging between 6.3 and 9.0 mm can be used to assess the stability of endodontic materials using micro-CT without affecting the percentage of volumetric change.

Resumo Novas metodologias utilizando micro-CT são propostas para avaliar a solubilidade além de alterações dimensionais e morfológicas em materiais endodônticos. No entanto, não há padronização nos métodos. O objetivo deste estudo foi avaliar o efeito de diferentes dimensões de corpos de prova na avaliação da alteração volumétrica de diferentes materiais endodônticos. Os cimentos obturadores AH Plus, FillCanal e Sealapex e os cimentos retrobturadores Biodentine, IRM e MTA foram utilizados nos testes. Foram confeccionadas amostras de cada material com espessura de 1.5 mm e diâmetros diferentes: 6.3, 7.75 e 9.0 mm. As amostras foram escaneadas em microtomografia computadorizada (micro-CT) após a presa e após 7 dias de imersão em água destilada. A alteração volumétrica foi avaliada por meio da diferença no volume total dos corpos de prova antes e após a imersão. Os dados foram submetidos aos testes ANOVA e Tukey (p<0,05). A dimensão das amostras não afetou o percentual de alteração volumétrica dos materiais (p>0,05). Todos os diâmetros de amostra mostraram maior perda de volume para Sealapex entre os cimentos obturadores e Biodentine entre os cimentos retrobturadores (p<0,05). Como conclusão, Biodentine e Sealapex mostraram a maior perda volumétrica após a imersão. Amostras com 1.5 mm de espessura e diâmetros variando entre 6.3 e 9.0 mm podem ser usadas para avaliação da estabilidade de materiais endodônticos utilizando micro-CT, sem influenciar no percentual de alteração volumétrica.

Influence of voxel size on micro-CT analysis of debris after root canal preparation

Abstract: The aim of this study was to assess the influence of micro-computed tomography (micro-CT) voxel size on the evaluation of debris accumulation after passive ultrasonic irrigation (PUI) in curved root canals prepared with rotary nickel-titanium files. Mesial root canals (n = 24) of mandibular molars with curvature between 25° and 35° were prepared using ProDesign Logic 30/.05 (PDL) or HyFlex EDM 25/.08 (HEDM). PUI was performed after root canal preparation of all root canals. The specimens were scanned using high-resolution (5 μm voxel size) micro-CT imaging before and after experimental procedures. The percentage of debris was analyzed in the middle and apical thirds using images with 5, 10 and 20 μm voxel sizes. Data were compared using unpaired and paired Student's t-test, ANOVA and Tukey's statistical tests (α = 0.05). There were no differences among the debris analyses performed at different voxel sizes (5, 10 and 20 μm) (p > 0.05). The percentage of debris was similar between the root canals prepared by PDL and HEDM before and after PUI (p > 0.05). In both groups, the percentage of debris decreased in the middle third after PUI (p < 0.05). Within the limitations of this ex vivo study, it can be concluded that the voxel sizes evaluated did not have a significant impact on the analysis of accumulated debris. However, the results showed a tendency for detection of more debris in the analysis performed using a lower voxel size. PUI decreased the debris accumulation in the middle third of curved root canals.

Effect of obturation technique using a new bioceramic sealer on the presence of voids in flattened root canals

Abstract The aim of this study was to evaluate the filling ability of a new ready-to-use calcium silicate-based sealer using thermoplastic or single-cone technique in flattened root canals. Twenty-four flattened distal canals of mandibular molars with a buccolingual diameter 4 or more times larger than the mesiodistal diameter were selected. The root canals were prepared and filled (n = 12), according to the following techniques: thermoplastic or single-cone technique using Bio-C Sealer. The teeth were scanned using Skycan 1176 micro-computed tomography (micro-CT) - voxel size 8.74 µm, before and after filling the root canal. The percentage of voids in the filled root canals was evaluated, and the data were statistically analyzed using the unpaired t-test (α = 0.05). The root canals filled using the thermoplastic technique created a smaller percentage of voids in the cervical/middle thirds than those filled using the single-cone technique (p < 0.05). There was no difference in the percentage of voids using either technique in the apical third (p > 0.05). The flattened root canals in the cervical/middle thirds were better filled using the ready-to-use calcium silicate-based sealer associated to the thermoplastic technique, compared with the single-cone technique. In the apical third, the techniques showed similar filling ability.

Filling ability and flow of root canal sealers: a micro-computed tomographic study

Abstract This study evaluated by micro-computed tomography (μCT) the filling ability in curved root canals, besides the flow of AH Plus (AHP) and Neo MTA Plus (NMTAP) sealers using different methodologies. Mandibular molars mesial roots with two root canals and degree of curvature between 20° and 40° were selected. The specimens were prepared with the ProDesign R system up to size 35.05 and were filled with the sealers by a continuous wave of condensation technique, Thermo Pack II (n=12). The teeth were scanned using μCT after root canal preparation and obturation. The volumetric percentage of filling material and voids were calculated. Flow was evaluated based on ISO 6876/2012 (n=10). Flow and filling were also evaluated in μCT using a glass plate with a central cavity and four grooves from the central cavity (n=6). Flow was linearly calculated into the grooves. The central cavity filling (CCF) and lateral cavity filling (LCF) were calculated in mm³. Data were submitted to non-paired t test with a significance threshold at 5%. The percentage of filling and voids between the root canals filled with AHP or NMTAP was similar (p>0.05). NMTAP presented the lowest flow in conventional test (p<0.05). Using μCT, sealers had similar CCF, LCF and linear flow (p>0.05). In conclusion, NMTAP and AHP had similar filling ability in curved mesial root canals of mandibular molars without presence of isthmus. Although AHP presented better flow than NMTAP using ISO methodology, there was no difference between these materials regarding volumetric filling when evaluated by μCT.

Resumo Este estudo avaliou por microtomografia computadorizada (μCT) a capacidade de preenchimento de canais radiculares curvos, além do escoamento dos cimentos AH Plus (AHP) e Neo MTA Plus (NMTAP) utilizando diferentes metodologias. Foram selecionadas raízes mesiais de molares inferiores com dois canais radiculares e grau de curvatura entre 20° e 40°. As amostras foram preparadas com o sistema ProDesign R até o tamanho 35.05 e foram obturadas com os cimentos por uma técnica de onda contínua de condensação, Thermo Pack II (n=12). Os dentes foram escaneados usando μCT após o preparo e obturação do canal radicular. A porcentagem volumétrica de material de preenchimento e vazios foram calculados. O escoamento foi avaliado com base na norma ISO 6876/2012 (n=10). O escoamento e o preenchimento também foram avaliados em μCT usando uma placa de vidro com uma cavidade central e quatro canaletas a partir da cavidade central (n=6). O escoamento foi calculado linearmente nas canaletas. O preenchimento da cavidade central (PCC) e o preenchimento da cavidade lateral (PCL) foram calculados em mm³. Os dados foram submetidos ao teste t não pareado com nível de significância de 5%. A porcentagem de preenchimento e vazios entre os canais radiculares preenchidos com AHP ou NMTAP foi semelhante (p>0,05). NMTAP apresentou o menor escoamento no teste convencional (p<0,05). Utilizando μCT, os cimentos apresentaram PCC, PCL e escoamento linear semelhantes (p>0,05). Em conclusão, NMTAP e AHP apresentaram capacidade de preenchimento semelhante em canais mesiais curvos de molares inferiores sem presença de istmo. Embora o AHP tenha apresentado melhor escoamento que o NMTAP usando a metodologia ISO, não houve diferença entre esses materiais em relação ao preenchimento volumétrico quando avaliados por μCT.

Physicochemical properties and bioactive potential of a new epoxy resin-based root canal sealer

Abstract The aim of this study was to evaluate physicochemical properties and bioactive potential of Sealer Plus, in comparison with MTA Fillapex, Sealapex and AH Plus. Setting time, flow, and radiopacity were evaluated based on ISO 6876 Standard. Flow was also assessed in area (mm²). The solubility and volumetric change of the sealers were evaluated after 7 and 30 days of immersion in distilled water. Solubility was evaluated by the difference in mass of materials before and after immersion. Volumetric change was evaluated by using microcomputed tomography (micro-CT). The bioactive potential was observed by Scanning Electron Microscopy (SEM) after immersion in PBS. Data were compared using ANOVA and Tukey tests (α=0.05). Sealer Plus presented the shortest setting time (196 min.) and Sealapex the longest (912 min.) (p<0.05). AH Plus showed the highest radiopacity (9.5 mm Al) and MTA Fillapex the lowest (2.7 mm Al) (p<0.05). All the sealers presented flow in accordance with ISO 6876/2012 (>17 mm). Sealer Plus showed low solubility and volumetric change (<1%), and MTA Fillapex showed the highest solubility (>25%), and volumetric change (>4%) after all time intervals (p<0.05). MTA Fillapex was the only sealer that showed bioactive potential. In conclusion, Sealer Plus presented proper physicochemical properties. However, this sealer did not present a bioactive potential.

Resumo O objetivo deste estudo foi avaliar as propriedades físico-químicas e o potencial bioativo de Sealer Plus, em comparação com MTA Fillapex, Sealapex e AH Plus. Tempo de presa, escoamento e radiopacidade foram avaliados com base nas normas ISO 6876. O escoamento foi também avaliado em área (mm²). A solubilidade e a alteração volumétrica dos cimentos foram avaliadas após 7 e 30 dias de imersão em água destilada. A solubilidade foi analisada pela diferença entre as massas dos cimentos antes e após imersão. A alteração volumétrica foi avaliada por meio de microtomografia computadorizada (micro-CT). O potencial bioativo dos cimentos foi observado por Microscopia Eletrônica de Varredura (MEV) após imersão em PBS. Os dados foram comparados usando os testes ANOVA e Tukey (α=0.05). Sealer Plus apresentou o tempo de presa mais curto (196 min.) e Sealapex o mais longo (912 min.) (p<0.05). AH Plus mostrou a radiopacidade mais alta (9.5 mm Al) e MTA Fillapex a mais baixa (2.7 mm Al) (p<0.05). Todos os cimentos tiveram escoamento de acordo com as normas ISO 6876/2012 (>17 mm). Sealer Plus mostrou baixos valores de solubilidade e alteração volumétrica (<1%) e MTA Fillapex teve os valores mais altos de solubilidade (>25%) e alteração volumétrica (>4%) em todos os períodos avaliados (p<0.05). MTA Fillapex foi o único cimento que mostrou potencial bioativo. Como conclusão, Sealer Plus apresentou propriedades físico-químicas adequadas, entretanto, não apresentou potencial bioativo.

Solubility, porosity, dimensional and volumetric change of endodontic sealers

Abstract The aim of this study was to evaluate physical properties of endodontic sealers (AH Plus, MTA Fillapex and Endofill), by conventional and micro-CT tests. Dimensional stability was evaluated after immersion of materials in distilled water for 30 days. Solubility and volumetric change were evaluated after 7 and 30 days of immersion in distilled water. Solubility was evaluated by means of mass loss and volumetric change was assessed by micro-CT. Porosity was evaluated under a microscope after 7 days of immersion in distilled water, and by using micro-CT after setting and immersion in distilled water for 7 and 30 days. Statistical analysis was performed by ANOVA and Tukey's test with 5% significance level. MTA Fillapex presented the highest solubility (p<0.05), showing values above the ISO/ADA recommendations. MTA Fillapex presented higher volumetric and dimensional changes, followed by Endofill and AH Plus (p<0.05). Dimensional stability of the MTA Fillapex and AH Plus did not follow ISO/ADA standards. The highest total porosity was observed for MTA Fillapex (p<0.05). Endofill had higher total porosity than AH Plus according to microscope evaluation (p<0,05), and both sealers were similar in micro-CT assessment (p>0,05). In conclusion, MTA Fillapex presented higher solubility, dimensional and volumetric change besides porosity compared to the other evaluated sealers. The assessed physical properties of sealers are related, and the different tests provided complementary data. Micro-CT is a valuable method for assessment of physical properties of endodontic materials.

Resumo O objetivo deste estudo foi avaliar propriedades físicas de cimentos endodônticos (AH Plus, MTA Fillapex e Endofill), por meio de testes convencionais e micro-CT. A estabilidade dimensional foi avaliada após imersão dos materiais em água destilada por 30 dias. A solubilidade e a alteração volumétrica dos materiais foram avaliadas após 7 e 30 dias de imersão em água destilada. A solubilidade foi avaliada por meio de perda de massa e a alteração volumétrica foi avaliada por micro-CT. A porosidade foi avaliada por microscopia após 7 dias de imersão em água destilada e por micro-CT após a presa e imersão em água destilada por 7 e 30 dias. A análise estatística foi realizada por meio dos testes ANOVA e Tukey, com nível de significância de 5%. MTA Fillapex apresentou a maior solubilidade (p<0,05), com valores acima das recomendações ISO/ADA. As alterações volumétricas e dimensionais foram maiores para MTA Fillapex, seguido por Endofill e AH Plus (p<0,05). MTA Fillapex e AH Plus não cumpriram os padrões ISO/ADA em relação à estabilidade dimensional. Uma maior porosidade total foi observada para MTA Fillapex (p <0,05). Endofill apresentou maior porosidade total que o AH Plus pela avaliação em microscopia (p<0,05), e ambos os cimentos foram semelhantes na avaliação por micro-CT (p>0,05). Em conclusão, MTA Fillapex apresentou maior solubilidade, alteração dimensional e volumétrica, além de maior porosidade em relação aos demais cimentos avaliados. As propriedades físicas avaliadas estão relacionadas, e os diferentes testes forneceram dados complementares. Micro-CT é um método valioso para avaliação das propriedades físicas dos materiais endodônticos.