Abstract: The aim of this study was to evaluate the bond strength of different triccalcium silicate cements to retrograde cavity using a push out test. Thirty maxillary central incisors were shaped using #80 hand files and sectioned transversally. Root slices were obtained from the apical 4 mm after eliminating the apical extremity. The specimens were embedded in acrylic resin and positioned at 45° to the horizontal plane for preparation of root-end cavities with a diamond ultrasonic retrotip. The samples were divided into three groups according to the root-end filling material (n = 10): MTA Angelus, ProRoot MTA and Biodentine. A gutta-percha cone (#80) was tugged-back at the limit between the canal and the root-end cavity. The root-end cavity was filled and the gutta-percha cone was removed after complete setting of the materials. The specimens were placed in an Instron machine with the root-end filling turned downwards. The push-out shaft was inserted in the space previously occupied by the gutta-percha cone and push out testing was performed at a crosshead speed of 1.0 mm/min. There was no statistically significant difference in resistance to push out by the materials tested (p > 0.01). MTA Angelus and ProRoot MTA showed predominantly mixed failure while Biodentine exhibited mixed and cohesive failures. The tricalcium silicate-based root-end filling materials showed similar bond strength retrograde cavity.

Resumo Avaliou-se a influência da técnica obturadora na penetração do cimento AH Plus nos túbulos dentinários, por meio de microscopia confocal de varredura a laser (MCVL), e o impacto na resistência de união do material obturador à dentina, por meio do teste de push out. Raízes de incisivos centrais superiores (n=40) foram preparadas com ProTaper Universal e distribuídas em 4 grupos: Condensação lateral, Compactação vertical, Híbrida de Tagger Modificada e Cone único. Após obturação com guta percha e AH Plus acrescido de fluoresceína 0,01%, as raízes foram seccionadas em slices de 2,0 mm. O primeiro slice de cada terço foi submetido à MCVL e, posteriormente, ao teste de push out. O segundo slice foi analisado em MEV. ANOVA demonstrou diferença estatisticamente significante para as técnicas obturadoras e terços radiculares (p<0,05). Para o percentual de penetração, Tukey evidenciou que compactação vertical (91,77±13,51), Condensação lateral (89,18±10,91) e Híbrida de Tagger Modificada (87,53±15,42) apresentaram os maiores valores, estatisticamente diferentes (p<0,05) da Cone único (78,19±22,46). Na resistência de união (MPa), Condensação lateral (3,42±0,54) e Compactação vertical (3,47±0,53) obtiveram os maiores valores, diferentes (p<0,05) da Híbrida de Tagger Modificada (2,19±0,41) e da Cone único (0,54±0,21), que teve os menores valores. Concluiu-se que as técnicas obturadoras Condensação lateral, Compactação vertical e Híbrida de Tagger Modificada propiciaram maior penetração e resistência de união à dentina intrarradicular.

Abstract The influence of root canal filling techniques on the penetration of AH Plus into dentinal tubules was evaluated using confocal laser scanning microscopy (CLSM) and the impact on the bond strength of the filling material on the root dentin was evaluated using the push-out test. Roots of the maxillary central incisors (n=40) were prepared with ProTaper Universal and assigned to four groups: lateral condensation, vertical compaction, modified Tagger hybrid and single cone. After root canal filling with gutta-percha and AH Plus, along with the addition of 0.01% fluorescein, the roots were cut into 2-mm slices. CLSM was performed on the first slice of each root third, followed by the push-out test. The second slice was analyzed under SEM. ANOVA demonstrated a statistically significant difference between the root canal filling techniques and the root thirds (p<0.05). For percent penetration, Tukey’s test showed that the vertical compaction (91.77±13.51), lateral condensation (89.18±10.91) and modified Tagger hybrid (87.53±15.42) presented the highest values, which significantly differed (p<0.05) from those of the single cone (78.19±22.46). For bond strength (MPa), lateral condensation (3.42±0.54) and vertical compaction (3.47±0.53) had the highest values (p<0.05), while the modified Tagger hybrid (2.19±0.41) and single cone (0.54±0.21) had the lowest. In conclusion, the lateral condensation, vertical compaction and Modified Tagger’s hybrid techniques resulted in greater penetration and bond strength to the intra-radicular dentin.

Abstract The aim of this study was to evaluate the effects of different root canal filling techniques on the bond strength of epoxy resin-based sealers. Sixty single-rooted canines were prepared using ProTaper (F5) and divided into the following groups based on the root filling technique: Lateral Compaction (LC), Single Cone (SC), and Tagger Hybrid Technique (THT). The following subgroups (n = 10) were also created based on sealer material used: AH Plus and Sealer 26. Two-millimeter-thick slices were cut from all the root thirds and subjected to push-out test. Data (MPa) was analyzed using ANOVA and Tukey’s test (α = 0.05). The push-out values were significantly affected by the sealer, filling technique, and root third (p < 0.05). AH Plus (1.37 ± 1.04) exhibited higher values than Sealer 26 (0.92 ± 0.51), while LC (1.80 ± 0.98) showed greater bond strength than THT (1.16 ± 0.50) and SC (0.92 ± 0.25). The cervical (1.45 ± 1.14) third exhibited higher bond strength, followed by the middle (1.20 ± 0.72) and apical (0.78 ± 0.33) thirds. AH Plus/LC (2.26 ± 1.15) exhibited the highest bond strength values, followed by AH Plus/THT (1.32 ± 0.61), Sealer 26/LC (1.34 ± 0.42), and Sealer 26/THT (1.00 ± 0.27). The lowest values were obtained with AH Plus/SC and Sealer 26/SC. Thus, it can be concluded that the filling technique affects the bond strength of sealers. LC was associated with higher bond strength between the material and intra-radicular dentine than THT and SC techniques.

Este estudo avaliou a resistência de união de materiais retrobturadores a cavidades retrógradas, usando uma nova metodologia. Vinte incisivos centrais superiores foram submetidos ao preparo biomecânico (lima manual #80) e seccionadas transversalmente a 2 mm do ápice e a 4 mm do primeiro corte. Os cilindros de raízes foram incluídos em resina acrílica e posicionado a 45° em relação ao plano horizontal para confecção das retrocavidades com ponta ultrassônica diamantada. Dois grupos (n = 10) foram formados de acordo com os cimentos utilizados: MTA e Super EBA. Um cone de guta-percha (#80) foi travado no limite da retrocavidade com o canal radicular. A retrocavidade foi preenchida e, após o tempo de endurecimento do cimento utilizado, o cone de guta-percha foi removido. Os espécimes foram fixados na máquina universal de ensaios Instron com a retrobturação voltada para baixo. A haste empregada para pressionar o cimento retrobturador no teste de push-out foi inserida no espaço anteriormente ocupado pela guta-percha e acionada com velocidade de cruzeta de 1,0 mm/min, para extrusão do material retroburador. Os dados foram analisados por meio do teste ANOVA (α=5%). O cimento Super EBA (6,03 ± 1,31) apresentou maior resistência de união (MPa) comparado ao cimento MTA (1,81 ± 0,45) (p> 0,05). Houve predomínio de falhas coesivas para o cimento Super EBA e falhas mistas para o MTA. O protocolo de preparação das amostras é eficaz e apresenta uma metodologia específica para avaliação da resistência de união de materiais retrobturadores à dentina. Dentre os materiais testados, o cimento Super EBA apresentou a maior resistência de união.

This study evaluated the bond strength of root-end filling materials to root-end cavities using a new methodology. Twenty maxillary central incisors were subjected to biomechanical preparation (#80 hand file) and sectioned transversally 2 mm short of the apex and 4 mm coronally to this point. The root cylinders were embedded in acrylic resin and positioned at 45° to the horizontal plane for preparation of root-end cavities with a diamond ultrasonic retrotip. Two groups (n=10) were formed according to the root-end filling material: MTA and Super EBA. A gutta-percha cone (#80) was tug-backed at the limit between the canal and the root-end cavity. The cavity was filled and the gutta-percha cone was removed after complete setting of the sealer. The specimens were placed in an Instron machine with the root-end filling turned downwards. The push-out shaft was inserted in the space previously occupied by the gutta-percha cone and run at a crosshead speed of 1.0 mm/min for pushing out the root-end filling material. Data were analyzed by ANOVA (α=5%). Super EBA (6.03±1.31) presented higher bond strength (MPa) than MTA (1.81±0.45) (p>0.05). There was a predominance of cohesive failures for Super EBA and mixed for MTA. The protocol of specimen preparation is effective and introduces a specific methodology for assessing bond strength of root-end filling materials to dentin. Among the materials, Super EBA presented the highest bond strength.