Evaluación del ajuste apical y la adaptación de los conos de gutapercha ProTaper Next, ProTaper Gold, WaveOne Gold y Reciproc Blue en conductos simulados instrumentados con estos sistemas / Evaluation of the apical tugback and adaptation of ProTaper Next, ProTaper Gold, WaveOne Gold and Reciproc Blue gutta-percha cones in simulated canals prepared with these systems

Objetivo: Evaluar el ajuste y la adaptación apical de los conos de gutapercha de cuatro diferentes sistemas de instrumentación y obturación endodóntica en conductos curvos simulados. Materiales y métodos: Se emplearon 4 Endo Training Blocks (Dentsply Sirona) con conductos curvos simulados, instrumentados hasta el límite de trabajo, fijado en el orificio de salida del conducto. Con ese propósito se empleó un tope metálico confeccionado ad hoc, ajustado en la concavidad de la salida del conducto, a fin de asegurar el límite de la instrumentación en todos los bloques de trabajo. El tope metálico se mantuvo en la posición por medio de una morsa de mesa. Los conductos fueron permeabilizados con una lima tipo K #10 (Dentsply Sirona). A continuación, se procedió con los protocolos de instrumentación de los sistemas por evaluar en cada Endo Training Block. Se emplearon los sistemas ProTaper Next (Dentsply Sirona), ProTaper Gold (Dentsply Sirona), WaveOne Gold (Dentsply Sirona) y Reciproc Blue (VDW) de acuerdo con las especificaciones del fabricante (grupos 1, 2, 3 y 4 respectivamente). Los conductos fueron irrigados con agua destilada a cada cambio de instrumento y al finalizar la preparación, y secados con conos de papel. Luego se evaluaron, en el respectivo Endo Training Block, el ajuste y la adaptación apical a la longitud de trabajo de 10 conos de gutapercha del sistema correspondiente. Para la evaluación del ajuste, se introdujeron los conos de gutapercha en el conducto simulado respectivo y se elevaron ambos hasta 10 cm de altura, manteniéndolos durante 10 segundos. Cuando se conservaban en esa situación, se consideraba que el cono ajustaba; si se desprendían antes de ese lapso, se establecía la falta de ajuste. Así mismo, se constató en cada caso su adaptación apical a la longitud de trabajo con un microscopio clínico operativo a 8,5X. Para la evaluación total se consideraron las siguientes categorías: 1, el cono de gutapercha llegaba a la longitud de trabajo y ajustaba; 2, el cono de gutapercha llegaba a la longitud de trabajo, pero no ajustaba; 3, el cono de gutapercha no llegaba a la longitud de trabajo; y 4, el cono de gutapercha sobrepasaba la longitud de trabajo. Resultados: Entre los grupos 1, 3 y 4 no se observaron variables intrasistemas de ajuste y adaptación apical a la longitud de trabajo. En el grupo 2 sí las hubo, pero la diferencia entre grupos no fue significativa (P>0,05). Conclusiones: De los cuatro sistemas utilizados, en tres de ellos el empleo de un cono único de gutapercha garantizó, en todas las pruebas, la adaptación y el ajuste a la longitud de trabajo (AU)

Aim: To evaluate in the tugback and apical adaptation at the working length of four different mechanized systems gutta-percha cones in simulated curved canals. Materials and methods: Four Endo Training Blocks (Dentsply Sirona) with simulated curved canals were instrumented up to the working length established at the orifice located in the canal exit. A metal stop was adjusted in the concavity present at the exit of the canal to ensure the working length during instrumentation in all blocks. The metal stop was maintained using a table walrus. Canal patency was achieved with a #10 K file (Dentsply Sirona). Then the instrumentation protocols for the different systems were performed in each Endo Training Block. ProTaper Next (Dentsply Sirona), ProTaper Gold (Dentsply Sirona), WaveOne Gold (Dentsply Sirona) and Reciproc Blue (VDW) were used according to the manufacturers' instructions (groups 1, 2, 3 and 4 respectively). The canals were irrigated with distilled water between instruments and at the end of the preparation and dried with paper points. Then, the tugback and the apical adaptation at the working length of 10 gutta-percha cones of each system were evaluated in the corresponding Endo Training Block. For the tugback analysis, the gutta-percha cones were introduced in the respective simulated canal and both were raised up to 10 cm in height, holding them for 10 seconds. If the cones remained intact in their position, it was considered that the cone tugback was appropriate, if the cones were detached, a lack of tugback was considered. Likewise, a clinical operating microscope at 8.5X was used to confirm the apical adaptation to the working length in each case. For the overall evaluation the following categories were considered: 1, the gutta-percha cone reached the working length with tugback; 2, the gutta-percha cone reached the working length without tugback; 3, the gutta-percha cone did not reach the working length; 4, the gutta-percha cone exceeded the working length. Results: In three groups 1, 3 and 4 they were not found intra-systems variables in the tugback at the working length. In one group there were observed intra-systems variables but the differences between groups were not statistically significant (P>0.05) (AU)

Sealing Ability of Gutta-percha in Apical Area and Degree of Tugback Sensation after Root Canal Preparation-In Vitro Study

Aims The aim of this study was to evaluate the degree of tug-back after root canal preparation with respect to the gutta-percha-occupied area (GPOA). Materials and Methods Roots of 50 mandibular premolar teeth were prepared till size 35/0.04, then gutta-percha (GP) cones of same size and taper were adapted to root canals, and the degree of tug-back sensation was scored as loose, slight, adequate and strong. Root canals were filled with GP and AH26 sealer, and then sectioned horizontally 1 mm from the apical end at three levels. GPOA and its sum from the three levels sum of GPOA (sGPOA%) were calculated using stereomicroscope. Statistical Analysis At each sectioned level, GPOA% was compared with the score of tug-back sensation using one-way ANOVA [Analysis of variance] at a 5% significance level. Multiple pair wise comparisons were performed using Tukey test. Results Tug-back sensation was present in all canals, described as slight, adequate and strong in 4, 8 and 8 canals, respectively. Among the tug-back scores, quantitative analyses of GPOA% showed significant differences at 1-and 2-mm levels. The strong tug-back with sGPOA of 76.5 ± 11.1% was significantly higher than that of slight tug-back. Conclusions Under the conditions of this study, the tug-back scoring system can be applied to determine the amount of GP adaptation inside the root canal.

Quantification of the tug-back by measuring the pulling force and micro computed tomographic evaluation

OBJECTIVES: The aims of this study were to quantify tug-back by measuring the pulling force and investigate the correlation of clinical tug-back pulling force with in vitro gutta-percha (GP) cone adaptation score using micro-computed tomography (µCT). MATERIALS AND METHODS: Twenty-eight roots from human single-rooted teeth were divided into 2 groups. In the ProTaper Next (PTN) group, root canals were prepared with PTN, and in the ProFile (PF) group, root canals were prepared using PF (n = 14). The degree of tug-back was scored after selecting taper-matched GP cones. A novel method using a spring balance was designed to quantify the tug-back by measuring the pulling force. The correlation between tug-back scores, pulling force, and percentage of the gutta-percha occupied area (pGPOA) within apical 3 mm was investigated using µCT. The data were analyzed using Pearson's correlation analysis, one-way analysis of variance (ANOVA) and Tukey's test. RESULTS: Specimens with a strong tug-back had a mean pulling force of 1.24 N (range, 0.15–1.70 N). This study showed a positive correlation between tug-back score, pulling force, and pGPOA. However, there was no significant difference in these factors between the PTN and PF groups. Regardless of the groups, pGPOA and pulling force were significantly higher in the specimens with a higher tug-back score (p < 0.05). CONCLUSIONS: The degree of subjective tug-back was a definitive determinant for master cone adaptation in the root canal. The use of the tug-back scoring system and pulling force allows the interpretation of subjective tug-back in a more objective and quantitative manner.