ABSTRACT
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.
ABSTRACT
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.