Objective·To explore the efficacy of the XP-Endo Shaper(XPS)and Reciproc(RC)engine-driven nickel-titanium file systems in removing root canal fillings,and to provide evidence for clinical application.Methods·The maxillary first permanent molars were obtained from patients who visited the Department of General Dentistry,Shanghai Ninth People's Hospital,Shanghai Jiao Tong University School of Medicine,between March and September 2022,which required tooth extraction due to periodontal disease.A total of 30 mesiobuccal or distobuccal root canals with moderate curvature were selected and randomly divided into the RC file group(control group,n=15)and the XPS file group(experimental group,n=15).All root canals were first negotiated and shaped using M3-PRO nickel-titanium files,followed by root canal obturation with bioceramic paste using the single-cone technique.Then,RC files(R25)were used in the control group,while XPS files were used in the experimental group to remove the root canal obturation.Cone Beam Computed Tomography(CBCT)scans were performed before and after the removal procedures.The time required for obturation removal,the percentage of residual obturation volume,the amount of apical debris extrusion,and the degree of instrument deformation were recorded.Independent-sample t-tests and chi-square test were used to compare the differences between the two groups.Results·The XPS group required slightly more time(118.87±18.58)s than the RC group(107.93±14.79)s,but the difference between two groups was not statistically significant.The XPS group had a lower percentage of residual obturation volume(7.51±8.06)%compared to the RC group(15.02±14.63)%,but the difference was not statistically significant.The XPS group had significantly less apical debris extrusion(6.15±1.42)mg than the RC group(8.29±2.01)mg,with a statistically significant difference(P=0.002).Both groups exhibited varying degrees of instrument deformation,but yet no instrument separation occurred in either group.Conclusion·The RC engine-driven nickel-titanium files were slightly more time-efficient in removing root canal fillings,whereas the XPS files achieved a higher canal cleanliness and produced less apical debris extrusion.As there was no significant difference in removal time,and considering the superior cleaning performance and reduced risk of postoperative complications,the XPS file system appears more suitable for removing root canal fillings in moderately curved root canals.

Objective·To explore the efficacy of the XP-Endo Shaper(XPS)and Reciproc(RC)engine-driven nickel-titanium file systems in removing root canal fillings,and to provide evidence for clinical application.Methods·The maxillary first permanent molars were obtained from patients who visited the Department of General Dentistry,Shanghai Ninth People's Hospital,Shanghai Jiao Tong University School of Medicine,between March and September 2022,which required tooth extraction due to periodontal disease.A total of 30 mesiobuccal or distobuccal root canals with moderate curvature were selected and randomly divided into the RC file group(control group,n=15)and the XPS file group(experimental group,n=15).All root canals were first negotiated and shaped using M3-PRO nickel-titanium files,followed by root canal obturation with bioceramic paste using the single-cone technique.Then,RC files(R25)were used in the control group,while XPS files were used in the experimental group to remove the root canal obturation.Cone Beam Computed Tomography(CBCT)scans were performed before and after the removal procedures.The time required for obturation removal,the percentage of residual obturation volume,the amount of apical debris extrusion,and the degree of instrument deformation were recorded.Independent-sample t-tests and chi-square test were used to compare the differences between the two groups.Results·The XPS group required slightly more time(118.87±18.58)s than the RC group(107.93±14.79)s,but the difference between two groups was not statistically significant.The XPS group had a lower percentage of residual obturation volume(7.51±8.06)%compared to the RC group(15.02±14.63)%,but the difference was not statistically significant.The XPS group had significantly less apical debris extrusion(6.15±1.42)mg than the RC group(8.29±2.01)mg,with a statistically significant difference(P=0.002).Both groups exhibited varying degrees of instrument deformation,but yet no instrument separation occurred in either group.Conclusion·The RC engine-driven nickel-titanium files were slightly more time-efficient in removing root canal fillings,whereas the XPS files achieved a higher canal cleanliness and produced less apical debris extrusion.As there was no significant difference in removal time,and considering the superior cleaning performance and reduced risk of postoperative complications,the XPS file system appears more suitable for removing root canal fillings in moderately curved root canals.

Objective: To identify the characteristics including clinical features and pulmonary computed tomography (CT) features of heart failure and novel coronavirus pneumonia(COVID-19). Methods: This study was a retrospective study. A total of 7 patients with Heart failure and 12 patients with COVID-19 in the Second Xiangya Hospital of Central South University between December 1, 2019 and February 15, 2020 were enrolled. The baseline clinical and imaging features of the two groups were statistically analyzed. Results: There was no significant difference in age and sex between the two groups, but the incidence of epidemiological contact history, fever or respiratory symptoms in the COVID-19 group was significantly higher than that in the heart failure group (12/12 vs. 2/7, P=0.001; 12/12 vs. 4/7, P<0.001). While the proportion of cardiovascular diseases and impaired cardiac function was significantly less than that of the heart failure group(2/12 vs.7/7, P<0.001; 0/12 vs.7/7, P<0.001). For imaging features, both groups had ground-glass opacity and thickening of interlobular septum, but the ratio of central and gradient distribution was higher in patients with heart failure than that in patients with COVID-19 (4/7 vs. 1/12, P=0.04). In heart failure group, the ratio of the expansion of small pulmonary veins was also higher (3/7 vs. 0, P=0.013), and the lung lesions can be significantly improved after effective anti-heart failure treatment. Besides, there are more disease with rounded morphology in COVID-19 (9/12 vs. 2/7, P=0.048) . Conclusions More patients with COVID-19 have epidemiological history and fever or respiratory symptoms. There are significant differences in chest CT features, such as enlargement of pulmonary veins, lesions distribution and morphology between heart failure and COVID-19.