Objective: To compare root canal transportation and centering ability of TF Adaptive (TFA), Reciproc (R) and Pro Taper Next (PTN) . Methods: 30 single rooted premolars extracted from orthodontic treatment were randomly divided into 3 groups (n = 10) and prepare by TFA, R and PTN Respectively. The teeth were scanned by Micro-CT before and after instrumentation. The images were reconstructed and exported to Adobe Photo-shop software for analysis. Canal transportation and centering change were determined accordingly. SPSS19. 0 software was used to analyze the data. Results: There was no statistical difference in canal transportation and centering ability for coronal and middle root canal among the 3 groups (P＞ 0. 05) ; for root apical, the canal transportation in group TFA was the smallest, followed by PTN group, that of group R was the largest (between each 2 groups, P ＜ 0. 05), the centering ability of TFA group was the best, followed PTN group, that of group R was the last (between each 2 groups, P ＜ 0. 05) . Conclusion:TFA Ni-Ti instrument is superior to Reciproc and Pro Taper Next for the maintenance of the original orientation of the root canal in root canal preparation.

OBJECTIVETo compare the bactericidal efficacy of two different cold plasma (glow discharge and dielectric barrier discharge) treatments on root canal infected with Enterococcus faecalis biofilms in vitro.

METHODSOne hundred and twenty teeth infected with Enterococcus faecalis biofilm in the roots for seven days were divided into twelve groups randomly. Two served as negative control group (gas only, no discharge). Five were teeth treated by dielectric barrier discharge cold plasma and the other five were treated by glow discharge cold plasma. The treatment time in each five groups was 2, 4, 6, 8 and 10 min, respectively. The disinfection of Enterococcus faeccalis biofilm was evaluated by colony forming unit (CFU) counting. The plasma component produced by different devices was analyzed by optical emission spectroscopy (OES).

RESULTSComparing the two plasma treatments, the plasma produced by dielectric barrier discharge had better bactericidal effect than that produced by glow discharge at different treatment time (P < 0.05). The advantage was obvious with the time getting longer. The OES indicated that active components of the two type plasmas were similar. But the peak of excited Ar atom of dielectric barrier discharge was twice as that of glow discharge.

CONCLUSIONThe cold plasma produced by dielectric barrier discharge has more bactericidal efficiency in the treatment of root canal infected with Enterococcus faecalis biofilms.

Biofilms ; Dental Pulp Cavity ; Enterococcus faecalis ; Humans ; Plasma Gases ; Root Canal Therapy ; Sodium Hypochlorite