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In orthodontic treatment, brackets need to slide along the archwire to allow for alignment of the teeth. The lesser the friction between the bracket and the archwire, the easier it is to align the teeth and the lighter the forces required to make such movements. In recent years, patients’ esthetic demands have driven the field of orthodontics to find alternatives to conventional stainless steel bracket systems. While ceramic brackets meet the esthetic demands, their inferior frictional characteristics have always been an issue for orthodontists.The present in-vitro research study evaluates and compares the frictional resistance between various types of brackets, archwire materials and ligation methods. The purpose of the study was to equate the frictional resistance among 12 different groups using the universal testing machine, so as to recognize the factors involved in the in-vitro appraisal of resistance to sliding (RS) and inferring their clinical implications. In this study, 120 pre-adjusted edgewise upper central incisor brackets with MBT 0.022″ slot were used, which included 40 standard metal brackets, 40 ceramic brackets, 20 self-ligating metal brackets and 20 self-ligating ceramic brackets. 0.019″ x 0.025″ SS (stainless steel) archwires, esthetic archwires, Teflon-coated ligatures and conventional elastic modules to ligate the archwire to the brackets except in self-ligating brackets, were used. The average frictional resistance of Group A10 was the minimum succeeded by A9, A12, A4, A11, A8, A3, A7, A2, A6, A1 and A5. In the comparison of the mean frictional resistance of 12 different groups, the ANOVA test showed noticeably different frictional resistance amongst the groups (F=745.80, P< 0.001). Self-ligating metal bracket combinations with different archwires showed a significantly smaller magnitude of friction than self-ligating ceramic, metal and ceramic bracket combinations. Teflon-coated ligature combinations possess less friction in comparison with conventional elastomeric module combinations.

The purpose of the present study was to evaluate the effect of manual dynamic activation (MDA) with a master gutta-percha point on the smear layer removal efficacy of 17% ethylenediaminetetraacetic acid (EDTA) and SmearClear. Fifty freshly extracted human single-rooted teeth were prepared using ProTaper rotary system up to F3 size. The prepared teeth were divided into five groups on the basis of final irrigation received. Group A: 3% NaOCl solution (negative control group). Group B: 5 mL of 17% EDTA. Group C: 1 mL of 17% EDTA + MDA for 2 min + 4 mL of 17% EDTA rinse. Group D: 5 mL of SmearClear. Group E: 1 mL of SmearClear + MDA for 2 min + 4 mL of SmearClear rinse. Prepared samples were decoronated and then longitudinally split into two halves and evaluated under scanning electron microscope. Representative images at coronal, middle and apical third level were taken and scored for the amount of smear layer present, using a three-score system. The data were analysed through Kruskal-Wallis and Mann-Whitney U-test. The root canal surfaces of samples of group C and group E (where MDA was done) were significantly cleaner in apical third regions than those of group B and group D (P < 0.05).

The purpose of the present study was to evaluate the effect of manual dynamic activation (MDA) with a master gutta-percha point on the smear layer removal efficacy of 17% ethylenediaminetetraacetic acid (EDTA) and SmearClear. Fifty freshly extracted human single-rooted teeth were prepared using ProTaper rotary system up to F3 size. The prepared teeth were divided into five groups on the basis of final irrigation received. Group A: 3% NaOCl solution (negative control group). Group B: 5 mL of 17% EDTA. Group C: 1 mL of 17% EDTA + MDA for 2 min + 4 mL of 17% EDTA rinse. Group D: 5 mL of SmearClear. Group E: 1 mL of SmearClear + MDA for 2 min + 4 mL of SmearClear rinse. Prepared samples were decoronated and then longitudinally split into two halves and evaluated under scanning electron microscope. Representative images at coronal, middle and apical third level were taken and scored for the amount of smear layer present, using a three-score system. The data were analysed through Kruskal-Wallis and Mann-Whitney U-test. The root canal surfaces of samples of group C and group E (where MDA was done) were significantly cleaner in apical third regions than those of group B and group D (P 0.05).

Aim: To compare the effect of passive ultrasonic irrigation with manualdynamic irrigation on smear layer removal from root canals using a closedapex in vitro model.Methods: The root canals of 45 freshly-extracted human single-rooted mandib-ular premolar teeth were prepared by the Pro-Taper rotary system to an apicalpreparation of F4 size. Prepared teeth were randomly divided into threegroups; two experimental groups and one control group (n = 15) on the basisof the type of activation of final irrigation as follows: (a) Group A, 3% sodiumhypochlorite (NaOCl) and 17% ethylenediaminetetraacetic acid (EDTA), noactivation received; (b) Group B, 3% NaOCl and 17% EDTA, ultrasonic activa-tion with a small file; and (c) Group C, 3% NaOCl and 17% EDTA, manualactivation with a master gutta-percha point. The prepared teeth were decoro-nated and split into two halves longitudinally, and observed under a scanningelectron microscope to assess the removal of the smear layer.Results: In the apical-third region, the mean smear scores for groups B and Cwere significantly less than those of Group A (control group) (P < 0.05).Conclusion: Both activation techniques are important adjuncts in removing thesmear layer, with manual dynamic activation being a simpler, safer, and morecost-effective technique.IntroductionThe removal of the smear layer generated during mechan-ical instrumentation achieves complete debridement anddisinfection of the root canal system.