Investigation of antimicrobial and cutting efficiencies of rotary root canal files coated with silver ion surface coating

The aim of this study is to evaluate the feasibility of a developing surface coat both providing cleansing of the root canal file surfaces deteriorated with the sterilization process by eliminating the need for sterilization and also not affecting their clinical usage. Surface coat with 2 % Ag ion compound was found to eliminate 100 % of E. Faecalis (ATCC 29212) in 10 min. in a pilot study before coating the files and then it was applied to ProTaper Universal rotary root canal files. Three groups (Group I files coated in 50 mm/min, Group II files coated in 25 mm/min, Group III non-coated files) were constituted and cutting efficiencies and preparation durations were evaluated by calculating the weight loss caused by the files in transparent acrylic blocks. Each of 8file series per group were used in 5 resin blocks (one files serie consists S1, S2, Sx, F1, F2). Weight loss following preparation was calculated on a scale with 0,0001 g precision, and preparation duration with a cronometer in seconds. Surface evaluation was performed under x200, 500 and 1000 magnification of SEM images before and after preparation and section evaluation was performed in order to measure coat thickness under x3000 magnification. Statistical analysis of preparation duration and cutting efficiency was performed with one way ANOVA and post hoc Bonferroni tests. Preparation in Group I was found to be the most effective in removing material (p <.05). Statistically significant difference could not be found between Group II and the Group III (p >.05). All the groups demonstrated statistically significant difference in the analysis of preparation durations (p <.05) and the longest preparation was completed in Group II while preparation was completed later in group I compared with Group III. Both Group I and Group II demonstrated distinctive surface irregularities especially in the flute regions compared with Group III files. Application of this antimicrobial surface coating material seems to be promising in improving antibacterial effectiveness of the files during preparation and finding an alternative way to the sterilization of the files. Key Words: Nitinol, Sterilization, Scanning electron microscopy, Enterococcus faecalis, Microbial inactivation