ABSTRACT
Statement of the Problem: File fracture can interfere with cleaning and shaping of the canal and compromise periradicular healing. Autoclave sterilization may prone the files to fracture
Purpose: The purpose of the present study was to determine the effect of autoclave sterilization on the cyclic fatigue resistance of Hero642 rotary instrument in two curvatures of 45 and 60 degrees
Materials and Method: For this experimental in-vitro study, 90 Nickel-Titanium HERO 642 rotary files #30 with 0.06 taper were selected. They were divided into two groups [curvature of 45 and 60 degree] of 45 files. Each group was then subdivided into 3 subgroups; group I: no sterilization, group II: 5 cycles of sterilization and group III: 10 cycles of sterilization. Files were used in artificial canals until fracture. The cyclic fatigue was measured as the number of cycles before fracture. The data was statically analyzed by Student's t-test and two-way analysis of variance
Results: There was a significant difference in cyclic fatigue of two curvature of 45 and 60 degrees [p= 0.001]. However, sterilization process has no significant effect on cyclic fatigue of HERO files [p= 0.557]
Conclusion: Sterilization had no effect on the cyclic fatigue of HERO 642 files when used in curvature of 45 or 60 degrees
Subject(s)
Sterilization , In Vitro TechniquesABSTRACT
The production of smear layer during canal instrumentation is thought to increase coronal microleakage even after canal obturation. Previous studies have shown that the type of irrigant does not necessarily affect the seal of the obturation. Our study aimed to evaluate the effect of three irrigation solutions [MTAD, citric acid and EDTA/NaOCl] on the coronal microleakage of root canals. Fifty five intact single rooted teeth were instrumented and randomly divided into three experimental groups [15 teeth each] and two control groups [5 teeth each]. Final irrigation was carried out with MTAD in group I, citric acid in group II, and EDTA/NaOCl in group III. EDTA/NaOCl was used for the negative control group and saline irrigation was carried out in the positive control group. After lateral compaction with gutta-percha, the access cavities of the experimental specimens were restored with temporary restorative material. Temporary cement was not used in the positive control group. In the negative control group, access cavities and foramen apices were sealed with glass ionomer. Microleakage of samples was measured using the dye penetration technique. Data were analyzed with ANOVA and Tukey test to determine statistical differences between groups. MTAD, citric acid and EDTA/NaOCl all had less microleakage compared to normal saline. However, no difference was detected between the experimental groups. In this study, all three groups demonstrated effective seal with gutta-percha obturation. This is likely to be due to various factors including their ability to remove smear layer