Assessment of contamination on sterilised dental burs after being subjected to various pre-cleaning methods

OBJECTIVE: To determine the effectiveness of different pre-cleaning methods by determining frequency and site of contamination on the sterilised dental burs using Phloxine B dye. METHODS: The in-vitro experimental study was conducted from June to August 2017 at dental clinics of Aga Khan University Hospital Karachi. Diamond dental burs were selected and divided into two control and four test groups. The two control groups were classified as Negative (new burs) and Positive (used contaminated). The four test groups were classified as Manual (Group-1), Ultrasonic (Group-2), Manual + Enzyme (Group-3) and Manual + Ultrasonic (Group-4). Phloxine B dye was used to determine the contamination. The images of the burs were taken and enlarged at 15X before subjected to visual assessment. Association between contamination and pre-cleaning methods were determined. Data was analysed using SPSS version 22. RESULTS: A total of 210 burs were selected for the study which were divided in 6 groups of 35(16.66%) each. One (2.8%) bur in negative control group and all burs in positive control group showed contamination. In test groups, 27(77.1%), 29(82.8%), 27(77.1%) and 24(68.5%) burs showed contamination in groups 1, 2, 3 and 4, respectively. There was no association between type of pre-cleaning method with the frequency of contamination (p =0.57). The head of bur was the most frequently contaminated site (p \u3c 0.003). CONCLUSIONS: None of the pre-cleaning method was found to be effective. Head of bur was the most frequently contaminated site

Visual and microscopic evaluation of the surface alterations In the protaper files after single clinical use

BACKGROUND: Different studies have been conducted in which defects of Ni-Ti files were reported after multiple usages but limited data is available regarding the defects in the rotary Ni-Ti files subjected to single clinical use. The objective of this study was to determine the frequency of surface defects caused by fatigue in the rotary ProTaper files after single clinical use assessed with visual and microscopic examination methods. METHODS: A cross-sectional study was conducted in the dental clinics of The Aga Khan University Hospital, Karachi, Pakistan. A total of 189 ProTaper Ni-Ti files (after single clinical use in multi-rooted molars) were analysed visually and then under stereomicroscope at 10Χ magnification for surface defects (straightening, denting, bending, twisting, pitting and change in length). Chi Square test was used to determine association between type of file and type of defect. Spearman\u27s correlation test was used for determination of correlation between visual and microscopic examinations at 0.05 level of significance. RESULTS: 19% of files showed straightening on visual assessment as compared to 66.1% under microscopic examination. There was a statistically significant association between the file type and the straightening of file (p-value ≤0.001). A weak correlation existed between visual and microscopic examination for all the defects, except for the change in length. CONCLUSIONS: The defects of ProTapers files are best detected by the microscopic examination. Straightening is the most common defect observed visually and microscopically. The first shaping and first finishing files underwent significantly more surface defects than the rest of the rotary files in the series