الفهرس 
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Abstract
Dental HP is an important device popularly used in dental procedures for drilling, filling, cleaning, extraction, and examination of teeth. dental HP is considered “Narrow lumen double ended open space device.” not a simple hollow device. Dental HPs are very challenging to clean, inspect, and sterilize relative to its little size and length of lumens, sophisticated working components, and inability to be easily disassembled. So, after every patient, the HPs should be cleaned, and autoclave sterilized since surface disinfection or soaking in chemical germicides are both unacceptable methods. Also, the efficiency of sterilization and steam penetration of dental HP should be evaluated. The nature of the steam penetration test may be using BD test or helix test.
The aim of current study was to evaluate helix test versus BD test as a chemical indicator for assessment of sterilization of dental HP.
Five steam sterilizers with the same sterilization parameters were used to sterilize 50 dental HPs. In each sterilization cycle, the chamber of autoclave had contained BD test pack, Helix test and 2 dental HPs. water irrigation samples were collected from 25 dental HPs after its use and before sterilization. Also, water irrigation samples were collected from all the 50 HPs after sterilization. Water samples (10 ml each) were collected in sterile disposable falcon tubes. Water samples were immediately processed in centrifugation device, then 25 microliters were cultured from the precipitate for bacteriological examination on Blood Agar, Mannitol Salt Agar, MacConkey Agar, and Sabouraud Dextrose Agar. A subculture of grown colonies was done to identify the isolated micro-organism. Gram staining, standard bio-chemical reactions and VITEK 2 system were used to identify micro-organisms.
In current study, the isolated bacterial contaminants from 25 dental HPs after its use inside oral cavity and before sterilization were Streptococci spp., Staphylococcus aureus, Klebsiella spp., Acinetobacter lwoffii, Pseudomonas spp., Bacillus spp., and Cupriavidus pauculus.
One of the 5 tested autoclaves showed failure of the sterilization in many cycles regarding air removal using both helix test and BD test, so it was excluded from the study.
After sterilization cycles, BD test was successful (100%) to assess the sterilization and steam penetration of dental HP as confirmed by the absence of bacterial growth from all the 50 water irrigation samples taken from dental HPs after sterilization, while helix test showed discrepancy in its result as only 48% of the PCD tested showed sufficient air removal and 52% showed partially sufficient air removal and steam penetration in-spite of the negative results of bacterial culture after sterilization.