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Authors

Popovic J, Gasic J, Zivkovic S, Petrovic A, Radicevic G

Year

2010

Title

IEvaluation of biological debris on endodontic instruments after cleaning and sterilization procedures

Reference

International Endodontic Journal 43(4):336−41

Findings:

The methods used to clean endodontic instruments are generally ineffective at removing biological debris

Abstract

Aim: To examine the presence of biological debris and the level of contamination on reusable endodontic instruments those were subjected to different cleaning methods prior to sterilization. Methodology: One hundred and eighty endodontic instruments from eighteen dental practices were analysed. These practices used different decontamination protocols for reusable instruments. The presence of organic debris was detected by the use of Van Gieson's stain. Forty-eight new stainless steel hand instruments were used as controls. The samples were examined by light microscopy. Results: Residual biological debris was observed in 96% of the samples. The mean value of maximum biological contamination was 34% in the group in which the instruments were brushed manually and immersed in alcohol, 25% in the group in which commercially available disinfectants were used and 5% in the group in which the instruments were cleaned ultrasonically. There was a statistically significant difference in the mean values with respect to the cleaning protocol applied (P < 0.001). Conclusions: The methods used to clean endodontic instruments appear to be generally ineffective for the removal of biological debris. The best method was the one that included mechanical, chemical and ultrasonic cleaning of instruments.

Authors

Walker JT, Dickinson J, Sutton JM, Raven NDH, Marsh PD

Year

2007

Title

Cleanability of dental instruments - implications of residual protein and risks from Creutzfeldt-Jakob disease

Reference

British Dental Journal 203(7):395−401

Findings:

Dental instruments that are difficult to clean are frequently contaminated after routine reprocessing and cannot be excluded as a potential transmission risk for infectious agents, including prions

Abstract

Cleaning of dental instruments is the first line of control in reducing the adherent bioburden. The threat of vCJD and the difficulty in removing prion protein has provided a new challenge for cleaning surgical and dental instruments. Prion proteins are also more resistant to many disinfection and sterilisation techniques. A number of different methods are currently available in primary care for cleaning instruments including manual washing, ultrasonic cleaners and washer disinfectors. Manual cleaning of dental instruments is time-consuming, introduces operator error and the risk of puncture wounds, is not reproducible and does not completely remove debris from instruments. Ultrasonic baths are significantly more effective than hand cleaning alone and are currently used by the majority of dental surgeries (often as an adjunct to manual cleaning). Automated washer-disinfectors appear to provide a validated, reliable and reproducible procedure for disinfection and sterilisation of dental instruments to ensure both the safety of patients and dental staff. Dental instruments that are difficult to clean are frequently contaminated with tissue debris after routine reprocessing and cannot be excluded as a potential transmission risk for infectious agents, including prions. The transmission of vCJD via dentistry is considered to be low risk, however, the Department of Health (DoH) has recently advised dentists to ensure that endodontic reamers and files are treated as single-use as a precautionary basis in order to further reduce any risk of vCJD transmission.

Authors

Smith A, Letters S, Lange A, Perrett D, McHugh S, Bagg J

Year

2005

Title

Residual protein levels on reprocessed dental instruments

Reference

Journal of Hospital Infection 61(3):237−41

Findings:

The cleaning of some instruments reprocessed routinely in primary care was incomplete; such instruments cannot be excluded as a potential source of cross-infection

Abstract

Reduction of the initial bioburden on instruments, prior to sterilization, is believed to reduce transmission risks of iatrogenic Creutzfeldt-Jakob disease. Endodontic files are used in the preparation of root canals and are likely to have close contact and become contaminated with neural material from branches of the maxillary and mandibular cranial nerves. This study examined methods used by 22 dental practices to clean endodontic files, and scored visible debris and residual protein levels adhering to 220 dental endodontic files that had been used, cleaned, autoclaved and were deemed ready for re-use. Visible debris was scored after examination under a dissecting light microscope. Residual protein was quantified using a fluorescent assay based on reaction of proteins with o-phthaldialdehyde/N-acetyl cysteine. There was wide variation in the methods used by practices to clean endodontic files. The cleaning process varied from a wipe with an alcohol-impregnated cloth to hand scrubbing and/or use of an ultrasonic bath. Surface debris was visually detected on 98% of files. Residual protein was detected on all the files examined (median amount: 5.4 μg; range: 0.5-63.2 μg). These results demonstrate that the cleaning of some instruments reprocessed routinely in primary care is incomplete, and such instruments cannot be excluded as a potential source of cross-infection.

Authors

Linsuwanont P, Parashos P, Messer HH

Year

2004

Title

Cleaning of rotary nickel-titanium endodontic instruments

Reference

International Endodontic Journal 37(1):19−28

Findings:

Complete removal of organic debris from contaminated rotary instruments was feasible but only with meticulous attention to detail

Abstract

AIM: To develop and evaluate an effective cleaning procedure for rotary nickel-titanium (NiTi) endodontic instruments. METHODOLOGY: New rotary instruments (ProFile size 25/.04) were contaminated by preparing canals of extracted teeth. Three factors were evaluated to develop an effective cleaning sequence: dry or moist storage before cleaning; mechanical removal (brushing); and chemical dissolution in 1% NaOCl with ultrasonication. Debris on flutes was scored after staining in situ with Van Gieson's solution at x45 magnification. Debris was classified as stained or unstained particulate debris and organic film, and rated as none, slight, moderate or heavy. The effectiveness of a recommended cleaning sequence was tested on different instrument types and in private endodontic practices. RESULTS: All new instruments showed metallic spurs and fine particulate debris on the surfaces. After contamination, brushing alone removed most particulate debris, but did not remove organic film. NaOCl effectively removed organic film. Under laboratory conditions, the sequential cleaning procedures (moist storage, brushing followed by immersion in 1% NaOCl and ultrasonic cleaning) totally removed organic debris. Dry storage before cleaning or autoclaving with debris present reduced cleaning effectiveness (P<0.001, one-way ANOVA). In three private practices, the cleaning protocol substantially reduced biological contamination, but complete cleaning was not always achieved (87% clean). CONCLUSION: Complete removal of organic debris from instruments is feasible using a combination of mechanical removal and chemical dissolution, but requires meticulous attention to details.