ST LEONARDS, Australia/ DUNEDIN, New Zealand: Owing to their internal construction, air or water syringes commonly used in dentistry are generally prone to bacterial contamination. Using disposable rather than non-disposable syringe tips however could potentially decrease the risk of cross-infection between dental procedures, even when the latter kind have been thoroughly sterilised several consecutive times, researchers from New Zealand have reported in the latest issue of the Australian Dental Journal.

 Of 68 used non-disposable syringe tips tested for microbiological growth, almost 40 per cent were found to be harbouring different kinds of bacteria after having been sterilised with a Class B autoclave. According to the researchers, the level of contamination did not decrease significantly regardless of the number of additional sterilisation cycles the tips were run through. Flushing the instruments simultaneously with air and water before the cleaning and sterilisation processes also resulted in no difference to the level of contamination, they said.

While control tips of the disposable kind also showed contamination, the level was significantly lower.

The researchers suggested that one of the main reasons for the build-up of bacteria or contaminants in non-disposable tips could be corrosion facilitated by continuous exposure of the instruments to humidity during treatment, which increases the roughness of the surface, allowing potentially harmful micro-organisms to accumulate over time. While such micro-organisms might be harmless, the researchers recommend the use of disposable tips over non-disposable tips to reduce the risk of cross-infection.

For the study, new and used non-disposable syringe tips from the urgent care unit at the School of Dentistry of the University of Otago in Dunedin were investigated. The research was funded by ACTEON GROUP, a French manufacturer of dental equipment.