Aim: Dental-medical devices may transmit infections caused by bacteria that are usually found in water distribution systems, and which are difficult to treat and control. High bacterial contamination in the water systems of dental units is due to the presence of biofilm inside the pipes. Our study evaluated the efficacy of glutaraldehyde formulated with quarternary ammonium salts (Sanicide T4) examined in a previous study, employing a series of assays to confirm or otherwise the results obtained previously.
Methods: A purification protocol for the dental unit water system, together with a protocol for daily maintenance treatment, were tested on two dental units (in the Departments of Conservative and Prosthetic Dentistry) taking specimens from the turbine, micro-engine and air-water gun. The chemical substance, at a concentration of 20 cc per litre of water, was allowed to act when the department closed, for a total of 15 days. The Sanicide T4 was handled with protective gloves and the dental units were fitted with two safety devices to avoid accidental ingestion.
Results: Laboratory results enabled us to compare values for bacterial load at 36 degrees C and at 22 degrees C and for Pseudomonas aeruginosa, before and after applying the test protocol. Data obtained are satisfactory except for Pseudo-monas in the fountain in the Department of Conservative Dentistry; the value was in any case below the safety level set by the American Dental Association, confirming the results obtained in our previous study.
Conclusions: The two protocols may now be considered an excellent solution to control the development of biofilm. Should the product be found to be effective for a longer period of use, each dental unit should be provided with: an anti-reflux valve to stop accidental ingestion of disinfectant; a hydraulic mechanism to pump the product to the handpieces and other water supply devices; possibility of discriminating the use of the public water system from the use of that in the disinfectant circuit; an automatic mechanism whereby the disinfectant can be flushed out with drinking water every morning.