Boyle, M.A., O’Donnell, M.J., Russell, R.J., Galvin, N., Swan, J., Coleman, D.C.

Objectives
Decontaminating dental chair unit (DCU) suction systems in a convenient, safe and effective manner is problematic. This study aimed to identify and quantify the extent of the problems using 25 DCUs, to methodically eliminate these problems and develop an efficient approach for reliable, effective, automated disinfection.

Methods
DCU suction system residual contamination by environmental and human-derived bacteria was evaluated by microbiological culture following standard aspiration disinfection with a quaternary ammonium disinfectant or, alternatively, a novel flooding approach to disinfection. Disinfection of multicomponent suction handpieces, assembled and disassembled, was also studied. A prototype manual and a novel automated suction tube cleaning system (STCS) were developed and tested, as were novel single component suction handpieces.

Results
Standard aspiration disinfection consistently failed to decontaminate DCU suction systems effectively. Semi-confluent bacterial growth (101-500 colony forming units [CFU] per culture plate) was recovered from up to 60% of suction filter housings, and from up to 19% of high and 37% of low volume suction hoses. Manual and automated flood disinfection of DCU suction systems reduced this dramatically (ranges for filter cage and high and low volume hoses of 0-22, 0-16 and 0-14CFU/plate, respectively) (P<0.0001). Multicomponent suction handpieces could not be adequately disinfected without prior removal and disassembly. Novel single component handpieces allowed their effective disinfection in situ using the STCS, which virtually eliminated contamination from the entire suction system.

Conclusion
Flood disinfection of DCU suction systems and single component handpieces radically improves disinfection efficacy and considerably reduces potential cross-infection and cross-contamination risks.

Clinical significance
DCU suction systems become heavily contaminated during use. Conventional disinfection does not adequately control this. Furthermore, multicomponent suction handpieces cannot be adequately disinfected without disassembly, which is costly in time, staff and resources. The automated STCS DCU suction disinfection system used with single component handpieces provides an effective solution.

J Dent 2015; 43 (10): 1268-1279.