Evaluation of Microbial Profile in Dental Unit Waterlines and Assessment of Antimicrobial Efficacy of Two Treating Agents

The quality of water in a dental unit used for cooling and flushing the high and low speed handpiece, air/water syringes and the scalers is of considerable importance. The present study was carried out to enumerate and identify the microorganisms present in water samples collected from dental unit waterlines of different dental specialty clinics and to find out the efficacy of two treating agents in disinfecting dental unit waterlines. Study design: Sample included 70 dental unit waterlines from different speciality dental clinics which were checked for microbial contamination. From these dental units 40 units were randomly selected and divided into two groups of 20 each. Group A, treatment was done in 20 dental units with 0.2% Chlorhexidine gluconate solution and Group B, treatment was done in 20 dental units with 10% Povidone iodine solution and the reduction in the microbial levels were assessed. Five dental units were randomly selected and checked the microbial contamination using mineral water, sterile distilled water, fresh tap water as a water source in the dental unit reservoir bottles. Also from the test group, five from each group were checked for the duration of efficacy of treating agent for one week by analyzing the water samples collected on 3 ,5 and 7 day intervals. Results: Most of the identified microorganisms are Gram negative and pseudomonas predominating up to 98.59% of the total isolates. Usage of disinfectants 0.2% Chlorhexidine and 10% Povidone Iodine were found to be very effective in reducing the microbial contamination and 10% Povidone iodine was found to be more efficient (97.13%) and active for a period of 3 days and gradually loosing its efficacy by 7th day. No significant difference were found in microbial contamination of water samples collected from different water outlets such as handpiece outlets, air water syringe outlets, scaler lines. Conclusion: To continue maintaining the sterility of the Dental unit waterlines and to complete the infection control measures adopted in the dental clinics, suitable disinfectants like 0.2% Chlorhexidine on daily basis or 10% Povidone iodine on every 3rd day basis intermittently maintain the sterility of dental unit waterlines it is essential to have a good water source and an effective disinfectant.

Dental unit waterline, microbial profile, Povidone Iodine, Chlorhexidine

1. Continuing Dental Education Wing , Indian Dental Education ,Coimbatore .A handbook of Infectious Diseases 1997: 118

2. Blake GC. The incidence and control of bacterial infection in dental spray reservoirs. Brit Dent J; 196:413-416, 1996.

3. ADA Statement on Dental Unit Waterlines. JADA; 127: 185-186, 1996.

4. Mills SE. The dental unit waterline controversy: Defusing the myths, defining the solutions. JADA; 131:1427-41, 2000.

5. Montebugnoli LL, Dolci GG. A new chemical formulation for control of dental unit water line contamination: An ‘in vitro’ and clinical ‘study’ BMC Oral Health; 2:1-4, 2002.

6. Cobb CM, Martel CR, McKnight III SA, Pasley-Mowry C, Ferguson BL, Williams K. How does time- dependent dental unit waterline flushing affect planktonic bacteria levels? JDE; 66: 549–555, 2002.

7. Szymanska J. Bacterial contamination of water in dental unit reservoirs. Ann of Agric Environ Med; 14:137- 140, 2007.

8. AnanthaNarayan R, Panicker JCK. Textbook of Microbiology 4th edition, Orient Longmann; 45-48, 1994.

9. Pankhurst CL, Johnson NW, Woods RG. Microbial contamination of dental unit waterlines: the scientific argument. International Dental Journal; 48: 359-368, 1998.

10. Shearer BG. Biofilm and the dental office. JADA; 127: 181-89, 1996.

11. Barbeau J, Tanguay R, Faucher E, Avezard C, Trudel L, Cote L, Prevost AP. Multiparametric Analysis of Waterline Contamination in Dental Units. Applied and Environmental Microbiology; 62: 3954–59, 1996.

12. Franco FFS, Spratt D, Leao JC, Porter SR. Biofilm formation and control in dental unit waterlines. Biofilms; 2: 9–17, 2005.

13. Martin MV. The significance of the bacterial contamination of dental unit water systems. Brit Dent J; 163:152–154, 1987.

14. Murdoch-Kinch CA, Andrews NL, Atwan S, Jude R, Gleason MJ, Molinari JA. Comparison of dental water quality management procedures. JADA;128:1235-43,1997.

15. Noce L, Giovanni DD, Putnins EE. An Evaluation of Sampling and Laboratory Procedures for Determination of Heterotrophic Plate Counts in Dental Unit Waterlines. J Can Dent Assoc; 66: 262-269, 2000.

16. Walker JT, Bradshaw DJ, Fulford MR, Marsh PD. Microbiological Evaluation of a Range of Disinfectant Products To Control Mixed-Species Biofilm Contamination in a laboratory Model of a Dental Unit Water System. Applied and Environmental Microbiol; 69: 3327–32, 2003.

17. Stone ME, Kuehne JC, Cohen ME, Talbott JL, Scott JW. Effect of iodine on mercury concentrations in dental-unit wastewater. Dent Mat; 22: 119–124, 2006.

18. Mills SE, Lauderdale PW, Mayhew RB. Reduction of microbial contamination in dental units with Povidone–iodine 10%. JADA; 113: 280–284, 1986.

19. Porteous NB, Cooley RL. Reduction of bacterial levels in dental unit waterlines. Quintessence Int; 35: 630-633, 2004.

20. Kettering JD, Stephens JA, Munoz-Viveros CA, Naylor WP. Reducing Bacterial Counts in Dental Unit Waterlines: Tap Water vs. Distilled Water. J Contemporary Dent Pract; 3: 1–9, 2002.

21. Szymanska J. Electron microscopic examination of dental unit waterlines biofilm. Ann Agric Environ Med; 12: 295-298, 2005.

22. Al- Hiyasat AS, Ma’ayeh SY, Hindiyeh MY, Khader YS. The presence of Pseudomonas aeruginosa in the dental unit waterline system of teaching clinics. Int J Dent Hygiene; 5: 36–44, 2007.