1. Dental Water System Contamination, Control Methods and Monitoring
Dr. Raghunath Puttaiah
Dental-IDEAS LLC.

2. Introduction
Dental unit water systems not cleaned/disinfected regularly, treatment water heterotrophic counts exceeds 1 million cfu/mL
Salts & Mature biofilms contaminate the water system within weeks
Microorganisms could be pathogenic in such high doses
High doses of Endotoxins
Potential for infection and disease
Disinfection-by-products generated while cleaning

3. Biofilms, bacteria & fungi
Types of Contaminants
Inorganic salts (calcium, magnesium)
Biofilms, bacteria & fungi
Courtesy: USAF-DIS
Endotoxins
Trihalomethanes
EPA limits:
80 ppb
Identified:
8000 ppb
Courtesy: PALL Corp.

4. Biofilm Characteristics and Formation
Laser Scanning Confocal Microscopy
Waterline Surface
Formation of Biofilms over time
Week 3
Week 8
Week 10
Week 26
>10 years

5. Older the system, longer to clean
Clean line surface
4 – 6 weeks
8 weeks
This is what we need
Older the system, longer to clean
>10 years
10 weeks
26 weeks

6. Scanning Electron Microscopy
1500 X
Treatment 1
Treatment 2
Treatment 3
Controls
Baseline
Baseline
Baseline
Baseline
Overnight contact
Overnight contact
Overnight contact
Overnight contact
This is what we need
Post Study
Post Study
Post Study
Post Study

7. Potential for Morbidity and Mortality
Pseudomonas = Super-infections
Mycobacterium = Lung infections
Legionella = Lung and gut infection
Moraxella = Bacterial Endocarditis
Fungi = Fungal infections
Possible high risk patients
Neutropenic Patients
Post Radiotherapy
Uncontrolled Diabetes
Spina Bifida
Patients with certain Cancers
Patients with other Chronic Illnesses
Chronic nutritional deficiencies
Lack of Surveillance -
Morbidity????
Mortality ????

8. Evidence of disease risk
Fotos et. al; JDR 1985, 64(12):
20% of students & employees in dental
settings showed higher IgG antibodies to
Legionella than Controls
- Reinthaler et. al; JDR 1988, 67:
High prevalence (50%) of
antibodies to Legionella in dentists
Oppenheim et. al; Epidemiol & Infect
1987, 99:
Aerosols from dental units found to be the
source of sub-clinical infection with
L. pneumophila in a dental school
Atlas et. al; Appl & Env. Microbiol 1995;
61(4):
-68% of DUW samples from 28
dental clinics had Legionella
-61% of potable water from
domestic/institutional faucets had
at least one form of Legionella

9. Advances in Contamination Control

10. Basic Approach Towards Contamination Control
Block/plug all dead-legs
Clean the quick-disconnect channels and Scalers
Retrofit bottle systems or use inline system
Remove Existing biofilms-
Need to clean/post-flush multiple times with an approved biofilm control agent/cleaner
Follow Cleaner Manufacturer’s Instructions
Consult with Dental Unit Manufacturer for Compatibility

11. Self Contained Reservoirs for Introduction of Periodic Cleaner/Disinfectant

12. Periodic Cleaners and Disinfectants
Chlorine Dioxide
Sterilex Ultra

13. Dental Treatment Water or Irrigant
After initial cleaning
dental treatment water could—
-Be sterile
-Be filtered/germ free
-Be boiled
-Be pasteurized
-Be distilled
-Have low mineral
Content
-Have low endotoxin content
After initial cleaning
irrigant should--
- Be a biocompatible low grade germicide
- Be compatible with equipment
- Be compatible with composite bonding to enamel and dentin
- Not form disinfection-by-products

14. Irrigant Generating Devices
Sterisil
Dentapure

15. Devices to Improve Water Quality
BluTab
ICX

16. Corrosion

17. Corrosion
20 days
60 days

18. Corrosion-Elemental Metal Analysis

19. Irrigant Compatibility with Bonding
Adhesive failure
Cohesive failure
Double Blinded Studies better
Survival Analysis
Censored Data Analysis
Mixed failure

20. Monitoring of Microbial Quality
Screening Vs. Diagnostic tests
1. HPC Water Samplers (Millipore Inc.)
2. Aquasafe Samplers (Pall Corp.)
3. R2A Agar is the Gold Standard
The error rate of HPC samplers was >40% When compared to R2A (Puttaiah, et al, AADR 2001; Abstract JDR)
Significant decrease in detection by HPC and Aquasafe in comparison to R2A (Puttaiah, et al, AADR 2002; Abstract JDR) 1 2 3