Caries and periodontal disease are infectious diseases and dental unit water lines are frequently contaminated with microorganisms. Research and development of novel agents, safe for use in the host, and specific effective against oral pathogens are needed. Objective: To determine the optimal concentration of ClO2 effective in inhibiting caries organisms and major periodontal pathogens. Methods: Growth inhibition was tested by the tube dilution technique (conditions standardized and test agent present throughout entire incubation period). Increasing concentrations of ClO2 was prepared with the nutritional composition in all tubes exactly the same. Series were inoculated with standardized suspensions of Streptococcus mutans, Lactobacillus casei, Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, Prevotella intermedia, Tannerella forsythensis and Eikenella corrodens and incubated at 37oC for 48h in an anaerobic atmosphere created where necessary with Anaerocult A (Merck). Control tubes containing media only was included (not inoculated). After 48 hours growth in terms of turbidity was measured with a spectrophotometer at wavelength 540nm. All growth experiments were done in triplicate. Analysis of results was done by ANOVA (Statistics V8 software). Results: Growth of the different organisms are summarized as follow:
| Organisms |
Concentration ClO2 (% of concentrated tablet) (Significant inhibition indicated as SI) |
|||||||||
|
0 |
10 |
20 |
30 |
40 |
50 |
60 |
70 |
80 |
90 |
|
|
S. mutans |
0.763 |
0.875 |
0.895 |
1.034 |
0.413 (SI) |
0.137 |
0.022 |
0.002 |
0.001 |
0.017 |
|
L. casei |
0.601 |
0.600 |
0.560 |
0.171 (SI) |
0.099 |
0.023 |
0.011 |
0.000 |
0.012 |
0.007 |
|
P. gingivalis |
1.151 |
1.184 |
0.042 (SI) |
0.095 |
0.033 |
0.000 |
0.031 |
0.018 |
0.013 |
0.000 |
|
A. actinomycetemcomitans |
0.305 |
1.218 |
1.086 |
0.188 |
0.281 |
0.005 (SI) |
0.014 |
0.000 |
0.011 |
0.009 |
| P. intermedia |
0.521 |
1.337 |
0.015 (SI) |
0.049 |
0.020 |
0.042 |
0.059 |
0.000 |
0.009 |
0.006 |
|
T. forsythensis |
1.248 |
1.213 |
0.672 (SI) |
0.786 |
0.568 |
0.000 |
0.022 |
0.025 |
0.017 |
0.035 |
|
E. corrodens |
0.211 |
0.168 |
0.216 |
0.121 (SI) |
0.018 |
0.000 |
0.013 |
0.006 |
0.014 |
0.020 |