Patent Application
20070267029
The following tables relate to the antimicrobial testing that was performed on prototypes of mouthpieces that include the use of micronized silver. The test method performed was ASTM E2180—Standard Method for Determining the Activity of Incorporated Antimicrobial Agent(s) in Polymeric or Hydrophobic Material. The ASTM method E2180 is the method used “to evaluate (quantatively) the effectiveness of agents incorporated or bound into or onto mainly flat (two dimensional) hydrophobic or polymeric surfaces”.
The test organisms utilized were Staphylococcus aureus ATCC 6538 and Pseudomonas aeruginosa ATCC 15442. Two separate agar slurries were prepared, one for each organism. The agar slurries contained 1 mL of the test organism (concentration=7.0×108 cells/mL). 0.85 g NaCl, 0.3 g agar, and 100 mL of deionized water. The final inoculum concentration was equal to ˜7.0×106 cells/mL.
All of the samples were prepared in triplicate and aseptically cut into twelve equally sized pieces. One mL of each agar slurry was applied to the prepared samples. Using both sonification and manual vortexing the agar slurry was immediately removed from one set of the control samples and plate counts were performed. The data recovered was designated as ‘0 hours’.
The remaining set of control samples and the treated material was incubated at 35° C. for 24 hours with the solidified agar slurry intact. The agar slurry was again removed and processed with sonication and vortexing. Plate counts were performed. The data retrieved from this set of samples was designated ‘24 hours’.
Calculation of ‘percent reduction’ compares the geometric mean of each time point data set with that of the relevant time point control. The results are shown in Table 1 below.
P. aeruginosa
S. aureus
P. aeruginosa
S. aureus
P. aeruginosa
S. aureus
The contol (#1) was for an untreated mouthpiece comprised of silicone rubber. Sample #2 was a separate mouthpiece manufactured using less than 3.5 grams of micronized silver mixed into the silicone rubber prior to injection molding. Sample #3 was another separate mouthpiece manufactured using as much as 3.5 grams of micronized silver mixed into the silicone rubber prior to injection molding. The silver was diluted with the silicone rubber part A used for injection molding. Part B of the silicone rubber used for silicone rubber molding did not have silver added. The micronized silver had been supplied in a tube which included a polysynthetic oil base, such as provided by Artic Silver. In other words, the concentration of micronized silver were significantly lower in sample #2 then in sample #3. One such manufactuer of micronized silver is Artic Silver. They produce micronized silver compounds contianing 99.9% silver including;
Artic Silver 5 that uses three unique shapes and sizes of pure silver particles to maximize particle-to-particle contact area and thermal transfer.
High-Density:
Arctic Silver 5 contains over 88% thermally Conductive filler by weight. In addition to micronized silver, Arctic Silver 5 also contains sub-micron zinc oxide, aluminum oxide and boron nitride particles. These thermally-enhanced ceramic particles improve the compound's performance and long-term stability.
Controlled Triple-Phase Viscosity:
Arctic Silver 5 does not contain any silicone. The suspension fluid is a proprietary mixture of advanced polysynthetic oils that work together to provide three distinctive functional phases. As it comes from the tube, Arctic Silver 5's consistency is engineered for easy application. During the CPU's initial use, the compound thins out to enhance the filling of the microscopic valleys and ensure the best physical contact between the heatsink and the CPU core. Then the compound thickens slightly over the next 50 to 200 hours of use to its final consistency designed for long-term stability.
(This should not be confused with conventional phase change pads that are pre-attached to many heatsinks. Those pads melt each time they get hot then re-solidify when they cool. The viscosity changes that Arctic Silver 5 goes through are much more subtle and ultimately much more effective.)
Not Electrically Conductive:
Arctic Silver 5 was formulated to conduct heat, not electricity. (While much safer than electrically conductive silver and copper greases, Arctic Silver 5 should be kept away from electrical traces, pins, and leads. While it is not electrically conductive, the compound is very slightly capacitive and could potentially cause problems if it bridges two close-proximity electrical paths.)
The product specification for this micronized silver are as follows:
Thermal Conductance:
>350,000W/m2 ° C. (0.001 inch layer)
Thermal Resistance:
<0.0045° C.-in2/Watt (0.001 inch layer)
Average Particle Size:
<0.49 microns <0.000020 inch
Extended Temperature Limits:
Peak: −50° C. to >180° C. Long-Term: −50° C. to 130° C.
Performance:
3 to 12 degrees centigrade lower CPU full load core temperatures than standard thermal compounds or thermal pads when measured with a calibrated thermal diode imbedded in the CPU core.
Table 2 shows the raw data for the triplicate counts for all three mouthpieces described above. It should be understood that these were prototype mouthpieces and that the distribution of the micronized silver was not controlled. Therefore, this initial test and manufacturing process provided surface areas where the silver was not evenly distributed, leading to large variability in bacteria counts. The trends, however, are unmistakable, in that the higher concentration of silver particles within the mouthpiece lead to significantly lower bacteria counts as shown in Tables 1 and 2.
P. aeruginosa
S. aureus
P. aeruginosa
S. aureus
This patent application claims priority to pending Provisional application No. 60/801,653 filed May 19, 2006; titled “ANTIMICROBIAL DENTAL APPLIANCES INCLUDING MOUTHGUARDS AND MOUTHPIECES”
| Number | Date | Country | |
|---|---|---|---|
| 60801653 | May 2006 | US | |
| 60814185 | Jun 2006 | US |
