15) For some strange reason, the CDC does not correlate rates of tooth decay with water fluoridation. Separate from its tooth-decay data, the CDC posts the Fluoridation Status of all 50 states between 1992 and 2006. During this time, the percentage of the U.S. population "served by community water systems received optimally fluoridated water" increased by more than 11% (from 62.1% in 1992 to 69.2% in 2006.)
But tooth decay rates in preschool-age children increased by 16%: from 24% (data collected between 1988 and 1994) to 28% (between 1999 and 2004), per a CDC report cited by The Bulletin. ("Tooth decay on rise for kids across U.S., rampant in Central Oregon," May 6, 2007. [Note: "Rampant" turned out to be anecdotal scare tactics.])
During this decade in Oregon and Washington, increased rates of water fluoridation between 2000 and 2006 were also accompanied by increased cavity rates in children:
Oregon's water fluoridation rate increased 59% (from 17.2% to 27.4%). This was accompanied by an 11% increase in tooth decay for first to third graders (from 57% to 64%*). 2007 Oregon Smile Survey, page 9
*66.3% according to the CDC, as of January 4, 2011,
which means there was a 16% increase in tooth decay rates
from 2002 to 2008 in Oregon.
Rates for untreated tooth decay in Oregon increased by 60%:
from 22.1% in 2002 to 35.4% in 2007.
The good news: Kids in non-fluoridated Portland were nearly 23% less likely to have a cavity; had 43% less untreated tooth decay; and were 83% less likely to need urgent dental treatment. 2007 Oregon Smile Survey, page 12
Washington's water fluoridation rate increased 53% (from 41.0 to 62.9%). This was accompanied by a 5% increase in children's tooth decay (from 56 to 59%). Table 6 of the 2005 Smile Survey Summary
More bad news: Kids living in fluoridated King County had a nearly 7% increase in caries experience.
Thus, as previously shown by the CDC's most extensive study on the effectiveness of fluoridation (Brunelle & Carlos, 1990), more water fluoridation is associated with more tooth decay. (See Reference #5.)
Update August 2010: The CDC has published fluoridation stats for 2008. Most changes were minor: seven states increased fluoridation by 2-6 percentage points; six states decreased fluoridation by 2-6 percentage points.
The only large increase was California (from 27% in 2006 to 59% fluoridated in 2008). The biggest decreases were Kansas (from 65% to 45%), Louisiana (from 40% to 28%), and New Jersey (from 23% to 14%).
In 2008, the percentage of Americans receiving fluoridated water increased to 72.4%.