Cochrane used more restrictive criteria for including studies in their analyses.
A consequence of their approach was that studies included in the Cochrane review were primarily conducted before1975
. As a result, Cochrane found insufficient information available to
determine if water fluoridation had an impact in an environment 
where fluoride products such as toothpaste are now widely used. Although valid, peer reviewed studies document the effectiveness of community water fluoridation in children and adults even after the use of fluoride toothpaste became widespread, these studies were not considered by Cochrane. CDC

I think the CDC review has a lot more credibility than Newsweak
.