There are certainly well demonstrated links with poor glucose control and poor dental health. There also appears to be a connection between periodontitis and other conditions such as nephropathy, heart attack and stroke. That said, it is probably not a good time to be asking for something from the Government which could be very expensive, especially when those on benefits may already qualify for assistance on income grounds
This forum is not, however, a campaigning body so cannot formulate a petition. Were a member of the forum to research and put together their own petition on http://epetitions.direct.gov.uk/index.html
then it may get the support of members of this forum, as well as others.
Hope this is of use