The Australian Dental Association has said: "Water fluoridation has been one of the most widely studied and endorsed public health measures of all time". The CSIRO and various Australian health departments all recommend fluoride treatment of water supplies continue.
There are conspiracy theorists who disagree, but their assertions are based around misinformation and fear-mongering. Those people can easily opt out of fluoride via buying bottled water or a home filtration system.
Please do not condemn the population (in particular the poorer households who have least access to dental treatment) of Cairns to poorer dental health due to the conspiracy theories of the vocal few ignorant people - please listen instead to medical experts.