The caries reduction benefits of water fluoridation to  primary teeth and permanent teeth  respectively -
Murray  reviewed  113  studies  conducted  in  23  countries to help clarify various reports on the benefits to primary teeth of communal water fluoridation.72  A thorough review of the data clearly showed that water fluoridation provides protection for primary teeth against dental caries but to a somewhat lesser degree for permanent teeth. The  caries  reduction  benefits  to  primary  teeth  ranged  between 40% and 50%, whereas the range for permanent teeth was between 50% and 60%.
10-30%, 30-50%
40-50%, 50-60%,
10-20%, 20-40%
50-70%, 60-80%