22 NZ studies In neither of these two NZ studies was there any attempt to control for the possible delayed eruption of teeth in F communities In neither of these two NZ studies was there any attempt to control for the possible delayed eruption of teeth in F communities Even so the best result indicates a saving of ONLY 0.5 of a single permanent tooth surface Even so the best result indicates a saving of ONLY 0.5 of a single permanent tooth surface There are either 4 or 5 surfaces to a tooth.