Score Criterion
F0 No demineralisation
F1 Demineralisation confined to the outer half of the enamel
F2 Demineralisation in the inner half of the enamel
3 Demineralisation broken enamel-dentine junction but without obvious spread in the dentine
F3 Demineralisation with obvious spread in the outer half of the dentine
F4 Demineralisation with obvious spread in the inner half of the dentine