AbstractThe effect of reducing the abrasivity of toothpaste on dental caries was observed in a 3‐year clinical trial involving 1106 11–13‐year‐old Berkshire schoolchildren. The children were divided into three groups; Group 1 were allocated a low abrasivity paste containing 0.8% sodium monofluorophosphate, Group 2 a paste of conventional abrasivity also containing 0.8% sodium monofluorophosphate and Group 3 a low abrasivity non‐fluoride paste. After 3 years the net DMFS increments (clinical and radiographic scores combined) were 4.22 in Group 1, 4.72 in Group 2 and 6.43 in Group 3. The differences between Groups 1 and 3 and between Groups 2 and 3 were highly significant (P<0.001). The mean increment in Group 1 was lower than in Group 2 but did not reach statistical significance. Reducing the abrasivity of the toothpaste had no meaningful effect on the standard of oral hygiene and prevalence of gingivitis as measured by the Gingival and Plaqu