ABSTRACTThe effect of professional prophylaxis given each month to individual children was investigated. A total of 225 schoolchildren, 10–12 years of age, participated during the experimental year. Each prophylactic session required about 15 min, and included tooth‐brushing instructions, professional tooth cleansings and fluoride rinses. Significantly fewer new interproximal carious lesions were obtained in the experimental group compared with the control group. No differences were observed for occlusal, buccal or lingual surfaces. The frequency of gingivitis was significantly reduced during the year of trial in the experimental group. The efficacy of the preventive treatment was most noticeable in children with high caries experience. For clinical practice monthly prophylaxes could be recommended to the most susceptible individu