Up to six attempts, at different days and time slots, were made to reach the participant by phone to arrange the dental examination appointment. As problems contacting mothers were expected, the initial questionnaire asked for wide range of
contact information (home, work, mobile phone numbers, addresses and phone numbers of further contact persons). If these means were not successful, medical records served as another source of contact information. When a participant did not attend for the dental examination, a new appointment was arranged. The overall retention thorough to the examination was 70.6%, higher in the test group (74.4%) than in the control group (66.8%; Table 1).