Motivational Interviewing (MI) has been included in dentistry programs. There exists a need for interventions in the mother-child dyad. The aim of this paper was to compare the effects of a MI-based educational program on oral care knowledge, attitudes, and practices (KAP) in the mother-child dyad to a Traditional Education-based program (TE). A community intervention trial was carried out. The experimental and control groups were made up of women between 18 and 45 years of age in the sixth month of gestation. Both groups were provided with TE. The experimental group additionally received a session based on the principles of the MI. Socio-demographic data, children’s oral health KAP (COHKAP), that of the mother (MOHKAP), and maternal self-efficacy (MSE) in relation to children’s oral health (COHMSE) were recorded. A baseline measurement was made, as well as a six-month follow up. The participants included 135 women with an average age of 24.88 ± 6.00. After intervention, the experimental group’s COHKAP, MOHKAP, and COHMSE all increased (p < 0.001). When MI-based interventions are combined with TE, MSE and dental care KAP for the mother-child dyad in pregnant women can be improved.