Motivational Predictors of Change in Oral Health: An Experimental Test of Self-Determination Theory

We tested the hypothesis that a psychosocial dental intervention formulated in terms of self-determination theory would increase patients’ perceived competence and autonomous motivation for dental care and would decrease their plaque and gingivitis over a seven month period, compared to standard dental treatment. We also tested a process model in which the intervention was expected to increase perceived dental competence and autonomous motivation, that they would be positively associated with oral health behaviors (i.e., brushing and flossing), which was expected to decrease plaque and, in turn, decrease gingivitis. We also examined whether: changes in perceived competence and autonomous motivationwouldmediate the effect of the intervention on dental-health behaviors; dental-health behaviors would mediate the links from changes in perceived competence and autonomous motivation to change in plaque; and change in plaque would mediate the relation of dental health behaviors to change in gingivitis. Finally, we examined the fit of the overall model with structural equation modelling. Results supported all predictions.