RESUMEN
The concept of self-efficacy (SE) was developed by BANDURA, in 1977. SE has been widely utilized in health care and has shown to be a powerful predictor in various domains of behavior such as in smoking cessation, weight control and participation in programs of disease prevention. This study investigated if a psychosocial intervention fosters improvements in clinical indices in patients who are about to receive dental treatment. It was predicted that the experimental group (EG) would show a greater progress as to plaque and bleeding clinical indices than the control group (CG), and SE would mediate that improvement. Besides the standardized dental procedures, the 30 participants from the EG received a psychosocial intervention based on the PROCHASKA; DiCLEMENTE'S model (1983). The 30 participants in the CG received only standardized dental procedures. The results revealed that the prevalence of scores 2 and 3 of the plaque and bleeding indices underwent a significant decrease in the EG, in relation to the CG (U = 97.00, p = 0.0001 and U = 179.00, p = 0.0001, respectively). Only the subjects from the EG presented a relevant increase of SE, considering the pre- and post-treatment periods (Z = -3.58, p < 0.0001). Yet, there was no difference between both groups as to the increase of SE between the pre- and post-testing periods. In short, the results showed that psychosocial intervention was effective and suggest that other factors besides SE may mediate a relevant improvement of clinical indices in the EG.