The aim of this study was to investigate associations of health literacy (HL), general self-efficacy (GSE), and sociodemographic variables with non-adherence to dental treatment among Brazilian young adults. This is a cross-sectional study based on a cohort study of 248 young adults aged 19 to 25 years followed up in an earlier study. The participants completed the perceived general self-efficacy scale (GSE), a questionnaire on socioeconomic and demographic variables and were examined for oral conditions. HL was measured using the Brazilian version of the health literacy questionnaire (HLQ-Br), which provides nine individual scores based on an average of the items within each of the nine scales. Dental treatment adherence was evaluated as the decision of young adults to seek a dentist to finish the recommended restorative treatment for dental caries. The effects of HL domains on the adherence to dental treatment were analyzed by logistic regression and the effect was adjusted for sex, age, family income, paternal and maternal education, type of housing, and self-efficacy. The results of the adjusted analysis showed associations among young adults who did not adhere to dental treatment with lower self-efficacy levels, living in non-owner-occupied homes, and lower HL levels in almost all of the HL domains (p < 0.05). Only the HLQ6 domain "Ability to actively engage with healthcare providers" was not associated with the outcome (p>0.05). Adherence to dental treatment in primary care among young adults was associated with their general self-efficacy levels, socioeconomic characteristics, and individual's lower HL aspects.