The aim of this study was to investigate whether educational quality is associated with schools' potential support for oral health promotion in Brazil, using a multilevel model. An ecological study was carried out using data from 940 public schools (school level) from the 27 Brazilian state capitals (city-level). The explanatory variable was educational quality, measured by the Basic Education Development Index (IDEB) for each city, and the four dependent variables referred to the Oral Health Promotion School Environment (OHPSE) indicator and its dimensions: Dimension 1 (In-school aspects), Dimension 2 (Aspects of the school surroundings), and Dimension 3 (Prohibitive policies at school). The OHPSE was developed using categorical principal components analysis (CATPCA) of data from the 2015 National Adolescent School-Based Health Survey (PeNSE). Covariates were human development index and oral health care coverage of cities. Multilevel Poisson regression models with robust variance were undertaken (p < 0.05). Bivariate associations were found between the IDEB and each Total OHPSE and OHPSE-Dimension 1 (In-school aspects: sale of foods with added sugar and health promotion actions/programs). After adjustment, IDEB (PR: 1.38, 95%CI: 1.01-1.90; p = 0.045) and oral health care coverage (PR: 1.01; 95%CI: 1.00-1.02; p = 0.001) remained associated with the OHPSE Dimension 1. It was concluded that educational quality measured by the IDEB was associated with schools' potential support for oral health promotion regarding the sale of foods with added sugar and health promotion actions/programs in schools.