Introduction: In the year of 2013, the São Paulo State Council of Dentistry examined the fluoride level of the public supply water in 105 municipalities in the state of São Paulo. The results pointed out that 25,7% had suboptimal levels and that the samples had levels close to zero in nine (8.5%) of the towns, differentiating them from the policy's success in the rest of the state of São Paulo, in which population coverage reached approximately 90% in that time. Objectives: (a) to identify how the political and administrative characteristics of the Brazilian state influence in the implementation of public policies at local level; (b) to situate the municipal entity in the history of the water fluoridation policy in the state of São Paulo, considering the historical journey of the sanitation's policies; (c) to understand how streetlevel operators act concerning fluoridation policy in a region of the state of São Paulo. Methods: the research had three stages. The first one was developed through a bibliographic research, which summarized the theoretical aspects of the Brazilian federative state's trajectory. The municipal governments' autonomies and the relations between the federative entities were compared with the reflections from the studies about the local power and the public policies in the country, recovering essential elements for the understanding of the federalist system implemented in Brazil. In the second stage, the history of Brazilian sanitation system was analyzed with the objective of situating the fluoridation policy of water public supply in this context, also with the aim of understanding how the adopted model in the sanitation system influenced the policy implementation. During the third stage, an empirical research was undertaken in two pairs of towns selected from the mentioned study. They had less than 25 thousand inhabitants and belonged to the region of São José do Rio Preto. Each pair had a town in which the fluoride level was considered optimal and another in which the level was considered low. In-depth interviews were undertaken with 11 professionals involved with the policy implementation, three dental surgeons, one dental assistant, three technicians responsible for the operation of the water supply system, one administrative agent who conducted the oral health policy, two primary healthcare policy facilitators nurses and one member of the regional department of the Sanitary Surveillance participated. The data collected were complemented through interpretation provided by observations registered in the field diary. Results: The literature points out that the political framework of the Brazilian state, characterized by the power levelling among the three federative entities, can hamper the implementation of policies that require the cooperative action among the federal, state and municipal levels. The legal autonomy of the national subunits imply building of several power arrangements that should not be neglected when the implementation of a certain public policy is aimed. In the case o...