The limited effect of conventional fluoridated formulations on preventing erosive tooth wear has stimulated the search for alternatives to enhance the protective effects of fluoride products have been proposed, including the addition of phosphates, such as sodium trimetaphosphate (TMP). Previous studies demonstrated a synergistic effect of fluoride (F) and TMP on enamel erosive wear, in which low-F formulations containing TMP were shown to promote similar or superior protective effects compared with their counterparts containing twice as much F (Danelon et al., 2018, Freire et al., 2016, Manarelli et al., 2011, Moretto et al., 2013, Pancote et al., 2014).

Considering the widespread use of F gels in clinical practice, as well as their potential for acute toxicity, especially when applied to young children without appropriate safety measures (Whitford, 2011), emphasizes the need for formulations with lower F content while maintaining its preventive and therapeutic effects. In this sense, low-F gels containing TMP were shown to be more effective on enamel erosive wear than its TMP-free counterpart ( Pancote et al., 2014), and such effects were further enhanced by the use of nanoparticles (Capalbo et al., 2020). Despite promising, these results cannot be directly extrapolated to dentin erosive wear, due to its lower mineral content, structural arrangement, and the existence of an organic matrix (Lussi & Carvalho, 2015), both of which could interfere with the mechanisms by which TMP acts in acid resistance. Thus, this study assessed the effects of low-fluoride gels supplemented with micrometric or nano-sized TMP on dentin erosive wear in vitro. The study’s null hypotheses were that (1) dentin erosive wear and (2) dentin mineral content would not be affected by the addition of TMP, regardless of the particle size.