Laboratory evaluation of the erosive potential of fluoride-free mouthwashes using a dental erosion simulation model

To investigate the enamel/dentin surface loss caused by acidic fluoride-free mouthwashes using dental erosion simulation model.

Enamel and dentin bovine slabs (n=8) were subjected to 5 days of treatment (four 1-minute mouthwash treatments/day). Six fluoride-free mouthwashes (MW1-MW6) with varying pH (3.03-5.12) were tested. Three 0.3% citric acid solutions (pH 3.0-5.0) and deionized water served as controls. Surface loss (SL) was measured using non-contact profilometry; enamel hardness was assessed via Knoop microhardness. Data was analyzed using one-way ANOVA.

For both substrates, the model was able to differentiate between the controls. Differences between PC5 and NC (0.06± 0.11/-0.13± 0.28) were only directional for enamel. SL ranged considerably between MW1-MW6; however, all were less erosive than PC3 in both substrates. In enamel, MW1 (0.20± 0.12), MW3 (-0.26± 0.29), and MW6 (0.01± 0.12) were not different from NC. MW4 (-0.48± 0.29) was not different from PC4 and PC5, whereas MW5 (-1.19± 0.59) was more erosive than PC5. The SL data for dentin were mostly comparable to enamel. In dentin, MW1 (-0.34± 0.30), MW3 (-0.68± 0.45), and MW6 (-0.79± 0.17) were also not different from NC. Some fluoride-free mouthwashes may cause dental hard tissue erosion, particularly in dentin. Erosive potential appeared to be influenced more by composition than by pH alone.

The findings highlight that mouthwash formulations significantly influence enamel and dentin surface loss, with acidity and specific ingredients playing a key role. Clinicians should exercise caution when recommending fluoride-free mouthwashes, especially to patients at risk of erosive tooth wear.