The aim of this study was to assess the effect in the enamel demineralization of low-intensity infrared laser (λ=810 nm, 100 mW/cm<sup>2</sup>, 90 sec, 4.47 J/cm<sup>2</sup>, 9 J) with or without photodynamic cream fluorinated or not fluorinated, using Optical Coherence Tomography (OCT). <i>Background data:</i> Lasers can be used as tools for the prevention of tooth enamel demineralization.<p> </p> All enamel specimens (n= 105) were analyzed using OCT at baseline, and randomly assigned into seven groups (<i>n</i>=15): C (+), laser application; C(-), no treatment; (F), acid fluoride gel; cream (IV); cream and neutral fluoride (IVF); cream and laser (IVL); and cream with neutral fluoride+ laser (IVFL). The specimens were submitted to all kind of treatments before demineralizing pH cycling challenge and were reanalyzed. <p> </p>ANOVA and Tukey's multiple comparative analysis (p <0.01) demonstrated a greater delta attenuation between baseline and post challenge for C + (0.034 ± 0.011) compared to IVF (0.016 ± 0.007) F (0.018 ± 0.010) IVFL (0.019 ± 0.008), and IVL (0.014 ± 0.010). The cream laser group (IVL) also showed lower delta (0.014 ± 0.010) compared to C - (0.025 ± 0.008). <p> </p>The OCT technique demonstrated that cream associated with laser showed the lowest quantitative enamel mineral looses after cariogenic challenge.