摘要： Background. Molar-incisor hypomineralisation (MIH) is a qualitative enamel defect. Aim. Investigate the low-level laser therapy (LLLT) associated with fluoride varnish for the desensitisation of teeth with MIH. Design. A randomised clinical trial was conducted with 66 children, randomly allocated to the treatments: laser (L); fluoride varnish (FV); and laser + fluoride varnish (L+FV). The participants in the L group underwent two sessions of LLLT (48-hour interval). The FV group received four applications of varnish at one-week intervals. The L+FV underwent two sessions of LLLT and four applications of varnish. Prior to each session and one month after the onset of treatment, tooth sensitivity and its magnitude were evaluated. Intra and inter-group comparisons were performed (α = 5%). Results. A significant reduction in the mean sensitivity score was found over time in all groups. After the final treatment, as significant difference was found between the L and L+FV group (p = 0.011), with a lower score in the L+FV group (0.09), whereas no difference was found between the FV and L+FV groups (p = 0.095). Conclusions. Fluoride varnish and the combination of treatments (L+FV) had greater desensitising action on teeth with MIH. Laser therapy demonstrated an immediate desensitising effect, whereas fluoride varnish had a late-onset effect.