A blinded randomized clinical trial will be conducted. The study will be conducted with children attending the Pediatric Dentistry Clinic of the Florence Institute's undergraduate course, in São Luís, Maranhão, Brazil. As inclusion criteria, children from 8 to 12 years of age will be adopted, with at least one first permanent or incisive erupted incisor (with occlusal / incisal surface free of gingiva) present in the oral cavity and presenting sensitive hypomineralization lesions. Exclusion criteria will be children with enamel malformations linked to syndromes, with dental fluorosis, enamel hypoplasia or with imperfect amelogenesis, teeth with loss of structure dental and carious lesions, children in orthodontic treatment, children with cognition problems, children who used any type of analgesic / anti-inflammatory medication before treatment, children undergoing desensitizing treatment in the last 3 months, children with behavioral problems and children with occlusal problems such as tightening and bruxism.

The instruments of data collection will be a general questionnaire (demographic, socioeconomic and etiological factors for HMI), clinical examination for diagnosis of HMI, dental sensitivity test with air syringe and visual analogue scale (to assess the magnitude of pain). In a clinical file will be recorded the teeth with HMI, the result of the sensitivity test and magnitude of dental pain before and after treatments. The general questionnaire will be answered by the parents / guardians. In cases of incomplete questionnaires, parents / guardians will be contacted by telephone.

The diagnosis of HMI will be performed according to the criteria proposed by the European Academy of Child Dentistry (WEERHEIJM et al., 2003). The researcher will be calibrated for the application of the questionnaire and for the diagnosis of HMI lesions.

The study groups will be: treatment with laser therapy (Group 1); treatment with fluorotherapy (Group 2) and treatment with laser therapy and fluorotherapy (Group 3). For the treatment of group 1, the low-power, infrared (808nm wavelength) diode laser with a power of 100mW will be used. The mode of irradiation is punctual, in contact and perpendicular to the dental surface. Three points on the crown of multiradicular teeth (mesial and distal of the cervical region and central part of the tooth lesion) and two points on the crown of unirradicular teeth (central point of the cervical region and central part of the tooth lesion) will be irradiated for 10s per point , 1J per point, with a 72-hour interval between treatment sessions. The distance between the irradiation points will be about 2 mm. The tip of the laser equipment will be positioned perpendicular to the application site. The treatment of Group 2 will be carried out with the application of fluoride varnish, with the aid of a microbrush. After the application, water will be dripped onto the applied varnish in order to promote its drying. Fluorotherapy will be performed once a week, totaling 4 sessions. Group 3 will be treated first with the laser (same specifications as Group 1), followed by application of fluoride varnish (same specifications as Group 2).