20 first permanent molars from children aged between 6 to 12 years old presenting MIH will be included. A calibrated pediatric dentist examined the selected teeth to classify MIH according to the European Academy of Pediatric Dentistry (EADP) criteria.

Intervention of Control: The restorative treatment using a total-etching adhesive system, which was performed according to the following operative sequence: prophylaxis, infiltrative anesthesia, rubber dam, application of 37.5% phosphoric acid to enamel (30 s) and dentine (15 s), extensive washing, drying with cotton and air jet (5 s), priming (5 s), light curing (20 s), restoration with composite resin (Filtek XT350), examination of occlusal contact, and final polishing.

20 first permanent molars from children aged between 6 to 12 years old presenting Molar Incisor Hypomineralization will be included. A calibrated pediatric dentist examined the selected teeth to classify MIH according to the EAPD criteria.

Intervention of test: the restorative treatment using a self-etching adhesive system, which was performed according to the following operative sequence: prophylaxis, infiltrative anesthesia, rubber dam, application of 37.5% phosphoric acid to enamel (30 s) and dentine (15 s), extensive washing, drying with cotton and air jet (5 s), priming (5 s), air jet (5 s), adhesive application (5 s), light curing (20 s), restoration with composite resin (Filtek XT350), examination of occlusal contact, and final polishing.

It was performed direct restoration using two kinds of adhesive system (total-etching adhesive and self-etching adhesive)