Molar-incisor hypomineralization (MIH) is a condition associated with qualitative changes in enamel manifesting as white, yellow, cream, or brown opacities. At least one permanent molar is affected, usually in addition to the permanent incisors. While the specific cause of this condition remains unclear, it is likely the result of multiple factors that occur between the 20th week of in-utero development and the child's fourth year of life. A new theory termed "mineralization poisoning" was proposed, calling into question the earlier belief that systemic conditions are the cause. The epidemiological data on MIH are highly inconsistent. The global prevalence is estimated to be 14.2%, with it being at 13% in Croatia in 2020. Treatment options are dependent on the severity of the case. Treatments may be non-invasive, minimally invasive, or invasive. The non-invasive approach focuses on preventing progression of lesions and development of dental caries and includes oral hygiene instructions, nutrition recommendations, remineralization procedures, fissure sealing, and regular follow-ups every 3 to 6 months. The minimally invasive procedures aim to preserve as much healthy tooth tissue as possible and include tooth whitening, microabrasion, and infiltration technique. The invasive procedures, which should be used in the most severe cases, include restorative treatments, prosthetic replacements, extractions, and orthodontic therapy. The paper concludes with a presentation of the treatment using the infiltration technique.