Molar Incisor Hypomineralization (MIH) is enamel hypomineralization defined as qualitative defects caused by disruptions in either the calcification or maturation phases of amelogenesis affecting one or more first permanent molars (FPMs) and permanent incisors.

Conventional treatment for such defects necessitates additional removal of the complete tooth structure to receive full crowns that cause more biologically harmful consequences like postoperative hypersensitivity and aggressive tooth structure loss. To fulfill the biological criteria for tooth preparation, conservatism is the major notion and goal that prosthodontists strive to achieve. Nowadays, minimally invasive techniques are frequently employed to support this idea. To meet the growing need for conservative and attractive tooth restorations, overlay ceramic restorations (covering all cusps) are becoming more necessary. These restorations show satisfactory mechanics, restoring function, and esthetic with preserving tooth structure Since all materials used to treat such cases, have distinct chemical compositions, they have different properties that affect their clinical outcome. Therefore, it is essential to compare them clinically because any restoration's clinical outcome affects its long-term success. According to the null hypothesis, different materials would not significantly affect the clinical result of ceramic overlay restorations.

Patients in all groups will receive a minimally invasive restoration with high esthetic advantages (Protection of the weak cusps and elimination of carious lesions with an esthetic way out) and long-term success of their MIH affected young permanent molars (either IPS e.max CAD, Direct nanohybrid flowable composite or VITA Suprinity PC-Glass ceramic (zirconia) that require minimal preparation depends on the type of restoration will receive.

Inclusion Criteria:

1. 8-18 years old
2. Cooperative children with large carious First Permanent Molars (FPM) lesions associated with weak cusps and defected hypo-mineralized enamel.
3. Controlled dental disease - no active caries or periodontal diseases
4. Patients will be available to be clinically reviewed up to 1 year

Exclusion Criteria:

1. Patients with Symptoms of pulpitis.
2. Patients with uncontrolled active tooth decay or periodontal disease (i.e. 4+ mm probing depth and bleeding on probing).
3. Poor oral hygiene and motivation.
4. Patients with parafunctional habits (e.g., bruxism, biting on hard objects).
5. Patients with debilitating illnesses or complicating medical conditions