Zirconia Versus Lithium Di-silicate Overlays for Restoring Hypomineralized Molars Affected With MIH

Inclusion Criteria: * Children's age ranging from 10 to 15 years old. * Existence of large carious lesion in young permanent first molar teeth associated with weak cusps. * Signs of vital pulp without symptoms of pulpitis. * Presence of antagonists and adjacent teeth and occlusal contacts with good level of oral hygiene. * Children should be able to physically and psychologically tolerate conventional restorative procedures. Exclusion Criteria: * Children with poor oral hygiene and symptoms of pulpitis. * Children suffer from parafunctional habits. * Children with any debilitating systemic disorder.