This study will be conducted to:
Evaluate and compare the clinical success, periodontal changes, and wear of antagonist teeth for three types of prefabricated crowns in primary molars: BioFlx crowns, Zirconia crowns, and Stainless Steel crowns.
Children who are free from any systemic disease.
Children with a carious lower primary molar indicated for crown restoration.
Teeth with an intact antagonist and neighboring primary molar.
Cooperative children with scores 1 and 2 (positive or definitely positive) according to Frankl's behavior rating scale.
Children with extremely poor oral hygiene.
Teeth showing radiographical furcation involvement or root resorption.
Children with para-functional habits, bruxism, or deep bite.
Teeth with inadequate non-restorable crown structure.