Inclusion Criteria:  Patients aged :  A-minimum:4years B-maximum: 7 years old  Patients who are medically free Premature loss of bilateral primary molar. Sound and healthy buccal and lingual surfaces of selected primary molars.  Exclusion Criteria:  Children with dental abnormalities (cross bite, open bite, and deep bite). Parafunctional oral habits. Carious lingual and buccal surfaces of primary molars. Lack of patient/parent compliance and cooperation.