The purpose of this clinical trial was to compare clinically three different crowns for primary molars; stainless steel crown, zirconia crown and Bioflx crown.

the main questions it aims to answer are: is Bioflex crown is an alternative to stainless steel crown and zirconia crown? Seventy-five patients their age range between 3 and 8 years participated in this study. The participants are divided into three groups representing group A for stainless steel crown (n=25), group B for zirconia crown (n=25) and group C for Bioflx crown (n=25). Plaque index, crown retentivity and gingival index will be evaluated at evaluated at baseline, 6 and 12 months.

Inclusion Criteria:

• Patient within the age group of 3-8 years old.
• Healthy children free of any systemic disease.
• Pulpotomized or pulpectomized (endodontically treated) lower second primary molars.
• Patients who have the behavioral rating of definitely positive or positive according to the frankl behaviour.

Exclusion Criteria:

• • Patient younger than 3 years old or older than 8 years old.

  • non-Healthy children or have any systemic disease.
  • primary molars with no pulpal treatment
  • Patients who have the behavioral rating of definitely negative or negative according to the frankl behaviour.

We are currently reviewing the potential for sharing individual participant data (IPD) following the completion of the study. Factors such as data privacy, participant consent, and regulatory guidelines are being considered. A final decision on data sharing will be made at the conclusion of the study, and the IPD sharing plan will be updated accordingly