This study aims to evaluate and compare the preparation time required for Bioflx crowns versus zirconia crowns on primary molars through a randomized clinical trial.

• Primary Objective: To compare the preparation time required for Bioflex crowns and zirconia crowns on primary molars in pediatric patients.

• Secondary Objectives:

To evaluate the clinical performance of Bioflex crowns compared to zirconia crowns, including:

Retention, Patient Satisfaction, Parental Satisfaction, Occlusal Wear and Gingival Health.

the main question it aim to answer: Is there a significant difference in the preparation time required for Bioflx crowns compared to zirconia crowns in the primary molars of pediatric patients?

In pediatric dentistry, achieving efficient and aesthetic restoration of primary molars remains a significant challenge, particularly when treating young or anxious patients who may struggle with long or complex procedures. Zirconia crowns are widely used due to their durability, excellent biocompatibility, and natural tooth-like appearance, making them the gold standard for full-coverage aesthetic restorations in children. However, their placement involves extensive tooth preparation, which results in longer chair time and an increased risk of pulp exposure. These factors can negatively impact both treatment outcomes and patient behavior management.

Bioflex crowns have emerged as a potential alternative, offering a more flexible and user-friendly design that simplifies placement and reduces the amount of tooth preparation required. This may result in shorter procedure times and improved patient comfort. Despite these potential benefits, there is currently limited clinical evidence comparing the preparation time and efficiency of Bioflex crowns versus zirconia crowns for restoring primary molars.

This gap in knowledge makes it difficult for clinicians to make fully informed decisions about which crown system offers the best balance of procedural efficiency, aesthetics, and patient cooperation. By directly comparing Bioflex and zirconia crowns in terms of tooth preparation time and overall clinical practicality, the proposed study aims to determine whether Bioflex crowns provide a significant advantage in pediatric settings. The results could help identify the most time-efficient and effective restorative option for primary molars, ultimately improving care outcomes for pediatric patients.

Inclusion Criteria:

• Children aged between 4 and 8 years with a primary molar that needs to be covered by a crown.

Medically healthy children (ASA I or II according to the American Society of Anesthesiologists classification).

Children whose parent or guardian is willing to sign an informed consent.

Children whose parent or guardian are willing to comply with follow-up visits.

Frankl's positive and definitely positive patient.

Exclusion Criteria:

• Molars with severe structural loss that may compromise crown retention.

Children with poor oral hygiene that may contribute to higher plaque levels and affect the clinical outcomes of the crown restorations.

Children with a history of allergies; known allergies to dental local anesthesia or to the materials used in Biofix crowns.

Children with any systemic conditions or disabilities that may affect their ability to participate in the study.