Vertical Dimension Changes After Bioflx vs Stainless Steel Crowns in Primary Molars

Early childhood caries commonly affects primary molars and often requires full-coverage restoration after pulp therapy. Stainless steel crowns are widely used because of their durability and clinical success, but they may have limitations related to esthetics and acceptance. Bioflx crowns are a more esthetic and flexible alternative, but there is limited evidence comparing their functional performance with stainless steel crowns.

This parallel randomized controlled trial will be conducted at the outpatient clinic of Pediatric Dentistry and Dental Public Health, Faculty of Dentistry, Cairo University, Egypt. A total of 18 children with pulp-treated primary molars will be enrolled and randomly allocated in a 1:1 ratio to receive either a Bioflx crown or a stainless steel crown.

The primary outcome is vertical dimension alteration measured in millimetres using a digital caliper. Secondary outcomes include mean biting force distribution measured by T-Scan digital occlusal analysis, parental satisfaction with esthetics, and parental satisfaction with treatment impact assessed by 5-point Likert scale questionnaires. Outcome measurements will be recorded at baseline, immediately after crown placement, at 1 week, and at 4 weeks, with parental satisfaction assessed at 4 weeks.

The purpose of this study is to determine whether Bioflx crowns provide comparable or improved functional and esthetic outcomes compared with stainless steel crowns in pulp-treated primary molars.

Inclusion criteria

• Pulp-treated primary molars (pulpotomy)

• Asymptomatic teeth after pulp therapy with no signs of infection, mobility, or radiographic pathology, such as internal resorption or periapical lesions
• Age 6 years to 9 years
• Male or female
• Cooperative child with positive Frankl behavior rating
• No missing teeth
• Normal occlusion, including normal overjet and overbite
• Free from systemic disease to allow continuity of follow-up

Exclusion criteria

• Medically compromised or uncooperative children

• Tooth indicated for extraction because of root resorption, teeth near exfoliation, or deep subgingival caries that prevents proper coronal seal
• Teeth with more than two-thirds root resorption
• Previous pulp therapy
• Parafunctional habits, including bruxism, thumb-sucking, or other habits that may affect occlusal force measurements
• Inability to attend follow-up visits or parental refusal to participate