Clinical performance of Bioflx versus stainless steel crowns in primary mandibular second molars: a randomized controlled trial

Preformed crowns are widely recommended for restoring endodontically treated primary molars due to their durability and full coronal coverage. Stainless steel crowns (SSCs) remain the gold standard; however, increasing esthetic demands have led to the development of alternatives such as Bioflx crowns. This study aimed to compare the clinical and radiographic performance of stainless steel crowns and Bioflx crowns in mandibular second primary molars over a 12-month follow-up period. This randomized controlled trial was conducted in the Department of Pediatric and Preventive Dentistry, A.B. Shetty Memorial Institute of Dental Sciences, Mangalore. Sixty-eight endodontically treated mandibular second primary molars in children aged 3–8 years were randomly allocated into two groups ( n = 34 each). Group I received stainless steel crowns, while Group II received Bioflx crowns. Randomization was performed using the Sequentially Numbered Opaque Sealed Envelopes (SNOSE) method. Clinical and radiographic parameters were evaluated at baseline, 3, 6, and 12 months. Statistical analysis was performed using Stata version 18 with significance set at p < 0.05. Both crown types demonstrated satisfactory occlusal harmony, absence of opposing tooth wear, and stable temporomandibular joint function throughout the study period. Radiographic findings showed no significant differences between the groups. However, stainless steel crowns exhibited superior morphologic stability and improved gingival health at the 12-month follow-up compared with Bioflx crowns. While Bioflx crowns provide improved esthetics with acceptable functional and radiographic outcomes, stainless steel crowns demonstrate superior long-term morphologic stability and gingival response. Bioflx crowns may serve as an esthetic alternative for restoring primary molars, although further long-term studies are required to confirm their durability. The trial was registered with the Clinical Trial Registry of India (CTRI/2024/06/069660) on 2024-06-28.