Clinical and radiographic success of bioflex versus stainless steel crowns using the hall technique in primary molars: a 12-month randomized controlled trial

Abstract Background The present study evaluated and compared the clinical and radiographic success of BioFlex crowns (BFCs) versus stainless-steel crowns (SSCs) using Hall Technique (HT) in primary molars. Materials and methods This two-arm randomized controlled trial included 74 healthy children aged 4–6 years with ICDAS 3–5 carious mandibular second primary molars. Each child contributed one tooth and was randomly assigned (1:1) to receive BFCs or SSCs using the HT. Baseline examination, radiographs, plaque, and gingival indices were recorded. Crowns were cemented with resin-modified glass ionomer. Primary outcomes were clinical and radiographic success; secondary outcomes included plaque and gingival indices, child and parental satisfaction. Evaluations were performed up to 12 months. Results At 12 months, no statistically significant difference in success rates was detected between the groups (BFCs 91.9% vs. SSCs 94.6%; RR = 0.97, 95% CI: 0.86–1.10). SSCs had a higher gingival index at 1 week (MD = − 0.32, 95% CI: −0.56–−0.08). BFCs showed higher plaque at 6 months (MD = 0.30) and 12 months (MD = 0.41). Child satisfaction favored BFCs (MD = − 0.67), with greater parental satisfaction for color (MD = 1.73) and overall satisfaction (MD = 0.41). Conclusions BFCs are an esthetic alternative to SSCs when used with the HT. They showed no significant differences in short-term clinical success but higher child and parental satisfaction. However, perforation risk and greater plaque accumulation indicate the need for careful case selection and longer-term evaluation. Trial registration: The trial was registered in the clinicaltrials.gov registry (# NCT06847646).