Which crown wins? Comparing BioFlx with steel and zirconia

Dental Tribune International

Wed. 4. November 2026

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WARDHA, India: BioFlx, a flexible resin crown, is promoted as an aesthetic alternative to zirconia crowns restoring primary molars because it requires less preparation than zirconia, but its clinical performance is less well established. A randomised controlled trial by researchers in India has compared stainless steel and zirconia crowns with BioFlx to assess clinical performance and parental satisfaction. The findings suggest that meeting parental preferences for tooth-coloured crowns can involve different clinical trade-offs, depending on the material.

The study included 72 primary molars in 54 children requiring crowns after pulpectomy. The researchers randomly allocated teeth to the three crown groups and assessed clinical outcomes and parental satisfaction over 12 months.

Stainless steel crowns had the highest retention at 12 months, followed by zirconia crowns and then BioFlx crowns. The authors suggested that cement loss might have contributed to BioFlx failures.

Zirconia performed favourably on gingival health and plaque accumulation, demonstrating healthy gingiva throughout follow-up, and almost all the zirconia crowns were plaque-free at the final assessment. BioFlx had the least favourable plaque findings. However, wear of opposing teeth was recorded only in the zirconia cases.

Appearance ratings also separated the materials. Most parents in the zirconia and BioFlx groups were satisfied with crown colour, whereas most parents in the stainless steel group reported low satisfaction with its metallic appearance. Moreover, no staining was reported in the zirconia group.

The trial gives clinicians reason to discuss retention and plaque control when offering BioFlx as an alternative for primary molars. Stainless steel showed the strongest retention, zirconia achieved favourable aesthetic ratings and gingival findings but posed a wear concern, and BioFlx received positive aesthetic assessments but had the lowest retention and least favourable plaque result.

Other clinical research has produced mixed findings. A previous 12-month comparison found no statistically significant differences between BioFlx, zirconia and stainless steel in retention, plaque accumulation or gingival health. However, a separate trial reported less favourable gingival health with BioFlx than with steel. Longer follow-up is needed to establish how the differences in clinical outcomes affect crown performance through to exfoliation.

The study, titled “Clinical performance and parental satisfaction of Bioflx, zirconia and stainless steel crowns in primary molars: A randomized controlled trial,” was published on 10 October 2026 in BMC Oral Health, ahead of final publication.