In Vitro Analysis of Enamel Abrasion Using a Novel Manual Nano-Bristle Toothbrush: An Atomic Force Microscopy Study

Introduction: To evaluate the enamel abrasion effects of soft, ultra-soft, and nano-bristle toothbrushes using atomic force microscopy (AFM) to guide toothbrush selection for optimal enamel preservation.

Methods: This in vitro study involved 45 extracted human teeth (central and lateral incisors), randomly assigned to three groups (n=15 each): Group I (nano-bristle), Group II (ultra-soft bristle), and Group III (soft bristle). Each specimen underwent 10,000 brushing cycles with a standardized 2 N force to simulate one year of brushing. A slurry of commercially available toothpaste mixed with saline was applied, and brushing was performed with a mechanical brushing simulator. AFM analysis measured enamel surface roughness before and after brushing.

Results: Nano-bristle toothbrushes caused a minimal increase in surface roughness (mean change: 4 nm; p = 0.001), significantly less than the increases seen with soft (mean change: 14.08 nm; p = 0.001) and ultra-soft (mean change: 14.86 nm; p = 0.001) bristle toothbrushes. AFM analysis confirmed that both soft and ultra-soft bristles caused greater enamel abrasion compared to nano-bristles, with no significant difference between soft and ultra-soft bristle groups.

Conclusion: Nano-bristle toothbrushes demonstrated the least enamel abrasion in this study, suggesting they may provide a gentle alternative for preserving enamel integrity.