In vivo pilot study on toothbrush filament end-rounding and surface integrity using 360° microscopy

Area of Science:

• Materials Science
• Biomaterials Engineering
• Dental Hygiene

Background:

• Toothbrush filament wear affects cleaning efficacy and oral health.
• Understanding filament degradation is crucial for toothbrush design and consumer guidance.
• Existing studies often lack in-vivo data on long-term filament changes.

Purpose of the Study:

• To investigate the morphological changes and end-rounding quality of polyamide 6.12 (PA 6.12) toothbrush filaments during six months of regular use.
• To assess the presence and reduction of surface residues on toothbrush filaments over time.
• To evaluate the utility of 360° rotational microscopy for in-vivo filament analysis.

Main Methods:

• A pilot study involving ten adult participants using standardized manual toothbrushes twice daily.
• Filament tip sampling at baseline, 90, 180, and 360 brushing cycles.
• 360° rotational microscopy to analyze filament geometry, wear patterns, and surface residues.

Main Results:

• Acceptably rounded filaments decreased from 64% at baseline to 29% after 360 cycles.
• Surface residues significantly decreased from 87% (unused) to 17% (180 cycles) and 18% (360 cycles).
• Asymmetrical wear and angle-dependent damage were observed, often missed by static imaging.

Conclusions:

• Regular toothbrush use leads to significant filament tip wear and reduced rounding.
• New toothbrush filaments possess substantial residues, potentially from manufacturing or micro-plastic contamination.
• Rinsing new toothbrushes before first use is advisable.
• 360° rotational microscopy provides a precise method for longitudinal, in-vivo assessment of toothbrush filament condition.