Physicochemical Properties of Curen® Filaments Versus Nylon Filaments in Toothbrush Bristles: An In Vitro Study.

Background Toothbrush manufacturers commonly use bristle materials such as nylon, polybutylene terephthalate, polypropylene, polyethylene terephthalate, boar hair, bamboo, carbon fiber, silicone, polylactic acid, or their modifications such as Curen. Nylon filaments have long been demonstrated to be durable and are widely used, but not much is known regarding the performance of Curen filaments compared to nylon filaments. This in vitro study compared the stiffness, abrasion potential, abrasion resistance, and bristle surface changes of Curen and nylon filaments. Methodology Ten specimens (five dry and five wet) each of Curaprox CS5460 toothbrushes featuring Curen filaments and those with nylon filaments were subjected to tensile strength and force-displacement analyses. Brushing simulation (1,000, 2,000, 3,000, and 5,000 cycles) was conducted using six freshly extracted central incisors (three specimens each for the Curen and nylon filament groups). Pre- and post-brushing simulation parameters included filament abrasion potential (atomic force microscopy of extracted tooth surface), filament abrasion resistance (field emission scanning electron microscopy), and bristle surface changes (stereomicroscopy and micro- and nano-computed tomography). Results Curen filaments exhibited lower tensile strengths (41.69 MPa [dry] and 35.18 MPa [wet]) than nylon filaments (321.56 MPa [dry] and 325.44 MPa [wet]), indicating that Curen filaments have lower abrasion potential (87% [dry] and 89% [wet]) and cause less mechanical wear of enamel, thereby resulting in a gentler cleaning experience compared to nylon filaments. Furthermore, the enamel surface roughness in the crown region decreased by 19.4% with the use of the Curen filaments, whereas it increased by 92.3% with the use of nylon filaments, indicating that Curen filaments are 72.84% less abrasive to enamel than nylon filaments. After 5,000 cycles of brushing simulation, Curen filaments showed 30% less splaying than nylon filaments, highlighting the longevity of Curen filaments up to six months of tooth brushing, which is twice the longevity of nylon filaments. There was a minimal decrease in height (12.0 mm to 11.95 mm, -0.4% change), an increase in top diameter (2.157 mm to 2.390 mm, 10.8% change), and a rise in base diameter (1.784 mm to 2.035 mm, 14% change) in the Curen filaments group. Taken together, these results indicate that Curen filaments are superior to nylon filaments as teeth-cleansing agents. Conclusion The findings of this in vitro analysis demonstrate the lower tensile strength and lesser abrasion potential of Curen filaments when compared with nylon filaments. Thus, Curen filaments cause fewer microscratches and abrasion of enamel when compared with nylon filaments, occurring due to day-to-day mechanical wear because of improper brushing technique. Furthermore, the lower tensile strength of Curen filaments provides greater flexibility, facilitating more effective cleaning of hard-to-reach areas compared to nylon filaments. Additionally, the lesser splaying of Curen filaments highlights their longevity, demonstrating that Curen filaments last twice as long as nylon filaments under regular brushing conditions. Based on these advantages, toothbrushes with Curen filaments should be a preferred choice over nylon filaments.