Changes in the Bristle Stiffness of Polybutylene Terephthalate Manual Toothbrushes over 3 Months: A Randomized Controlled Trial

Abstract

We previously reported that polybutylene terephthalate (PBT) toothbrushes become less effective for plaque removal after two months of use. However, it remains unknown how the bristle stiffness of PBT toothbrushes changes after several months of use. We performed a single-center randomized controlled trial to evaluate the bristle stiffness and bristle splaying of soft and medium manual toothbrushes among dental and medical students of Hiroshima University. Subjects were 80 participants who met the criteria. Participants were randomly assigned to the soft toothbrush group (n = 40) or the medium toothbrush group (n = 40). We collected toothbrushes immediately after first use (T0), after one month of use (T1), after two months of use (T2), and after three months of use (T3). Bristle stiffness was measured according to the International Organization for Standardization (ISO) 22254. The mean bristle stiffness (N/cm2) of soft and medium toothbrushes was significantly lower at T2 and T3 than at T0 (T2 vs. T0, soft; 3.63 vs. 3.89, P < 0.01 and medium; 4.33 vs. 4.52, P < 0.05, respectively, and T3 vs. T0, 3.62 vs. 3.89, p < 0.01 and 4.18 vs. 4.52, p < 0.001, respectively). Bristle stiffness was significantly reduced in soft and medium PBT toothbrushes after two months of use.

Analysis of the Deflection, Bristle Splaying, and Abrasion of a Single Tuft of a Polybutylene Terephthalate Toothbrush after Use: A Randomized Controlled Trial

“…ISO has specified a test method for measuring the resistance to deflection of the tufted portion of a conventional manual toothbrush [ 5 ]. In a previous study, we assessed the resistance to deflection of a PBT toothbrush in accordance with the ISO 22254 test method [ 6 ]. In this study, we found that the deflection of a single tuft of a PBT toothbrush can be measured using a soft-material bending-resistance tester.…”

“…The bristle stiffness of a toothbrush is associated with safe and effective toothbrushing [ 18 , 19 ]. In a recent study, we found that the bristle stiffness of a PBT toothbrush significantly decreased 2 months after use [ 6 ]. The bristle stiffness of a PBT toothbrush gradually decreased with use [ 6 ].…”

“…In a recent study, we found that the bristle stiffness of a PBT toothbrush significantly decreased 2 months after use [ 6 ]. The bristle stiffness of a PBT toothbrush gradually decreased with use [ 6 ]. In this study, the deflection of the top–middle tuft increased more rapidly compared with that of the bottom–middle tuft for a PBT toothbrush with medium stiffness.…”

“…PBT is a polyester-based thermoplastic material with low moisture absorption [ 4 ], and it is therefore used for wet applications, such as toothbrushes. Additionally, the results of the International Organization for Standardization (ISO) 22254 test [ 5 ] have revealed that the bristle stiffness of PBT toothbrushes with soft stiffness and medium stiffness significantly decreases after 2 months of use [ 6 ]. These results suggest that a PBT toothbrush should be replaced approximately every 2 months because of deteriorating bristles, as well as decreased plaque removal efficacy.…”

Prevalence of oral Capnocytophaga species and their association with dental plaque accumulation and periodontal inflammation in middle‑aged and older people

“…Periodontitis is a common infectious disease caused by periodontopathic bacteria with dysbiosis of the oral microbiota (1) and is associated with systemic diseases such as diabetes, cardiovascular disease and adverse pregnancy outcomes (2). For prevention of periodontitis, daily toothbrushing , flossing between teeth, promotion of oral hygiene, professional dental care and regular replacement of toothbrushes to avoid bristle splaying and softening are required (2)(3)(4)(5). Among periodontopathic bacteria, 'red complex' bacteria such as Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola are major pathogens for chronic periodontitis (6).…”