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813 Development of novel toothbrush to prevent a penetrating injury of children
  1. Yoshifumi Nishida1,2,
  2. Koji Kitamura1,2,
  3. Mikiko Oono1,2,
  4. Tachio Takano1,
  5. Tatsuhiro Yamanaka1,2,3
  1. 1National Institute of Advanced Industrial Science and Technology, Japan
  2. 2Safe Kids Japan, Japan
  3. 3Ryokuen Children’s Clinic, Japan


Background Brushing teeth is an important hygiene practice in our lives. However, this practice sometimes causes a serious injury for children. According to a report from Tokyo Fire Department, Japan, 45 children under 5 on average admitted an emergency room by ambulance annually because of a penetrating injury by a toothbrush. A half of the cases occurred in 1 year old, and 75% of all cases occurred either in 1 or 2 years old. It is necessary to design a new innovative product which promotes children’s self-reliance and prevent injury. The purpose of this study was to measure a force inside a mouth when a child brushes his or her teeth and fell down and to design a new product which can prevent a serious oral injury caused by fall.

Methods We developed a device to measure the force when a child falls while brushing teeth. A 2.65 kg weight which was the average weight of a child head was attached to a tip of toothbrush and let it fall from a height of 50 cm. We put a piece of chicken meat under the toothbrush and then observed what happened to the meat. We used the chicken meat assuming inside of a mouth.

Results When the toothbrush with 2.65 kg weight was dropped, the maximum pressure in the toothbrush was about 15.6 MPa. Previous research clarified that the breaking stress of human skin is 3 to 15 MPa, and so this pressure is large enough to penetrate human skin.

Conclusions Based on our previous study, the time to fall is in only 0.5 second. A serious injury occurred in such short period of time. We collaborated with a corporate company dedicated to a safe toothbrush production and designed a “bendable” toothbrush. This toothbrush can bend when the pressure of 1.3[MPa] at a maximum is applied to the brush while maintaining the capability of brushing. The pressure is smaller than the breaking stress of human skin. The new toothbrush allows us to prevent serious injury. This flexible toothbrush is commercialised in Japan since May, 2015.

  • Toothbrush Safety
  • Safe product
  • Penetration Injury
  • Fall Injury
  • Biomechanics

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