Fig. 9From: The state of the art and future trends of root canal files from the perspective of patent analysis: a study designPrevent fracture of root canal files. Reproduced with permission. Source: USPTO, www.uspto.gov: CNIPA, www.cnipa.gov.cn. a–b Counting type root canal files [85,86,87]. c–g Preventing stress concentration in root canal files [88,89,90,91,92]Back to article page