Fig. 7From: The state of the art and future trends of root canal files from the perspective of patent analysis: a study designDiscontinuous root canal files. Reproduced with permission. Source: USPTO, www.uspto.gov: CNIPA, www.cnipa.gov.cn. a A series of adjacent 3D pyramids [66]. b–f Discontinuous cutting edge [67,68,69,70,71]. g–k Root canal files for molar teeth [72,73,74,75,76]Back to article page