This post mainly introduces the main difference between K file and H file.
K files
K files are made of rectangular blanks. Twist them so that the working end of the instrument spirals. The cross section of the K file is square. The K file is the most “universal” hand file, covering the most clinical indications. K files has moderate cutting force. It is suitable for all preparation techniques with filing motion and enlargement of severely curved canals. The Angle between the cutting groove and the long axis of the K file is generally in the range of 25-40 degrees.
H files
The h file has a circular cross section. H file has strong cutting force and high efficiency, due to the design of screw thread. But it is easy to damage the root canal wall, so h files are designed for vertical movement, not rotary movement. The Angle between the cutting groove and the long axis of the H file is generally in the range of 60-65 degrees. H-files are specially designed for shaping canals after they are previously cleaned and enlarged with K-files in root canal treatment. The H file can effectively enlarge the canal during filling motion.
K file and h file can be made of stainless steel and nickel titanium materials, both of which have their own advantages. Stainless steel files are not elastic, while nickel-titanium files are flexible and are more suitable for curved root canals. Stainless steel files have more cutting force, but less breaking resistance. Compared with the NITI files is easy to break, and NITI files is not easy to break, which is safer. However, the cutting force of nickel-titanium files is weaker and less efficient than stainless steel files.
