 Hello everyone, I am Dr. Amrita, a conservative dentist and endodontist, so today we will be discussing about endodontic hand files. Endodontic hand files are manually operated endodontic instruments used for cleaning and shaping of root canals in root canal therapy or any other endodontic procedures. Stainless steel and nickel titanium root canal instruments have replaced the before use carbon steel instrument because they are more flexible, less likely to fracture and less susceptible to corrosion. Smaller size instruments meaning files are manufactured from square planks and are more resistant to torque fractures whereas large size instruments are manufactured from triangular blocks as this improves their cutting efficiency. Now the general classification of endodontic instruments group 1 hand operated endodontic instruments which includes broaches, files, reamer, group 2 non-rotary endodontic instruments used with a handpiece which includes engine driven instruments, ultrasonic and sonic instruments. Group 3 rotary endodontic instruments used with a handpiece. Now some of the hand operated files are K type files, K flex files, flex R files, H files, safety headstrong files, Uni files and S files. So coming to K files which are the most commonly used hand files, it is manufactured by the Kerr manufacturing company. It is used with a rasping or pulling motion. Traditional files are usually square in, they are square in cross section and they have tighter flutes compared to reamer's which have looser flutes. Files have more number of flutes than reamer. So basically the difference between files and reamer's, they have, files have tighter flutes when compared to reamer's and also they have more number of flutes than a reamer. Now K flex files, it is a modification of the K file. It is rhomboidal or diamond shaped in cross section which increases the flexibility and cutting. Rhomboidal blanks produce alternative high and low flutes. Flex R files, it is also another modification of K file. The cutting tip angles are reduced here. It makes the files stayed more efficiently centered within the canal. So these are the different cross sections of the K files and the different modifications of K files and basically smaller size files, K flex, K reamer files and K files have spare cross section, larger size files have triangular cross section and the clay flex files which is a modification of K file has a rhomboidal cross section. Now coming to the headstrong files. So these are made from round stainless steel wire. They have higher cutting efficiency than K files that is they have more positive rake angle but it should be employed only in one direction. That is retraction and never talking motion should be used. So they have a pure drop cross section. These you can see on the right side the cross section of headstrong files and also all the modifications which are the Uni file and S files. So safety headstrong, it is a modification of headstrong with a non cutting side and then we have Uni files which is another modification which has a round stainless steel wire with cut out superficial grooves to produce flutes in a double helix design. It is less subjected to fracture but are less effective. And we have high flex files which has a cross section which represents the S shaped files and S file which has a double helix cross section and is a variation of the Uni file. So that's all regarding the files, different types of files. So we can conclude that a hand operated end-around files may be time consuming but it is wise to use hand files as well because of good tactile sensation required during the cleaning and shaping of root canal. It also reduces the excessive widening of root canal that might weaken the tooth. So this is the importance of using hand files. Thank you.