*Root Canal Preparation

- Objectives of Root canal preparation:

1- Remove remaining pulp tissue2- Eliminate microorganism3- Remove debris4- Shape the root canal5- So that root canal system can be cleaned and filled

- Requirements of Root canal preparation:

1- Prepared canal should include the original canal2- Apical constriction should be maintained3- Canal should end in an apical narrowing4- Canal should be tapered from crown to apex5- Preparation should be undertaken with copious irrigation6- The final length of the preparation should not be reduce by treatment 

- Root canal preparation techniques:

According to Direction:1- Apical to coronal2- Coronal to apical According to Type:1.Standardized technique2. Step back technique3. Balanced forces technique4- Step down technique5- Double flared technique6- Crown down pressure less technique 

- Standardized techniqueCan be use for straight tiny canalUnsuitable for curve canals Common problems:1- Ledging2- Zipping3- Elbow formation4- Perforation5- Loss of working length - Overcomes procedural errors of Standardized technique:- Suitable for Slight to moderate curve canals- Not suitable for severely curve canals- Can be improve by: "Specific filing technique - Non-cutting tip - Flexible files"

*- Steps of successful Root Canal Preparation:

1- Obtain a good pulp chamber cleaning. 2- Make sufficient deroofing for the pulp chamber area "ensure that files enter orifices in a straight manner" 3- Use GG to widen the orifices. 4- Insert the initial file which is "size 15 for centrals and premolars" and "size 10 for molars" Note: "size 8 may be useful for severely narrow canals ex: MB of the lower first molars"

*5- Start to measure the full working length using the initial file and X-ray or by using the Apex Locator. Note: file size 10, 8 and 6 may not appear in the X-ray so that they may lead to misleading or interpretation for the working length, Note: It's better to have a good X-ray image with the length measured by Apex Locator to avoid false Apex Locator's readings ..

6- Start to widen canals to 3 files larger than the initial file to the full working length measured before, to create the good apical stop ... "The third file will be called the patency file". 7- Start to use the larger next file with a length 1 mm shorter than the previous one .. 8- Use 5 more larger files, every one 0.5 mm shorter the previous one. 9- Use the patency file between  files to avoid blockage of canals ...  10- Start to put the master cone and complete obturation ....