In the form of insitu gel can be applied as solution or suspension that undergoes gelation after administration.

- In the form of Insitu gel system can be applied as solution or suspension that undergoes gelation after administration. Applied once inside the root canal after chemo-mechanical preparation.

Post-operative pain following chemo-mechanical endodontic treatment will be measured.

A pain chart using visual analogue scale (VAS) will be used to record the patients' pain levels. The VAS (0-10 scale) consists of a line anchored by two extremes "No pain" and "the worst pain". Patients will be asked to choose the mark that represented their level of pain from 0 to 10. Pain level will be assigned as follow:

• 0, "no pain"
• 1-3, "mild pain"
• 4-6, "moderate pain"
• 7-10, "severe pain" Using the VAS chart, the patient will choose and record the most appropriate pain rating according to the pain intensity endured.

The bacterial count method will be used. Once the samples will arrive to the microbiology department, Cairo University, the tubes containing the thioglycolate 14(transport medium) with the paper points will be placed in micro centrifuge and vortexed for 30 sec. One hundred (100) μl aliquots of the vortexed samples will be placed in a new sterile tube containing 1 ml of thioglycolate to obtain 1/10 concentration to assess the microbial load of common aerobes and anaerobes found in each root canal. The effect of the treatment in each group, the initial colonizers (S1), the mechanical preparation (S2) and after the intra-canal medication (S3) will be compared.