This study will evaluate and compare the microbial efficacy of rotary and manual filing system using Neem extract, NaOCL and saline . with hypotheses that neem can used alternative to sodium hypochlorite and there is no difference between rotary and manual filling in bacterial reduction.

The calculated sample size of the study will be 22 participants for each group at 5% level of significance and 80 % power 30 participants for each group (10 for The sample size will be increased tocompensate for incomplete data and to increase the study each subgroup) topower

Grouping:

30 child will be selected from the Pediatric Clinic, Faculty of Dentistry, Mansoura University .the child should have 2 contralateral primary molars indicated for pulpectomy. The children will be randomly divided into 2 main groups according to type of file used in root canal preparation: Group I with manual file. Group II with rotary file.

Then the children will be randomly sub grouped according to irrigant that will be used:

Group IA and group II A with normal saline. Group IB and group II B with neem . Group IC and group II C with NaOCl . clinical procedures :

1. Psychological management of child
2. X-ray for inclusion criteria
3. The procedural tooth is anesthetized and isolated with rubber dam. The tooth and adjacent rubber dam will be disinfected with tincture of iodine solution
4. . All carious tissue will be removed by sterilized round bur and root canal access will be done
5. On gaining the access, distal cannel of mandibular primary molars and palatal cannel of maxillary primary molars will be chosen for sampling procedure.
6. A sterile broach will be inserted to obtain root cannel content then sterile paper point inserted to root canal and will be left for 1 min 19 The paper point will be removed with sterilized tweezer which will immediately transferred to tube containing transport medium (eppendrof of containing 200 μl nutrient broth medium).
7. In-group 1 will be prepared with manual files the irrigation with saline in IA, with neem in IB and irrigation with NaOCl in IC.
8. In group II will be prepared with rotary files the irrigation with saline in IIA, with neem in IIB, with NaOCl in IIC
9. The sterile paper point will be introduced into root cannel and will be left for 1 min, the paper point will be removed with sterilized tweezer and then transferred to a tube containing transport medium 19.
10. Post irrigation sample and pre-preparation sample will be transferred to microbiological laboratory.
11. Canals will be filed with obturation material(Metapex)then crown will be restored with glass inomar and stainless steel crown

Laboratory procedures :

1. All samples will be incubated on blood agar aerobically and anaerobically at 37 for 48-72 hours and aspectically streak the plates 19,20.
2. Identification of bacteria by culture characteristics ,microscopic examination and biochemical reaction 21.
3. Number of colony forming unit will be counted (CFU/ml)

Inclusion Criteria:

• age group 4 -8 years.
• good health.
• No recent history of antibiotic coverage for at least two weeks
• necrotic teeth.
• restorable tooth structure.

Exclusion Criteria:

• more than 2/3 resorption of root.
• uncooperative patient.
• detection perforation on radiograph.