Adequate shaping and cleaning, followed by a good coronal seal, are prerequisites for a favorable outcome. The goal of root canal preparation is to create optimized canal geometry to allow effective irrigation and obturation with preservation of the original canal morphology.

The aim of current study is to evaluate the effectiveness of Fanta and Zunba rotatory instruments in cleaning of infected root canal of primary molars to those instrumented with manual K-files.

Inclusion Criteria:

• Class I or II according to American Society of Anesthesiologists (ASA)
• Necrotic pulp tissues which may be asymptomatic or manifested with dull ache pain
• Pathological tooth mobility
• Percussion sensitivity
• Swelling close to involved tooth accompanied with or without fistula
• The extension of radiolucency at the furcation area did not exceed half of the space between the furcation and the permanent successor
• No internal root resorption
• External root resorption (Physiologic or pathologic) limited to apical third and with at least two-third root intact

Exclusion Criteria:

• Uncooperativeness of child and/or parents or caregiver's behavior.
• Unrestorable tooth.
• Presence of calcific metamorphosis inside root canals.