To evaluate the incidence and severity of postoperative pain after root canal therapy of necrotic teeth in one appointment versus two appointments using Protaper next instrument.

The key to endodontic success was described as the debridement and neutralization of any tissue, bacteria, or inflammatory products within the root canal system.

Endodontic treatment used to take multiple visits to complete, with one of the main reasons for this being that it required a considerable amount of time to complete the treatment.

The single-visit treatment was bought back in the 1950s by Ferranti, who advocated the use of diathermy for pulpal disinfection and hydrogen peroxide for irrigation.

The use of contemporary endodontic techniques and equipment, such as use of rubber dam, magnifying devices, electronic apex locators, engine-driven rotary nickel titanium files, and so forth, not only increases the success rate of endodontic treatment but also, shortens the time needed for the treatment. Endodontic treatment may therefore be completed in a single visit.

It is generally agreed upon that the prepared canals can never be sterile before obturation, no matter how potent the antibacterial irrigants or intracanal medications are. There are currently two measures to reduce bacterial persistence and reinfection in the canals. We can either dress the canals with antibacterial agents in multiple visits or immediately obturate the canals, to reduce the space for bacterial colonization, in a single-visit approach. Calcium hydroxide is the most commonly used intracanal medicament, however its efficacy towards Enterococcus faecalis is questionable.

Inclusion criteria:

• Medically free patients.
• Patient's age above 18 years old.
• Teeth diagnosed clinically with necrosis.
• Positive patient's acceptance for participation in the study.
• Sex includes both male and female.
• Patients who can understand visual analogue scale.
• Patients able to sign informed consent.

Exclusion criteria:

• Pregnancy or lactation.
• Medically compromised patients.
• Patient with multiple teeth that required treatment in the same quadrant to eliminate the possibility of pain referral.