METHODOLOGY

Mandibular block anesthesia performed using local anesthetics solution 1.8ml 2% lidocaine with 1:80000 epinephrine. The procedure started after lip numbness was achieved. Occlusal reduction will be done followed by  straight-line access cavity  and the procedure was completed under rubber dam isolation. The working length was determined using an electronic apex locator (J morita), and Endomotor (Canalpro cl2i ,Coltene ,India) , Protaper gold  (Dentsply Maillefer, Ballaigues, Switzerland) was  used according to the manufacturer’s instructions for cleaning and shaping .

A size 10 K-file was used to maintain apical patency, 2 mL 2.5% sodium hypochlorite was used between in-and-out pecking motions, and After instrumentation, The needle was advanced to a depth of 2–3 mm short of WL and the canal will be irrigated with 3 mL of  2.5% NaOCl. Final irrigation will be done with 5 mL of 17% EDTA for 1 min followed by a final rinse with 5ml of saline.

Randomization

After that, patients were randomly assigned to one of the three groups based on the post operative therapy  

ROOT CANAL INSTRUMENTATION

The  patients will be randomly divided into 3 groups containing  teeth in  each group namely:

§  GROUP I(n=20):  N acetyl cysteine 

§  GROUP II(n=20) : 970 nm diode laser

§  Group II(n=20): 970 nm diode laser + N acetyl cysteine 

Group I :

After the canals are dried with paper point N acetyl cysteine  paste was applied as intra-canal medicament , and the access cavity was sealed using a temporary restorative material

GROUP II:

The final irrigation was performed , after the canals were dried with paper-points. During the laser treatment, both the operator and patient wore protective eyewear. Laser irradiation was applied using a 970-nm diode laser (Sirolaser blue , Dentsply Maillefer, Ballaigues, Switzerland) coupled with a 200-μm optical fibre. The settings were as follows: output power of 1.5 W in the pulsed mode irradiation for 10 s, followed by a 10-s pause, which comprised one cycle. This cycle was applied four times to each root canal. The  power used was 1.5 W  with a low frequency of 15 Hz. The optical fibre tip (length of 25 mm) was inserted at the working length. The root canals were then slowly (at a speed of 2 mm/s) irradiated from the apical to coronal using a continuous circling movement touching the dentinal walls in one cycle for each power. and the access cavity was sealed using a temporary restorative material.

GROUP III:

The final irrigation was performed as in the control group, and the canals were dried with paper points. During the laser treatment, both the operator and patient wore protective eyewear. Laser irradiation was applied using a 970-nm diode laser (sirolaser blue Dentsply Maillefer, Ballaigues, Switzerland ) coupled with a 200-μm optical fibre .The settings were as follows: power of 1.5 W and in the pulsed mode , irradiation for 10 s, followed by a 10-s pause, which comprised one cycle. This cycle was applied four times to each root canal. The power used was 1.5 W with a low frequency of 15 Hz. The optical fibre tip (length of 25 mm) was inserted at the working length. The root canals were then slowly (at a speed of 2 mm/s) irradiated from the apical to coronal using a continuous circling movement touching the dentinal walls in one cycle for each power.

Following the irradiation procedure, N acetyl cysteine  paste was applied as intra-canal medicament , and the access cavity was sealed using a temporary restorative material, as in the control group

Subsequently, a temporary restorative material (Cavit-G; 3 M ESPE, St Paul, MN) was used to seal the access cavity.

At the time of the first visit, all the patients were given a VAS  to rate their PP. A second appointment was scheduled for 7 d later. All patients who met the final inclusion criteria were given  a pain chart to be completed to record the incidence of pain (yes/no), level of posttreatment pain and duration of pain (days). They were asked to submit the forms after 1 week. Patients have been prescribed an optional medication of ibuprofen (400 mg, 8–12 h). Patients were asked to record the information if they took the medication. A modified visual analogue scale (VAS) was employed for assessment and statistical comparison of pain scores: score 0, absolutely nothing; scores 1–3 (mild), very weak discomfort or mild pain but requiring no intervention and not influencing ordinary activities of daily life; does not require analgesics; scores 4–6 (moderate), moderate pain which is distracting for the patient and occasionally negatively influences the patient from performing his normal daily activities; the pain is relieved with analgesics; scores 7–10 (severe), this score range covered very severe and extremely severe/ unbearable pain that forces the patient to give up his/her daily activities and needs rest; this pain is not relieved by analgesics. (11)

The patients were instructed to use 400 mg ibuprofen (Brufen; Abbott, Latina, Italy) if the pain was unbearable and asked to record analgesic intake. The patients recorded their pain experience on a customized form, which was also used to record any analgesic intake.

The following variables were recorded:

1. Age

2. Sex

3. Tooth number

4. Number of canals

6. Preoperative pain on the VAS

7. Preoperative and postoperative percussion pain levels (on the 7^th day) on the VAS

8. Pain level on the 8 hr ,24 hr, 48hr , 72hr & 7 day

11. Analgesic intake after the procedure