Achieving effective pain control after endodontic treatment is still a disruptive event to all the clinicians. There is a knowledge gap regarding the effect of protease on postoperative pain following root canal treatment, therefore, the efficacy of Trypsin-Chymotrypsin on post endodontic pain was evaluated clinically in a randomized triple-blind trial.

This study approved by the institutional review of board (IRB) of the ethics committee at the Faculty of Dentistry, Ain Shams University, Cairo, Egypt under approval number FDASU-Rec IM012110.

This study design was a prospective, parallel triple blind phase IV randomized clinical trial.

A pilot study was performed on five patients in each group and its results were used for sample size calculation. Based upon the results of the pilot study; the minimum estimated sample size was a total of 52 patients. Sample size was increased to 60 for compensation of the drop-out. Sample size calculation was performed by using G*Power Version 3.1.9.2.

All included patient signed an informed consent prior to start of the study.

Randomization and blinding:60 patients who had the eligibility criteria were allocated randomly according to the ratio of 1:1 to each group. Randomization was performed by using computer software (www.randome.org).

Allocation concealment mechanism: Random sequence generations, allocation concealment and interventions preparation were occurred before starting by the help of one independent person who concealed the allocation sequence from the investigators in opaque and tightly sealed envelope. Before study implementation, this person also divided the medicaments into 60 tightly sealed opaque envelopes contained a treatment with the recommended dose and labeled by one-digit alphabetical symbol (X, Y, Z, R).

Implementation of the study: After root canal treatment, post-operative medicaments were assigned by telephone verification. This independent person informed the operator which drug should be prescribed in the form of X, Y, Z or R to maintain operator blinding. The investigators used the computerized generated randomization protocol for each eligible patient. So, patients were enrolled into each of the groups and prescribed with different post-operative intervention. All pain assessment forms and data were monitored by a trained clinician. He was not a part of the study team.The statistician was also blinded.

Patient history revealed diffuse lingering pulpal pain. Cold sensibility testing with Endo-Ice (1,1,1,2 Tetrafluoroethane; Hygenic Corp) indicated a moderate to severe response. Vitality was matched with the contra lateral as control. The vitality was established clinically by blood observation in the canal. Teeth had no sensitivity to percussion or palpation. Radiographically had normal periapical condition. Endodontic treatment procedures were done by the same operator in the post-graduate clinic of the Endodontic Department of the Faculty of Dentistry, Ain Shams University, Egypt. Patients were assessed by a trained clinician who was not a part of the study team.

85 patients were assessed for the eligibility criteria. 25 individuals were excluded due to different reasons. 60 participants were included. They were randomized into four groups (N = 15).

Group I: (ibuprofen) Participants were given ibuprofen 600 mg 3 times per day for 3 days after each of the three meals.

Group II: (Trypsin-Chymotrypsin) Participants were given (Trypsin 5 mg Chymotrypsin 5 mg3 times per day for 3 days one hour before each of the three meals.

Group III: (ibuprofen + Trypsin Chymotrypsin) Participants were given ibuprofen 600 mg 3 times per day for 3 days after each of the three meals and (Trypsin 5 mg Chymotrypsin 5 mg) 3 times per day for 3 days one hour before each of the three meals.

Group IV: (placebo) Participants were given postoperatively placebo sugar pills 3 times per day for 3 day.

All participant were asked to record their postoperative pain intensity at 6h ,12h ,24h, 48h ,72h following obturation. They also asked to report the occurrence of any side effects.

Data analysis:

Statistical analysis was undertaken with IBM SPSS Statistics. Age difference was analyzed by using one-way ANOVA test. For Pain records, Kruskal-Wallis test for comparison among the four groups, Friedman's test for changes by time intervals in each group and for pair-wise comparisons when Kruskal-Wallis or Friedman's test was significant, Dunn's test was used. Chi-square test was used for qualitative data. The significance level was set at P ≤ 0.05.

Inclusion criteria:

• Egyptian healthy symptomatic both gender patients
• aged (18- 40) years old
• with no physical disability, facial paresthesia or psychological problems
• had mandibular first molars with symptomatic irreversible pulpitis and with normal appearance radiographically.

Exclusion criteria:

• The vulnerable group
• participants who un abled to read and fill the questionnaire,
• those who took preoperative analgesics 24 h prior to treatment
• those with known sensitivity to the drugs used in this study

from 6 hours following drug intake after obturation to 72 hours (start with 6 hours first interval then at 12 hours intervals)

Only healthy individuals and those with no sensitivity to pharmaceuticals used in our study participated in the trial, so they were not liable for any adverse effects.

Even no one complained about the possible side effects of these pharmaceuticals.