IRCT2015010120523N1 IRCT 2015-04-16 Dental Research Center, Research Institute of Dental Sciences of Shahid Beheshti University of Medic the effect of benzocaine-contained tooth paste in decreasing fixed orthodontic pain Evaluation of the effect of benzocaine-contained tooth paste on relieving orthodontic pain 2015-03-20 anticipated 33 Complete https://irct.ir/trial/18187 interventional Randomization: Randomized, Blinding: Double blinded, Placebo: Used, Assignment: Crossover, Purpose: Supportive. N/A pain percieved after fixed orthodontic appointment. Intervention 1: benzocaine group: 5% benzocaine is added to a commercially available toothpaste, along with 0.075% Aspartam in order to mask benzocaine taste. each patient is given a toothpaste and asked to brush his/her teeth immediately after appointment, after breakfast and lunch and before sleep for 3 days. meanwhile, they are asked to mark their pain in a 0-100 scale, 2hours and 6hours after appointment, the same night before sleep, 10am and 6pm in second and third day and 10am at 7th day. Intervention 2: placebo group: a commercially available toothpaste is filled in identical tube as benzocaine tooth paste and is given to patients. patients are asked to use this toothpaste immediately after appointment, after breakfast and lunch and before sleep for 3 days. they are asked to mark their pain in a 0-100 scale 2 hours and 6 hours after appointment, at the same night before sleep, at 10am and 6pm on second and third day and at 10am on 7th day. Intervention 3: control group: the patients are given a questionnaire with a 0-100 scale to mark their pain 2hours and 6 hours after appointment, at the same night before sleep, at 10am and 6pm on second and third day, at 10am on 7th day.