The greatest dropout rate of orthodontic treatments is pain, from the installation of the elastomeric separators, to the exchange of wires and accessories. This process that presents both physiological and psychological responses negatively affects patients' quality of life due to the difficulty of chewing and biting. The sample will be comprised of individuals who will receive elastomeric spacers on the mesial and distal surfaces of the upper first molars, randomized into two groups, the group being irradiated with the low intensity laser, called the experimental group, and the placebo group, simulated laser. In the installation of the tabs, the experimental group will receive a single application in the mesial and distal cervical portion and in the apical third of the molars. The energy delivered at each point will be 2J, per vestibular and lingual, 6 points, totaling 12 J of energy per tooth. To evaluate the perception of pain we will use the Visual Analogue Scale (EVA) after 1h, for all groups. The gingival pockets cytokines will be collected with an absorbent paper cone for 30 seconds on both groups and compared between them by ELISA. It is expected that patients in the irradiated group will have lower pain perception and less cytokines than in the placebo group.

Inclusion Criteria:

• Clinical conditions of normality;
• Healthy periodontium;
• Healthy molars;
• Presence of interproximal contacts between the second molar and premolar;
• Permanent dentition phase;
• Who have not been taking anti-inflammatory drugs or analgesics for 4 days.

Exclusion Criteria:

• Systemic diseases that routinely use medications;
• Patients with periodontal disease;
• Patients who remove the tabs or who do not respond to the questionnaire;
• Papers contaminated with blood or saliva will be excluded for cytokine analysis.

In the Placebo group, participants will receive the simulated application with the laser set off, only using the beep to play the application. Therefore, they not know to which group they belong.