To evaluate the effect of the low power density 940nm diode laser in the total relief of dental crowding during the alignment phase and the perception of pain in patients who initiate orthodontic treatment.

Objectives: To evaluate the effect of the low power density 940nm diode laser in the total relief of dental crowding during the alignment phase and the perception of pain in patients who initiate orthodontic treatment.

Design: Randomized clinical trial. Setting: orthodontic treatment from the Orthodontic postgraduate course at the CIEO University (CIEO), located in the city of Bogotá, Colombia Participants: 50 randomized subjects, 25 per group, seen during the alignment phase with ages between 20 and 40 years, male or female, with all lower permanent teeth or at least 36 to 46, with Little's irregularity index 3mm to 6mm, without prior orthodontic treatment, periodontally stable, non-smokers and who voluntarily agreed to participate in the study by signing the informed consent. Patients with a history of long-term medications that interfere with bone metabolism and / or pain synthesis (bisphosphonates, anti-inflammatory or analgesic drugs and hormonal supplements, with systemic diseases (Diabetes, hyperthyroidism, disease with bone metabolism) were excluded. , pregnant women, infants and patients who, during the alignment phase, require the implementation of metal ligatures, springs to expand spaces and lace back uses in the technique.

Intervention: group 1 irradiated with low power laser (940nm) and. Group 2: it was simulated that they were irradiated. The therapeutic laser was applied for a time of 10 seconds on the buccal surfaces of the teeth and 10 seconds on the lingual surfaces of the teeth, both at the gingival level and at the apical level in scanning mode, on the day of cementation of the appliance and subsequently every fifteen days for 3 months.

Main outcome measures: total relief of dental crowding measured through the little index in digital models and pain perception through the visual analog scale.

Randomization: Four patients were randomized with the randomized blocks technique.

Blinding (masking): The patients participating in the clinical trial, the statistician, the students and the study operators who are going to measure Little's irregularity index will be blinded to the interventions, except the principal investigator.

Inclusion Criteria:

• Ages between 20 and 40 years
• Male or female
• All lower permanent teeth or at least 36 to 46
• Little's irregularity index 3mm to 6mm
• Without prior orthodontic treatment
• Periodontally stable
• Non-smokers
• Voluntarily agreed to participate in the study by signing the informed consent

Exclusion Criteria:

• Patients with a history of long-term medications that interfere with bone metabolism and / or pain synthesis (bisphosphonates, anti-inflammatory or analgesic drugs and hormonal supplements
• Systemic diseases (Diabetes, hyperthyroidism, disease with bone metabolism)
• Pregnant women
• Infants
• Patients who, during the alignment phase, require the implementation of metal ligatures, springs to expand spaces and lace back uses in the technique.

The patients participating in the clinical trial, the statistician, the students and the study operators who are going to measure Little's irregularity index will be blinded to the interventions, except the principal investigator.